US 3701024 A
An alarm and information communication system utilizing existing radio broadcast facilities to transmit a warning alarm signal and emergency information to the population in the event of a local or national emergency; the system consists of a warning alarm signal generator as an available program source at the broadcast stations and warning alarm signal and emergency information receivers are provided for use by the general public. The system provides for designation of some radio broadcast stations as "local stations" and some as "regional stations" by Civil Defense or other appropriate authority; each alarm signal and information receiver is adapted to continuously monitor one local and one regional broadcast station whereby, upon reception of a signal of a specified frequency from the local station or reception of a signal from the regional station, the receiver will emit an alarm signal and then broadcast the pertinent information.
Description (OCR text may contain errors)
United States Patent Knowles et al.
[451 Oct. 24, 1972 Filed: Dec. 30, 1970 Appl. No.: 102,844
US. Cl. ..325/364, 325/51, 325/302, 325/303, 325/466, 340/224 Int. Cl. ..H04b 1/16 Field of Search ..325/364, 466, 51, 302, 303; 340/164, 181, 224
References Cited UNITED STATES PATENTS 7/1963 Schneiderrnan ..325/364 X Primary Examiner-Richard Murray Assistant Examiner-Kenneth W. Weinstein Att0mey Cushman, Darby & Cushman  ABSTRACT An alarm and information communication system utilizing existing radio broadcast facilities to transmit a warning alarm signal and emergency information to the population in the event of a local or national emergency; the system consists of a warning alarm signal generator as an available program source at the broadcast stations and warning alarm signal and emergency information receivers are provided for use by the general public. The system provides for designation of some radio broadcast stations as local stations and some as regional stations by Civil Defense or other appropriate authority; each alarm signal and information receiver is adapted to continuously monitor one local and one regional broadcast station whereby, upon reception of a signal of a specified frequency from the local station or reception of a signal from the regional station, the receiver will emit an alarm signal and then broadcast the pertinent information.
7 Claims, 3 Drawing Figures I I/lSl/HL 4d HEM L LOCAL AND NATIONAL WARNING ALARM SYSTEM BACKGROUND OF THE INVENTION The present invention relates to a system for providing a warning alarm signal and emergency information to members of the public in the event of a local or national emergency and also relates to a receiver which automatically receives the alarm signal and emergency information. More particularly, the present invention consists in part of an alarm signal generator which is connected to the control console of a designated existing AM radio broadcast station. In the event of a local or national emergency, the generator is used to generate an alarm signal which is broadcast by the radio station to be followed by a broadcast of emergency information. As part of the system, the invention includes a warning alarm signal and emergency information receiver for use by members of the public. The receiver is adapted to continuously monitor a particular signal frequency from a local station as well as a particular frequency from a regional station. Upon reception by the receiver of a signal of the specified frequency, the receiver will respond and sound an alarm and then automatically function as a conventional radio receiver to transmit emergency information to individuals within audio range of the receiver.
Prior to the present invention, no practical warning system has been proposed that is capable of alerting individuals of either a local or national emergency and at the same time disseminating useful information in the form of precautionary instructions to enable individuals to cope with the emergency. Moreover, there has long been a need for a system that is capable of awakening persons who are asleep to warn them of an impending danger. Such a system is of particular importance in localities where tornadoes or hurricanes occur. Additionally, since many of the present day building structures are designed to specifically keep out external noise, thus rendering the use of the common Civil Defense sirens substantially ineffective, the need for an interior alarm system has become increasingly important.
The warning systems suggested by the prior art have, in general, required the installation of costly equipment into the communication facilities normally found in an individual s residence. Such systems have also required the installation of expensive transmitting equipment to provide a suitable source for an alarm signal.
The system of the present invention overcomes all the foregoing disadvantages, on the one hand, by making use of presently existing radio broadcast facilities and, on the other hand, by providing an inexpensive yet reliable receiving unit which is effective to alert individuals at any hour whether they are asleep or not and to apprise them of an emergency which is either local or national in character.
SUMMARY OF THE INVENTION The system of the present invention includes an alarm signal generator which is installed at designated local and regional radio stations. Such stations would be designated by the Civil Defense authorities or other appropriate authority and would be selected such that the entire nation would be divided up into a plurality of regions and each region would be divided into a plurality of localities having a local radio station capable of broadcasting to all the inhabitants of the locality. A regional radio station would be one that has a higher broadcast power output such that it would be able to broadcast to all of the inhabitants within a specified number of contiguous localities as well as having a reasonably clear. channel frequency.
The system of the present invention also includes alarm signal and emergency information receivers for' location in homes, offices, factories, businesses, schools and the like which is tuned for the reception of a signal from a local station and from a regional station. The receivers are designed so that when the local radio station is in operation and transmitting, the receiver will not respond to the regional station. If a station selected as a local station-is not transmitting, then the receiver will automatically receive and respond to the alarm signal and information transmitted from a regional station.
