U.S. patent number 3,864,674 [Application Number 05/315,856] was granted by the patent office on 1975-02-04 for emergency radio warning system.
This patent grant is currently assigned to Criminalistics, Inc.. Invention is credited to Stephen J. Martin, Robert Worsham.
United States Patent |
3,864,674 |
Worsham , et al. |
February 4, 1975 |
Emergency Radio Warning System
Abstract
A radio warning system includes emergency condition sensors for
actuating respective radio transmitters which are modulated by
identification generators to produce identification signals which
contain one or more frequencies selected from groups of four
frequencies in accordance with selected identifying binary coded
decimal digits. A transmitted identification signal is detected by
a radio receiver in a mobile unit or central dispatch location to
operate a memory and a decimal display unit to indicate the
existence and location of the emergency condition until reset by an
operator. The transmitters are deactuated by a timing circuit after
a predetermined period. Delay circuitry prevents operation of the
memory and decimal display unit until the identification signal has
been received for a predetermined continuous duration.
Inventors: |
Worsham; Robert (Opa Locka,
FL), Martin; Stephen J. (Miami, FL) |
Assignee: |
Criminalistics, Inc. (Opa
Locka, FL)
|
Family
ID: |
23226358 |
Appl.
No.: |
05/315,856 |
Filed: |
December 18, 1972 |
Current U.S.
Class: |
340/530; 340/8.1;
340/13.29; 340/12.51; 375/242; 340/539.18; 340/539.1 |
Current CPC
Class: |
G08B
25/016 (20130101) |
Current International
Class: |
G08B
25/01 (20060101); H04b 007/00 (); H04q
011/02 () |
Field of
Search: |
;325/64,18
;340/224,171,171PF,171R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Yusko; Donald J.
Attorney, Agent or Firm: O'Brien; Anthony A.
Claims
What is claimed is:
1. An emergency radio warning system comprising:
a sensor operable upon an emergency condition;
means operated by the sensor in response to an emergency condition
for generating and transmitting a radio signal having a
predetermined frequency;
means for modulating the generating and transmitting means with an
identification signal having one or more simultaneously generated
frequencies selected from a group of four frequencies in accordance
with an identifying binary coded decimal digit;
said modulating means including one or more oscillator circuits,
each having in circuit a tuning fork filter resonant at a
respective selected frequency;
means for receiving the modulated radio signal and detecting the
identification signal;
said receiving and detecting means including four tuning fork
filters resonant at the respective four frequencies; and
means responsive to the identification signal for displaying the
decimal digit corresponding to the detected identification signal
to indicate the location of the emergency condition.
2. A system as defined in claim 1 wherein said receiving and
detecting means includes
delay means for preventing the operation of the displaying means
for a predetermined continuous duration of the presence of an
identification signal.
3. An emergency radio warning system comprising:
a sensor operable upon an emergency condition;
means operated by the sensor in response to an emergency condition
for generating and transmitting a radio signal having a
predetermined frequency;
means for modulating the generating and transmitting means with an
identification signal having one or more simultaneously generated
frequencies selected from a group of four frequencies in accordance
with an identifying binary coded decimal digit;
timing means for terminating the operation of the generating and
transmitting means a predetermined duration after initiation of the
operation of the generating and transmitting means;
means for receiving the modulated radio signal and detecting the
identification signal;
said receiving and detecting means including four filter means for
detecting the respective four frequencies, each of said four filter
means being non-responsive to signals of less than a predetermined
continuous duration;
memory means actuated by the identification signal for producing
output signals corresponding to the identifying binary coded
decimal digit until reset by an operator; and
means responsive to the output signals of the memory means for
displaying the decimal digit corresponding to the identifying
binary coded decimal digit to indicate the location of the
emergency condition.
4. A system as defined in claim 3 which includes:
an arming circuit interposed between the sensor and the generating
and transmitting means, said arming circuit including means for
latching in response to the operation of the sensor to operate the
generating and transmitting means;
means between the latching means and the transmitting means,
operated by the timing means, for terminating the operation of the
generating and transmitting means;
means for resetting the latching means; and
means for indicating the latched condition of the arming
circuit.
5. A system as defined in claim 3 wherein:
each of the four filter means includes a tuning fork filter and
delay means responsive to the output of a respective filter for
producing a respective delayed signal after at least a
predetermined continuous duration of the presence of an
identification signal; and
the memory means includes four binary memory means each responsive
to a respective delayed signal for producing an output signal.
