CA1304134C - Scanning receiver for nationwide radio paging system - Google Patents

Abstract

SCANNING RECEIVER FOR
NATIONWIDE RADIO PAGING SYSTEM
ABSTRACT OF THE DISCLOSURE
A scanning radio receiver for a wide area paging system which interconnects conventional radio common carriers (RCC) for broadcasting page information. A plurality of RCC's in each geographical area served by the paging system of the invention are connected to a local page processor. The local page processor processes incoming page information find transfers the information to an available RCC for broadcast in the local area. If broadcast of the page information is also desired in a remote geographical area, a copy of the page information is transferred to a central page processor for distribution to the selected remote geographical area for broadcast.
The paging receiver is designed so that it scans the frequency of a plurality of RCCs. Thus, the same receiver may be used to receive pages from more than one RCC.

Description

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SCANNING RECEIVER FOR
NATIONWIDE RADIO PAGING SYSTEM
BACKGROUND OF THE INVENTION
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The present invention relates to the ~ield of remote signaling systems, and more p~rticul~rly, is directed to a nationwide radio paging system which interconnects presently existing local paging services into 8 nationwide network. The system permits subscribers to tr~vel vir-tually ~nywhere in the country ~nd continue to receive pAges origin~ted from their home serYice area.
The concept o~ a wide area paging system is not new. In fflct, several such systems have been proposed and descri~ed in the prior Rrt. One such system is described in U.S. Patent No~ 3,575,558 issued to Leyburn. The Leyburn patent discloses a paging system which is said to p~rmit simultaneous pag~ng in more than one geographical areR.
The system compri~es one or more storage eenters which control ~
plurality o~ transmitters located in dlfferent geogr~phical Areas. When R stornge ~enter receives ~ page r~guest, it consults its intern~l memory to determine in which areas the subscriber d~sires p~ging ser-vice. The storsge center then transfers the paging iaformation via telephone lines to dedicated transmitt2rs serving the are~s selected for p~ging by the subscriber.
Other wide areQ psgîng systems are disclosed in UOS. Pstent No. 3,818,145 to HanwQy ~nd U.S. P~tent No. 3,7149375 to Stover.
The Hanway pAtent describes a paging system which extends the p~ging ~rea by broadcastin~ the page over ~ plurality of transmitters. A
p~ge request received ~t one transmitter site is relayed to other tr~ns-mitter sites. The transmitters are then activ~ted to tr~nsmit the page. The Stover patent is directed to a p~ging systelT which ,1- ~
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~3~ ?4 tr~nsmits paging information over existing AM broadcast stQtions using a non-interferring phase modulation technique. E~xtended area coverage is achieved due to the relatively high power used by the broadcast station.
A more sophisticated wide area paging system is disclosed in U.S. Patent No. 4,178,476 to Frost. The Frost p~tent is directed to ~
wide area paging system which privides local-only pQging as well as wide area p~ging. In the local-only mode, the system operates in the same manner as convention~l paging systems known prior to Frost. In the wide area paging mode, however, psging service may be transferred îrom one location to another by a transfer command entered into the system vi~ a telephone hook-up. Thus, all pages originated anywhere within the system sre transferred to the area where the subscriber is located. Broadcast of pages is temporarily suspended while the sub-scriber is in tr~nsit. Any psges which originate during this period are stored and then tras~3ferred to the area to which the subscriber h~s relocated when paging i3 reinstated on his srriv~l. The area from which the pages originate is also identified to the subscriber when they ~re broadcast. When a subscriber wishes to suspend p~ging service prior to travelling to ~nother location9 he ~irst di~ls ~ predetermined telephone number to access the system. On rec0ipt of ~n answer tone, the subscrlber dials his un3que idenêification number followed by a "suspend" digit. The system then suspends all paging to that su~
scriber and ctores any pages rece~ved during the suspension period~
When the subscriber resches his destination, he makes another local telephone call to access the system in that area. Upon receipt of the answer $one the subscriber di~ls his unique identi~i~ation number and a "reinstate" digit. Paging is then resumed and any p~g~s originated during the time p~ging was suspended are torwQrded to the new paging system and transmitted in the new area. Subsequent p~ges are trAns-îerred to the su~scriber in that area until pRging is again suspended and transferred to snother area.

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Though the above-descrlbed wide area paging systems represent an improvement over the existing prior art at the time, they fail to provide a cost effective system for broadcasting pages over a wide area~ For example, these systems all rely on dedicated e~uipment installations to process and broadcast pages. Thus, these systems cannot be easily and economically extended to cover additional service areas.
SUM~ARY OF THE INVENTION
It is therefore an object of an aspect of the present invention to provide a wide area paging system which is simple in operation and cost effective to implement.
It is an object of an aspect of the present invention to provide a wide area paging system which uses existing radio common carxier paging syste~s to broadcast pages.
It is an object of an aspect of the present invention to provide a wide area paging system which can economically process and broadcast alphanumeric, numeric and tone only messages to a remote signalling receiver.
It is an object of an aspect of the present invention to provide a wide area paging system which provides distribution of pages inexpensively through an orbiting satellite to Earth stations.
It is an object of an aspect of the present invention to provide a wide area paging system which concentrates the paging data into digital packets in order to reduce data transmission requirements.
It is an object of an aspect of the present invention to provide a wide area paging system wherein the subscriber can roam anywhere in the country covered by the system and continue to receive pages originated from his home service area.
It is an object of an aspect of the present invention to provi~e a wide area paging system wherein the calling party is not required to know where the subscriber is physically located within the country in order to effect a page to the subscriber.

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It is an object of an aspect of the present invention to provide a wide area paging system wherein local paging as well as nationwide paging is provided.
It is an object of an aspect of the present invention to provide a wide area paging system wherein one paging receivar is used for local as well as nationwide pages.
It is an object of an aspect of the present invention to provide a wide area paging system wherein the pages can be broadcast over any presently existing radio common carrier paging system within any of the RCC
frequency bands.
It is an object of an aspect of the present invention to provide a wide area paging system wherein the paging receiver automatically scans a plurality of frequency channels of presently existing radio common carrier or wireline paging systems for paging information.
An aspect of the invention is as follows:
A scanning radio paging receiver for a paging system, said receiver comprising:
antenna means ~or receiving a paging signal;
mixer means coupled to said antenna means and t,o said local oscillator means for mixing said paging signal with a local oscillator signal to produce an IF
signal;
local oscillator means coupled to said mixer means for generating said local oscillator signal;
logic means connected to said local oscillator means for controlling said oscillator means to generate said local oscillator signal at a plurality of predetermined frequencies, wherein said paging receiver is caused to scan said predetermined frequencies;

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4a detector means coupled to the output of said mixer means for receiving said IF signal and detecting said paging signal on any one of said predetermined frequencies and providing a detecting signal when said paging signal is received, said logic means receiving said detection signal and controlling said local oscillator means to lock said receiver onto the current frequency and receive said paging signal;
decoder means for decoding said paging signal to retrieve said paging information; and output means coupled to said decoder means for outputting to a user at least some of said paging information.
The foregoing and other objects of the present invention are achieved by connecting presently existing local paging systems into a nationwide network. Local paging systems, or so-called radio common carriers (RCCs), now operate on frequencies in the low band VHF, UHF, and 900MHz band. The paging receivers used with these RCCs are tuned only to the frequency used by their respective RCC. Thus, one RCC's receivers cannot be used with another RCC operating on a different frequency. Moreover, in order to avoid interference, only one RCC can use the same frequency in the same geographical area at the same time. The RCC~ are local-only systems as the subscriber can receive pages only while present in his assigned geographical area served by the RCC from which he has contracted for services.
The Federal Communicakions Commission (FCC) recently recognized that local-only paging systems fail to meet the paging needs of a mobile society and has taken steps to establish a structure for development of a nationwide common carriex paging system. Three frequency channels were set aside in the 900 MHz band for nationwide '`,i ~i~;

:~3~ 3~1 paging use. Local-only psging, however, will not be permitted on ~hese frequencies under current FCC regulations. Eflch of the frequencies will be controlled by one licensed common c~rrier, the so-called 931 MHz "Network organi~ers,'~ who will det~ the structure of the system and decide such technical details as the modes of operation, signaline format snd interconnection schemes~ The serv-ices of the 931 MHz organizers will be distributed to subscribers through a 1OCRI com mon carrier in each community, the so-called 931 MHz "Network operator." The 931 MHz operators will provide locnl page initiation ~nd/or local distribution of nationwide pages on the frequency controlled by their respective organizer. In sum m~ry, the 931 MHz organizers will be the licensees o~ the frequencies, control their operation asld furnish nationwide interconnection services to the local 931 MHz oper~tors ~round the countl y. Though the designs vary, each system ultimately uses one of the three 931 MHz frequencies as the nationwide connecting linlc to deliver the paging information.
~ ne of the drawbacks to the 931 MHz scheme is thRt it does not provide for loc~l-only p~ging. Thus, a subscriber would hflve to c~rry two paging receivers, one for ndtionwi~e p~ging tuned to one of the three n~tionwide p~ging frequencies and one for loc~l p~ging tuned to one of the loc~l p~ging frequencies. Secondly9 the 931 MHz scheme i9 A tot~lly new concept and equipment for its implementation presently exlsts in limited qu~ntity only. Thus, e~ch component of the syst~m will have to be developed, tested and then produced in suf~i-clent quantity to implement the 931 MHz system.
The nationwide p~ging system developed by applicants does not operate on the n~tionwide paging frequencies and thus avoids the above-mentioned drawbacks. The system of the invention bssically permits connection of all of the presently existing local p~ging systems, i.e., radio common carriers or RCCs or wireline, by way of a satellite. P~ges may then be broadcast in any of the major metropolitan ~re~s of the United Stat0s using sn @xi5ting local paging .. ~,.................................. .

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P~CC. The system of the in7ention also permits customary local paging ~s well, using the same paging receiver.
In accordance with the present invention, the subscriber is assi~ned a paging telephone number in his home service ~rea by the local RCC with whom he has contracted for service. When a caller wants to pQge this p~rticul~r subscriber, the calling party dials the assigned telephone number using a sltandard DTMF telephone and is connected to an RCC site processor located in the same service area as the loc~l RCC. Orice the site processor has been accessed, the calling psrty relays a rnessaKe or other information by use of the DTMF telephone or, in the case o~ alphanumeric dat~, by use of a stand~rd ASCII keyboard with n CRT, personal computer, or similar device in conjunction w~th a telephone modem. Up to this point, the p~ging system of the invention processes both local and nationwide pAgeS in the same manner. Means ~re provided, however, such that when a subscriber travels out of his local area, the system may be controlled to forward a copy of the subscriber's pages to ~mother &rea.
This is the nationwide paging aspect of the invention And these copies are referred to as nationwide psges. The system continues to broadcast the origlnal p~ges locally even though the subscriber may alre~dy have left the area. Continued loc~l broadcasting permits the subscriber to receive his pages up to the very moment he leaves the areQ. ~uch ~ feature is important ~ince lthe subscriber is ~ssured of receiving "that very l~st p~ge". Thus the paging system of the present inYengion elimin~tes the problem of premature termination of local paging. Transfer of a copy of the subscriber's pages to another area is controlled in advance by the subscriber. Using a standard DTMF telephone, the subscriber merely inputs a special code th~t lets the RCC site processor know where a copy of the p~ges are to be routed. Incoming p~ges re then stored for ~ predetermined time to permit the subscriber to arrive at this destination and then are passed ~long to ~ local RCC which serves the new area for bro~dcast to the subscriber.

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The RCC site processor stores a copy of each page that it processes for ~ predetermined time. Thus, during those periods when the subscriber is not ~vailsble to receive p~ges, he does not have to worry about missing any pages. When the subscriber b~comes available to receive pages, he merely informs the system th~t he wishes a rebroadc~st of his p~ges. The system then passes along copies OI any psges which were previously stored to ~ local RCC which serves the area where the subscriber is presently located for broadcast to the subscriber.
Where a nationwide page is to be sent, ~ copy of the original p&ge is valid~ted by the RCC site processor then routed via the most cost effective service (e.g., GTE TELENET telephone lines or satellite return link) to a tr~ffic route processor located in n geographic~lly convenient place. The traf~ic route processor receives packets of digital data (pHges~ from the variou~ RCC site processors located around the country flnd tempor~rily stores this information in memory.
The traffic route processor outputs the data to ~n uplink control processor which groups the page ~nd/or data trsnsmi~sion requests into appropri~te groups on ~ location and/or regional basis. Billing and other st~tistical data may also be compiled at this point. The digit~l data stream is then fed to a satellite uplink facility for transmission to ~ satellite. The dsta ~tre~m i~ then bro~dcsst n~tionwide ViQ the sfltellite. A nationwide network of telephone lines m~y also be used ns an alternative to Q satellite for distribution of the digitfll data. In e~ch oî the loc~l cities participating in the ~ystem, the satellite downlink signal is received by a satellite receiver loc~ted at a receiver downlink facility at the s~me locstion as the RCC site processor for th~t city. The s~tellite receiver may be ~ direct broadcast (DBS) Ku-band receiver specially modified to receive digit~l data. The raceived d~ta stre~m is input to ~ p~cket extr~ctor which searches for addl ess information unique to the local city. When local ~ddresses are found, the packet extractor removes the data from the data stream and sorts 3~

it according to the local paging systems (RCCs~ which will actu~lly broadcAst the paging information and then by subscriber.
A p~ging formHtter then transforms the digital datQ received from the pecket extractor into the proper format necessary to broadcast the paging information by the particular RCC or wireline.
The paging formatter provides specisl ~oding on the trQnsmitted signal which allows a subscriber's paging receiver to function on ~ny of the frequency channels now assigned to locsl RCCs or telephone comp~nies.
The p~ging receiver may be a conventional paging receiver adapted with a scanning receiver module in accordance with the present inven-tion. Thus, 8 subscriber hss the ability to receive several nationwide pages while in a given geographical location but not necessarily from the same local RCC over the s~me frequency. This redundancy is designed into the ~ystem as a safeguflrd should a particular frequency not be av~ ble in ~ given city. Thus, the subscriber is ~ssured that an alternate paging system frequency can be used. This system also permits use of the same paging receiver for eveiy area of the country.
Applicants have also developed the electronic clrcuitry needed to convsrt a convention~l fixed frequency paging receiv0r to a scanning receiver which scans across a plurality of p~ging frequency chQnnels In ~ny one of the p~ging frequewy b~nds looking for paging inîorm~tion intended for ~ p~rticular subscriber. A scanning type receiver Is required because n~tionwide page inform~tion msy be broadcast locally over finy frequency available to bro~dcast the page. The s~me concept is applicable in other paging frequency b~nds. Therefore, a subscriber may recei~e a number of pages ftom different local RCCs, thus requiring a paging receiver which can tune all of the RCC frequencies in ~ given p~ging frequency band.

