CA1290083C - Analog "blue" signal detector - Google Patents
Analog "blue" signal detectorInfo
- Publication number
- CA1290083C CA1290083C CA000568166A CA568166A CA1290083C CA 1290083 C CA1290083 C CA 1290083C CA 000568166 A CA000568166 A CA 000568166A CA 568166 A CA568166 A CA 568166A CA 1290083 C CA1290083 C CA 1290083C
- Authority
- CA
- Canada
- Prior art keywords
- blue
- signal
- detector
- indication
- analog
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M3/00—Automatic or semi-automatic exchanges
- H04M3/08—Indicating faults in circuits or apparatus
Abstract
Abstract of the Disclosure An analog "blue" signal detector detects when the amplitude of a spectral component of an input signal associated with a blue signal exceeds a given level for a predetermined period of time to provide an indication that the blue signal is present. When the blue signal is removed, the indication is rapidly removed also.
Description
~.2~
AN~L9G ~BLUE" SIGNAL DETECTOR
aok~ound o~ the Invention The present invention rel~te~ to ~ault detection, and more particu~arly to ~n analog "blue" det.ctor ~or identi*ylng ~ ~ault ~ignal at ~ down tream location in ~ digital telecommunications Gystem ~rom the fault.
In a digital telecommunication network, su~h a~ a common carrier telephone ~y~te~, a hierarchy o~
digital signal3 ln~lud~3 variously defined ~requen~y formats, ~uch a~ a DS3 45 ~Bit sign~l, for thQ
tran~mi~sion o~ digital lnformation. An alarm ~ignal 0 i8 u~ed to transmit down~trea~ in the digltal network the infor~ation that a 6y8tem ~ailure ~a~ b~en detected. The alarm signal i~ var~ously callad an Alanm ~nd~ation Sign~l (AIS), an Al~rm Inh~bit 8ignal, Xeep ~live 8ign~1 or ~ Blue 8i~nal ~B iæ
~cribed 1~ ~ell Co~munic~tlo~ Re~earch T~chn~cal R~fer~nc~ TR-~SY-000191 "Ala~m Indic~tion S~gn~l R~guiro~ent~ 2nd Ob~cti~n. ~he purpose ~f ~he AIS
i8 to $nh1bit th~ generation o~ unproductive and po~ibly ~ ad~ng al~rms downstr~am fxo~ ~h~ s~urc~
O~ ~h~ ~ailure, ~n~ ~o açtiv~t~ statu~ lndioations and to ~od~Yy carrier ~larm report~ ~ ~k~t ~he locatlon ~`
~290q~
o~ ~ ~ailure may be ~ore readily Ascert~ined, For th~
DS3 format the AIS i~ ~ DS3 signal with information bit8 eet to alternating ones and zeros with the bit following the control bit of sach block in th~ ~ ~rame a one. The framing bitB ~r~ set ~sr valid ~ra~ing, the parity bit are ~et to indicate parlty, the two X
blts ar~ set to be the a~e, ~nd the ~tuf~ indlcator bits are ~et to zero~ ~iving what ~B called "gtuck stuffing~O
In order to make u~e o~ the AIS it i5 nec~ssary to detect ~hen ~uch a signal i~ pressnt. Digit~l techniqueR entail co~plet~ decoding, clock recovery, ~rame ~etect~on, etc. of the DS3 ~ignal~. Th~
r~sult6 in a compl x ~ircuit for deterting a ~ignal 1~ which occurs rel tiv~ly rarely. What i~ d sired is a ~imple ~ircuit ~or detecting the AIS without the need ~or co~plete deeoding of the DS3 ~ign 1~.