It is contemplated that in the event of a local emergency, the proper local authority would notify the local radio station of such an emergency and provide the station with emergency information for broadcast. The station operator would turn the alarm signal generator on as a program source to transmit the alarm signal to the receiver units within its broadcast range. Reception of the alarm signal by the receiver units would initiate the emitting of an alarm as an audio outputfromthe receiver unit and, subsequently, upon termination of the transmission of the alarm signal, the receiver unit would broadcast emergency information. The station operator would allow the alarm signal generator to operate for a sufficiently long period of time so as to effectively attract the attention of persons within an audio range of a receiver unit. I
In the event of a national emergency such as an enemy attack, emergency information can be transmitted to the individual, local and regional radio transmitting stations by existing Civil Defense networks. The station operators, both local and regional, would then actuate their respective alarm signal generators for designated periods of time as a program source and then broadcast the pertinent information as it is received from the Civil Defense network. If the local station is not in operation at the time of the emergency, the alarm signal and information would be received automatically from the regional station by the individual receivers.
It is an object of the present invention to provide a system using existing radio broadcast facilities to transmit a warning alarm signal and emergency information to the population in the event of a local or national emergency.
Another object of the present invention is to provide an inexpensive and uncomplex alarm signal generator at designated broadcast stations and inexpensive and reliable warning alarm signal and emergency information receivers for distribution to members of the public.
A further object of this invention is to provide a system wherein an audible alarm would be sounded by the receiver units capable of arousing a sleeping individual.
A still further object of this invention resides in the provision in a system of receiver units capable of continuously monitoring both local and regional broadcast stations, the operation of which is controlled by reception of an alarm signal from one of said stations.
Another object of the present invention resides in the provision of a system having a receiver unit capable of broadcasting emergency information automatically.
Still another object of the present invention is to provide an alarm signal generator for use in existing radio stations which can be inexpensively installed and maintained in operation and which will not interfere with normal broadcasting operations.
Another object of this invention is to provide a warning alarm signal and emergency information receiver that .will remain in a quiescent state until a warning alarm signal is transmitted and received, in which case the receiver will respond and sound an alarm and serve automatically as a radio to receive and relay emergency information.
Another object of this invention is to provide a system in which the alarm signal generator produces the same type of alarm signal thus rendering the receiver unit usable in any locality of the nation.
BRIEF DESCRIPTION OF THE DRAWINGS Further additional objects and advantages will become apparent as consideration is given to the following detailed description of the preferred embodiment of the invention as is illustrated in the accompanying drawings forming part of this specification and wherein:
FIG. 1 is a diagrammatic illustration showing a simplified version of the distribution and relationship between local and regional broadcast stations and alarm receivers comprising the system of the present invention;
FIG. 2 is a schematic illustration of the warning alarm signal generator to be used to produce the alarm signal at a radio broadcast station; and
FIG. 3 is a schematic diagram of the warning alarm signal and emergency information unit.
DETAILED DESCRIPTION OF THE INVENTION With reference to FIG. 1 of the drawings, there is graphically illustrated a simplified example of a regional broadcast area which is made up of three localized broadcast areas 12, 14 and 16. These areas are chosen so that each will have a local broadcast station 18, and 22, respectively, each having a radio broadcast power output capable of reaching all of the inhabitants within its boundary. The regional broadcast radio station 24 must, of course, have a broadcast power output capable of reaching all of the inhabitants within the region made up of areas 12, 14 and 16. In the diagram illustrated, the regional broadcast station is indicated as operating on carrier frequency f and the three local broadcast stations are indicated as operating on carrier frequencies f f and f respectively. It will be noted that each warning alarm signal and emergency information receiver, one of which is indicated at 26, is capable of receiving signals from one regional as well as from one local station. It is within the contemplation of the present invention that the broadcast distribution network illustrated in FIG. 1 will be repeated throughout the nation so as to include all inhabited areas.
With reference now to FIG. 2 there is illustrated in schematic form an arrangement for generating an alarm signal consisting of a sine wave oscillator 28, a
square wave oscillator 30 and a modulator 32. The sine wave oscillator 28 preferably operates at a frequency f to be selected in the range of SOD-2,000 Hz and the square wave oscillator operates at a frequency f}, chosen within the range of 2-20 Hz. The sinusoidal signal from oscillator 28 is passed through line 34 to modulator 32. The square wave signal from oscillator 30 is passed through line 36 to modulator 32. The sinusoidal signal is modulated by the square wave signal to produce a modulated signal that is passed through line 38 to the broadcast facilities of the radio station. Direct current power to operate the alarm signal generator would be derived from the standard 60 Hertz station power system using a conventional rectifier and filter contained within the generator. Provision would be made to prevent the alarm signal generator from being turned on accidentally so as to preclude the inadvertent broadcast of the alarm signal. I
Referring now to FIG. 3 of the drawings there is illustrated in schematic form a'waming alarm signal and emergency information unit for use in the system of the present invention. Generally, the unit comprises two radio signal receivers of conventional design which operate in the standard radio broadcast band (540 to 1,600 KHz) and switching means such as gating devices which are actuated in response to an electrical potential to activate a loudspeaker when the warning alarm signal is broadcast from the appropriate radio station. More particularly, there is provided a local receiver 40 which is tuned to a previously designated local broad cast station and a regional receiver 42 which is tuned to receive broadcasts from a previously designated regional radio station normally operating on a 24 hour basis. Both receivers 40 and 42 would be pretuned by a local distributor or any competent service technician to the proper stations. Tuning controls would not be provided in order to prevent unintentional detuning of the receivers. Direct current power to operate the warning alarm signal and emergency information receiver unit would be derived from the commercial 60 Hertz power system using a conventional rectifier and filter contained within the unit, or a suitable battery source for use when commercial power is not available.
The circuitry of the unit is arranged so that when the unit is connected to a power source (not shown) both receivers 40 and 42 are on and functioning to monitor their respective predetermined frequencies. In the event that the local receiver 40 is receiving signals generated by a previously selected local radio station, a reference voltage such as the automatic gain control voltage (the direct voltage obtained from rectification and filtering of the amplified station signal) from the receiver will be established across line 44 to operate a signal gate 46 so that the output of receiver 40 will be passed through line 48, signal gate 46 to lines 50, 52 and 54 and cut off the output of the regional receiver 42 which would ordinarily be present on line 56. When the local receiver 40 is not receiving a signal, there will be no reference voltage across line 44 and the circuitry of the signal gate 46 will function to pass the output of the regional receiver 42 from line 56 through the signal gate 46 to lines 50, 52 and 54. It will be understood that the output of the signal gate 46 to lines 50, 52 and 54 is normally the program signal from the local broadcast transmitter when that station is operating or the normal program signal from the regional broadcast transmitter when the local station is not operating.
The output from signal gate 46 which is the normal broadcasting program of the local station is passed through line 52 to a signal gate 56, the output of which is connected by line 58 and through switch 60 and by line 64 to an audio power amplifier 62. Under normal conditions, signal gate 56. operates to block passage of the output from signal gate 46 to amplifier 62 with the switch 60 in the alarm position illustrated in solid lines in FIG. 3. With switch 60 in the alarm position, that is connecting line 58 to line 64, the unit is in a squelched mode and loudspeaker 78 does not emit any sound.
In the event a warning alarm signal is transmitted by the local broadcast station (or by the regional broadcast station when the local broadcast station is not operating), the output of signal gate 46 is passed through line 50 to filter 66 where the signal is passed through a narrow band pass filter with center frequency f, and then to amplifier 68 and then to demodulator 70, the output of which is the low frequency square wave which was used to modulate the signal from the sine wave oscillator 28 at the broadcast station. The square wave signal is passed to a counter 72 where when a desired specific number of pulses of the square wave have occurred, the voltage output of the counter is passed over line 74 to signal gate 56 to open the gate and allow the output of signal gate 46 to pass through line 52, gate 56 line 58 switch 60 and line 64 to the input of the audio power amplifier 62. If a visual alarm is desired in addition to or instead of the audible alarm, the output of counter 72 may be passed over a line to a visual alarm 76. The output of the audio amplifier 62 is passed to loudspeaker 78. The sound emitted from the loud speaker 78 is a tone of frequency f, which is square wave modulated at a lower frequency The full output from the receiver 40 (or receiver 42) will be present at the input of the audio amplifier 62 as long as switch 60 is in the alarm position as illustrated in FIG. 3
v in solid lines. If the user chooses to reduce the loudspeaker to a lower level, he may shift switch 60 to the position shown in dotted lines in FIG. 3 which is the monitor position and then set the audio level by means of the potentiometer 80. In order to preclude the possibility of making the unit ineffective as an alarm by inadvertently leaving switch 60 in the monitor position with the audio gain reduced to zero, an additional resistor 82 is placed in series with the potentiometer 80 to ground so that the gain cannot be reduced to zero. With switch 60 in the monitor position, the normal broadcasting program material would be heard issuing from speaker 78 which would also indicate to the user that the switch 60 was not in the alarm position. Of course, in the event the alarm signal is broadcast while the switch is in the monitor position, the same will be received and emitted from the speaker. With switch 60 in the alarm position and when an alarm signal is received, signal gate 56 will continue to pass the signal from line 52 to line 58 and produce an audio output until switch 84 which is mechanically ganged with switch 60 is placed in the monitor position, at which time a DC. voltage supplied over line 86 will be passed over line 88 to signal gate 56 causing the gate to shift and block ofi signals from line 52. Thus signal gate 56 is reset so that when switches and 84 are returned to the alarm position, the unit will be placed in its squelched mode ready for the reception of a subsequent alarm signal.