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g Figure 1 is an overall block di~gra m of the p~ging system of the pres E3nt invention.
Figure 2 is a block di~ m of the computer system which com~
prises some of the elements shown in Figure 1.
Figure 3 is an illustrdtion o~ the p~ging record format which is cre~ted for e~ch psge processed by the paging system o~ the invention.
Figures 4 ~nd 5 are more detailed illustr~tions of the p~ging record format for each page processed by the paging system of the invention.
Figure 6 is ~ more detailed illustr~tion of the RCC site processor shown in Figure 1.
Figure 7 is ~ more detailed illustration of the up-link processor, traffic route processor, ~utomatic pQge gener~tor, and centr~l site processor shown in Figure 1.
Figures 8-14 illustrate various signals and circuit diagrsms flssoci~ted with the sc~nning receiver of the present invention.
DESCRIPTION OF l`lIE PR~FER_~
A block diagram illustrating the wide area psging system of the present invention is set forth ~n Figure l. In ~ccordance wlth the invention, each subscriber is ~ssigned a paging telephone number in his home service are~ by the local RCC with whom he has contracted for service. As shown in Figure 1, the local RCC is indic~ted by reference No. 1. When ~ c~ller wishes to page a p~rticular subscriber, the calllng p~rty dials the subscriber's assigned telephone number using standard DTM~ telephone 2 or a suitable device connected through 8 telephone modem ~nd is connected to RCC site processoP 3. E~ch service area served by the system of the invention is provided with its own site processor. The site processor is connectedl to alr of the local RCCs in the service ~re~ ~nd, as described below, may form~t a page req33est for bro~dc~st by any local RCC in its own loc~l sers~ice ~rea.

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Once site processor 3 is accessed, the cAllin~ p~rty enters the subscriber's paging reeeiver identificfltion number using DTMF
telephone 2. The c~lling party may also enter an ~lphanumeric message for the subscriber using a standard ASCII keyboard and CRT, personal computer, or similar device in conjunction with a telephone modem (not shown~. For those c~lling parties not h~ving access to facilities for entering RlphAnumeric mess~ges, R~C 1 may be equipped with one or more operator consoles through which the cAlling party may request that an ~Iphanumeric message be entered for the su~
scriber. Another alternative is to provide & console, modem ~nd perh~ps a printer to the subscriber for install~tion in his office.
Of~ice personnel could then originate the p~ge and any ~lphanumeric mesxage for the subscriber by typlng in the message ~nd pressing fl "send" key. The eonsole would be programmed to sutomstic~lly dial site processor 3 to initiste the page ~nd to send the alph~numeric message. ~ince many subscribers ere likely to already hsve sophisti-cated computer systems, word proeessors or person~l computers, such devices could also be used to initlate pages in rT uch the sarne way as a dedicated paging installation. The required inter~ce protocol would be provided to the subscriber so that his computer system could communic~te with sJte processor 3.
When site processor 3 receives a page request, it must determine where the identified pager is loc~ted. If the pager is currently in the local ser~rice area, site processor 3 formats the paging inform~tion for bro~dcast in the locsl service area by local R C C 1.
The page is then re~eived by paging receiver 4 carried by the sub-scriber.
When the subscriber travels out of his local service area, the gystem may be controlled to forwsrd a ~e2 of the subscriber'~ pages to ~nother area. This is the nationwide p~ging Aspect of the invention ~nd these copies are referred to as nationwide pages. The system continues to bro~dcast the original pages over local RCC~ 1 to which - ~3~ 13~

the subscriber is assigned even though the subscriber may Alre~dy h~ve left the ~rsa. Continued locsl broadcasting permits the subscriber to receive his p~ges up to the very rnoment p~ging receiving 4 is out of range or RCC 1. Thus the paging system of the present invention eliminates the problem of premature termination QI loc~l paging.
Transfer of ~ copy of the subscriber's pages to flnother are~ is controlled in advance by the subscriber. Using a standard DTMF tele-phone, such as telephone 2, the subscriber merely enters ~ transfer code that lets RCC site processor 3 know where a copy of the pages are to be routed. As will be described below, A COpy of the page re-quest is then tran3ferred to tr~ffic route processor 6 for distribution to another subscriber service area ~or bro~dcast in ~ccordance with the subscriber's request.
A copy of each psge request received by site processor 3 is stored for a predetermined period. These page copies may be retrieved by the subscriber at ~ny time during this period by merely accessing site processor 3 using DTMF telephone 2 ~nd entering a rebroadc~st code. Site processor 3 then csuses the rebroadcast of any psges whi~h were previously stored.
When site processor 3 determines that a page is to be routed to another service area for broQdcast, a copy of the original page is v~
dated by RCC site processor 3, i.e., checked for errors and corrected ig necessary, then i'orrnatted into packets of digit~l inform~tion. The packets of information are routed via the most cost ef~eetive communication link (e.g., GTE TELENET or a satellite r eturn link) to traffic route processor 6. Traffic route processor 69 along with uplink processor 7, satellite uplink 8, central site ~ocessor 9 ~nd autom~ti page gener~tor 10, is located in a geographically eonvenient place for All Or the loc~l site processors 3 in the system. Tr~ffic` route processor 6 receives the p~ckets o~ digital dat~ p~ge requests and p~ge messages ~rom the various site processors 3 in the system9 checks and correets the data if necessary, then tempor~rily stores it for tr~nsfer ~3~ 4 to uplink control processor 7 at the Rppropriate time. Uplink control processor 7 groups the data into data packets on a location and/or regional bssis. Billing and other statistical data may also be compiled at this time. The datfl packets are then transferred to satellite uplink 8 for transmission to satellite 12 for brofldcast n~tionwide. The satellite downlink signal is received in each of the subscriber service areas by satellite receiver 5 located at ~ receiver downlink fRcility at the same locfltion as RCC site processor 3 for th~t service area.
Satellite receiver 5 may be a direct broadc~st ~DBS) Ku-band receiver specially modified to receive digitsl data. The received data packets are input to site processor 3 which searches for address information unique to the local service area for the particular sîte processor.
When d~ta p&ckets with a local address are found, site processor 3 removes those data packets from the dsta stream and sorts them Qccording to the local RCCs which will actually broadcast the paging information ~nd then by subscriber. Site processor 3 then converts the received information into locsl transmission p~ge format for forw~rding to the appropriate RCC 1 for brosdcQst.
As shown in FiguFe 1, the nstionwide paging system of the present invention al30 includes automatic p~ge generator 10. Page generator 10 m~intains a list Or events that could cause pages to be generated for ~ particulsr subscriber. These automatic pages ~all into two ~ategories: tlme }nitiMted p~ges and event initi~ted pages. Time initiated pages are p~ges that must be broadcast ~t ~ specific time.
Pages Or thls type include wake-up calls, birthday notices, reminders to take medication, etc. When the event time occurs, page gener~tor 10 sends a page request to tra~fic route processor 6 for distribution via satellite 12 to the appropriate local ser~ice area ~or broadcast. Event initiated pages are pages that must be broa~cast when an` event occurs. For exsmple, page generator lO could be progr~mmed to monitor the stock market "ticker-tape" telephone lines. When the price of a specified stocl~ v~lue changes by a certain ~mount, R p~ge ~3~3~

request could be generated announcing the change to the sl~bscriber requesting the informationO
The p~ging system of the invention also includes central site processor 9 which is very similar in operation to RCC site processor 3. However, central site processor 9 is connected to WAl~ lines rather th~n local telephone lines. The primary ~unction of central site processor 9 is to allow remote programming changes of p~ger location.
In those csses where a subscriber is already in a remote service area and wishes to route p~ges to ~nother remote service area, the change can be effected by accessing central site processor 9 using any DTMF
telephone such as telephone 11 shown in Figure 1. Centr~l site processor 9 also includes voice generation equipment to allow auditory verific~tion of p~ger location changes. The voice generation equipment also has the cap~city of prompting the calling pQrty for the informa-tion reguired to efect a pQger location chsnge.
At least one of the local site processors 3 of the invention includes monitoring fQcilities. This particular site processor, hereafter referred to QS the "monitoring site processor," has the capability of monitoring all other site processors within the system. Each site processor may be accessed by the monitoring site processor to obtain detailed status information. Each site processor also periodic~lly sends a "p~ge" through the system contAining current status information destlned for the monitoring site processor. In the event that an out-o~-range condition occurs anywhere in th~ system, the site processor which detects the condition immediately notifies the moni toring site processor of the condition by ncces~ing a local telephone line and dialing the monitoring site processor with a service notice.
The monitoring site processor stores the service notice and the status information from each site processor for "trend ~nal ysis" in order to pinpoint potential service problems. The monitoPin~ site processoP can ~Iso initiate a pArtial or complete warm or cold start reset of any site processor in the system.

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RCC site processor 3, automatic page generator 10, central site processor 9, traffic route processor 6, and uplink control processor 7 ~11 comprise a computer system which includes a number of interconnected elements as shown in Fi~ure 2. Each computcr system comprises master centrQl processing unit (CPU) 20û, floppy disk con-troller 201 and associ~ted nOp~y disk drive 202, hard disk controller 203 Hnd associ~ted h~rd disk drive 204 and at leflst one function CPU
205. Floppy disk drive 202 and hard disk drive 204 provide mass stor~
age and retriev~l of utility programs and data. Master CPU 200 pro-vides internal d~ta transfer between ~ll function CPUs (205) and con-trols floppy disk controller 201 ~nd hard disk controll~r 203. Disk controllers 201 ~nd 203 provide the control signals and I/O data path interfaces for floppy disk drive ao2 and hard disk drive 204, respec-tively. Function CPUs (205) ~ctudlly perform the work that the outside world calls upon the computer system to do such as the vari-ous functions per~rmed by the site processors in processing a page re-quest. Master CPU 20Q merely superv}ses the operation of the function CPUs (205) snd, in doing so, takes care of much of the rou-tine housekeeping or so-called overhe~d for the computer system.
Thus, function CPUs (205) CQn operate more efficiently ~n perforrning their assigned t~sks.
As shown in Figure 2, master CP~ 200 also includes RAM
memory 206 ~nd ROM memory 2û7 where instructions and temporsry d~ta stordge areas of a computer progr~m reside and peripheral l/O
ports 208 which allow the master CPU to communic~te with the outside world. Function CPUs (205) also has its own RAM 2d9 and ROM 21û where instrustions and temporary data stor~ge areas of a computer program reside and p0ripheral l/O ports 211 wh~ch allow the function CPUs to communicate with the outside world ~s well through such devices as modems 214 and 215, eonsoles 216 ~nd 217, and printer 212. Consoles 216 and 217 are interactive terminals which allow the computer system to communciate with a control operator.

~L3~ 4 The computer system is electrically powered by uninterruptible power supply 21 B shown in phantom in Figure 2. Power supply 218 maintains operating voltage to the computer system in the event of fl local power out~ge. It also prevents damaging power line transients from reaching the computer system. Power supply 218 includes sufgicient battery backup to operate the computer system for up to 15 minutes.
This length may be increased if necessary by proYiding additional bat-tery packs.
The wide area paging system of the present invention requires generation ~nd internfll storAge of nt least one p~ging record for each psge processed by the system ~qnd a p~ging record control block.
Psging rscords flnd p~ging record control blocks ~re the primary data files used by the v~rious function CPUs. A p~ging record cont~ins inform~tion pertinent to the pflge it represents in a fc>rmQt that can be used by each element of the system and which c~n be deciphered into a 'Page Record Line' for output on ~ printing d~vice. The p~ging record format. of the present invention is shown in Figure 3. As shown, the format provides ~ number of data blocks for each page including packet indentification, package routing control, sortable date and time tracers, pager account identificatiorl, dsta type identific~tion, send verification, data block integrity verificntion and vari~ble length me3sages. All of this in~ormation is stored in each page record.
The first 32 bytes of e~ch p~ge record contain the control information which controls processing OI the page through the system.
The page record format is shown in Figure 4. The v~rious bytes are described belo~N with the byte number or range of bytes in p~r-entheses.
CONTROL/DATA RECORD ~LAG ~ This byte is set to the ASCII
~ ~.
char~cter ' ' ~5EH) to indicate the stnrt of a 128 byte record if the first 32 bytes cont~in control in~ormation.. Any other character defines the record as a continuAtion of a preYious data record. If there are less than 96 data characters in the message, there will be no ~3~3~

continuing dat~ records. If there ~re more than 96 characters in the record~ there will be continuing d~ta records contAining up to 128 d~ta characters per record. The ' ' character is the ~nly character that may not be used in ~ny dat~ message.
ORIGINATING SYSTEM PACKET ID CODE - (2-5) These four bytes contain a hexsdecimal (OOOO-OFFF) pflcket ID code. Each packet oî
dflta sent to the local control groups or the m~ster control group is ID coded sequenti~lly. If ~ control ~roup receives ~ pscket that has a higher ID code than expected, it will request a repeflt of the missing packet(s). If sn ~dditional data record is required ~'or the message data, the second data record is ~ssigned the next p~cket ID code.
When the v~lue exceeds OFFFH, the ID code rolls-over to 0000H.
This allows tracking up to 409~ records.
REPEAT TO DESTINATION PACKET ID CODE - (6-9) These four bytes .
contain ~ hexadecimal (OOOO-OFFF~ packet ID code. E~ch packet of data sent by a control group to another control group is ID coded sequentially. The destin~tion control group has a separste counter. If the destination control group receives a packet that hfls a higher ID
code th~n expected, it wIIl request a repest of the missing packet(s).
If an sdditional data record is required for the message data, the second data record is assigned the next p~cket 11:~ code. When the vslue exceeds OFFFH, the ID code rolls over to OOOOH. This allows tr~cking up to 4096 records.
OWNER SYSTEM CODE - (10-12) These three bytes contain the ... ~
hexadecimal Yalue of the source system (RCC cite loc~tion~ where the p~ge ori~inated. Three bytes allow up to ~096 source locations (OOOH-FFFH~.
DESTINATION SYSTEM CODE - ~13-15~ These three bytes contain the __ _ _ _~_ hexadecimal v~lue of the destination system (RCC cite loc~tion) where the page is to be transmitted. Three bytes allow up to 4096 destination stations (OOOH-S:)PFH).