Summary ~f the Invent~o~
Accordingly th~ pre6ent inve~tion provldeR ~n analog "blue" ~ignal detector whi~h looks for spe~tral line~ ln ~n input d$gital ~ignal character~tic ~f a blue signal. Tha input digital ~ignal i~ i~put to a bandpa~s filter centered about th~ characteri~tlc ~pectral c~nt~nt o~ the blue ~ignalL The output o tha bandpa~ ~ilter 1B i~PUt tO an anvelops dets~tor to gener~t~ a D.C. l~vel. Th~ D.~ vel 1B input to ~ slow ~ttack/~ast de~ay network to provid~ an output ~ndic~tion of the prssQnce of the ~lue ~ignal when a give~ l~vel is ~xce~ded.
~ he ob~ect~, adv~ntage~ and novel ~eatur~s o~ ~ha pr~ent ~nvention wil~ be ~ppar~nt ro~ thQ followlng detaile~ descr~t~on when ~ad in ~on~un~tion with the ~ppendQd ~la~ attached drawing.
.29(~
~rie~ Des ription o~ the Drawing Fig. 1 is a block diagram vi~w of a simple analog blue signal detector acc:ording to the present invention.
Fig. 2 i~ a blocX diagram view o~ a qua~i-sya~chronous analog blue ~ignal detector according to the present lnvention.
~igO 3 is a block ~agraffl v~ew 3~ ~ ~ynchronou~
analog blue 6ignal ~etQctor according to the pra~ent inventioTl.
Fig. 4A 'I6 a graphic Yiew o~ t~e ~reguency ~pectrum for a normal digital input ~ignal.
~?ig. 4B i~ a graphic view o:E the fregue~c:y ~pectrum for a blue Elgnal.
Fig. 5 is a schematic diagram YilE~W ~f ~n ~n~log 1~ blue ~ignal detector ccording to the present invention.
aescription 0~ the ~referred~odimen~
Referring now to Fig. 1 . n input digital signal DS3 ~ pas~ed lchrough a bandpa~s filter 10 centered at ~requency wh$ch i~ Ghar~cl:eri~t~c o~ a blue ~ignal.
~he detected spac:tral line ~ro~ thQ bandpa~ gilter 10 whsn the blue signal i~ present i~ input to an 25 ~nv~lopQ dete;:tor 12. ~h~ output o~ the ~nYelope d~t~ctor 12 is input tc~ a ~low att~ck/fast d~cay network 14. Sinc~ a ~3ignal patt~ nilar to th8 blue signal m~y occur oc:ca~lonally ~ring ~ norm~l DS3 l; an indlc~tiorl o~ the ~1UQ ~ign~ d~sired 30 only 1~ the pattern i~ pres~nt or a predet~rmin~d period of 't;im80 I~ a blue aignal ~5 pr~s~nt long ~nough, a logic output s~gnal :Erom th~ l;low lZ90083 ttack/fast decay network 14 ind~cate~ such pre~ nce.
When the blue signal i~ removed the logic output ~lgnal rom the 810w attack/fa6t decay network 14 quickly changes from a blue signal pre~ent indication 5 to ~ normal ~ign~l lndication. Thi~ $mple ~r~ion detect~ a ~ingle ~pectral line or a number of closed ~paced ~pectral llnes. ~he fllter may be a c~ystal filter, ~ ceramic re~onator, ~C or the llXe.
For qua~-synchronou~ op~r~tion ~ æhown in Fig. 2 the Prequency selectivity i~ dlRtribut~d between the bandp3~ filter 10 and a 1OWP~QR ~ilter 16 at the input ~nd sutput, r2~p~ctively, o~ the envelope ~etector 12'. The ~ynchronous ~r~$on o~ Fig. 3 reguires ~ ~lock input CL~ which i~ divided by N by a divider 18, The CLX/N i~ ~ixed with th~ i~put ei~nal and input to th~ input ~iltsr 10' w~ich ~ay ~2 either a bandpas~ filter or a lowpa~ ~ilter. The synohronou~ vereion can detect clos~ly ~paced ~pectral l~ne~ or spectral lines which are ~lightly displa ed ~ro~ integer 6ubmul~iple~ of the DS3 input clock.