6. An emergency radio warning system comprising
a sensor operable upon an emergency condition;
means operated by the sensor in response to an emergency condition
for generating and transmitting a radio signal having a
predetermined frequency;
means for modulating the generating and transmitting means with an
identification signal having one or more frequencies selected from
a group of four frequencies in accordance with an identifying
binary coded decimal digit;
means for receiving the modulated radio signal and detecting the
identification signal;
said receiving and detecting means including four filter means for
detecting the respective four frequencies, each of said four filter
means being non-responsive to signals of less than a predetermined
continuous duration;
memory means actuated by the identification signal for producing
output signals corresponding to the identifying binary coded
decimal digit until reset by an operator;
means responsive to the output signals of the memory means for
displaying the decimal digit corresponding to the identifying
binary coded decimal digit to indicate the location of the
emergency condition;
a relay having normally open contacts for applying voltage from a
source to the generating and transmitting means when a coil of the
relay is energized;
a transistor having an emitter and collector connected in series
with the coil and the source;
a resistor;
a first silicon controlled rectifier having its anode and cathode
connected in series with the resistor and the source;
means connecting the sensor to a control electrode of the first
silicon controlled rectifier for initiating conduction through the
first silicon controlled rectifier in response to an emergency
condition;
means connected across the resistor for biasing the base of the
transistor into conduction in response to the conduction of the
first silicon controlled rectifier to operate the generating and
transmitting means;
a unijunction transistor timing circuit connected across the
resistor;
a second silicon controlled rectifier having its anode and cathode
connected between the base of the transistor and a reverse bias
potential;
means connecting the unijunction transistor timing circuit to a
control electrode of the second silicon controlled rectifier for
terminating conduction of the transistor to terminate the operation
of the generating and transmitting means; and
means actuated by an operator for momentarily interrupting the
source.
7. An emergency radio warning system comprising
a sensor operable upon an emergency condition;
means operated by the sensor in response to an emergency condition
for generating and transmitting a radio signal having a
predetermined frequency;
means for modulating the generating and transmitting means with an
identification signal having one or more frequencies selected from
a group of four frequencies in accordance with an identifying
binary coded decimal digit;
timing means for terminating the operation of the generating and
transmitting means a predetermined duration after initiation of the
operation of the generating and transmitting means;
means for receiving the modulated radio signal and detecting the
identification signal;
said receiving and detecting means including four filter means for
detecting the respective four frequencies, each of said four filter
means being non-responsive to signals of less than a predetermined
continuous duration;
each of the four filter means including a tuning fork filter and
delay means responsive to the output of a respective filter for
producing a respective delayed signal after at least a
predetermined continuous duration of the presence of an
identification signal;
memory means actuated by the identification signal for producing
output signals corresponding to the identifying binary coded
decimal digit until reset by an operator;
said memory means including four binary memory means each
responsive to a respective delayed signal for producing an output
signal;
means responsive to the output signals of the memory means for
displaying the decimal digit corresponding to the identifying
binary coded decimal digit to indicate the location of the
emergency condition; and
timing means responsive to the operation of a binary memory means
for disabling the receiving and detecting means and for enabling
the operation of the displaying means after the periods of
operation of all the four delay means.
8. A system as defined in claim 7 wherein the timing means for
disabling the receiving and detecting means and for enabling the
displaying means includes:
a unijunction transistor timing circuit having a predetermined
delay which is greater than the difference between the delays of
any two of the four delay means;
means for sensing the operation of memory means to operate the
unijunction timing circuit;
a relay having a contact arm for normally engaging a first contact,
said contact arm disengaging the first contact and engaging a
second contact when a coil of the relay is energized, said contact
arm connected to a voltage source, said first contact connected to
the receiving and detecting means, said second contact connected to
the displaying means;
a silicon controlled rectifier having its anode and cathode in
series with the coil; and
means connecting an output of the unijunction transistor timing
circuit to a control electrode of the silicon controlled rectifier
for energizing the coil after the predetermined delay of the
transistor timing circuit to disable the receiving and detecting
means and for enabling the displaying means.
9. A sensing and transmitting system for generating a radio signal
modulated by identification signals for identifying the location of
an emergency condition comprising:
a sensor operable upon an emergency condition;
means operated by the sensor in response to an emergency condition
for generating and transmitting a radio signal having a
predetermined frequency;
means for modulating the generating and transmitting means with an
identification signal having one or more simultaneously generated
frequencies selected from a group of four frequencies in accordance
with an identifying binary coded decimal digit;
said modulating means including one or more oscillator circuits
each having in circuit a tuning fork filter resonant at a
respective selected frequency; and
timing means for terminating the operation of the generating and
transmitting means a predetermined duration after initiation of the
operation of the generating and transmitting means.
10. A system as defined in claim 9 which includes:
an arming circuit interposed between the sensor and the generating
and transmitting means,
said arming circuit including means for latching in response to the
operation of the sensor to operate the generating and transmitting
means and to operate the timing means;
manual means for resetting the latching means; and
means for indicating the latched condition of the arming
circuit.