~L3~3~

To preserve space in the dAta record~s, day, month~ end year ~re encoded in 8 four byte hexadeciminal form, while the hour and minute inf~rm~tion is encoded into letters. The ASCIT letter ' ~ is the st~rting point for all letter codes. The letter is equ~l to '0' in the case of hours ~nd minutes. The date ~ode ~t~rts with dsy 1 ~OOOIH) equa~ to 01J~N48. This rormQt allows very specific definition of ~ date ~nd time in only six bytes.
All time references internally are based on ~;reenwich Mean Time, the internationel standard. Extern~lly3 all time references are b~sed on 10~!8l time~ ~s defined by the system location. This elim-inates ambiguities associ~ted with the different time zones.
DATE CODE - (16-19) - The d~te code is ~ four byte entry represent-ing ~n integer in hexadecimal. DAY O is 31DEC~7. The Date Code is the day the page origin~ted.
HOUR COVE LETTER - (2D) - The hour code letter is the hour the page originRted (' ' to 'W~').
NUTE CODE LETTER - (21~ - The minute ~ode letter is the minute the pRge originated (' ' to ' ').
PAGER ACCOUNT 111/11~ 22-27) - The p~ger ~ccount number defines ths 'look-up' account record which contains the Pager C~p Code (described below) and other fnformation (see Account Record Inform~-tion). The range of this number is 000000 to ~99999. Hex characters A-F m~y Q]S0 be placed in the Cnp Code, ~llowing 1 6,77792û0 possible Cap Codes to be handled by the syst~m. E~eh RCC Site System has a look-up file ~ontaining the Cnp Code of every pager in the system.
When a packet d~ta is received ~nd ~rmatted ~y the site processort the site processor looks up the account number, obtains the Cap Code and transmits the pRge.
PAGER CAP CODE - (28-33) The P~ger C~p Code is the unique . .
identifier which causes the local site processor to generate a specific bit p~ttern for tr~nsmission on the RCC trQnsmitter to set off a pager. The norm~l Cap Code cont~ins the numbers 0-9, but the ~l3~

system will allow full hexadecimin~ 9, A-F entry. These codes are not defined in POCSAG, ~nd may therefore be used by any other process in the system.
PAGER STATUS - (34) - The pager status is not ~ly defined. The presence Or a 'O' as the pager st~tus code will9 howe-rer, inhlbit any pagin~ ~ctivities regarding this pager Account, ~nd an qnvAlid Pager Number' error will be displ~yed.
SOURCE SYSTEM - (35-37) - The source system eode identifies the loc~l RCC where the current Page Record originated. (See Owner System) THP~EAD LIST - (38-40) - The thre~d list is used in local systems to keep track of psges to the sflme pager account numbers in the local current page buffer~ It is always set to '000' by the site proeessor for tr~nsmission to network systems.
PAGE TYPE CODE - (41) ~ This byte defines the type of d~tA stored in the dat~ blocks. The code is ~ letter, st~rting with the ehar~cter ' ~ '. The ~urrently assigning paging code3 ~re:
@ None - No data is stored in the data records A Numeric - Numeric only d~ta is stored B Alphanumeric - Alpha and numeric data is stored C Update - Changes to P~ger Control Block File D Time Set - Periodic clock set for all syst~ms HOUP~ PAGE SENT - (42) - This byte eontains, after transmission of the page at the termin~ting site, the Hour Code letter of the hour the p~ge WQS sent.
N UTE PAGE_ SENT ~ (42) - This byte cont~ins9 after transrnission of the page at the terminating site, the Minute Code letter of the minute the page w~s sent.
NOT USED - (44-47) - This l~ange of bytes is presently not defined.
NUMBER OF BLOCKS - (433 - This byte contains the nunber of d~tA
bloeks in the record. The st~rting point is lOI (30h).

~3~iL3~

DATA E~LOCKS - The subsequent data blocks ~re 16 bytes each. For __ numeric d~t~ blocks, norm~lly only one bloek is required. For ~Iphanulmeric d~t~ blocks, any number of blocks may be appended, up to the range of the d~ta block charactel "~vhich is ' ' ~7Eh~, or 78 dQt~ blocks. Thus, an ~lph~numeric messRge ~or the subscriber maycontain up to 1248 ~78~16) charaeters. ~ive dat~ Iblocks, or 80 char~cters9 reside in the first record, and will ~u~fice for most ~lphflnumeric mess~ges.
E~ch record is sent from one station to another ststion over whatever medium is av~ilable, I)ue to the 'printing' nature of the datH reeord, simple monitors may be ~ttQ~hed to the transmission link at ~ny point to determine I~ datQ integrity i~ being m~int~inedO
lf ~ data block cont~ins fewer than the maximum number of char~cters expected (lB), then the data block is filled with null char-~cters (OOH). A complete dsta block of 16 bytes is always trAnS-mitted if there ~re any ch~r~cters within the block.
The P~ger Control Block is the prim~ry file which controls all pager acti~ities. It is locflted Jn every system, and is the same in all systems, each change to the pager control ~lock file (except record pointer chan~es) forces ~ n~tional upd~te o~ ~ll pAger control block files. Each record in the Pager Control Block is eight bytes in length. The ~ormat is ~hown in Figure 5.
Pl P6 - Pager Cap C:~ode in modified BCD form~t (O~F) Al-A3 - Owner ~y~tem. The system to receivs ~ccounting records when ~ page is plac~d to the pager.
ST - Status ~nd Control ch~r~cters.
L1-L3 - Current Loeation System of the Pager.
R3 - L~st P~ge Record Processed loc~lly for their P~ger The Data Re~ord is ~he method used by the sy~tem to tr~nsfer all ~ta within the system. The ~ype identifier is ufflized to identify the type of ~ta in the record. This ~llows files t9 be ulp-dated to all systerns ~rom the Upliilk ~t the s~me time.

~;f 13~

- ~o -Figure 6 is a rurther illustration of RCC site processor 3 shown in Figure 1. As described above and shown in Figure 2, site processor 3 is a computer system which performs a numb~r of ~unctions with plurality of ~unction CPUs (205). E~ch ~unction is Iflbelled ~n Figure 6 to identify ~ particul~r function CPU within site processor 3. As sho~n is~ Figure 61 and in conjunction with Figure ~L, the DownLink SerYice Unit (DSU) function CPU is eorlne~ted to the output o~
satellite receiver 5. The DownLink Service Unit is actually two to four units. The two un}ts work in ~onjunction with each other, ~nd cross monitor recei~rer 5. Only one of the units is on-line at any given time.
One DownLink Service Vnit constantly monitors the data nOw from the satellite. When ~ data record ~ddress is "~ll" or when the correct system address is decoded in either the source or destin~tion system field, then the receiving DSU signals the next DSU to begin decoding, stores the current record, and ceases moniltoring the d~ta flow. The received record is checked for ~ccuracy, corrected if necessary, then "stored" for processing by the TSVJ and an "event"
code is 3ent to the TSU. Where dat~ records ~re involved, a Dat~
File Follows reccrd is sent by up-link controller 16 followed by up to 32,7~8 bytes of dst~. The DSU decodes and stores the block of d~ta in the approprlate dat~ file ~t the loc~tion specified in the DATA
FILE FOLLOWS Page Record. No actu~l pages ~ill be gent during the period th~t ~ d~t~ file tr~nsrer is occurring to any RCC ~ite. All RCC site processors rnay receive the same dat~ ~ile at the sRme time by using the 'All Call' destin~tion ~ddress. A~ition~l ~unctions pe~
formed by site processor 3 are set ~orth below.
TSU ~ Termin~l Service Unit The Terminal Ser~ice Unit provides the interi~ace to the ~res RCC transmitterts) it controls. When an '~vent' ~ignal is received from the DSV, the TSU gets the peging record from the PA~REC îile, checks to ~ee if any records are mis~ing ~enerating a RSUERR ~IFD

~3~4:J1 3~

record for processing by the ~SU if so) obt~ins and proeesses the p~ge record. The TSU loads until one of several conditions occurs. I~ the paging block becomes full, or 'MAXT~ql' el~p~e~ prior to the filling of p~ging block, then the pflging output sequence will begin. On com-pletion of the paging output sequen~e, the TSU writes a 'pflge com-plete' record to the ASU FIFO for ~ccounting ~unctions.
RSU - Remote Service Unit The Remote Service Unit provides modem connection to other 'system' sites, using the PAGREC form~t~ System routing is aecom-plished by the programming of the 'dial' number. When ~ p~ge or data record is gueued for output of the ?system' the loc21 modem is activsted. The appropriate 'system' number is dialed, ~nd the dsta is transferred to the remote device. ~ONIXOFF handshake is provided.
Comple~e Dat~ Files m~y be ~ansferred between ma~h:ines by the RStJ, using a data file transfer fvrm~t.
LSU - Line Service Unit The Line Service tJnit controls ~ bank of inter~ee circuits for telephone input of numeric only pages. The interl~ce circuits ~re polled, with periodic output o3~ p~ging records to the PAGREC ile.
CSU - t: ustomer Service Unit The Customer Service IJnit provides remote p~ge entry ~nd look up at 300 or 120n b~ud using a modem. The CSU pro~rides two ports per slsve. The accessing device or user identiries itself at the onset of the session, then m~y enter ~ ~ge or interrog~te the current page list for previous pages to ~ ren account. ~ystem and user ID's are required for oper~tion. The following fun~tions are provided:
hqANUAL PAGE ENTRY - If the c~lling device pro~rides ~ 'm~nual flagged' ~ccess II), then the ~alling device will be prompted b~sed upon the de-rice type~ Sereen form~ttin~ is pro~rided this ~yO E~ch 'm~n-ual' device type h~s - 8 unique identifier to .,,~, ~3~

.

allow the module to send the corre~t control codes to perform screen form~tting for th~t type device. If the module has no instructlon set for th~t device, then the default 'ques-tiOn/AnSwer~ mode ~vIII be used. This is most applicable lto 'dumb' terminstion operations.
AUTOMATIC PAGE ENTRY - If the calling device provides an 'automAtic flsgged' ~c~ess ID, then the subsequent dat~ will be ~ssumed to be pre-fGrmatted snd no prompts will be issued. The calling device m~y then enter up to sixteen p~ges In the P A G R E C for m ~ t .
The date and time data is not provided by the ~ccessing unit. On completion of the dats input, lthe CSU will discollnect.
PAGE LOOK-UP - Look up of pages previously processed {s provided. If the call-ing device is m~nual, then the eQller will be prompted ~or the look-up information. If the ~ccessing device is autom~tic, then the leAd~in code w311 request tbe look-up of previous pnges. The P~ger Control Block ~nd ~11 stored p~ges wlll be output to the accessing de~ice. If 'm~nufll', then th~ CSU will ~use îollowing each screen of d~ta and QW~it a prompt ~rom the c~lling party to ~isplay the next screenO
OS~ r~tor ServJ~e IJnit The Operstor Service Unit runs in sl~ve with ~oth seriàl ports connected to 9consoles'. Each port may be connected~to a moden for off-site operntion Rt 1200 baud, or to ~ lo~l console for on-site oper~tion at 9600 bsud. The basic functiQns of the OSIJ are:

~3~43L34 (START-UP) - I,oc~l consoles will be assumed if no operator dial number is provided, anZ
deî~ult b~ud rate will be 9600. If an operstor dial number is provided, then the module will sttempt connection to the oper~tor port until ~onnnection is made~
Operstor port b~ud rate will defsul~ to 1200 b~ud, but 300 b~ud mdy be selected.
MENU - Once a connection is est~blished, a menu will be displayed, Qnd the operator will be prompted to 9elect one of the following functions:
PAGE ENTRY - Manu~l P~ge Entry -L O O K-U P A PA G E R - Looks up and displ~ys the basic control inform~tion for any p~ger on the system. This includes the C~p-Cod~, the Owner system9 the Curreslt ll.o~tion xystem, and pre~ious pages to the pager (loc~l or n~tionwide).
CHANGE PAGEE~ LOCATION - Looks up fl Psger Control Block, ~nd Qllows the destin~tion system ~ddress to be changed. This requires only thst the operstor knows the are~ code and one exchange of the destination city. The destinatioll system is the determined by the system and the sity n2me is displayed prior to terminatioll o~ the sequence.
Figure 7 is ~ further illustrntion csf uplink contPol processor 79 tr~fic route processor 69 ~utom~tic page 6enerator 10 ~nd central site processor 9 ~hown in Figure 1. In addition ~o the ~ove~described flmctions, the following funceions s~re pro~rided by ~unction (: PU's in these computer systems.