Further, ~ever~l detector~ for ~veral dl~erent ~pectral lineE ~ay b~ AN~ed together ~or enhanced reliability.
As ~hown in Figs. 4~ and 4B ln normal communications the DS3 sl~n~l ~t ~h~ input has a *r~quency ~pectrum center~d around on~-hal~ ~he DS3 clock r~te, or 22 N~z. However, ~h~n thsre 1~ an up~trQam eo~municatlon~ Qrror th~ blue ~ignal i3 generatsd ~hi~h h~ ~ pronounc~d ~requency ~pe~tru~
componen~ c~nter~d at 11 ~z. Ther~ Bt$ll ~XiBt~ o a component cent~rQd ak 22 M~z, but thi~ co~ponent 18 ~uch w~aker ~han ~h~ co~pon~nt c~ntered a~ 11 MHZ.
~ rrlng no~ to Fig. 5 th~ DS3 input ~ign~
lnput ~ia ~ppropriat~ i~pedance mAtching impedancas to ~ ~:9~V8~
two tuned freguency envelope detæctorE; 20, 22, 3uc:h as ~C1330~ manufactured J:y Notorola Inc. The ~rst ~tector 20 i~ tuned to the blue ~ignal ~requency, l.e., 11 P~Hz, by ~ ~irst ad~u~table LC tank circult 24 S connected to the tan~ terminals, ~nd the ~econd detector 22 1~ tuned to 22 ~Hz by ~1 6econd ad~u~table ~C tanX c~rcult 26 connected to itB tank terminals.
~rhe emitter outputs of the ~etector6 20, 22 ar~
conrlected to respective lowpa6~ RC ~ilter~ 28, 30.
10 ~rhe output of the ~econd lowpas~ Iilter 30 i~ input to the inverting input terminal of a comparator 3~. To pro~ide a ~low attack when a blue ~ignal i6 prf~ent, long time s:on~tant RC c$rcuit 34 i6 conneated in ~erie6 with t:he output og the ~lr~t lowpass ~ilter 28 15 ~nd the output o~ the long tis~le con6tant RC c~rouit 1 oonnected to the noninvertlng input ter~inal o~ the compar~tor 32. A fa~t off circuit 36 i~ connected in p~rallel with t~e long Sime constant RC circuit 34.
Th~ output of the comparator 32 i8 a log~c output ~ignal indicating the pre6ence or ab~ence of th~ blue ~ignal. The output o~ the oomp~rator 32 al o ser~e6 to drive an LED 38 to present a visual indication of the pre onc~ o~ ~he blu~ signal.
In operation ths r~spective tuned oircuit~ 24, 26 ar~ tu~ed to th~ appropriat~ frQ~uen~i2s ~nd tha ~o~pari~on l~v~1 fro~ ~he se~ond d~tactor 22 1~
ad~u~ted v~a a lev~l res~tor 40 betw~n ~h~ a~Ster output and th~ 6econ~ lowpas ~ilter 30O Wh~n a vnlld D~3 ~lgnal 1~ present, th~ a~litud~ of any ~requency ~o~ponent at 11 ~Hz 1~ ~uch la~ than that at 22 ~z ana th~ ~tput of th~ ~con~ d~te~tor 22 i~ ~or~
po~it~v~ than tha output o~ the ~irat detector 20.
~h~ output o~ th~ oo~parator 3~ i~ a positlv~ logic lavel, hold.~.ng tha LED 3B cut off, lndic~tiv~ of the ~90~3 pre~ence of a vAlid DS3 signal. W~en the l~lue ~ignal i~ pre~nt, then ths amplitude o~ the freguency component at 11 MEIz i~ greater th~n tha~ ~t 22 I~Hz and the output of the 6~econd detector ie ~ore negative 5 than the output of the fir~t detector. HoweYer, dus to the RC time co2l~tant circuit 34 this change irl the output of the f irst detector 2 0 i~ not lnput i~mediately to the comparator 32. 6nlen the capas~itor of the RC time constant c:ircuit 34 charges to ~
10 voltage great~r th~n that at the output of the ~cond detector 22, t~en the output of the co~nparator 32 s:hange~ from a positive logic l~vel to ~ ~egative level indicating th~ presence of the blu~ ~ignal.