With the switches 60 and 84 in the alarm position upon termination of the transmission of the alarm signal by the radio station, emergency information will be received and passed to the amplifier and speaker without any adjustment being required of the unit.
It is possible that occasional noise pulses or tone bursts near the center frequency f, of the filter 66 might, over a considerable period of time, produce enough pulses to the counter 72 to cause shifting of signal gate 56 and resultant audio output. To prevent such an occurrence, counter 72 may be equipped with a very low frequency square wave oscillator having a period somewhat greater than the time requiredfor the counter 72 to operate signal gate 56 when an alarm signal is detected. This oscillator will reset the counter 72 on each cycle and prevent accumulation of a count on extraneous signals and possible resultant false operation.
From the foregoing it will be understood that the system of the present invention provides a broadcasting network using a plurality of local stations and a smaller number of regional stations which in effect function as a back up network in the event that one or more local stations are not operating. By using presently existing telecommunication systems, the system of the present invention can be utilized to alert the populations of various localities of emergencies which are only of local concern. In addition, the regional broadcast network may be resorted to in order to alert citizens of a regional or even national emergency. In the latter situations, of course, the local broadcast stations would also broadcast the alarm signal and information if operatmg.
The foregoing embodiment illustrates the principles of the present invention which is capable of modifications without departing from such principles. The invention accordingly includes all variations encompassed within the scope of the appended claims.
What is claimed is:
1. A local and national alarm and information communication system comprising:
alarm signal generating means for supplying an alarm signal of a predetermined frequency to be broadcast by designated local and regional radio stations,
receiving units for use by individuals in the system,
each of said units including a first receiving means for receiving said alarm signal and audio signals broadcast by said designated local radio station and a second receiving means for receiving said alarm signal and audio signals broadcast by said designated regional radio station, first switching means connected to said first and second receiving means, said first switching means including a signal gate, means for supplying a reference voltage from said first receiving means to said signal gate, second switching means movable between a first and second position in response to reception of said alarm signal by a said receiving unit, said second switching means being connected to said signal gate and said signal gate being shiftable between a first position wherein signals are passed only from said first position wherein signals are passed only from said first receiving means to said second switching means when said local radio station is broadcasting and a second position in response to the absence of a broadcast signal from said local radio station wherein signals are passed only from said second receiving means to said second switching means,
audio broadcasting means connected to said second switching means and operating to broadcast said alarm signal and information when said second switching means is in said second position.
2. The system as claimed in claim 1 wherein said second switching means is a signal gate and said alarm signal passed through said first switching means is fed through a narrow band pass filter to an amplifier and to a demodulator connected to the output of said amplifier, said demodulator being connected to a pulse counter providing a voltage output for shifting said signal gate from said first position to said second position upon sensing of a predetermined number of pulses by said counter.
3. The system as claimed in claim 2 wherein the output of said counter actuates a visual alarm.
4. The system as claimed in claim 1 wherein said audio broadcasting means comprises an audio amplifier and speaker connected to said amplifier.
5. The system as claimed in claim 2 wherein a manual switch is provided between said second switching means and said audio broadcasting means, said manual switch being shiftable between one position wherein said second switching means is connected to said audio broadcasting means and another position wherein said audio broadcasting means is connected through a potentiometer to said first switching means.
6. The system as claimed in claim 5 wherein said manual switch is mechanically linked with a second switch in a circuit for providing a resetting voltage to said second switching means so that when said manual switch is moved to said other position said second switch will close said circuit and said second switching means will be reset.
7. A receiving unit for use by persons in a local and national alarm warning system comprising:
first receiving means for receiving an alarm signal 0 a specified frequency and audio signals broadcast by a first radio transmitter, second receiving means for receiving said alarm signal and audio signals broadcast by a second radio transmitter, first switching means including a signal gate and means for supplying a reference voltage from said first receiving means to said signal gate, said signal gate being connected to said first and second receiving means, second switching means including a signal gate movable between a first, circuit breaking position and a second, circuit closing position, a narrow band pass filter connected to said first switching means, an amplifier and demodulator connected in series to said filter, a pulse counter connected to said demodulator for providing a voltage output for moving said signal gate of said second switching means from said first position to said second positlon upon sensing of a predetermined switching means and operating to broadcast said alarm signal and information when said second switching means is in said second position.