~L3~3~

VLSU - Voice Line Ser~ice Unit The Yoice Line ~ervice llnit is ~imilar to the LSU Line Ser~rice Unit. It has the addition~l c~pability of voice generation to provide ~utomatic prompting to the accessing customer for Pager Address Location Chsnges.
Two methods of voice generation may be used~ In one9 a 'phonetic' voice synthesizer is used, in the other~ direct voice storage ~nd recall is used.
The 'phonetic' synthesizer requires much less processor overhead than the direct storage ~pproa~h. The appropriate 'phonemes~ are sele~ted to provide the words, stored in the hard disk, and output at the time required.
In the 'direct' voice stor~ge method, each voice mess~ge is recorded locally, stored on u herd di~k, and provided to one of eight voice generator circuits. When a efoice mess~ge is required, the TSU
obtains the voice data from the h~rd disk and outputs it to the voice generator.
SSU - Ststus Service Unit The St~tus SerYice Unit constantly cheeks the operation of all other units in the system, and connects to Q console ~or displQy of the system stQtus. It's console dAts may be routed to either it's local console (detault), or on ~ccess by the ~entral monitoring facility, it's ~onsole data may be routed over the modem line to the central moni~
toring ~acility. All Iunction CPUs in the system generate periodic 'ticks' and send 8 st~tus msssage to the SSU at a pre-determined interval (e.g., five seconds). If the SSU ~ails to recei~re a 'tick' from a particular iunction CPU9 it sends an ~interrogation' to that îunction CPU, which, if not returned within five seconds9 will ~aus~
message to the monitoring site processor th~t ~ ~a~lure has o~curied in the faulty function CPU" ~nd 2) ~a re-boot (tot~l reset) of lthe affected ~unction CPU. The 5SU ~Iso outputs 'ticks' to ~n external àevice which is capable o~ perfQrming ~ complete loc~l systern hardware ~3~L3~

- ~5 -reset. If the SSU f~il5 to tickle the h~rdware device within thirty seconds, the hardw~re reset is initi~ted.
The SSU maint~ins a log of the ~tatus of e~ch ~unction CPU.
If one fun~tion CPU becomes b~cklogged~ it can assign ~nother function CPU to the b~cklogged fuwtion. Any ~neq~ity between the function CPUs is nagged and output to the monitoring site processor.
The SSU ~lso monitors the external hardwflre monitoring device, ~nd periodicslly generates 'status' pQges to the monitoring si te processor vis ~he nationAI network.
ASU - Accounting Service Unit The Accounting Service Unit receives the 'p~ge complete' record from the TSU And updates the ~ppropriate account ~ile. On corn-pletion of the update, the ASU sends An 'accounting ~omplete' record to the RSIJACT FIFO for later (polled) tr~nsmission to the m~ster system. It is typically m~tiplexed in with an SSU.
DBU - D~ta Base Unit (option~l) The Data B~se Unit provldes complete control of the d~ta records pert~ining to each Qccount ~nd pager. It allows up to 255 d~ltB b~ses per logical drive partit;on, up to 1,0~8,580 records per dQts b~se, up to 255 elements p~r data dat~ record, ~nd up to 255 data char~cters per element. High-speed indexing and look-up mny be per-formed based on sny of the data elements within the data bAse.
A page request is processed through the system in the ~ollowing m~nner, For numeric only pages, the subscriber p~ces ~ numeric only ~all by di~ling the local ~ccess line ~ssigned to that pQger and inputting l) the desired pnger number, then 2) the desired display dAt~
(if any~.
The local system RCC site processor receives the call request, then determines where the p~ger is located (station ~ddress). Iî the pager is currently lo~ted within range of the lo~al station, the local system processes t~e call loeally, and stores a Page Record for later transmission to the trafIic site processor for billing control. If, ~3~39~

howeYer, the p~er is not loc~ted within range o~ the local station the locsl system gener~tes ~ Page Record for immediate transmission to the traffic route processor.
PQges cont~ining alph~numeric dsta (letters A-Z, numbers, and punctuation) require a different method of input to the system since this inrorm~tion is not possible to ~nput using n st~nd~rd 'touch-tone' telephone. Four methods are provided:
l.ocal Operator - Tbe RCC m~y have one or more 'Operator Consoles' installed at the RCC site. Sin~e most RCC's provide ~nswering service to their customers in ~on~unction with paging, this should not present ~ problem. The person p~cing the ~ge (c~ller) dials the loc~l number of the answering service ~nd requests ~ pageO
The oper~tor places the p~ge by inputting the pager number ~nd the fllphanumeric d~ta messsge Vifl an operator console. The syo~tem then processes the call. The local oper~tor is connected to the RCC site processor through the OSU.
Encoder - An Encoder device comprised of ~ console, modem~
and possibly ~ printer, is supplied to the user for install~tion in his offi~e. The user's oficer personnel would ori~n~te the page by typing in the message ~nd pressing the 'send' keyD The 3:ncoder then diuls the loc~1 modem ~ccess line of the local RCC9 or the û00 service number (if provided), flnd sends the c~ll request to the loc~l RCC.
The system then processes the c~ll. The Encoder connects to the RCC site processor through the CSU Modu}eO
Computer Interconnect - Since many users of the system wo~d ~lreAdy have sophisticated computer systems, word processors, or personal computers, these devices would be ~llowed access to the system to f~cilitate page processing. Oper~tion would be sinul~r to operation under 'EncodeP. The interf~ce protocol would be provided to the user so th~t the user's system ebuld be progr~mrne~ to communic~te with the RCC site processor. The computer interconnect connects to the R~C site processor through the CSU.

~3~13~

Automatic - Autom~tic pages could be placed by the system itself sienslling ~n 'event occurrence'. The system may be connected to one or more news wire services and stock exch~nge wire services.
The user would request, for Inst~nce, fi page in the event ~ word or combination of words appears on the wire service, or in the event of a stock value change in exces of ~ requested ~mount, or at a predetermined date and time. When the event occurs, the system pl~ces the page. Also, time sensitive events like birthdays could be programmed in ~dvance. On the desired date the pr~programmed page would be plaeedc The ~utomatic pages are gener~ted in automatic page gener~tor 10 which connects to traffic route processor 6 via ~n RSU.
Repeat - In the event that the user feels that he has missed fl page for any reason, he may dial into the local RCC ~nd, using a special access code, request that all of his pages be repeAted. This wQuld be valu~ble since the p~ger would probably be incap~ble of receiving pag-es in an aircraft traveling between t~o service areas.
The stored pages would be repe~ted sequenti~lly in order of occurrence.
After a p~ge request is made ~s described above, it Is processed through the ~ystem in the following manner. As also described ~bov~9 each p~ge ~equest generates a P~ge Record. The Page Record is stsndard throuE~hout the 8ystem, and contains the r~y infor~nation to process the page throughout the system. The P~ge Record is processed locally for local p~ges by the RCC site proce~sor.
Nationwide pages ~re processed through the remotely located traffic route processor. When a p~ge request is made, the local RCC
si te processor seizes one of it's Remote l[)ata Lines and dials into one of the lines connected to the tr~ffic route processor. These lines m~y be a b~nk of nationel and stdte 800 numbers in rotAry configurstion, or ~ series of d~t~ lines prs~vided by a dat~ serYice, ~u~h as GTE
telenet. The trs~fic route processor answers the call snd inputs the Psge Record. Included in the P~ge Record is the current pnger .

~l3~

station ~ddress, prvgrammed by the user on the loca] Qccess lines using a 'touch-tone' telephone. The traffic route processor receives the Pa~e Records, checks ~nd corrects it, stores it, then forwards it to the uplink controller.
The uplink controller ~ssembles the Page Records into a data p~cket l~vhich is tr~nsmitted by the Uplink equipment to the s~tellite along with ull other 'current' Page Records. The ~tellite receives the date packet and repests it to all RCC Site Processors simultaneously.
Each RCC Site Pro~essor extracts the page &nd data paclcet(s) intended for it from the d~ta packet stream, converts the received page record(s) into local transmission p~ge format, then forw~rds the formatted page data to the TSU for output on the loc~l transmitter.
The TSU handshakes with other control equipment working with the local RCC trAnsmitter, ~nd then transmits the local p~ge over th RCC transmitter when a ltime slot becomes available. Thus, the page is completed.
W here a pager location change is desired, the user dials into the 1OCA1 system operator (if provided) who selects the 'Change Pager' ~unction on the loe~l console of the RCC site processor. The change pager runction prompts the operator ~or the information pertlnent to the chanl~e ~nd the oper~tor asks the user for the information9 then imputs it to the system.
Where the subscriber is ~lre~dy in a remote location snd wishes to tr~nsfer his pages to Imother service ~res, he dials into the centr~l site processor ~nd is prompted for the function he desires. He inputs his pager number and the area ~ode and exchange o~ someone he is going to visit in the destination city. The centrHl site processor responds with the city name (for handshake) ~nd the level of c~verage in the ~rea. The user also is prs~mpted for the pertinent times o~
service, or sn itineFarg may be progr~mmed weeks in adv~nce i~
desired.

~3~34 The local station address is defined ~y 8 number of six digit identifiers, the SiX digits are the 10(!!8l st~tion's site ~ddress and consist of the area code ~nd ~11 e~changes served by th~t RCC site processor.
All local stations h~ve ~ 'look-up' tsble o~ all exchanges where nationwide paging service is providedO This ~implifies the system ~or the user, since he probably knows the number of someone in the city he is going to visit. Ideally9 the user would input ~ 'number where he - can be reached' in the city he Is going to. If service is not provided in that exchange, then the system can immediately notify the user.
The user c~n then decide whether to 'turn-o~ his pager by inputting ~n ares code / exchflnge of '000000'. This will prevent 'missed pages' from occuring wlthout the user knowing in ~dvance that he will be unable to receive the page, and it s~ill prevent the user being billed for pages he did not receive because of nationQI p~girlg syQtem limit~-tions. In the event that more th~n one RCC Site Processor serves the same exchang~es9 the Traffic Route Processor will alternate the tr~nsmission between the RCC's to provide equ~l air time utilization.
Paging receiver 4 shown in Figure 1 is a convention~ ging receiver which h~s been modified in accord~nce with the present inven-tion to permit scanning of the RCC ~requency channels. Such d conventional receiver can be selected from amoung fl number of receivers Iknown in the art including receiver model number D-4-ALPHA
munuf~ctured by NEC. The NEC D-4-ALPHA p~ger is ~n FM-FSK
alpha-numeric p~ger ~apable of receiving a ~ingle modulated earrier.
In order to conserve b~ttery life, certain sections of the pager's subsysterns are turn off for a msjority of the time and turned on only when absolutely necessary. The turn-ofI period (hereafter referred to as "sleep"3 is controlled by ~ "wAtchdog" timer resident in the pager~s VLS1 components. The slee~w~ke duty cycle is arrarlged so t~t the pager is given ~mple opportunity to reccgnize an ~ncoming p~ge while rn~ximizing battery po~er conservstion. An e~mple of a typic~l page acquisition sequence is shown in Figure 8D