Aleo the l;~D 38 i8 biased on to prov~de a Yi~ual 15 indication o~ the blue ~ignal pr~sence. The tran~i~tor o~ the ~a~t off clrcuit 36 provid~ a fa~t discharg~ path for th~ capacitor o~ the RC ti~ne con tant circuit 34 when the blue ~ B r~moved and the normal DS3 ~gnal returns so that the output 2 o o~ the comparator 3 2 ~witche6 logic 12vel ~r~m negativa to positive ~rtu~lly in~tantaneou~ly with the removal of thQ blue ~ignal.
Thu~ the present irlvention provide ~n ~nalog "blue" signal detector by comparing thQ a~pli~ud~ of the 6pectral line corresponding tc~ the blu~ ~ignAl with the amplitude o~ the ~pectr~l lin~ corre~ponding to a nor~al sign~l ~o provide an ind~r~tion of th~
prQ~enc~ o~ th~ blue ~i~nal.
AN~L9G ~BLUE" SIGNAL DETECTOR
aok~ound o~ the Invention The present invention rel~te~ to ~ault detection, and more particu~arly to ~n analog "blue" det.ctor ~or identi*ylng ~ ~ault ~ignal at ~ down tream location in ~ digital telecommunications Gystem ~rom the fault.
In a digital telecommunication network, su~h a~ a common carrier telephone ~y~te~, a hierarchy o~
digital signal3 ln~lud~3 variously defined ~requen~y formats, ~uch a~ a DS3 45 ~Bit sign~l, for thQ
tran~mi~sion o~ digital lnformation. An alarm ~ignal 0 i8 u~ed to transmit down~trea~ in the digltal network the infor~ation that a 6y8tem ~ailure ~a~ b~en detected. The alarm signal i~ var~ously callad an Alanm ~nd~ation Sign~l (AIS), an Al~rm Inh~bit 8ignal, Xeep ~live 8ign~1 or ~ Blue 8i~nal ~B iæ
~cribed 1~ ~ell Co~munic~tlo~ Re~earch T~chn~cal R~fer~nc~ TR-~SY-000191 "Ala~m Indic~tion S~gn~l R~guiro~ent~ 2nd Ob~cti~n. ~he purpose ~f ~he AIS
i8 to $nh1bit th~ generation o~ unproductive and po~ibly ~ ad~ng al~rms downstr~am fxo~ ~h~ s~urc~
O~ ~h~ ~ailure, ~n~ ~o açtiv~t~ statu~ lndioations and to ~od~Yy carrier ~larm report~ ~ ~k~t ~he locatlon ~`
~290q~
o~ ~ ~ailure may be ~ore readily Ascert~ined, For th~
DS3 format the AIS i~ ~ DS3 signal with information bit8 eet to alternating ones and zeros with the bit following the control bit of sach block in th~ ~ ~rame a one. The framing bitB ~r~ set ~sr valid ~ra~ing, the parity bit are ~et to indicate parlty, the two X
blts ar~ set to be the a~e, ~nd the ~tuf~ indlcator bits are ~et to zero~ ~iving what ~B called "gtuck stuffing~O
In order to make u~e o~ the AIS it i5 nec~ssary to detect ~hen ~uch a signal i~ pressnt. Digit~l techniqueR entail co~plet~ decoding, clock recovery, ~rame ~etect~on, etc. of the DS3 ~ignal~. Th~
r~sult6 in a compl x ~ircuit for deterting a ~ignal 1~ which occurs rel tiv~ly rarely. What i~ d sired is a ~imple ~ircuit ~or detecting the AIS without the need ~or co~plete deeoding of the DS3 ~ign 1~.