11. A sensing and transmitting system for generating a radio signal
modulated by identification signals for identifying the location of
an emergency condition, comprising:
a sensor operable upon an emergency condition;
means operated by the sensor in response to an emergency condition
for generating and transmitting a radio signal having a
predetermined frequency;
means for modulating the generating and transmitting means with an
identification signal having one or more frequencies selected from
a group of four frequencies in accordance with an identifying
binary coded decimal digit;
said modulating means including one or more oscillator circuits
each having in circuit a tuning fork filter resonant at a
respective selected frequency;
a relay having normally open contacts for applying voltage from a
source to the generating and transmitting means when a coil of the
relay is energized;
a transistor having an emitter and collector connected in series
with the coil and the source;
a resistor;
a first silicon controlled rectifier having its anode and cathode
connected in series with the resistor and the source;
means connecting the sensor to a control electrode of the first
silicon controlled rectifier for initiating conduction through the
first silicon controlled rectifier in response to an emergency
condition;
means connected across the resistor for biasing the base of the
transistor into conduction in response to the conduction of the
first silicon controlled rectifier to operate the generating and
transmitting means;
a unijunction transistor timing circuit connected across the
resistor;
a second silicon controlled rectifier having its anode and cathode
connected between the base of the transistor and a reverse bias
potential;
means connecting the unijunction transistor timing circuit to a
control electrode of the second silicon controlled rectifier for
terminating conduction of the transistor to terminate the operation
of the generating and transmitting means; and
means actuated by an operator for momentarily interrupting the
source.
12. A receiving and displaying system which senses and displays an
identifying decimal digit from a radio signal which is modulated by
an identification signal containing one or more frequencies
selected from a group of four frequencies in accordance with a
binary coded decimal digit which corresponds to the identifying
decimal digit to indicate the location of an emergency condition,
comprising
means for receiving the modulated radio signal and detecting the
identification signal;
four filter means responsive to the respective four frequencies in
the identification signal for producing parallel signals
corresponding to the binary coded decimal digit;
each of said four filter means being non-responsive to signals of
less than a predetermined continuous duration;
means responsive to the signals produced by the four filter means
for displaying the identifying decimal digit to indicate the
location of the emergency condition;
four memory means actuated by the respective signals from the four
filter means for continuing the operation of the displaying means
to display the decimal digit after the termination of the radio
signal until reset by an operator; and
timing means responsive to the operation of a memory means for
disabling the receiving and detecting means and for enabling the
operation of the displaying means after the periods of operation of
all the four delay means.
13. A system as defined in claim 12 wherein the timing means for
disabling the receiving and detecting means and for enabling the
displaying means includes:
a unijunction transistor timing circuit having a predetermined
delay which is greater than the difference between the delays of
any two of the four delay means;
means responsive to the actuating of any of the four memory means
for operating the unijunction timing circuit;
a relay having a contact arm for normally engaging a first contact,
said contact arm disengaging the first contact and engaging a
second contact when a coil of the relay is energized, said contact
arm connected to a voltage source, said first contact connected to
the receiving and detecting means, said second contact connected to
the displaying means;
a silicon controlled rectifier having its anode and cathode in
series with the coil; and
means connecting an output of the unijunction transistor timing
circuit to a control electrode of the silicon controlled rectifier
for energizing the coil after the predetermined delay of the
transistor timing circuit to disable the receiving and detecting
means and to enable the displaying means.
14. A system as defined in claim 12 which includes:
four memory means actuated by the respective signals from the four
filter means for continuing the operation of the displaying means
to display the decimal digit after the termination of the radio
signal until reset by an operator.
15. A system as defined in claim 12 wherein each of the four filter
means includes:
a tuning fork filter, and
a delay means between the respective filter and the displaying
means for preventing the operation of the displaying means for a
predetermined continuous duration of the presence of an
identification signal.
16. A system as defined in claim 12 wherein each of the four filter
means includes a tuning fork filter.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to emergency warning systems which
are used to detect and warn appropriate authorities or personnel of
emergency conditions such as crime, fire, pollution, or failure of
critical equipment. This invention particularly concerns a remote
emergency warning system which utilizes radio signals to indicate
the existence and location of an emergency condition.
2. Description of the Prior Art
Present warning systems for alerting law enforcement personnel or
police of a crime involve the use of a telephone system to call and
alert the police department. The police department then contacts
the nearest patrol car through the use of a radio communication
system by a dispatcher. This procedure involves much time, with 5
to 10 minutes being typical in some cases, from the moment the
emergency occurs to the moment that help is dispatched. Certain
systems that automatically call the police department are being
banned in many municipalities due to the fact that they tend to jam
telephone switchboards and cause confusion. Further, the automatic
calling systems are not under the direct control of the law
enforcement agency, but represent systems and devices installed by
individuals or companies using very unreliable alarm systems, prone
to false alarms.