13~3~

The upper half of Figure 8 represents the signal transmitted by the RCC. Section A is the page pre~mble (typically a single tone) which precedes all p~ging messages. The purpose of the pre~mble is to cause 811 receiving pagers to awAken and begin ~ooking for the syn-chronization codework (B) which identifies uniquely the pager which is being signaled. In ~ddition to this function, the synchronization codeword also specified the time dom~in location of the message pscket C.
The lower half of Figure 8 represents the pager's power save response to the transmitted signal. The two short dur~tion pulses (D, E) represent the normal sleep process the pager uses to conserve b~tter life. Should the preamble (A3 be present while the pager is awake, the RF power save signal ma3nt~ins the pager In an ~w~ske sts-tus in sy~achronous with the synchronization codeword IF) and subse-quent message pflckets ~G, etc.~O Should the pager ~il to recognize the synchronization codeword (~s would be the cQse during periods of heavy radio Jnterferences9 ~ weak sign~l or an invnlid synchronization codeword) or messsge packet, the pager returlls to the normal sleep-long/~w~ke-short bRttery save status.
Among the pager subsystems which are slaved to the power save awQke/sleep cycle is the RF "front end." This section of the p~ger i5 shown in Figure ~.
The receiving stages o~ the pflger are implemented ~s simply ~s possible whil~ mainWning high sele~tivity and sensltivity. Low noise ampliIier gOO is a single stage RF transisto~ ~mpliîier. BQnd pllS5 îilter stage 901 is ~ cascade OI factory turled "tanlc" circuits. The first IF I21.4 MH~) is obtained from a downconverter mflde up of band pass filter ~1, local oscillator 903 and mixer 902 and b~nd pass filter 904. Mixer 9û2 is a BJT (bipolar junction tr~nsistor) mixer which is biased for nonlinear oper~tionO Local oscill~tor 903 is a fixed ~requency crystal oscillator which supplies the down conversion frequency. It is local oscillator 903 which fs repl~ced by ~ sc~nning ~3~

local oscill~tor module in accord~nce with the present invention. ~he pager IF is subsequently passed to the FM discriminAtor (not sho~rn) for demodul~tion. In order to turn the front end on ~nd off (aw~ke/sleep), the RF power s~ve signal from the NEC VLS1 circuit drives the base Or ~ switching tr~nsistor. The tr~nsistor switches the DC supply volt~ge rail to the elements shown in Figur~ 0.
Modific~tion of the receiver to permit reception of any of a plurality of separate RF signals can be accomplished in accordance with the present invention v~ith little modification to the original p~ger design. Further" the useful b~ttery life for the modified p~ger should be no less th~n 150 hours using A size l'AA" alkaline 1.5 volt cell.
L~stly, the origin~l design performance specifieations of the pager ~re m~int~ined.
The sleep/awske signature of the modiried p~ger snd RCC tr~ns-mitted signal is discussed in lFigure 10. The upper half of Figure 10 represents the signal transmitted by the RCC. Section A is a special preamble unique to the RCC's whicll support the scanning pager network. This preamble is Q single tone (alternnting 1, 0 bit p~ttern~
of e duration sufficiently long Ior a p~ger to completely scan ~lï
frequencies at least once. Sections B, C ~nd D ~re the page prearn-ble, synchronization codeword, nnd message pAcket, respect~vely. These l~st 3 sections are the same as their counterpQrts in Figure 8.
The lower h~lf Or Figu~e 10 represents the modi~ied p~ger's response to the transmitted signal. The ~wske perivd E is the perisd of the pre~mble search et each frequency. In the above example, the speci~l preamble A is searched fol and not found until ~equency #7 shown in T~ble 1 îor example is re~ched by tlle p~ger. At tllis point9 the p~ger remains ~wake through periods F and G and subsequent message pscke~s. T~ble 1 is a listing of several ~requer3eies in the VHF b~nd which the pager of the invention c~n scan. This list is by no me~ns inclusive &nd is presented by wsy o~ ex~mple only. Mor~
over9 the E~ger of the in-/ention m~y ~Iso ~ used to sc~n a plur~lity of frequencies in other bands ~s well.

~3~

In order to scan ~ll twenty-two ~requenc~es, the conventIonal ~ixed frequency re¢eiver is modified as shown in F~gure 11. The pager's cryst~l loc~l oscillAtor is electrically disconnected ~nd replaced with frequency agile lo~l oscillator 950 sn~ ~ssociated logic ~ircuitry 951. The local oscillator ~requency is chosen ~o th~t the difference ~requency between the local oscill~tor and RF Is 21.41 M~lz when the RF/LO frequency numbers are corret~ted. Logic circuitry ~51 uses the flowchart shown in Figure 12 to control the LO ~requen~y b~sed on the psger's status (i.e., aw~ke, sleep, preQmble detect, etc.), A transmission ~onsists of two preambles ~ollowed by 8 b~tch of complete ~odewords, each b~tch beginning with ~ synchronization codeword (SC~ (see Figure 13). The first pre~mble allows for frequency synchronization by the receiving pagers. This preamble is a sequence of logic reversals, 101010... repeatlng for a period of ~t least 1200 m~ec. The pre~mble rr~quency is, ~or example, 500 Hz.
The second preamble is transmitted for pager bit synchroni~ation which also allows for word synchronization. This pre~mble is ~ pattern of logic reversals, 101010... r~peated for ~ duration of 1125 msec.
One example of a preamble frequency is 256 ~Iz but other ~requencie~
may be used ~s well.

RF Freq. LO Freq. IF Freq.
Channel No. MHz) (MHz) (MHz)_ 15a.03 130.63 21,4 2 152.06 130.6fi 21.4 3 152.09 130.69 21.4 4 152.12 130.7~ 21.4 152.15 130.75 2104 6 152.18 130.7~ 2~.4 7 152.al 130.81 8 152.24 130.84 21~4 9 158.70 137.30 21.d~
As ~hown in Figure 14, there are si~ points of interface between ~3~3~3~

the module of the present inYentiOn ~nd the paging receiver. The scanning receiver module is required to perform the following ~unctions:
1. Receive the RF power ~ave from the peger and dstermine if the pager ~s in the b~ter saYe mode or receiving mess~ges.
2. Receive the p~ger dlscrirninator data and determine if a valid preambl~1 has occurred.
3. Provide the necessary control signals to the scanning local oscillator section to set the frcquency.
The ~ollowing tsbles 2-11 more det~ily describe the processing of a page through the paging system o~ the present invention under Yari ous conditions.

NUMERIC:~ CALL ~ AUTOMATIC DTMF -- LINE -- LOGAL

RCC SITE PROCESSOR
LSU WAIT STATE polls all idle lines for ring voltage detection periodically sends 'tick' to SSU
User Dials 10CR1 line ar~d connects to one of the 'LINE n' inputs LSU Detects ringing on line Siezes line Gives Dial Tone User Di~ls ~irst ~igit of pager account number LSU Remove~ Dial Tone User Dials next five digits OI p~ger flccount number LSU Gi~res }3EEP
LSU Gives Dial Tone User DjA1S display d~ta User Makes mistake - presses '*' LSU 13ives B~EP
LSU Gives Dial Tone IJser Dials display data ~3~ 3Lq~9~

Vser Is through di~ling displ~y d~tQ - press '#' LSU Gives BEEP - BEEP - BEEP
l,SU Disconnects LSU Form~ts Page P~ecord IntRlls Pager Number Installs Data Code Looks up Destinat30n Code, installs Calculates d~ta blocks required Obt~ins source ID number Installs datn LSU Determines that p~ge destin~tion Is one Or the locsl TSU's LSU ) Requests ~nd obt~ins p~cket ID number LSU Stores PAG:E~EC in CURRENT PAGE BUFFER
LSU Sends Page Record Holding messRge to TSU
TSU WAIT STAGE periodic~lly sents 'tick' to St~tus Service Unit TSU Recelves P~ge Record Ready message TSU Lo~ds Page Record into bu~fer TSU Form~ts Page ~Record into POCSAG form~t and installs in POCSAG bu~fer TSU Checks Holding Time If not stsrted, st~rts Holding Time TSU Aw~its Holding Time Time-out or next P~ge Record Ready ~less~ge TSU ~ends Tr~nsrnitter Time Request to RCC transmitter controller RCC TrRnsmitter controller sends 'WAIT' or ~ao~
If T3U recieves WAIT
TSU starts '~ax Wsit Timer' If MRX Wait Timer times out TSU ~ends error messAge to RSU
RSU receiYes error mess~ge RSU connects to Monitor F~eility RSU sends 'RCC Transmittr Controller Out-Of-Service Mess~ge' ~3~3~

TSU Receives 'GO' TSU Sends 'Tr~nsmitter On (: omm~nd Sequen¢e' TSU Starts 'Msx W~it 'rimer' If T51J receives 'l'r~nsmitter F~ult' from RCC Tr~nsmitter Controller Or if M~x Wait Timer times out TSU sends 'Transmitter ~ault' mess~ge to RSU queue RCC Transmitter Controller sends 'Tr~nsmitter On' 41cknowledgement TSU Sends POCSAG buffer to RCC Tr~nsmitter TSU P~uses TSU Sends 'Transmitter Release' message to RCC Transmitter Con-ltroller TSU Starts Max Wait Timer TSU St~qrts Repe~t Control Burst timer If Repeat Control Burst Timer times out TSU sends "rr~nsmitter Release' message ~gain If Max Wait Timer times out TSU sends rTrAnsmitter Controller Fault 2' message to RSU
Queue TSU Sends Page Complete mess~ge to ASU
TSU Returns to WAIT 5t8ge -- END OF SEQUENCE --NUMERIC CALL -- AUTOMATIC DTMF -- LINE --_NATIONWIDE

RC::C SITE PROCESSOR
User Di~ls local line and conne~ts to one oî the 'Line nl inputs I,SU Detects ringing on line Siezes line Gives dial tor!e User Di~ls ~irst digit of psger account number L~SU Removes Dial Tone 31 3~4~3~
~ 36 User Disls next rlve digits of pager Account number LSlE~ GiYes BEEP
LSU Gives Dial Tone User Dials displ~y d~ta User M~kes mi~take - presses ~*' LSU Gives BEEP
LSU Bi~es Dial Tone User Dials displ~y dat~
User Is through dialing display data - press '#' LSU aives BEEP - BEEP - BEEP
LSU Disconnects LSU Formats Page Record Intalls Pager Number Installs Data Code Looks up Destinat50n Code, installs Calcul~te~ d~ta blocks required Obt~ins source ID number Installs d~tA
LSU Determines that page reguires NAtion~l routing I,SU Requests and obt~ins p~cket ID number LSU Stores PAGREC in CURP~ENT PAGE E~VFFER
LSU Sends Page Record Holding message to TSU
RSU Receives P~ge Record Holding messsge If no Page Records holding RSU set page holding time to ~wait ~dditional blocks If Page Record Holding Time not timed-out, w~it RSU connects modem to Central R~U Traffic Route Processor lf un~ble to make connection Repeat connection ~ttempt If five attempts Connect to Monitor Facility snd report error 413~

RSU Sends ~11 current Holding Records RSU Awaits handsh~ke for Repeat :Request(s~
R5V Resets9 awaits neact P~ge Record TRAFFIC ROUTE PROCESSOR
RSU (From P~CC Site) receiYes Page Records ~rom RCC site RSU Checks Source Record ID Number If not sequentifll RSU sends 'Repe~t nmln Request' to RCC Site Processor RSU receives repeated Records RSU Checks DestinAtion Code Address If Destin~tion inaccurate, g~nerates lNew Destination Code' Record for tr~nsmission to RCC Site Processor RSU Assigns Destination P~cket ID number to each Page Record RSU Sends P~ge Record Re~dy message to Uplink RSU
UPLINK PP~OCESSOR
RSU (To Uplink) recei~res Page Records Re~dy message RSU Loads P~ge Records into Page Record Block Queue RSU Sends Psge Records Ready me~s~ge to next USU
USU Receives P~ge Records Ready message from RSU
USU Losds Page Records USU A-Yaits Trsnsmission Time loop IJSU Output Page Records in Block ~ormat SATI~LLITE SYSTEM SENDS TO DOWNLINK
DESTINATION RCC SITE PROCESSOR
DSV Det~cts record block with correct Destination ID
DSU Signals next DSU to prepare for input DSU Finishes input of P~ge Record DSU Signals 'GO' to next DSU
DSU Checks ~nd corrects received Page Record DSU Requests ~nd obt~ins n P~cket ID from the local 5SU
DSU LoQds P~ge Record to TSU queue DSU Sends P~ge Record Ready to TSU

~3~39~

DSU Awaits next 'Prepare to Receive Data' from other DSU(s) TSU WAIT STATE: periodically sends 'tick' to Status Service Unit TSU Receives Page R~cord Ready message TSU Loads P~ge Record into buffer TSIJ Form~ts PQge Record into POCSAG format and installs in POCSAG buffer TS LJ Checks Holding Time If not st~rted, stal ts Holding Time TSU AWQitS Holding Time Time-out or next Page Record Resdy mess~ge TSU Sends Tr~nsmitter Time Request to RCC trAnsmitter controller RCC Tr~nsmitter controller sends 'WA~T' or 'GO' If TSU receives WAIT
TSU starts 'Max W~it Timer' If Max Wait timer times out TSU sends error message to RSU
RSU receiYes error message RSU ¢onnects to Monitor Fscility RSU sends 'RCC TrQnsmitter Controller Out-of-Service Mess~ge' TSU Receives 'GO' TSU Sends Plr'ransmitter C~n Command ~equence TSU Starts 'M~x W~it Timer' If TSU receives 'Tr~nsmitter Fault' from RCC Tr~nsmitter Control Or if M~x W~it Timer times out TSU sends PTransmitter Fault' message to RSU queue RCC Tr~nsmitter Controller sends 'Transrnitter On' ~cknowledgement TSU Sends POCSAG buffer to RCC Transmitter TSU Pauses TSU Sends Prransmltter Release' message top RCC TrQnsmitter Con-troller 13~

TSU Starts Max Wait Timer TSU Starts Repest Control Burst timer If Repe~t Cotnrol Burst Timer times out TSU sends 'Transmitter Relesse' message again If Max Wait Timer times out TSU sends 'Trensmitter Controller Fault 2' message to RSU
Queue TSU Sends Page Complete message to ASU
TSU Returns to WAIT stage -- END VF 5EQUENCI:

ALPHANUMEYtlC INPUT ~ I)PERATOR -- LOCAL
. ~
OSU Initlalization If modem connection required If DIAL NUMBER contains dflt~
OSU prompts modem ~or connectlon If five trys with no modem response OSU sends IModem Fault Detect' to SSU
Modem Responds Sends Di~l Data to Modem Modem dials number Modem sends 'Waiting for Carrier' message to OSU
If modem does not detect c~rr}er Modem sends 'No Datfl C~rrier message to OSU
OSU retryg Every fifth try OSU ses~ds 'Line Fault l)etect' to ~SU
Modem sends 'D~ta Carrier Detect' OSU Sends 'Console Type Request' to remote terminal If ~onsole does rlot respond to type sele~t QSU selects 'dumb console' default pflrflmeters If console respondo with type ~L3~