Summary ~f the Invent~o~
Accordingly th~ pre6ent inve~tion provldeR ~n analog "blue" ~ignal detector whi~h looks for spe~tral line~ ln ~n input d$gital ~ignal character~tic ~f a blue signal. Tha input digital ~ignal i~ i~put to a bandpa~s filter centered about th~ characteri~tlc ~pectral c~nt~nt o~ the blue ~ignalL The output o tha bandpa~ ~ilter 1B i~PUt tO an anvelops dets~tor to gener~t~ a D.C. l~vel. Th~ D.~ vel 1B input to ~ slow ~ttack/~ast de~ay network to provid~ an output ~ndic~tion of the prssQnce of the ~lue ~ignal when a give~ l~vel is ~xce~ded.
~ he ob~ect~, adv~ntage~ and novel ~eatur~s o~ ~ha pr~ent ~nvention wil~ be ~ppar~nt ro~ thQ followlng detaile~ descr~t~on when ~ad in ~on~un~tion with the ~ppendQd ~la~ attached drawing.
.29(~
~rie~ Des ription o~ the Drawing Fig. 1 is a block diagram vi~w of a simple analog blue signal detector acc:ording to the present invention.
Fig. 2 i~ a blocX diagram view o~ a qua~i-sya~chronous analog blue ~ignal detector according to the present lnvention.
~igO 3 is a block ~agraffl v~ew 3~ ~ ~ynchronou~
analog blue 6ignal ~etQctor according to the pra~ent inventioTl.
Fig. 4A 'I6 a graphic Yiew o~ t~e ~reguency ~pectrum for a normal digital input ~ignal.
~?ig. 4B i~ a graphic view o:E the fregue~c:y ~pectrum for a blue Elgnal.
Fig. 5 is a schematic diagram YilE~W ~f ~n ~n~log 1~ blue ~ignal detector ccording to the present invention.
aescription 0~ the ~referred~odimen~
Referring now to Fig. 1 . n input digital signal DS3 ~ pas~ed lchrough a bandpa~s filter 10 centered at ~requency wh$ch i~ Ghar~cl:eri~t~c o~ a blue ~ignal.
~he detected spac:tral line ~ro~ thQ bandpa~ gilter 10 whsn the blue signal i~ present i~ input to an 25 ~nv~lopQ dete;:tor 12. ~h~ output o~ the ~nYelope d~t~ctor 12 is input tc~ a ~low att~ck/fast d~cay network 14. Sinc~ a ~3ignal patt~ nilar to th8 blue signal m~y occur oc:ca~lonally ~ring ~ norm~l DS3 l; an indlc~tiorl o~ the ~1UQ ~ign~ d~sired 30 only 1~ the pattern i~ pres~nt or a predet~rmin~d period of 't;im80 I~ a blue aignal ~5 pr~s~nt long ~nough, a logic output s~gnal :Erom th~ l;low lZ90083 ttack/fast decay network 14 ind~cate~ such pre~ nce.
When the blue signal i~ removed the logic output ~lgnal rom the 810w attack/fa6t decay network 14 quickly changes from a blue signal pre~ent indication 5 to ~ normal ~ign~l lndication. Thi~ $mple ~r~ion detect~ a ~ingle ~pectral line or a number of closed ~paced ~pectral llnes. ~he fllter may be a c~ystal filter, ~ ceramic re~onator, ~C or the llXe.