In addition to the warning systems using the telephone system,
there are a number of prior art warning systems which utilize radio
waves. Examples of prior art warning or communication systems which
utilize radio signals are described in U.S. Pat. No. 3,581,208, No.
3,618,067, and No. 3,629,837. The prior art radio warning systems
generally have one or more deficiencies, such as being subject to
noise and interfering signals, being complex and expensive,
interfering with other use of the frequency channels, etc.
SUMMARY OF THE INVENTION
An object of the present invention is a new and improved radio
warning system utilizing identification modulation signals for
readily identifying the location of an emergency condition.
A further object of the invention is a new and improved sensing and
transmitting system for generating a radio signal modulated by
identification signals for warning and identifying the location of
an emergency condition.
A still further object of the invention is a new and improved
receiving and displaying system for sensing an identification
modulated radio signal and for indicating the location of an
emergency condition.
In accordance with these and other objects, an embodiment of the
invention includes an emergency condition sensor operating a radio
transmitter modulated by an indentification signal generator which
produces one or more frequencies selected from a group of four
frequencies in accordance with an identifying binary coded decimal
digit. A radio receiver detects the indentification signal and
operates a decimal display in accordance with the frequencies in
the indentification signal to indicate the location of the
emergency condition.
Further, a sensing and transmitting system includes facilities for
terminating the operation of the transmitter after a predetermined
period.
A receiving and display system for a radio warning signal
containing selected frequencies in accordance with an identifying
binary coded decimal digit includes facilities for detecting the
binary coded decimal digit and operating a decimal display to
indicate the decimal digit. Further, the receiving and display
system includes a memory for operating the decimal display after
the radio warning signal has been terminated. Still further, the
receiving and display system has delay facilities for preventing
operation of the decimal display until the identifying signal has
been received for a predetermined continuous duration.
Other objects and advantages of the present invention will become
apparent from the following description taken in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram illustrating the utilization of a radio warning
system in accordance with the invention;
FIG. 2 is a block diagram of a sensing and transmitting system for
producing radio signals modulated by one or more frequencies
selected from a group of four frequencies in accordance with an
identifying binary coded decimal digit;
FIG. 3 is a block diagram of a receiving and displaying system for
detecting the signals from the system of FIG. 2 and displaying the
indentifying decimal digit;
FIG. 4 is a detailed circuit diagram of arming and timing circuits
in the system shown in FIG. 2;
FIG. 5 is a detailed circuit diagram showing an identification
generator for producing identifying modulation signals in the
system shown in FIG. 2;
FIG. 6 is a detailed diagram of a circuit for detecting an
identification signal in the receiving and displaying system shown
in FIG. 3;
FIG. 7 is a detailed diagram of a memory, driving and displaying
circuits in the receiving and displaying system shown in FIG.
3;
FIG. 8 shows a timing circuit for delaying the operation of the
displaying circuit of FIGS. 3 and 7 and for terminating the
operation of a radio receiver of FIG. 3; and
FIG. 9 illustrates the allocation of identification numbers for
different uses in a radio warning system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As is illustrated in FIG. 1, a sensing and transmitting unit 10
produces a radio signal in response to an emergency condition. The
radio signal produced by the unit 10 is modulated by one or more
frequencies which are selected from groups of four frequencies in
accordance with a binary coded decimal (BCD) number which
identifies the location and/or nature of the emergency condition.
Receiving and detecting units 11--11 are located in a central
dispatch station 12, a vehicle 13 and/or a helicopter 14. The
receivers 11--11 may share antennas and radio frequency amplifying
and detecting functions with the normal transceiver units used for
communication by using directional couplers and other appropriate
circuitry. Each of the receivers 11--11 detect the indentification
frequencies and operate respective decimal displays 15--15 to show
the decimal number and thus indicate the location of the emergency
condition.
Referring next to FIG. 2 there is shown a block diagram of
transmitting circuitry in the unit 10 which is actuated by the
operation of a sensor 17. The sensor 17 may be any electronic
device which can be used to detect a condition. For example, the
sensor 17 may be a switch device operated by (1) a teller in a
bank, (2) the breaking of a window, (3) excessive heat, (4)
pollution or (5) failure of critical equipment. An arming circuit
18 is triggered and latched by the operation of the sensor 17 to
initiate operation of a radio frequency (RF) transmitter 19 and a
BCD identification signal generator 20 to transmit radio warning
signals from an antenna 21. The BCD generator 20 applies the
identification signal to the audio or modulation input of the
transmitter 19. A timing circuit 22 is also activated by the arming
circuit 18 to disable the arming circuit 18 and terminate operation
of the RF transmitter 19 and BCD generator 20 after a predetermined
period of operation. The period is selected to avoid unduly
interfering with other use of the RF frequency channel. The arming
circuit 18 remains latched and disabled until reset by an operator,
such as a police officer, momentarily opening a switch 23 to
interrupt current from a battery 24 which is charged by a charger
25. A lamp 26 indicates that the arming circuit 18 has been
actuated and latched. A lamp 27 indicates that the RF transmitter
19 and BCD generator 20 are operating. The arming circuit 18 and
the timing circuit 22 are more fully described hereinafter under
the heading "Arming Circuit and Transmitter Timing Circuit". The
BCD generator 20 is more fully described hereinafter under the
heading "BCD Generator". The RF transmitter 19 may be any suitable
commercially available radio transmitter which can operate at a
selected radio frequency under the appropriate government
regulations. A frequency modulated transmitter is preferred, but a
suitable amplitude modulated transmitter may also be employed. It
is contemplated that the identification signals from the BCD
generator 20 contain frequencies in the audio range, however,
frequencies not within the audio range may be used where a suitable
RF transmitter is employed.
A block diagram of circuitry for receiving, detecting and
displaying a warning signal generated by the transmitting circuitry
of FIG. 2 is shown in FIG. 3. The radio warning signal is received
by an RF receiver 32 from an antenna 31. The RF receiver 32 may be
any radio receiver, or channel in a multichannel receiver, which is
tuned to the radio frequency transmitted by the warning
transmitters 19 of FIG. 2. The receiver 32 detects the
indentification signal and applies it to the input of a BCD
frequency detector 33. The BCD detector 33 produces an output
corresponding to a first binary coded decimal digit in the
indentification signal after the identification signal has been
received for a predetermined continuous duration. The first binary
coded decimal digit is applied to a memory circuit 34 and a driving
circuit 35 which operates a decimal display 36. If the
indentification signal contains a second binary coded decimal
digit, a detector 33a, a memory circuit 34a, a driving circuit 35a,
and a decimal display 36a are employed to detect and display the
second digit. A timing circuit 37 senses the presence of an
identification number in the memories 34 and 34a to disable the
receiver 32 and to enable the driving circuits 35 and 35a and the
displays 36 and 36a after a predetermined delay. Also, an audio
alarm 38 is actuated by the timing circuit 37 after the
predetermined delay. The duration of delay by the timing circuit 37
insures that the identification signal is detected and applied to
the memories 34 and 34a prior to disablement of the receiver 32 and
operation of the displays 36 and 36a. The displays 36 and 36a and
the audio alarm 38 remain activated until current from a battery 39
is momentarily interrupted by the opening of a manual reset switch
40. The BCD detector 33 is more fully described hereinafter under
the heading "BCD Detector". The memory circuit 34, driving circuit
35 and display 36 are more fully described hereinafter under the
heading "Memory, Driver, and Display" . The timing circuit 37 is
more fully described hereinafter under the heading "Receiver Timing
Circuit".
ARMING AND TIMING CIRCUITS
The arming circuit 18 is shown in detail in FIG. 4. The operation
of the sensor 17 by an emergency condition applies a triggering
signal to a voltage divider consisting of resistors 42 and 43 and
thus to a control electrode of a silicon controlled rectifier (SCR)
44. The SCR is connected in series with a resistor 45 and the
battery 24 so that a voltage is produced across the resistor 45
when the SCR 44 is triggered into conduction. The voltage on the
resistor 45 is applied by a resistor 47 to the base of a transistor
48 to render the transistor 48 conductive. The transistor 48 is
connected in series with the battery 24 and a coil 49 of a relay
50. When the coil 49 is energized by conduction of the transistor
48, contacts 51 of the relay 50 are closed to apply an energizing
voltage from the battery 24 to a terminal 53 which energizes the RF
transmitter 19, BCD generator 20 and lamp 27 of FIG. 2. Also, the
voltage across the resistor 45 is applied by a resistor 54 to a
base of a transistor 55 connected in series with the battery 24 and
the lamp 26 to render the transistor 55 conductive and energize the
lamp 26. The SCR 44 and the lamp 26 remain activated until the
arming circuit is manually reset by the momentary opening of the
reset switch 23 which interrupts the current from the battery
24.
The timing circuit 22 is also energized by the voltage produced
across the resistor 45. Current through a variable resistor 57
charges a capacitor 58 to trigger a unijunction transistor 59
connected in series with a resistor 60 across the resistor 45 after
a predetermined delay. When the unijunction 59 is triggered, the
increase in voltage across the resistor 60 produces a pulse through
a capacitor 62 connected to a control electrode of a SCR 63. The
SCR 63, when triggered by the pulse through capacitor 62, connects
the base of the transistor 48 to a reverse bias potential or ground
to render the transistor 48 non-conductive. This deenergizes the
relay 50 to terminate operation of the RF transmitter 19, the BCD
generator 20 and the lamp 27 of FIG. 2. A diode 64 connected across
the coil 49 provides a bypass for induced current when transistor
48 is rendered non-conductive. The values of the capacitor 58 and
the variable resistor 57 are selected to produce the predetermined
period of operation of the transmitter 19 and BCD generator 20. The
SCR 63 is delatched when the reset switch 23 is opened.
BCD GENERATOR
Referring to FIG. 5 there is shown a circuit diagram of a single
digit BCD generator 20 which is energized by the application of a
voltage to terminal 53 by the arming circuit 18 of FIG. 4. Inverter
amplifiers 66-69 with positive feedback through respective filters
71-74 and resistors 76-79 operate as individual oscillators
producing frequencies F1, F2, F3, and F4. As shown the inverter
amplifiers 66-69 may be a Quad NAND gate package 80, energized by
the application of the voltage to terminal 53, with the inputs of
each gate connected together. The RCA CD 4011AE has been found to
work well in this circuit. The filters 71-74 are preferably a
narrow bandwidth type, such as miniature piezoelectric coupled
tuning fork filters for audio signalling, series EMR-S manufactured
by the MURATA Corporation of America. High Frequency decoupling
capacitors 81-84 prevent the oscillators from producing higher than
audio frequencies. Capacitors 86-89 couple the outputs of the
amplifiers 66-69 to a terminal 70 connected to the audio input of
the RF transmitter of FIG. 2.
The oscillators are selectively disabled to produce only one or
more of the frequencies F1, F2, F3, and F4 in accordance with a
selected binary coded decimal digit which identifies the
transmitter and the location of the emergency condition. The BCD
generator shown in FIG. 5 generates an identification signal which
contains simultaneously generated frequencies in accordance with a
single binary coded decimal digit. If an identification signal is
to include two or more binary coded decimal digits, additional
oscillator circuits substantially similar to that of FIG. 5 are
added. The additional circuits would produce additional groups of
frequencies which are different from the group of frequencies F1-F4
but simultaneously generated with frequencies F1-F4. For example,
100 indentifying decimal digits 00 through 99 may be provided by
using two groups of four frequencies F1-F4 and F5-F8.
BCD DETECTOR
FIG. 6 shows in detail the BCD detector circuit 33 of the circuit
shown in FIG. 3. The audio output of the RF receiver 32 is applied
in parallel to filters 91-94. The filters 91-94 are selected to
pass the respective frequencies F1-F4. The filters 91-94, like the
filters 71-74 of FIG. 5, are preferable narrow bandpass type
filters, such as miniature piezoelectric coupled tuning fork
filters, to prevent erroneous operation by noise and voice signals.
The outputs of the filters 91-94 are amplified by the amplifiers
96-99 which are biased linearly by respective resistors 101-104.
Like the amplifiers 66-69 of FIG. 5, the amplifiers 96-99 may be a
Quad NAND gate package 100 with the inputs of each gate connected
together.
The outputs of the amplifiers 96-99 are applied to respective
voltage rectifying and doubling circuits including capacitors
106-109, diodes 111-114 and 116-119, capacitors 121-124 and
resistors 126-129. During negative half cycles of the identifying
signals from the amplifiers 96-99, the respective capacitors
106-109 are charged by current through the diodes 111-114. During
positive half cycles of the identifying signals, the diodes 116-119
conduct to transfer the charges on the respective capacitor 106-109
to the capacitors 121-124 and produce output voltages on terminals
131-134 which are about double the maximum amplitudes of the
respective identifying signals. The resistors 126-129 provide loads
for the diodes 116-119. The capacitors 121-124 are relatively large
D.C. filtering capacitors while the capacitors 106-109 are
relatively small coupling capacitors. This produces a delay in the
voltage on the terminals 131-134 reaching maximum amplitudes. This
delay is selected, taking into consideration the bandpass of the
filters 71-74, to prevent the operation of the memory circuit 34 of
FIG. 3 until the one or more of signals F1-F4 have been present for
a predetermined continuous duration to prevent spurious noise
signals or voice signals from erroneously actuating the memory
circuit 34. The selection of the values of the components in the
rectifying and doubling circuits is made to produce the
predetermined delay taking into consideration the different
frequencies of operation.
The BCD detector circuit of FIG. 6 will only detect one binary
coded decimal digit. Additional circuits substantially similar to
FIG. 6 are used to sense additional digits in an indentification
signal. For example, one additional circuit which senses
frequencies F5, F6, F7, and F8 would provide for the detection of
100 decimal numbers 00 through 99.
MEMORY, DRIVER AND DISPLAY
Referring to FIG. 7 there is shown in detail the memory circuit 34,
display driving circuit 35, and the decimal display 36. The outputs
of the BCD detector 33 on terminals 131-134 are applied by
respective diodes 136-139 to control electrodes of SCR's 141-144.
If a sufficiently large signal is present on any of the terminals
131-134, the respective SCR is triggered to produce a voltage
across a respective resistor 146-149. The SCR's 141-144 remain
activated to retain the binary coded decimal digit until the
circuit is reset by interruption of voltage on a terminal 150. The
voltage or voltages across the resistors 146-149 are applied to
terminals 151-154 of the display driving circuit 35 which operates
the decimal display 36. The driving circuit 35 is selected to
produce appropriate energizing voltages for the particular decimal
display in response to a binary coded decimal digit input. For
example, the display 36 may be a seven element type, such as RCA
model DR 2000. RCA CD 2500E may be used to drive the RCA display. A
switch 155 is provided for testing the display 36.
As previously explained, the driving circuit 35 and display 36 are
prevented by the timing circuit 37 (FIG. 3) from operating for a
predetermined duration after the memory 33 has received a binary
digit. Diodes 156-159 are connected to the resistors 146-149 in an
OR gate arrangement to apply a signal to terminal 160 when any of
the SCR's 141-144 are actuated. This operates the timing circuit 37
(FIG. 3) which, after the predetermined duration, applies an
operating voltage to a terminal 177. A transistor 181 connected
between the terminal 177 and the power inputs of the driving
circuit 35 and the display 36 is controlled by a zener diode 182
and bias resistor 183 to provide a regulated voltage to the driving
circuit 35 and the display 36.
RECEIVER TIMING CIRCUIT
Referring to FIG. 8 there is shown the timing circuit 37 for
disabling the RF receiver 32 of FIG. 2 and enabling the driving
circuit 35 and display 36. When a binary digit has been received by
the memory 34, a voltage on the terminal 160 is applied to a series
connected resistor 161 and capacitor 162. When the capacitor 162
has sufficiently charged, a unijunction transistor 163 is operated
to produce a voltage across a resistor 165. A capacitor 167
connected to the resistor 165 applies a pulse to a control
electrode of an SCR 166 which is connected in series with the
battery 39 and a coil 168 of a relay 169. Before the coil 168 is
energized, a contact arm 171 engages a contact 172 to apply voltage
from the battery 39 to a terminal 178 and filtering capacitor 179.
The terminal 178 supplies voltage to the RF receiver 32. After the
coil 168 has been energized by the conduction of SCR 166, the
contact arm 171 disengages the contact 172 and engages a contact
173 to apply a voltage from the battery 39 to the terminal 177 and
the audible alarm 38. Thus, the RF receiver 32 is disabled and the
driving circuit 35 and display 36 are enabled. The delay of the
timing circuit 37 is selected to be greater than any difference in
the delays of any two of the outputs of the BCD detector 33 so that
the display 36 will indicate the correct identification digit. The
alarm 38 and the display 36 remain activated until the reset switch
40 is manually opened to interrupt the current to the SCR 166 and
the SCR's 141-144 (FIG. 7) in the memory 33.
OPERATION
In operation of the radio warning system, sensing and transmitting
units 10 (FIG. 1) are placed in locations where it is desired to
monitor or sense a condition which may require immediate attention.
When such a condition occurs, the respective sensing and
transmitting unit 10 transmits a radio signal modulated by one or
more frequencies selected from one or more groups of four
frequencies in accordance with one or more identifying binary coded
decimal digits. One or more receiving units 11--11 in the central
dispatch station 12, automobile 13 and helicopter 14 receive the
radio warning signal and display the identification decimal digit
or digits on displays 15--15 and operate audible alarms 38 (FIGS. 3
and 8). The appropriate authority, such as a police officer, may
immediately respond and take the appropriate action to overcome or
meet the emergency condition.
It is contemplated that the system of the invention be under the
control of an appropriate governmental agency, such as the police.
The locations to be monitored can thus be selected and limited to
readily cover the areas of greatest need within the capabilities of
the available personnel. Also the quality of the sensing and
transmitting units may be readily controlled and maintained to
produce a high standard of service.
The identifying modulation signals for one binary coded digit are
produced by the oscillator amplifiers 66-69 shown in FIG. 5. To
select the frequencies in accordance with the identifying binary
coded decimal digit, the oscillating circuits are selectively
disabled by open circuiting the inputs or outputs of selected
amplifiers 66-69 or eliminating or disconnecting selected filters
71-41, resistors 76-79 or capacitors 86-89. Thus, the modulation
signal contains one or more simultaneously generated frequencies
selected from the group of frequencies F1-F4. For additional
identifying decimal digits, additional oscillator circuits may be
added to supply additional groups of four frequencies. The use of
identification frequencies selected in accordance with indentifying
binary coded decimal digits allows the use of inexpensive
conventional binary coded decimal circuits.
TABLE I ______________________________________ Binary Inverted
Coded Binary Coded Decimal Decimal Decimal Inverted Digit Digit
Frequencies Digit Frequencies
______________________________________ 0 0000 None 1111 F1, F2, F3,
F4 1 0001 F1 1110 F2, F3, F4 2 0010 F2 1101 F1, F3, F4 3 0011 F1,
F2 1100 F3, F4 4 0100 F3 1011 F1, F2, F4 5 0101 F3, F1 1010 F2, F4
6 0110 F3, F2 1001 F1, F4 7 0111 F3, F2, F1 1000 F4 8 1000 F4 0111
F3, F2, F1 9 1001 F4, F1 0110 F3, F2
______________________________________ In TABLE I, there are
illustrated two schemes for selecting frequencies F1, F2, F3, and
F4 in accordance with a binary coded decimal digit. The third
column lists a selection of frequencies made in accordance with
binary coded decimal digits listed in the second column which
correspond to the respective decimal digits in the first column.
The fourth column is the inverse of the second column while the
fifth column illustrates a selection of frequencies in accordance
with the inverted binary coded decimal digits. Other conventional
binary coding schemes and frequency selection may be used so long
as they are readily employable with available decimal
circuitry.
One of the advantages of the invention is the large number of
identifying numbers which are available for a relatively few
modulation frequencies. Four frequencies provide 10 identifying
digits, eight frequencies provide 100 identifying digits, 12
frequencies provide 1,000 identifying digits, etc. This allows
flexibility in the employment of a radio warning system with a
minimum use of a radio frequency channel.
In FIG. 9 there is illustrated an allocation of the identifying
numbers for a variety of uses. The numbers may be allocated for use
in (1) sensing crime, such as burglary, robbery, etc.; (2) sensing
a fire or fire alarm; (3) sensing other matters concerning public
health and safety, such as air or water pollution, etc.; (4)
sensing an emergency distress, such as a need for service on a
highway; and (5) sensing industrial equipment failure. The
allocation of the identifying numbers and use of the system may be
under the control of a local governmental organization, such as a
police department, thus enabling optimum usage of the system.
After a predetermined period of operation, the transmission of a
radio warning signal is terminated by the operation of the
unijunction transistor 59 (FIG. 4) which fires the SCR 63 to render
the transistor 48 non-conductive and open the relay 50 to disrupt
power to the transmitter 19 and BCD generator 20. This prevents the
transmitting unit from unduly interfering with other use of the
radio frequency channel. The period of operation may be selected by
adjusting the variable resistor 57. Typically, the period may be
selected from the range of 10 to 100 seconds, but periods outside
this range may be readily used.
Once the sensor 17 (FIGS. 2 and 4) has triggered and latched the
arming circuit 18, the lamps 26 and 27 are energized. The lamp 27
remains energized only during the operation of the transmitter 19
and BCD generator 20. The lamp 26 remains energized until the
arming circuit 18 is delatched by manually opening the reset switch
23.
The radio frequency warning signal is received by the RF receiver
32 (FIG. 3) which detects and produces the identifying signal. The
receiving and displaying system may be readily employed with
conventional radio communication equipment used by commercial
establishments or governmental authorities, such as the police. The
radio receiver 32 and the antenna 31 may be part of their normal
communication equipment.
The frequencies in the identification signal are sensed by the
filters 91-94 (FIG. 6) and applied to rectifying and doubling
circuits. The use of narrow bandpass filters helps prevent
interference from noise and spurious signals or ordinary
communication in the operation of the warning system. Also, the
delays caused by the capacitors 106-109 and 121-124, diodes 111-114
and 116-119, and resistors 126-129 in the rectifying and doubling
circuits insure that the identification signals have been present
for a predetermined continuous duration and help prevent
interference from erroneously operating the SCR's 141-144 (FIG. 7)
in the memory 34 or 34a. A range of delays from 1/2 to 1 second is
acceptable but durations of delays outside that range may produce
equally acceptable results.
Once a binary digit or digits have been received by the memories 34
and 34a, the timing circuit 37 (FIG. 8) is operated after a
predetermined delay to disable the RF receiver 32 and to enable the
driving circuits 35 and 35a, the displays 36 and 36a and the alarm
38. The delay of the timing circuit 37 allows for differences in
the delays of the rectifying and doubling circuits of the BCD
detector 33 to insure that all the binary digits of the binary
coded decimal digit or digits have been received by the memories 34
and 34a. After the operation of the timing circuit 37, the
identifying decimal digit or digits remain displayed on the
displays 34 and 34a and the alarm 38 remains actuated until an
operator resets the timing circuit 36 by momentarily opening the
switch 40.
Inasmuch as the present invention is subject to many variations,
modifications and changes in detail, it is intended that all matter
contained in the foregoing description or shown in the accompanying
drawings shall be interpreted as illustrative and not in a limiting
sense.
* * * * *