- 4~ -OSU selects appropriAte control code comm~nds based on received console type OSU Displ~ys Operator Menu OSU Enters WAIT STATE
OSU W~IT STA7'E periodicslly sends 'tick' to ~SU
-- End C)SU initializ~tion Operator selects desired flmction (PLACE A PAGE~
OSU Prompts for Pager Number If Operator press CR without dat~
OSU r~displays menu Operator enter p~ger number, using backspace Qnd delete for edits Operator presses CR
OSV Looks up pa~e number, sets control block If pager number is not valid OSU sends 'Invalid Pager Number Error' message to OperAtor C)SU re-prompts for P~ger Number OSU Prompts for Displ~y Dat~
If Oper~tor presses CR without dat~
Tone Only Page, proceed to OSU rormats Pa~e Record Oper~tor types in Display DAta, using backspaee and delete for edits Operator presses C~
OSU Formats Page Record InstQlls Pager Num~r Installs Data Code Looks up Destin~tion Code, Installs Calcul~tes d~ta blocks required Obtains source ID number Is~stalls d~ta OSU Determines th~t the page is to be pl~ced locally ~3~3~

OSU Requests ~nd obti~ns Packet ID number OSU 5tores PAGREC in ClJRRENl` PAGE BUFPER
OSU Sends Page Record Elnlding mess~ge to TSU
TSU WAIT STATE periodic~lly sends 'tick' to St~tus Service Unit TSU Receives Page Record Ready messflge TSU Lo~ds Pag~ Record into buffer TSU Formats P~ge Record into POCSAG format ~nd installs in POCSAG buffer TSU Checks Holding Time îf not started, starts Holding l`ime TSU Aw~its Holding Time time-out or next Page Record Re~dy message TSU Sends Tr~nsmitter Time Request to RCC Transmitter Con-troller RCC Tr~nsmitter Controller sends 'WAIT' or 'GO' If TSU receives WAIT
TSU st~rts ';~l~x W~it Timer' If Max W~it Timer times out TSU sends error message to RSU
RSU receives error mess~ge RSU ~onne~ts to Monitor F~cility RSU sends 'RCC Tr~nsmitter Controller Out-oî-Service Message' TSU ReceiYes 'GO' TSU Sends ITrsnsmitter On Comm~nd Sequence' TSU Stsrts 'M~x Woit Timer' If TSU receives 'Transmitter F~ult' from RCC Transmitter Controller Or if M~x Wait Tirner times out TSU sends 'Trsnsmitter Fault' message to RSU queue RCC Transmitte- Controller sends ITr~nsmitt~r On' ackno~ledged TSU Sends POCSAG buffer to RCC Transmitter 31 3~ .3~

TSU Pauses TSU Sends ITrsnsmitter Release' mess~ge to RCC Transmitter Con-tr~ller TSU Starts MQ~ Wait Timer TSU St~rts Repeat Control Burst timer If Repeat Control Burst Timer times out TSU sends 'Transmitter Release' m~ssage ~g~in If Max W~it Timer Times out TSU sends 'Transmitter Controller Fault a~ message to RSU Queue TSU Send~ Page Complete message to ASU
TSU Returns to WAIT st~ge -- END OF SEQUENCE --TABLl~ 5 ALPHANUMERIC INPUT -- OPERATOR -- NATION~IDE
.
t)SU Initialization If modem ~onneetion required If DIAL NU MBER ~ontains data OSU prompts modum ~or conneetion lf fivo trys with no modem response OSU ~ends 'M~em ~ault Dete~t' to SSU
Modem response OSU send~ Di~l Dat~ to Modem Modem di~ls number Modem YeDds 'W~iting for Carrier' message to OSU
If modem does not dleteet carrier Modem ~ends 'No D~t~ Cerrier' message to OSU
OSU retrys Every rifty try ()SU sends 'Line P~ult Detect' to SSU
Modem sends iData Carrier Oetect' OSU sends 'Console Type Request' to remote termin~l ~3~3~

If ~onsole does not respond to type select OSU selects 'dumb console' default parameters If console responds qith type OSU seleets appropria$e control code comm~nds based on received console type OSU Displays Oper~tor lUenu OSU Enters WAlT STATE
OSU WAlT STATE periodic~lly sends 'tick' to SSU
-- End OSU initialization Oper~tor selects desired function (PLACE A PAGE) OSU Prompts for Pager Number If Operstor press CR without data OSU re-displ~ys menu Operator enter pager number, using backspQce ~nd delete ~or edits t)perator presses CR
OSU Looks-up page number, gets control block If p~ger number is not valid OSU sends 'Invalid Pager Number Error' message to Operator QSU re-prompts for Pager Number OSU Prompts for Display Data If Oper~tor presses CR ~vithout data Tone Only Page, proceed to l:)S~J form~ts P~ge Record Operator types in Display Data, usirlg b~ckspace and delete for edits Operator presses CR
05U Formats Page Record O
Inst~lls PMger Number Installs D~t~ Code J,ooks up Destination Code, Inst~lls Calculates dat~ blocks required ~L3~ 3~
- 4~ -Obtsins source ID number Inst~ls data OSU Determines th~t the ~11 is to be routed N~tion~l system OSU Requests ~nd obt~ins Packet ID num~r OSU Stores PAGREC in CURRENT PAGE BUFFER
OSU Sends Page Record Holding messsge to RSU
RSU Receives P~ge Record Holding mess~ge II no P~ge Xecords Holding RSU set page bolding time to ~wait addition~l bloeks If P~ge Record ~olding Time Not timeed out, wait RSU connects modem to Centr~l RSU Traffic Route Processor If unable to make connectaon Repeat connection attempt 1~ fi~re ~ttempts Connect to Monitor ~acility ~nd report Error RSU Sends all current Holding Re~ords RSU AYvaits handsh~lce ~or Repeat Request(s) RSU Resets, ~waits ne3~t Page Record TRAFFIC ROUT PROCESSOR
RSU (~rom RCC Site) recei~es Page Records frorn RCC SITE
RSU Checks Source Record lD Number If not sequential ~SU sends 'Repe~t nnnn Request' to RCC ~ite Processor RSIJ reee~ves repeflted Records RSU Checks Des~in~tion Code Address r Destination ina~curate, generates 'New Destination Code' Reeord for trulsmission to RCC:: Site Processor RSU Assigns Destiniation Pflcket ID Number to esch Page P~ecord RSU Sends P~ge ~ecord neady message to Uplink FlSU

.3~

-- ~5 --UPLINK PROCESSOR
RSU (To Uplink) receives Page Records R~dy message RSII Loads Page Records into P~ge Reoord Block Queue RSU Sends Psge P~ecords Refldy messRge to next USU
USU Receives Page Records Ready me~sage ~rom RSU
USU Loads Page Records into ram buffer USU Awaits Transmission Time loop USU Output Psge Records in Block îorm~t STAELLITE SYSTEM SENDS TO DOWNLINK

DESTINATION RCC SITE PROCESSO}~
DSU Detects record block with corre~t Destination ID
DSU Signnls next DSU to prepare for input DSU Finishes input of Puge Record DSU Sign~ls 'GO' to next DSU
DSU Checks and corrects received Page Record DSU ~eques~s and obtains ~ Packet ID from lthe lo~t SSU
DSU Loads P~ge Record to TSU queue DSU Sends Page Record Ready to TSU
DSU Awaits next 'Prepare to Receive D~ta' from other DSU(s) TSU WAIT STATE periodically sends 'tick' to Status Service Unit rsu Receive Page Record Ready messRge TSU Loads Page P~ecord into buffer TSU Pormats Page Reoord into POCSAG form~t and instslls in POCSAG burfer TSU Checks Holding Time 1~ not started, starts Holding Time TSU Awaits Holding Time time out or ne~ct Page ~Record Ready Messflge TSIJ Sends Tr~nsmitter Time Request to RCC Tr~nsmitter Con-troller RCC Transmitter ControIler sends 'WAIT' or 'GO' ~3~

If TSTJ receives WAIT
TSU st~rts 'M~x Wait Timer' If MAX Wsit Timer times out TSU sends error message to RSU
RSU receives error mess~ge RSU ~onnects to Monitor F~cility RSU sends 'P~ CC Transmitter Controller Out-o~-Service Message' TSU Receives 'GO' TSU Sends 'Transmitter On Command Sequence TSU Starts 'Max Wait Timer' If TSU re~ieves 'Tr~nsmitter F~ult' from RCC Transmitter Controller Or iî Max W~it Timer times out TSU sends ~r~nsmitter Faultl message tO RSU queue RCC Tr~nsmitter Controller sends 'Tr~nsmitter On' acknowledgement TSU Sends POCSAG buffer to RCC Transmitter TSU Pauses TSU Sends 'Transmittel Rele~se' message to RCC Transmitter Con-troller TSU St~rts M~x W8it Timer TSU Starts Repeat Control Burst timer If Repe~t Control Burst Timer times out TSU sends 'Trflnsmitter Release' messaE~e again If M~x W~it Timer times out TSU sends fTr~nsmitter Controller Fault 2' messsge to RSU
Queue T5U Send Page Complete mess~ge to ASU
TSV Returns to ~AIT state -- END OF SEQUENCE --. , ' .

-- .
.

~3~ 3~

-- ~7 -ALPHANUMERIC INPUT ~ MANUAL ~ uc (Customer Equipped with Console ~nd Modem -- No Processor)' CSU WAIT STATE periodic~lly sends 'tick' to SSU
C~lling party di~ls llne number Modem Detects ring signal ~lodem answers Calling party presses or sends CR
CSU Requests logon ID (whieh contains type specification) If c~lling pQrty ~ends invfllid logon ID
CSU sends 'Inv~lid Logon ID' CSU disconnects modem CSU returns to WAIT STATE
C~lling party responds with ~alid logon ID
CSU selects qppropriate console comm~nd codes based on type specific~tion in Logon ID
CSU Sends ~ppropri~te Customer Service Menu CSU Resets 'De~d Console' timer If 'De~d Console' Timer times out CSU sends 'No Activity Time out Error' CSU ~isconnects modem Calling p~rty selects desired function (PLACE A PAGE) CSU Prompts ~or Pager Number Tf Customer press CR w~thout dat~
CSU re-displays menu C~ustomer enter p~ger number using backs~ce ~nd delete for edits Customer presses CR
CSU Looks up page number, gets control block lf pQger number is not v~lid CSU ~ends 'Invalid P~ger Number Error' mess~ge to Customer ~,....... . . ~ .

~3~ 3~
- 4~

CSU re-prQm pts for P~ger Num ber CSU Prom pts ~or Displ~y ~ata If Customer presses C R without data Tone Only Page, proceed to CSU form~ts Page Record Customer types in Display Dat~, using backspace and delete for edits Customer presses CR
CSU Formats P~ge Record Inst~lls Pager Number Inst~lls Date Code Looks up Destin~tion Code, ~ntalls C~lcul~tes d~ta blocks required Obtians source ID num ber Inst~l~ dat~
CSU Determines that page should be processed loc~lly CSU Requests ~nd obti~ns Packet ID Number CSU Stores PA G RE C in CURRENT PAGE BUFFER
CSU Sends Page Record holding mess~ge to TSU
CSU I)isconnects modem TSU WAIT STATE periodically sends 'tick' to Status Bervice Unit TSU Receives Page Record Re~dy message TSU Loads Page Record into buffer TSU Form~ts Page Record into POCSAG format ~nd installs in POCSAG buffer TSU ~hecks E~oldin~ Time If nolt st~rted, starts ~olding Time TSU Awaits Holding Tîme time out or Next P~ge lRecord Ready mesSRge TSU Sends Transmitter Time ~Request to RCC Trarllsmitter Con-troller RCC Tran~mitter Controller sends 'WAIT' or 'GO' If 'I SU receives WAIT

13~

.~9 TSU starts ~Msx Wdit Timer' If Max W~it Timer times out TSU sends error mess~ge to RSIJ
RSU receives error message RSU connects to Monitor FBCj1itY
RSU sends 'RCC Tr~nsmitter Controller Out~f-Service Message' TSU Receives 'GO' TSU Sends 'Transmitter On Commsnd Se~quen~e' TSU Starts 'Max Wait Timer' lf TSU receives 'Transmitter Pault' from R5:~C Transm~tter Controller OF if Max Wait Timer times out TSU sends 'Transm~tter Fault' message to RSU Queue RCC Tr~nsmitter Controller sends 'Tr~nsmitter On' acknowiedgement TSU Sends POCSA~ buffer to RCC Tr~nsmitter TSU Pauses TSU Sends 'Transmitter Release' message to RCC Transmitter Con-troller TSU Starts Max W~it Timer TSU Starts Repeat Control 8urst timer If Repeat Control Burst Timer times out TSU sends 'Trandmitter Relesse' message again 1~ Max Wait Timer times out TSU sends 'Transmitter Control FHult 2' message to RSU
Queue TSU Sends P~ge Complete mess~ge to ASU
TSU Returns to WAIT STATE
-- END OF SEQUENCE --~3~39L

- so -ALPHANUMERIC INPUT -- MANUAL -- CUSTOMER SERVICE UNIT -- MATIONWI
C5U WAIT STATE periodic~lly ~ends 't3ck' to SSU
C~lling p~rty dials line number Modem Detects ring sign~l Modem ~nswers C~lling party presses or sends CR
CSU Requests logon ID qwhieh contains type specification) If calling pQrty sends invalid logon liD
CSU sends 'Inv~}id Logon ID' CSU disconnects modem CSU returns to WAIT STATE
Calling party responds with valld logon ID
CSIJ seleets ~ppropri~te console comm~nd codes based on type specification in Logon ID
CSU Sends appropri~te Customer Service Menu CSU Resets 'De~d Console' timer If 'Desd Console' Timer $imes out CSU sends 'No Activity Time out Error' CSU disconnects modem Calling party selects desired function (PLACE A PAGE) C5U Prompts ~or Psger Num~er If Customer press CR without d~t~
CSU re-displnys menu Customer enter pager number using backspace and delete for edits Customer presses CR
CSU Looks up psge number, gets control bloek If psger number is not Yalid CSU sends 'Invalid P~ger Number Error' mess~ge to Customer CSU r~prompts ~or Pager Number l3~