For qua~-synchronou~ op~r~tion ~ æhown in Fig. 2 the Prequency selectivity i~ dlRtribut~d between the bandp3~ filter 10 and a 1OWP~QR ~ilter 16 at the input ~nd sutput, r2~p~ctively, o~ the envelope ~etector 12'. The ~ynchronous ~r~$on o~ Fig. 3 reguires ~ ~lock input CL~ which i~ divided by N by a divider 18, The CLX/N i~ ~ixed with th~ i~put ei~nal and input to th~ input ~iltsr 10' w~ich ~ay ~2 either a bandpas~ filter or a lowpa~ ~ilter. The synohronou~ vereion can detect clos~ly ~paced ~pectral l~ne~ or spectral lines which are ~lightly displa ed ~ro~ integer 6ubmul~iple~ of the DS3 input clock.
Further, ~ever~l detector~ for ~veral dl~erent ~pectral lineE ~ay b~ AN~ed together ~or enhanced reliability.
As ~hown in Figs. 4~ and 4B ln normal communications the DS3 sl~n~l ~t ~h~ input has a *r~quency ~pectrum center~d around on~-hal~ ~he DS3 clock r~te, or 22 N~z. However, ~h~n thsre 1~ an up~trQam eo~municatlon~ Qrror th~ blue ~ignal i3 generatsd ~hi~h h~ ~ pronounc~d ~requency ~pe~tru~
componen~ c~nter~d at 11 ~z. Ther~ Bt$ll ~XiBt~ o a component cent~rQd ak 22 M~z, but thi~ co~ponent 18 ~uch w~aker ~han ~h~ co~pon~nt c~ntered a~ 11 MHZ.
~ rrlng no~ to Fig. 5 th~ DS3 input ~ign~
lnput ~ia ~ppropriat~ i~pedance mAtching impedancas to ~ ~:9~V8~
two tuned freguency envelope detæctorE; 20, 22, 3uc:h as ~C1330~ manufactured J:y Notorola Inc. The ~rst ~tector 20 i~ tuned to the blue ~ignal ~requency, l.e., 11 P~Hz, by ~ ~irst ad~u~table LC tank circult 24 S connected to the tan~ terminals, ~nd the ~econd detector 22 1~ tuned to 22 ~Hz by ~1 6econd ad~u~table ~C tanX c~rcult 26 connected to itB tank terminals.
~rhe emitter outputs of the ~etector6 20, 22 ar~
conrlected to respective lowpa6~ RC ~ilter~ 28, 30.
10 ~rhe output of the ~econd lowpas~ Iilter 30 i~ input to the inverting input terminal of a comparator 3~. To pro~ide a ~low attack when a blue ~ignal i6 prf~ent, long time s:on~tant RC c$rcuit 34 i6 conneated in ~erie6 with t:he output og the ~lr~t lowpass ~ilter 28 15 ~nd the output o~ the long tis~le con6tant RC c~rouit 1 oonnected to the noninvertlng input ter~inal o~ the compar~tor 32. A fa~t off circuit 36 i~ connected in p~rallel with t~e long Sime constant RC circuit 34.
Th~ output of the comparator 32 i8 a log~c output ~ignal indicating the pre6ence or ab~ence of th~ blue ~ignal. The output o~ the oomp~rator 32 al o ser~e6 to drive an LED 38 to present a visual indication of the pre onc~ o~ ~he blu~ signal.
In operation ths r~spective tuned oircuit~ 24, 26 ar~ tu~ed to th~ appropriat~ frQ~uen~i2s ~nd tha ~o~pari~on l~v~1 fro~ ~he se~ond d~tactor 22 1~
ad~u~ted v~a a lev~l res~tor 40 betw~n ~h~ a~Ster output and th~ 6econ~ lowpas ~ilter 30O Wh~n a vnlld D~3 ~lgnal 1~ present, th~ a~litud~ of any ~requency ~o~ponent at 11 ~Hz 1~ ~uch la~ than that at 22 ~z ana th~ ~tput of th~ ~con~ d~te~tor 22 i~ ~or~
po~it~v~ than tha output o~ the ~irat detector 20.
~h~ output o~ th~ oo~parator 3~ i~ a positlv~ logic lavel, hold.~.ng tha LED 3B cut off, lndic~tiv~ of the ~90~3 pre~ence of a vAlid DS3 signal. W~en the l~lue ~ignal i~ pre~nt, then ths amplitude o~ the freguency component at 11 MEIz i~ greater th~n tha~ ~t 22 I~Hz and the output of the 6~econd detector ie ~ore negative 5 than the output of the fir~t detector. HoweYer, dus to the RC time co2l~tant circuit 34 this change irl the output of the f irst detector 2 0 i~ not lnput i~mediately to the comparator 32. 6nlen the capas~itor of the RC time constant c:ircuit 34 charges to ~
10 voltage great~r th~n that at the output of the ~cond detector 22, t~en the output of the co~nparator 32 s:hange~ from a positive logic l~vel to ~ ~egative level indicating th~ presence of the blu~ ~ignal.
Aleo the l;~D 38 i8 biased on to prov~de a Yi~ual 15 indication o~ the blue ~ignal pr~sence. The tran~i~tor o~ the ~a~t off clrcuit 36 provid~ a fa~t discharg~ path for th~ capacitor o~ the RC ti~ne con tant circuit 34 when the blue ~ B r~moved and the normal DS3 ~gnal returns so that the output 2 o o~ the comparator 3 2 ~witche6 logic 12vel ~r~m negativa to positive ~rtu~lly in~tantaneou~ly with the removal of thQ blue ~ignal.
Thu~ the present irlvention provide ~n ~nalog "blue" signal detector by comparing thQ a~pli~ud~ of the 6pectral line corresponding tc~ the blu~ ~ignAl with the amplitude o~ the ~pectr~l lin~ corre~ponding to a nor~al sign~l ~o provide an ind~r~tion of th~
prQ~enc~ o~ th~ blue ~i~nal.
Claims (5)
1. An analog "blue" signal detector comprising:
means for separating a spectral component of an input signal associated with a blue signal; and means for comparing the amplitude of the spectral component with a given level to provide an indication that the blue signal is present.
means for separating a spectral component of an input signal associated with a blue signal; and means for comparing the amplitude of the spectral component with a given level to provide an indication that the blue signal is present.
2. An analog "blue" signal detector as recited in claim 1 further comprising:
means for determining the presence of the blue signal for a predetermined period of time prior to providing the indication; and means for rapidly removing the indication after the blue signal is removed.
means for determining the presence of the blue signal for a predetermined period of time prior to providing the indication; and means for rapidly removing the indication after the blue signal is removed.
3. An analog "blue" signal detector comprising:
a bandpass filter to which a digital signal is input, the bandpass filter being centered about a frequency characteristic of the presence of a blue signal, to output a spectral component of the digital signal;
means for detecting the envelope of the spectral component from the bandpass filter; and means for comparing the envelope with a given level to provide an indication of the presence of the blue signal after the blue signal has been present for a predetermined period of time.
a bandpass filter to which a digital signal is input, the bandpass filter being centered about a frequency characteristic of the presence of a blue signal, to output a spectral component of the digital signal;
means for detecting the envelope of the spectral component from the bandpass filter; and means for comparing the envelope with a given level to provide an indication of the presence of the blue signal after the blue signal has been present for a predetermined period of time.
4. A detector as recited in claim 3 wherein the comparing means includes means for rapidly removing the indication when the blue signal is no longer present.