CSU Prompts for Displ~y Dat~
II Customer presses CR without d~ta Tone Only Page, proceed to CSU ~ormats Psge Record Customer types in Displey Data, using backspsce and delete ~or edits Customer presses CR
CSU Formats P~ge Record Installs P~ger Number Installs Date Code Looks up Destination Code, Intalls C~lculates dbt~ blocks required Obtisns source ID number Installs dat~
CSU Determines thst page should ~ placed on the Nstion~l System CSU Requests ~nd obtains Packet ID Number CSU Stores PAGREC in CURRENT PAGE BUFFER
CSU Sends P~ge Record holding message to TSU
CSU Disconnects modem RSU Receives Page Record Holding message If no Page Records Holding RSU set page holding time to ~wait additional blocks If Pags Record Holding Time not timed out, wait RSU Connects modem to Centr~l RSIJ Traffic Rout Proc~ssor lf unflMe to make connection Repeat ~onnection attempt I~ five attempts Connect to Monitor Facility and report Error RSU Sends Rll current Holding Records RSU Awaits hand~hake for Repeat Request(s) RSU Resets, ~WRit next Page Re~ord ~L3g~

TRAFFIC ROUTE PROCESSOR
RSU (From RCC Site) receives P~ge Records rrom RCC SITE
RSU Checks Ssurce Record ~D Number If not sequential RSU sends 1Repe~t nnnn Requestt to RCC Site Porcessor RSU receives repested records RSU Checks Destination Code Address If Destinetion inaccurste, generates iNew Destination Code' Record for tr~nsmission to RCC Site Processor RSU Assigns Destin~tion P~cket ID Number to eQch Page Record RSU Sends Page Record Re~dy mess~ge to Uplink RSU
UPLINK PROCESSOR
RSU ~To Uplink) receives Page Records Ready message RSU Loads Page Records into Page Record Block Queue RSU Sends PAge P~ecords Ready mess~ge to ne2~t USU
USlU Receives Page P~ecords Resdy rnessage from RSU
USU Loads Page P~ecords into ram buffer USU Awaits Tr~nsmission Time lDop USU Output P~ge Recsrds in Block formet SATELLITE SYSTEM SENDS TO DOWNLINK
DESTINATION RCC SITE PROC:ESSOP~
DSU Detects record block with correct Destination ID
DSU Signsls next DSU to prepare ~or input DSU Finishes input o~ P~ge Record DSU Signsls 'GO' to next DSU
DSU Checks and corrects received Page RecoFd DSU Requests and obtains ~ Packet ID from the ~o~al SS~J
DSU Loeds Page Record to TSU queue DSU Sends Page Record Re~dy to TS,U
DSU Awsits next 'PrepAre to lRecei~e Data' from other DSU~s) TSU WAIT STATE periodic~lly sends 'tick' to Statu~s Servace Unit TSU Receives P~ge Record Reudy messege 3~

TSU Lo~ds P~ge Record into buffer 7SU Forrn~ts P~ge Record Into POCSAG format and installs in POCSAG buffer TSU Checks Holding Time lf not started, ~tarts Holding Time TSU Aw~its Holding Time time out or Next Page Record Ready message TSU Sends Trdnsmitter Time Request to RCC Transmitter Con-troller RCC Tr~nsmitter Controller sends 'WAIT' or 'GO' If TSU receives WAIT
TSV starts 'Max Wait Timer' Iî Max Wait Timer times out TSU sends error message lto RSU
RSU receives error mçssage RSU conneets to Monitor l~scility R5U sends 'RCC Transmitter Controller Out-of-Service Message' TSU Receives 'GO' TSU Sends 'Transmitter On Commsnd Sequence' TSU Starts 'Max Wsit Timer' If TSU receives 'Tr~nsmitter Fault' from RCC TrRnsmitter Controller Or if Max W~it Timer times out TSU sends 'Transmitter P~ult' message to R5U Queue RCC Transmitter Controller sends 'Tr~nsmitter On' acknowledgement TSU Sends POCSAG buffer to RCC Tr~nsmitter TSU Pauses TSU Sends 'Transmitter Rele~se' message to RCC Transmitter Gon-troller TSU Starts Max Wait Timer TSU Starts RepeAt Control Burst timer ~3~

- 5~ ~

If Repe~t Control Burst Timer times out TSU sends 'Transmitter Rele~se' mess~ge ~in If Max Wait Timer times out TSU ~ends 'Tr~nsmitter Control Fault a~ message to RSU
Queue TSU Sends Page Complete mess~ge to ASU
TSU Returns to WAll` STATE
-- END OF SEQUENCE --TAB~E 8 ALPHANUMEP~IC INPUT -- ENCODER ~ LOCAL
CSU WAIT STATE periodlcally sends 'tick' to SSU
Calling device dials line number Modem detects ring sigrlal Modem ~nswers Calling device presses or sends C R
CSU Requests logon ID (which cont~ins type spec~fîc&tion) 1~ calling dev~ce sends invalid logon ID
CSU sends ~nv~lid Logon ID' CSU disconnects modem CSU returns to W AIT STATE
Calling device responds with valid logon ID
CSU selects no echo, no prompt Ca~ing device sends Pager Number9 CR
CSU looks up P~ger Number If Pager Number not v~lid CSU sends "ErrQr Respsnse ~qesssge' CSU disconnects CSU returns to WAIT STATE o C~lling device inputs~ Display Dat~
Calling device inputs CR
CSU Formats P~ge Record Installs Psger Num ber ~3~3gl Installs D~te Code Looks up Destin~tion Code9 Int~lls Calcul~te3 data blocks required Obtisns source ID number Installs data CSU Determines th~t page should be processed locally CSU Requests and obWns Packet ID Number CSU Stores PAGREC in CURR13NT PAGE BUFFER
CSU Sends Page Re~ord holding message to TSU
CSU Disconnects modem TSU WAIT STATE periodically sends 'tick7 to St~tus Service Unit TSU Receives Page Re~ord Ready message TSU Loads Page Record into buffer TSU Form ats Page Record into P O CSA G format ~nd inst~lls in PO CSA G buffer TSU checks Holding Time 1~ not started, starts Holding Time TSU A waits Holding Tim e tim e out or Next Pege Record Re~dy message TSU Sends Transmitter Time lRequest to RCC Transmitter Con-troller RCC Tr~nsmitter Controller sends 'WAIT' or 'GO' If TSU receiYes WAIT
TSUI starts 'Max Wait Timer' If Max Wait Timer times QUt TSI~ sends error message to RSU
RSV receives error message RSU connects to Monitor ~acility RSU sends 'RCC Tr~nsmitter Controller Out~f-Service Message' TSU ReceiYes 'GO' TSU Sends 'Transmitter C)n Commalld Sequen~e' ~3~

TSU Starts 'MAx W~it Timer' If TSU receives 'Transmitter F~ult' ~rom RCC Tr~nsmitter Controller Or if Max W~it Timer times out l~U sends 'Transmitter Fault' mess~ge to RSU Queue RCC Tr~nsmitter Controller sends 'Tr~nsmitter On' ~eknowledgement TSU Sends POCSAG buffer to RCC Transmitter TSU Pauses TSU Sends 'Transmitter Release' mess~ge to RCC Transmitter Con-troller TSU St~rts Max Wait Timer TSU St~rts Repeat Control Burst timer Ir Repe~t Control Burst Timer times out TSU sends 'Tr~ndmitter Release' rnessage again If M~x W~it Timer times out TSU sends 'Transmitter C3ntrol F~ult 2' message to RSU
Queue TSU Sends Pflge Complete mess~ge to ASU
TSU Returns to WAIT STATE
-- END O~ SEQUENCE --ALPHANUMERIC INPUT ENCODER -- CUSTOMER SERVICE UNIT -- NATIONWI~
CSU WAIT STATE periodic~lly sends 'tick' to SSU
Calling device dials line number Modem l~etects ring signal Modem ~nswers Calling device presses or sends CR
CSU Requests logon ID Iwhich contains type specifi~tion) If ~alling device sends invalid logon ID
CSU sends 'Invalid Logon ID' CSU disconnects modem CSU returns to WAIT STATE

~3q~ L&~L

If c~l~ing device responds Yalid ID ~nd Automst~c Encoder CSU selects no echo, no prompt Calling dev~ce sends Pager Number, CR
CSU looks up Pager Number Iî Pager ~umber not ~alid CSU sends 'Error Response Mess~ge' CSU disconnect3 CSU returns to WAIT STATE
C~lling device 1nputs Display D~ta CAlling device inputs CR
CSU Formats Page P~ecord Installs Pager Number Installs Date Code Looks up Destination Code, Intalls C~lculates data blocks required o~tains source ID numb~r Installs d~t~
CSU Determines that p~ge ~hould be pl~ced on the NQtion~l System CSU Requests ~nd obtAlns Packet ID Numb~r CSV Stores PAGRXC in CUlRRENT PAGE BUFF:ER
CSU Sends P~ge P~ecord holding mes~ge to TSU
CSU Disconnects modem RSU Receives Page Record Holding message If no PQge P~ecords Holding RSU set page holding time to ~wait Qddition~l blocks If !P~ge Record Holding Time not timed out, l~vsit RSU Connects modem to Centra~ PsSU Tr~ffi~ Route Processor If unable to make connection Repe~t connection attempt If five attempts Connect to Monitor F~cility ~nd report Error RSU Sends all current Holding Records ~, ~3 - 5~ -RSU Awaits hsndsh~ke for Repe~t Request(~
RSU Resets, ~wnit next P~ge Record TRAFFIC ROUTE PROCESSOR
RSU (From RCC Site3 receiYes P~ge Records from RCC site RSU Checks Source Record ID Number I~ not sequential RSU sends 'Repest nnnn Request' to RCC Site E~rocessor RSU receives repested records RSU Checks Destination Code Address If Destination in~ccur~te, generstes 'New Destination Code' Record for tr~nsmlssion to RCC Site Processor RSU Assigns Destination PQcket ID Number to e~ch P~ge Record RSU Sends P~ge Record Ready messags to Uplink RSU
UPLINK PROCESSOR
RSU (To Uplink~ receives Psge Records Re~dy mess~ge RSU Loads Page Records into P~ge Record Block S;~ueue RSU Sends Page Records Re~dy message to next USU
USU Receives P~ge Records Re~dy message from RSU
USU Lo~ds Page Records into ram buffer USU Awaits Tr~nsmission Time loop USU Output P~ge Records in 131ock ~ormQt SATELLITE SYSTEM SENDS TO DOWNLINK

DESTINATION RCC SITE P~OCESSOR
DSU Detects record block with correl!t Destination ID
DSU Sign~ls next DSU to prepare for input DSU Finishes input of P~ge Record DSU Signals 'GOI to next l~SU
DSU Checks and ~orrects received Page Record DSU ~e~uests ~nd obt~ins a Packet ID frorn the local !3SU
DSU Loads Page Record to TSU queue DSIJ Sends Page Record Re~dy to TSU

~3~Ll7?4 DSU Awaits next 'Prepsre to Receive Dnta' from other DSU(s) TS17 WAIT 5TATE periodic~lly ~ends 'tick' to St~tus Service Unit TSU ~eceives P~ge Record Re~dy mess~ge TSU Loads Page Record into buffer TSU Pormats P~ge Record into POC~AG form~t Elnd inst~lls in POCSAG buffer TSU Checks Holding Time If not started, starts Holding Time TSU Aw~its Holding Time time out or P~ext P~ge Record Re2dy messflge TSIJ Sends Transmitter Time P.equest to RCC Tr~nsmitter Con-troller RCC TrQnsmitter Controller sends 'WAIT' or 'GO' If TSU receives WAIT
TSU starts 'Max Wai$ Timer' If M~x W~it Timer times out TSU sends error message to P~SU
RSU receives error message RSU conne~ts to Monitor F~cility RSU sends IR CC Transmitter Controller Out-o~-Ser~ice Mess~ge' TSU Receives 'GO' TSU Sends ~ransmitter On CommQnd Sequence' TSU St~rts 'Max Wait Timer' If T5U re~eives 'Tr~nsmitter FRult' from RCC Tr~nsmitter Controller Or if ~ x WAit Timer times out TSU ~ends 'Transmitter FHult' message to RSU Queue RCC Transmitter Controller sends 'Tr~nsmitter Vn' ackno~ledgement TSU Sends POCSAG buf~er to RCC Transmitter TSU Pnuses TSU Sends 'Transmitter Release' mess~ge to RCC Transmitter Controller ~3g~

TSV Starts M~x Wait Timer TSU St~rts Repeat Control Burst timer If Repe~t Control Burst Timer times out TSU sends 'Tr~nsmitter ReleQse' message ~gain If Max Wait Timer tfmes out TSU sends 'Tr~nssnitter Control F~ult 2' mess~ge to RSU
Queue TSU Sends Page Complete message to ASU
TSU P~eturns to WAIT STATE
END OF SEQUENCE ~

OSU In W~it State, periodic~lly sends 'tick' to SSU
Operator presses 'D' for Displ~y ~ P~ger Control 810ck OSU prompts for Pager Account Number Operator made mistAke, pressed 'D' key by mist~ke Operator presses RET U R N without p~ger number OSU re-dlspl~ys M enu OSU returns to W ait St~te Oper~tor enters P~ger Account Number OSU converts ~ccount num ber to binary record number OSU otains Pager Control Block from hard disk data file OSU displ~ys ~urrent Pager Control Blo~k contents OSU Prompts for 'Chunge of Menu' command Oper~tor selects Menu OSU re-displays Menu OSU returns to lVait ~tate Oper~tor selects Chsnge OSU Prompts for new P~ger C~p~Code Operator does not want to change P~ger Cap Code Operator presses REl`URN with no d~ta OSIJ proceeds to 'Owner System' ~election Oper~tor enters new P~ger CAP Code OSU stores Pager C~p Code in Dsta File (Qwner ~election) OSU Che~ks Owner System If Owner System is '000' (new pager on ~ystem) QSIl installs loc~l ~ystem ID ~s Owner System OSU installs 'New Pager' page type ~n PAGREC
If Owner System is not ~000~ (update exi~ting p~ger) oSu installs ~Update~ page type in PAGREC
OSU Prompts for Current Lo~ation telephone number of 'L' if loc~l OperAtor presses RETURN with no dat~
OSIJ proceeds to 'Current Status' se~tion Operator presses 'L' key OSU installs current system ID as Current Lo~ation Operator enters an Area Code and Exchange of Location City OSU ~lculat~s re~ord position in Service Are~ File OSU obtains destinstlon system ID
OSU installs destin~tion system ID in PAGREC (Current Status) OSC Prompts ~or current status of p~ger Operator presses RET U R N with no d~ta OSU proceeds to 'PA G REC' section Operator cnters new Status Code OSU Instal~ new status code in PAGREC ~PAGREC) OSU Checks PAaREC to see iI u~y ch~nges have ~en made If any changes made OS17 formats Page r ecord Installs Pager Numlber Installs Data Code Obtains Source ID Number Inst~lls data OSU Reques~s snd obtains Pscket ID Number OSV Stores PAGREC in CURRENT PAGE BUFFER

~3~ 4 OSC Sends Page Record Holding message to RSU
RSU Receives PAge Record Holding Message If no Psge Records holdlng RSU set psge holding time to await addition~l blocks If Page Record Holding Time not timed out, wait RSU Connects modem to Central RSU Traffic Route Processor lf unable to make connection Repeat connection attempt If five attempts Connect to Mon~tor Facility snd report error RSU Sends all current Holding Records RSU Awaits handshake for Repeat Request(s) RSU Resets, Awaits next Pa~e Record TRAFFIC ROUTE PROCESSOR
RSU (From RCC Site) receives Page Records from RCC SITE
RSU Checks Source Record ID Number If not sequential RSU sends 'Repeat nnnn Reguest' to RCC Site Porcessor RSU receiYes repeated records RSU Checks Destination Code Address If Destination inaccurste, generates 'New Destination Code' Record for tr~nsmission to RCC Site Processor RSU Assigns Destination Packet ID Number to esch Page Record RSU Sends Page Record Ready message to Uplink RSU
UPLINK PROCESSOR
RSU (To Uplink) receives Page Records Ready message RSU Loads Page Records into Page Record Block Queue RSU Sends Page Records Ready message to next USU
USU Receives Page Reeords Ready message from RSU
USU Loads Page Records into ram buffer USU Awaits Tr~nsmission Time loop USU Output P~ge Records in 810ck format 13~41~9L

SATELLITE SYSTEM SENDS TO DOWNLINK

DESTINATION RCC SITE PROCESSOR
DSU Detects record block with correct De3tin~tion ID
DSU Sign~ls next DSU to prepare ~r input DSU Finishes input of Page Record DSU Signals 'GO' to next DSU
DSU Checks and corrects receiv~d Page Record DSU Requests ~nd obt~ins fl Packet ID from the locsl SSV
DSU Stores PAGREC in CURRENT PA~3: BUFF13R
DSU l Ietermines thAt PAGREC is not ~ Page but an upd~te DSU Sends Pager Update Record ~olding to A5U
ACCOUNTING SERVICE UNIT
ASU Receives P~ger Update Record Holding from DSU
ASU Looks up P~ger Account ~umber in Pager Control Block File ASU Installs Pager Cap Code in Pager Control Block ASU InstRlls Owner Service in Pager Control Block ASU Installs Current Loc~tion in Pager Control Block ASU Installs Current Status in Pager Control 810ck ASU Writes Pager Control Block tv File ASU Returns to W~it State TAE~LE ll PROCESS ~EVEL BACKC;ROUND FUNCTlONS
System operation reguires n number of background functions, and funetJons which have nolt been previously discussed. These functions Qre transparent to the system.
SSU - St~tus Service Unit - The SSV performs monitoring OI
~11 processes in the system and attempts to correct errors if they occur. The process failure detection sequenee depends upon each process in the system 'repor~ing' to the SSliJ peraodic~lly by sending A
~t~ck~o The timers used to determine when ~ process has ~ailed are dependent upon ~n RTC interrupt.

:~3~

-- 6~ --The SSU also m~intains a d~ta t~ble which can be interrogated by a loc~l process. The SSU norm~lly runs in the Utility Processor, ltherefor the STATUS ufflity progr~m Ig c~pable of displQying the SYSTEM status.
SSU Receives 'tick' from external process SSU resets process timer to m~x v~luQ
SSU Receives timer interrupt SSU decrernents all timers If process timer times out SSU requests 'reset' by master o~ faulty process SSU upd~tes st2tus ta~le showing reset If ~nvironment status timer times out SSU interrogQtes the extern~l Status ~onitor I?evice SSU fills in st~tus form SSU checks for out-of-range condition If condition cut-o~-range SSU initiates Serviee Request via P~ge Record SSU Recei~res Packet ID request SSU sends packet ID to requesting process ~SU increments Packet ID eounter If P~cket ID counter ~xceeds 4096 SSU reset P~cket ID counter to 0 END
DSU - Downlink Service Unit - The DSU ~l~o looks ~or p~ge records from the downlink which m~tch the local ~Owner System.~' When one is detected, the r ecord is stored ~nd the ASU is notified.
OSU Detects Page Record with eorrect '~oner System' DSU Requests and receives a P~cket ID nunnber ~rom the SSU
DSU Stores the Page Record DSU Sends 'Page Record Holding Message' to ASIJ
END
ASU - Aecounting Ser~ice Unit - The ASU is responsible for ~3~ 4 posting p~ges to loc~l psger accounts. The DSU will send a P~qge Record e~ch time it detects one on the downlink.
The ASU is ~Iso the local system whenever a Pager ~ te is received (see Additional Operator Functions1.
ASU P~e~eives ~P~ge Record Holding Message' from DSU
ASU Loc~tes the account record in the local account file II the page was local ASU increments the Local Page Counter If the pnge was National ASU increments the National Page Counter END
The present invention has been described in det~il in connection with preferred embodiments. These embodiments, however, are merely ex~mples snd the invention is not restricted thereto. It will be under-stood by those skilled in the art from a readirlg OI the specification that variations ~nd modificstions can be made within the ~cope of the present invention ~s defined by the appended claims.

Claims (28)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A scanning radio paging receiver for a paging system, said receiver comprising-antenna means for receiving a paging signal;
mixer means coupled to said antenna means and to said local oscillator means for mixing said paging signal with a local oscillator signal to produce an IF
signal;
local oscillator means coupled to said mixer means for generating said local oscillator signal;
logic means connected to said local oscillator means for controlling said oscillator means to generate said local oscillator signal at a plurality of predetermined frequencies, wherein said paging receiver is caused to scan said predetermined frequencies;
detector means coupled to the output of said mixer means for receiving said IF signal and detecting said paging signal on any one of said predetermined frequencies and providing a detecting signal when said paging signal is received, said logic means receiving said detection signal and controlling said local oscillator means to lock said receiver onto the current frequency and receive said paging signal;
decoder means for decoding said paging signal to retrieve said paging information; and output means coupled to said decoder means for outputting to a user at least some of said paging information.

2. The scanning radio paging receiver of Claim 1 wherein said logic means is a microprocessor.

3. The scanning radio paging receiver of Claim 1 further comprising energy saver means coupled to said logic means for repetitively switching said paging receiver between a first energy consumption level and a lower energy consumption level, said paying signal being detected by said detector means when said paging receiver is operating at said first energy consumption level.

4. The scanning radio paging receiver of Claim 3 wherein said paging signal includes a first preamble code and a second preamble code, said logic means causing said paging receiver to operate at said first energy consumption level for repetitive predetermined periods of time, said logic means causing said paging receiver to remain at said first energy consumption level when said first preamble code is detected and to return to repetitive operation between said first energy consumption level and said lower energy consumption level if said second preamble code is not detected within a predetermined time after said first preamble code is detected.

5. The scanning radio paging receiver of Claim 1 wherein said logic means controls said local oscillator to cause said receiver to remain tuned to each of said predetermined frequencies for a predetermined dwell time, if said paging signal is not received within said dwell time, said logic means controlling said local oscillator means to cause said receiver to tune to another of said predetermined frequencies.

6. The scanning radio paging receiver of Claim 5 wherein said logic means controls said local oscillator means to cause said receiver to remain tuned to the current frequency beyond said dwell time when said paging signal is received.

7. The scanning radio paging receiver of Claim 5 wherein said receiver remains tuned to the current frequency for a receive time of predetermined duration.

8. The scanning radio paging receiver of Claim 7 wherein the duration of said receive time is determined by the length of said paging signal.

9. The scanning radio paging receiver of Claim 7 wherein the duration of said receive time is a function of said paging signal.

10. The scanning radio paging receiver of Claim 7 wherein the duration of said receive time is determined by the information within said paging signal.

11. The scanning radio paging receiver of Claim 1 wherein said predetermined format of said paging signal comprises a preamble code word of predetermined duration, a synchronization code word and a data packet, said data packet containing said paging information.

12. The scanning radio paging receiver of Claim 11 wherein said receiver means further includes energy saver means coupled to said logic means for repetitively switching said receiver means between a first energy consumption level and a lower energy consumption level at a predetermined rate, the time duration between said first energy consumption level and said second energy consumption level being equal to or less than the duration of said preamble code word, said logic means causing said receiver to remain at said first energy consumption level when said preamble code word is detected and to return to repetitive operation between said first energy consumption level and said lower energy consumption level if said synchronization code word is not detected within a predetermined time after said preamble code word is detected, upon detection of said synchronization code word, said logic means causing said receiver to remain at said first energy consumption level for the duration of said synchronization code word.

13. The scanning radio paging receiver of Claim 12 wherein said synchronization code word includes addressing information which identifies selected receivers, said logic means having address means which identifies said receiver, said logic means also having comparison means for comparing said addressing information in said synchronization code word and controlling said local oscillator means to tune said receiver to another of said plurality of frequencies when said addressing information does not correspond to the identity of said receiver.

14. The scanning radio paging receiver of Claim 12 wherein said synchronization code word includes timing information which identifies the time domain of said data packet, in response to said timing information, said logic means causing said receiver to be at said first energy consumption level during the time domain of said data packet for receiving said data packet.

15. The scanning radio paging receiver of Claim 14 wherein said logic means causes said receiver means to return to said second energy consumption level after said data packet is received.

16. The scanning radio paging receiver of Claim 11 wherein the duration of said preamble code word exceeds the length of time required for said receiver means to scan each of said plurality of frequencies.

17. The scanning radio paging receiver of Claim 1 wherein said predetermined format of said paging signal comprises a first preamble code word of a first predetermined duration and a second preamble code word of predetermined duration, a synchronization code word and a data packet, said data packet containing said paging information.

18. The scanning radio paging receiver of Claim 17 wherein said receiver means further includes energy saver means coupled to said logic means for repetitively switching said receiver means between a first energy consumption level and a lower energy consumption level at a predetermined rate, the time duration between said first energy consumption level and said second energy consumption level being equal to or less than the duration of said first preamble code word, said logic means causing said receiver means to remain at said first energy consumption level when said first preamble code word is detected and to return to repetitive operation between said first energy consumption level and said lower energy consumption level if said second preamble code word is not detected within a predetermined time after said first preamble code word is detected, upon detection of said second preamble code word, said logic means causing said second receiver means to remain at said first energy consumption level for the duration of said second preamble code word.

19. The scanning radio paging receiver of Claim 18 wherein said first preamble code word is formed of a sequence of logic reversals (101010...) repeating for a predetermined period of time at a predetermined rate.

20. The scanning radio paging receiver of Claim 19 wherein said predetermined rate is 218 Hz.

21. The scanning radio paging receiver of Claim 19 wherein said predetermined period of time is 1200 msec.
and said predetermined rate is 500 Hz.

22. The scanning radio paging receiver of Claim 18 wherein said second preamble code word is formed of a sequence of logic reversals (101010...) repeating for a determined period of time at a predetermined rate.

23. The scanning radio paging receiver of Claim 22 wherein said predetermined rate is 256 Hz.

24. The scanning radio paging receiver of Claim 22 wherein said predetermined period of time is 1125 msec.
and said predetermined rate is 256 Hz.

25. The scanning radio paging receiver of Claim 13 wherein said synchronization code word includes addressing information which identifies selected receivers, said logic means having address means which identifies said receiver, said logic means also having comparison means for comparing said addressing information in said synchronization code word and controlling said local oscillator means to tune said receiver to another of said plurality of frequencies when said addressing information does not correspond to the identity of said receiver.

26. The scanning radio paging receiver of Claim 18 wherein said synchronization code word includes time information which identifies the time domain of said data packet, in response to said timing information said logic means causing said receiver means to be at said first energy consumption level during the time domain of said data packet for receiving said data packet.

27. The scanning radio paging receiver of Claim 26 wherein said logic means causes said receiver to return to said second energy consumption level after said data packet is received.

28. The scanning radio paging receiver of Claim 18 wherein the duration of said preamble code word exceeds the length of time required for said receiver means to scan each of said plurality of frequencies.