5. A detector as recited in claim 3 further comprising a lowpass filter between the output of the detecting means and the input of the comparing means to convert the envelope to a d.c. level for comparison with the given level.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US6027387A | 1987-06-10 | 1987-06-10 | |
| US060,273 | 1987-06-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1290083C true CA1290083C (en) | 1991-10-01 |
Family
ID=22028472
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000568166A Expired - Fee Related CA1290083C (en) | 1987-06-10 | 1988-05-31 | Analog "blue" signal detector |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5123032A (en) |
| CA (1) | CA1290083C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5339335A (en) * | 1992-12-15 | 1994-08-16 | Elsag International B.V. | Method and apparatus for digitally processing and filtering signals in industrial control applications |
| DE69938098T2 (en) * | 1999-05-05 | 2009-02-05 | Freescale Semiconductors, Inc., Austin | Method and system for transmitting data on a serial bus |
| US9628507B2 (en) * | 2013-09-30 | 2017-04-18 | Fireeye, Inc. | Advanced persistent threat (APT) detection center |
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| US3404231A (en) * | 1965-01-05 | 1968-10-01 | Bell Telephone Labor Inc | Framing of pulse code transmission systems by use of an added tone signal |
| GB1308078A (en) * | 1969-03-07 | 1973-02-21 | Licentia Gmbh | Data transmission systems |
| US3706854A (en) * | 1971-01-14 | 1972-12-19 | Us Navy | Performance monitor unit for frequency multiplexed hf modems |
| US3757315A (en) * | 1971-08-30 | 1973-09-04 | Rollins Protective Services Co | Diversity rf alarm system |
| US3863030A (en) * | 1972-06-01 | 1975-01-28 | Gte Automatic Electric Lab Inc | Pcm tone receiver using digital spectrum analysis |
| NL7211675A (en) * | 1972-08-26 | 1974-02-28 | ||
| US3936801A (en) * | 1974-09-12 | 1976-02-03 | Bell Telephone Laboratories, Incorporated | Multifrequency signal receiver timing circuit |
| US3947769A (en) * | 1974-10-23 | 1976-03-30 | Hoffman Electronics Corporation | Threshold correction system in FSK transmissions |
| US3953674A (en) * | 1975-04-04 | 1976-04-27 | Nasa | Telemetry Synchronizer |
| US3978407A (en) * | 1975-07-23 | 1976-08-31 | Codex Corporation | Fast start-up adaptive equalizer communication system using two data transmission rates |
| US4045620A (en) * | 1976-05-10 | 1977-08-30 | Conrac Corporation | Digital tone detector |
| US4042789A (en) * | 1976-05-17 | 1977-08-16 | Stromberg-Carlson Corporation | Tone combination detector and coincidence timer circuit |
| FR2358061A1 (en) * | 1976-07-08 | 1978-02-03 | Ibm France | EQUALIZATION METHOD AND DEVICE USING THE FOURIER TRANSFORM |
| US4606045A (en) * | 1982-08-02 | 1986-08-12 | Trw Inc. | Method and apparatus for detecting an equalizer training period in a receiving-end modem |
| US4494240A (en) * | 1983-01-03 | 1985-01-15 | Codex Corporation | Modem end of message detector |
| JPH0619904B2 (en) * | 1983-05-20 | 1994-03-16 | 日本ビクター株式会社 | Waveform processing method for digital signals |
| US4534043A (en) * | 1983-06-27 | 1985-08-06 | Racal Data Communications, Inc. | Test tone detector apparatus and method modem using same |
| US4584690A (en) * | 1984-05-07 | 1986-04-22 | D.A.V.I.D. Systems, Inc. | Alternate Mark Invert (AMI) transceiver with switchable detection and digital precompensation |
| US4626629A (en) * | 1984-12-14 | 1986-12-02 | Gte Communication Systems Corporation | Digital multifrequency signal receiver |
| EP0211995B1 (en) * | 1985-08-28 | 1989-11-15 | International Business Machines Corporation | Method and arrangement for detecting the presence of a training signal in a modem receiver |
-
1988
- 1988-05-31 CA CA000568166A patent/CA1290083C/en not_active Expired - Fee Related
-
1989
- 1989-07-20 US US07/383,279 patent/US5123032A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US5123032A (en) | 1992-06-16 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |