U.S. patent number 3,852,740 [Application Number 05/351,164] was granted by the patent office on 1974-12-03 for alarm system with radio alarm link and equipment-activating power line link.
This patent grant is currently assigned to Kenneth Borzage, Earl Yale Fine, Steven Fine, Soley Goldberg. Invention is credited to Irving Haymes.
United States Patent |
3,852,740 |
Haymes |
December 3, 1974 |
ALARM SYSTEM WITH RADIO ALARM LINK AND EQUIPMENT-ACTIVATING POWER
LINE LINK
Abstract
An alarm system has both radio and power line communication
links between the protected premises and a monitoring station.
Intrusion alarm monitoring equipment at the monitoring station is
activated to respond to radio alarm signals from the protected
premises by "activate" signals that originate at the protected
premises and are transmitted over power lines to the monitoring
station. The monitoring station signals back to the protected
premises over the power lines the fact that it is "armed" or
activated as to intrusion alarm signals from those premises, and
also signals any intrusion alarm detected at said protected
premises. The intrusion alarm transmitter or transmitters at the
protected premises can send a radio alarm signal only in compliance
with current F.C.C. requirements.
Inventors: |
Haymes; Irving (Tamarac,
FL) |
Assignee: |
Fine; Earl Yale (N/A)
Borzage; Kenneth (N/A)
Goldberg; Soley (N/A)
Fine; Steven (N/A)
|
Family
ID: |
23379835 |
Appl.
No.: |
05/351,164 |
Filed: |
April 16, 1973 |
Current U.S.
Class: |
340/538; 340/541;
379/40; 379/42; 340/539.1; 340/539.14 |
Current CPC
Class: |
G08B
25/06 (20130101) |
Current International
Class: |
G08B
25/06 (20060101); G08B 25/01 (20060101); G08b
025/00 () |
Field of
Search: |
;340/224,416,420,31R,276,274 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Swann, III; Glen R.
Attorney, Agent or Firm: Oltman and Flynn
Claims
I claim:
1. In an alarm system having:
a monitoring station with alarm monitoring equipment;
a protected premises which is interconnected with the monitoring
station through electrical power lines;
a radio link comprising one or more radio transmitters at the
protected premises for transmitting an intrusion alarm signal when
an intrusion alarm condition is detected there, and a radio
receiver at the monitoring station for receiving said radio alarm
signals and operatively coupled to said alarm monitoring equipment
to actuate the latter when a radio alarm signal is received;
and a power line link comprising means selectively operable at the
protected premises for transmitting over power lines to the
monitoring station signals for activating the alarm monitoring
equipment there to respond to intrusion alarm signals broadcast
from the protected premises;
the improvement wherein said power line link further comprises
means at the monitoring station for transmitting over power lines
to the protected premises signal information as to whether the
alarm monitoring equipment there is activated to respond to
intrusion alarm signals broadcast from said protected premises.
2. An alarm system according to claim 1, wherein said transmitting
means at the monitoring station is operative to transmit over power
lines to the protected premises a distinctive signal which tells
that an intrusion alarm condition exists at said protected
premises.
3. An alarm system according to claim 1, and further comprising
signal indicator means at the protected premises for responding to
the power line signal coming from the monitoring station.
4. An alarm system according to claim 3, and further
comprising:
means for modifying said last-mentioned signal when the radio
receiver at the monitoring station receives an intrusion alarm
signal from said protected premises.
5. An alarm system according to claim 4, wherein
said transmitting means at the monitoring station transmits a
distinctive carrier signal over the power lines to said protected
premises which is unmodulated in the absence of an intrusion alarm
signal received from said protected premises and which is modulated
when such reception occurs;
and said means at the protected premises for responding to said
last-mentioned signal produces different indications for
unmodulated and modulated signals, respectively.
6. In an alarm system having:
a monitoring station with alarm monitoring equipment;
a protected premises which is interconnected with the monitoring
station through electrical power lines;
a radio link comprising one or more radio transmitters at the
protected premises for transmitting on intrusion alarm signal when
an intrusion alarm condition is detected there, and a radio
receiver at the monitoring station for receiving said radio alarm
signals and operatively coupled to said alarm monitoring equipment
to actuate the latter when a radio alarm signal is received;
and a power line link comprising means selectively operable at the
protected premises for transmitting over power lines to the
monitoring station signals for activating the alarm monitoring
equipment there to respond to intrusion alarm signals broadcast
from the protected premises;
the improvement wherein said selectively operable means at the
protected premises comprises;
means for applying a carrier signal to the power lines to be
transmitted to the monitoring station;
means for modulating said carrier signal at either of two different
frequencies;
and selectively operable means for activating said modulating means
and for selecting the modulating frequency.
7. An alarm system according to claim 6, and further comprising
means at the monitoring station for receiving the modulated carrier
signal coming over the power lines from said protected premises and
for responding separately to the two different modulating
frequencies to condition the alarm monitoring equipment at the
monitoring station to respond to intrusion alarm signals broadcast
by radio from said protected premises.
8. An alarm system according to claim 7, wherein said means for
responding separately to the two different modulating frequencies
is sensitive to the sequence in which said two different modulating
frequencies are transmitted over the power lines from said
protected premises to the monitoring station.
9. An alarm system according to claim 8, wherein said means for
responding separately to the two different modulating frequencies
comprises;
a first decoder that is sensitive substantially only to a first
modulating frequency, F1;
a second decoder that is sensitive substantially only to a second
modulating frequency, F2;
means coupled to the output of said second decoder for conditioning
the alarm monitoring equipment at the monitoring station to respond
to intrusion alarm signals from said protected premises in response
to the activation of the second decoder by an incoming F2
signal;
and circuit means interconnecting said first and second decoders
for inhibiting the second decoder from being activated by an
incoming F2 signal until after said first decoder has received an
F1 signal.
10. An alarm system according to claim 9, and further comprising
means acting between said radio receiver at the monitoring station
and said second decoder for inhibiting the latter from being
activated by an incoming F2 signal when said receiver receives an
intrusion alarm signal from said protected premises.
11. In an alarm system having:
intrusion alarm condition-signalling means at a protected
premises;
alarm monitoring equipment for receiving alarm signals at a
monitoring station which is linked to the protected premises
through electrical power lines;
and selectively operable means at the protected premises for
transmitting signals over the power lines to the monitoring station
to activate the monitoring equipment there to respond to intrusion
alarm signals from the protected premises;
the improvement which comprises:
a transmitter at the monitoring station for transmitting a signal
over the power lines to the protected premises when the alarm
monitoring equipment at the monitoring station is conditioned to
respond to intrusion alarm signals from the protected premises;
and means at the protected premises for responding to said
last-mentioned signal.
12. An alarm system according to claim 11, and further
comprising:
means for modifying said last-mentioned signal when the alarm
monitoring equipment responds to an intrusion alarm signal from
said protected premises.
13. An alarm system according to claim 12, wherein
said transmitter at the monitoring station transmits a distinctive
carrier signal over the power lines to said protected premises
which is unmodulated in the absence of a response by said
monitoring equipment to an intrusion alarm signal from said
protected premises and which is modulated when such a response
occurs;
and said means at the protected premises for responding to said
last-mentioned signal produces different indications for
unmodulated and modulated signals, respectively.
14. An alarm system according to claim 13, wherein said selectively
operable means at the protected premises may be operated to
de-activate the alarm monitoring equipment at the monitoring
station from responding to intrusion alarm signals at said
protected premises.
15. In an alarm system having:
intrusion alarm condition-signalling means at a protected
premises;
alarm monitoring equipment for receiving alarm signals at a
monitoring station which is linked to the protected premises
through electrical power lines;
and selectively operable means at the protected premises for
transmitting signals over the power lines to the monitoring station
to activate the monitoring equipment there to respond to intrusion
alarm signals from the protected premises;
the improvement wherein said selectively operable means at the
protected premises comprises:
means for applying a carrier signal to the power lines to be
transmitted to the monitoring station;
means for modulating said carrier signal at either of two different
frequencies;
and selectively operable means for activating said modulating means
and for selecting the modulating frequency.
16. An alarm system according to claim 15, and further comprising
means at the monitoring station for receiving the modulated carrier
signal coming over the power lines from said protected premises and
for responding separately to the two different modulating
frequencies to condition the alarm monitoring equipment at the
monitoring station to respond to alarm signals from said protected
premises.
17. An alarm system according to claim 16, wherein said means for
responding separately to the two different modulating frequencies
is sensitive to the sequence in which said two different modulating
frequencies are transmitted over the power lines from said
protected premises to the monitoring station.
18. An alarm system according to claim 17, wherein said means for
responding separately to the two different modulating frequencies
comprises:
a first decoder that is sensitive substantially only to a first
modulating frequency, F1;
a second decoder that is sensitive substantially only to a second
modulating frequency, F2;
means coupled to the output of said second decoder for conditioning
the alarm monitoring equipment at the monitoring station to respond
to intrusion alarm signals from said protected premises in response
to the activation of the second decoder by an incoming F2
signal;
and circuit means interconnecting said first and second decoders
for inhibiting the second decoder from being activated by an
incoming F2 signal until after said first decoder has received an
F1 signal.
19. An alarm system according to claim 18, and further comprising
means at the monitoring station operable in response to receipt of
an intrusion alarm signal for inhibiting the second decoder from
being activated by an incoming F2 signal.
20. In an alarm system having:
intrusion alarm condition-signalling means at a protected
premises;
alarm monitoring equipment for receiving alarm signals at a
monitoring station which is linked to the protected premises
through electrical power lines;
selectively operable means at the protected premises for
transmitting signals over the power lines to the monitoring station
to activate the monitoring equipment there to respond to intrusion
alarm signals from the protected premises;
the improvement which comprises means for preventing said
selectively operable means for activating the monitoring equipment
at the monitoring station when an intrusion alarm condition already
exists at said protected premises.
Description
SUMMARY OF THE INVENTION
This invention relates to an alarm system for responding to various
types of alarm conditions, particularly in an industrial plant, a
museum or other public building, or a private estate, condominium,
apartment building, or house where security from burglars, fire or
other hazards is particularly important.
In broad outline, the present system has radio alarm transmitters
at or near the premises to be protected from intrusion and
intrusion alarm monitoring equipment at a different location which,
for purposes of this discussion, may be called the security
headquarters. The monitoring equipment is conditioned to respond to
intrusion alarm signals at the protected premises by an action
initiated there by a custodian. For example, at the end of the
workday in an industrial plant all the doors and windows may be
closed, and from then until the beginning of the next workday they
should remain closed. During this time period when nobody would
open a door or window except an unwelcome intruder, the system
should be activated to detect such intrusions and it is the
custodian's responsibility to do this. The present system has
provision for activating the intrusion alarm monitoring equipment
at the security headquarters by signals transmitted over power
lines from the premises to be protected. Also, this system has
provision for signalling back over the power lines from the
security headquarters the fact that the system has been activated
for intrusions at those premises or that a door or window is open
there, so that the custodian will be so informed. Also, the
security headquarters automatically notifies the custodian over the
power lines whenever an intrusion alarm condition occurs at his
premises. The window and door alarm transmitter or transmitters in
the present system have a tamper-proof arrangement for insuring
that these transmitters comply with current F.C.C. regulations
governing the duration of intermittent "on" and "off" broadcast
intervals.
It is a principal object of this invention to provide a novel and
improved alarm system.
Another object of this invention is to provide such an alarm system
which has both a radio link and a power line link between the
premises to be protected and a station where alarm monitoring
equipment is located.
Another object of this invention is to provide a hybrid alarm
system with both radio and power line links which has all the
versatility of previous all-wire alarm systems.
Another object of this invention is to provide such an alarm system
in which the power line link is used to activate the equipment at
the monitoring station to respond to intrusion alarm signals from
the protected premises, and to signal back to the protected
premises that such activation has occurred.
Another object of this invention is to provide such an alarm system
in which the power line link is used to signal from the monitoring
station back to the protected premises when an alarm condition has
occurred at said protected premises.
Another object of this invention is to provide a novel and improved
alarm system having a radio alarm link with provision for insuring
that the intrusion alarm signal transmissions comply with current
F.C.C. requirements.
Further objects and advantages of this invention will be apparent
from the following detailed description of a presently-preferred
embodiment that is described with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 illustrates the present alarm system schematically,
primarily in block diagram form;
FIG. 2 is a circuit diagram of equipment at the monitoring station
in FIG. 1 for receiving coded signals coming over power lines from
the protected premises; and
FIG. 3 is a circuit diagram showing schematically a burglar alarm
transmitter at the protected premises in the present system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
OVERALL SYSTEM - FIG. 1
Referring to FIG. 1, at the protected premises 10 are located one
or more window alarm transmitters 11, which transmit a
distinctively modulated radio signal whenever a window is open
there, and one or more door alarm transmitters 12, which transmit a
distinctively modulated radio signal whenever a door is open there.
These window and door alarm transmitters 11 and 12 are described in
more detail hereinafter with reference to FIG. 3. In some
situations, a single transmitter may transmit both window alarms
and door alarms.
Also located at the protected premises are one or more fire alarm
transmitters 13, which broadcast a distinctively modulated radio
signal whenever a fire is detected, and one or more emergency alarm
transmitters 14, which broadcast a distinctively modulated radio
signal whenever a particular type of emergency occurs on the
premises, such as a malfunction of refrigerators or freezers in a
food store, for example, or a signal purposely initiated by a
person in need of help.
The carrier frequency is the same for all the different types of
radio alarm signals. The modulation for door alarms may be the same
as for window alarms, since both indicate a burglary or they may be
different. The respective modulations for emergency alarms and fire
alarms are different from each other and from the door and window
alarms since each calls for a different type of response.
Also located at the protected premises is a key jack 15 for
receiving a portable key plug 16 carried by a custodian. The key
jack 15 is connected to an oscillator 17 which produces pulses at a
frequency F1 or at a different frequency F2, as explained
hereinafter. The oscillator 17 pulse-modulates a carrier signal
oscillator 18, whose output is connected through a conventional
wall socket (not shown) to a 115 volt power line 19.
For the sake of simplicity, this power line 19 is shown connected
directly to the monitoring station 20 of the present system, which
is remote from the protected premises and which may serve a number
of different protected premises. However, it is to be understood
that this simplified, direct power line connection might actually
be a more complex power distribution system in a large factory or
group of industrial buildings. Nonetheless, the principle
illustrated is correct, in that the pulse-modulated carrier output
from oscillator 18 will be transmitted over power lines from the
protected premises 10 to the monitoring station 20.
At the monitoring station, the pulse-modulated carrier signal
coming from the protected premises 10 operates a key receiver 21
which will determine from this incoming signal whether or not the
burglar alarm monitoring equipment at the monitoring station should
be "armed" as to those protected premises (i.e., activated or
conditioned to respond to various door or window alarm conditions
that may occur at those protected premises).
The key receiver 21 controls a transmitter 22 at the monitoring
station whose output is connected to a conventional wall power
socket there to send a signal over the power lines 19 back to a
decoder 23 at the protected premises 10. The output from this
decoder is a D.C. signal whose plurality is reversed by a polarity
reverser 24 before being applied to terminal 25 of the key jack 15,
which is engaged by a corresponding terminal 26 on the key plug 16
when the latter is inserted in the key jack. When such insertion is
made, another terminal 27 on a key plug contacts the grounded key
jack terminal 28.
A light emitting diode 29 in the key plug is connected across
terminals 26 and 27 to be energized by the decoded signal coming
back over the power lines from the transmitter 22 at the monitoring
station such that:
1. if a continuous, unmodulated carrier signal is received from the
monitoring station transmitter 22, the light emitting diode 29 will
be on continuously;
2. if the carrier signal received from the transmitter 22 is pulse
modulated, the light emitting diode 29 will flash on and off, which
indicates that the protected premises 10 are not secure, such as
due to a door or window being open; and
3. if no carrier signal is received from the monitoring station
transmitter 22, the light emitting diode will be off, which
indicates that the entire burglar alarm system is disarmed for
these protected premises.
Also, a horn, buzzer or other audible warning device (not shown)
may be connected to a suitable decoder plugged into any power
outlet at the protected premises to sound an alarm at the protected
premises only if the carrier signal from the monitoring station
transmitter 22 is pulse-modulated.
The monitoring station 20 also has a radio receiver 30 which
receives the alarm signals transmitted by any of the alarm
transmitters 11-14 at any protected premises 10. The incoming
radio-transmitted alarm signal is applied to alarm decoders 31
which may differentiate among the emergency, fire and window or
door (burglary) radio alarm signals. In one practical embodiment,
each decoder is a Signetics "tone decoder phase locked loop", Model
SE/NE 567, as disclosed in the product manual of Signetics
Corporation, copyright 1972, pages 219-228.
The decoded alarm signal is applied to an alarm detection and
distribution panel 32 at the monitoring station, one of whose
functions is to signal an appropriate recipient that a
predetermined alarm condition has occurred at the protected
premises 10. For example, the police may be notified of a door-open
or window-open alarm condition, and the fire department may be
notified of a fire alarm condition at these premises. A private
security service may be notified by telephone through an automatic
dialer that an emergency alarm condition has occurred at the
protected premises. In one practical embodiment, the alarm
detection and distribution panel 32 is a Model 12-240 alarm,
manufactured by Design Controls, Inc., 111 Cantiague Rock Road,
Westbury, N. Y. 11590, and shown in that company's drawing no.
500-541, revision E, dated Aug. 4, 1971, and supplied to installers
of such alarms, including applicant, prior to the filing date of
the present application.
The monitoring station 20 is armed, or activated, as to a
particular protected premises 10 by turning on circuitry in the
panel 32 to signal the police and to operate the automatic dialing
equipment and the audible alarms. Preferably, the monitoring
station 20 is armed continuously at all times for emergency and
fire alarms from the protected premises, and the alarm signalling
for such conditions is not under the control of the custodian's key
plug 16.
PROTECTED PREMISES
Referring again to the equipment at the protected premises 10 in
FIG. 1, when the key plug 16 is inserted into the key jack 15, an
end terminal 33 on the key plug engages a spring-contact terminal
34 on the key jack which is connected to a control terminal 17a of
the pulse oscillator 17. A pair of resistors 35 and 36 in the key
plug are connected between its end terminal 33 and the terminal 27
which is grounded when the key plug is inserted into the key jack.
The juncture 37 between resistors 35 and 36 is connected to the
mobile contact 38 of a manually operable switch in the key plug.
This switch has a fixed contact 39 that is connected directly to
terminal 27. When switch 38, 39 is closed it shorts out resistor
36. Switch 38, 39 is a normally-open switch that returns to its
open condition as soon as its manually operated actuator is
released.
The key jack has a normally-open switch 40, 41 with a fixed contact
41 that is grounded and a mobile contact 40 that is connected to
the negative terminal of a battery 42. The mobile switch contact 40
is suitably coupled mechanically to the key jack terminal 34
through an electrically insulating coupling designated
schematically by the dashed line 43, such that switch 40, 41 closes
when the key plug 16 is inserted into the key jack 15.
All of the alarm transmitters 11-14 at the protected premises are
energized at all times, irrespective of whether the key plug 16 is
in the key jack for those premises. Therefore, each of these
transmitters is ready continuously to transmit an alarm signal to
the monitoring station at all times. As already stated, the
monitoring station 20 is armed at all times to respond to emergency
and fire alarm signals from the protected station, but it is armed
to respond to intrusion alarm signals only after the key plug 16 is
inserted in the key jack 15 at those premises.
The pulse oscillator 17 at the protected premises is an intergrated
circuit of known design that is capable of generating pulses at
different frequencies, depending upon the voltage at its control
terminal 17a. In the present system, this control voltage at
terminal 17a may have either of two values, and the output pulse
frequency of the oscillataor may be either of two values, F1 or
F2.
The positive terminal of battery 42 is connected to a second
terminal 17b of the pulse oscillator to provide the power supply
for this oscillator when switch 40, 41 in the key jack 15 is
closed. The voltage at the first-mentioned terminal 17a of this
oscillator determines its pulse frequency, and this voltage depends
upon whether or not the resistor 36 is shorted out. Thus, with key
plug 16 inserted into the key jack 15 and the manual switch 38, 39
in the key plug open, the oscillator terminal 17a will be connected
to ground through the series-connected resistors 35 and 36, and its
voltage will be at the higher of two values, and the pulse
oscillator frequency will be F1. However, when the manual switch
38, 39 in the key plug is closed, the oscillator terminal 17a will
be connected to ground through resistor 35 only (resistor 36 being
short-circuited), and its voltage will be at the lower of two
values, and the pulse oscillator frequency will be F2.
KEY RECEIVER AT MONITORING STATION
FIG. 2 illustrates schematically important components of the key
receiver 21 at the monitoring station 20. The pulse-modulated
carrier signal from the protected premises 10 comes in over the
power lines 19 to a selective carrier amplifier 50, which amplifies
this carrier, and then is demodulated in a demodulator 51 and
limited in a limiter 52 before being applied to one or more similar
key detecting blocks Ka, Kb, Kc, etc., one for each different
protected premises in the system.
The key detecting block Ka for the particular protected premises 10
in FIG. 1 is shown as comprising two frequency sensitive decoders,
an F1 decoder 53 and an F2 decoder 54. Each of these decoders is an
integrated circuit with eight terminals, terminal 3 being the input
terminal and terminal 8 being an output terminal. Each decoder is
the solid state equivalent of a reed relay, responding only to a
particular frequency, F1 or F2. Each decoder may be a Signetics
Corporation Model SE/NE 567 decoder, as already referred to.
Terminal 8 of the F1 decoder 53 is connected through a resistor 55
to the positive terminal of a battery 56 and is connected through a
capacitor 57 to the grounded negative terminal of this battery.
Terminal 8 of the F1 decoder is connected through a resistor 58 and
diode 59 to terminal 1 of the F2 decoder 54. Normally, terminal 8
of the F1 decoder and terminal 1 of the F2 decoder are at the
positive battery voltage, and this inhibits the F2 decoder 54 from
responding to an F2 signal. However, when the F1 decoder receives
an F1 signal, the voltage at its terminal 8 drops to zero, as does
the voltage at terminal 1 of the F2 decoder 54, so that now the F2
decoder is no longer inhibited and it can respond to an F2 input
signal at its terminal 3. Such an F2 input signal at terminal 3 of
decoder 54 produces a signal at its output terminal 8 that operates
a sequential relay (not shown) for arming the monitoring station 20
as to intrusion alarm signals from these premises by turning on
power supplies for circuits in panel 32 for police signalling,
operating the automatic dialer, and sounding audible alarms. This
sequential relay is energized by the first signal it receives from
the F2 decoder, and it is deenergized by the next signal it will
receive from the F2 decoder, as described hereinafter.
With this arrangement, to arm, or activate, the system as to
intrusion alarm signals from these protected premises, the
monitoring station must receive over the power lines 19 from the
protected premises the carrier pulse-modulated by F1 and then the
same carrier pulse-modulated by F2, and in that order (F1 preceding
F2). Otherwise, the F2 decoder 54 will remain inhibited, and the
system arm relay will not be energized.
The F1 decoder 53 at the monitoring station has a narrow pass-band
whose center frequency is determined by the values of a capacitor
60, an adjustable resistor 61, and a resistor 62 which is part of a
key code module 63.
Similarly, the F2 decoder 54 has a narrow pass band whose center
frequency is determined by a capacitor 64, an adjustable resistor
65, and a resistor 66 which also is part of the key code module
63.
The key code module 63 corresponds to the pulse frequencies F1 and
F2, which are assigned to only one protected premises, as
determined by the resistors 35 and 36 in the key plug 16 for those
premises. Therefore, each key code module 63 at the monitoring
station is frequency-matched to a particular key plug for a certain
protected premises.
Each of the other key detecting blocks Kb, Kc, etc., has circuitry
identical to that of the block Ka, except that the resistors in the
respective key code modules are different, so that each block Kb,
Kc, etc. is frequency-tuned to only the two different modulating
frequencies, F1 and F2, that are assigned to a particular protected
premises. The carrier signals coming over the power lines from the
different protected premises are all at the same frequency.
Resistor 55 and capacitor 57 provide a time-delay circuit for
preventing the F2 decoder 54 from being inhibited again until about
250 milliseconds after the F1 input signal disappears from the F1
decoder 53. This is ample time for the F2 decoder 54 to respond to
the F2 signal and energize the sequential relay for panel 32.
When the system is to be armed to respond to the window and door
alarm transmitters at a particular protected premises, the key plug
switch 38, 39 is open when the key plug 16 for those premises is
inserted into the key jack 15, so that the carrier signal
transmitted from these protected premises will be modulated first
by the F1 pulses. Then, when the key plug switch 38, 39 is closed
momentarily, this carrier will now be modulated by the F2 pulses,
so as to operate the system arm relay through the F2 decoder 54.
However, as already explained, this action can take place only if
the F2 pulses have been preceded by the F1 pulses. The key plug
switch 38, 39 re-opens automatically when released manually, so as
to re-transmit the F1-modulated carrier to the key receiver 21 and
thereby condition the F2 decoder in the key receiver to respond to
the F2 modulation signal the next time the key plug switch 38, 39
is closed.
If all the doors and windows at the protected premises are closed
when the foregoing action takes place, then none of the door and
window transmitters 11 and 12 will broadcast an intrusion alarm
signal to the receiver 30 at the monitoring station. However, if at
this time there is an open window or door at the premises to be
protected, the monitoring station cannot be armed or activated as
to those premises until this condition is corrected. Also, a
distinctive signal will be transmitted from the monitoring station
transmitter 22 over the power lines 19 back to the key plug 15 to
notify the custodian that there is an open door or window there
which must be closed before the system can be activated.
The intrusion alarm signal received by the receiver 30 at the
monitoring station will cause panel 32 to produce an "inhibit"
signal on line 70 (FIG. 1) that is applied to terminal 1 of the F2
decoder 54 in the key receiver 21, so as to prevent the F2 decoder
from responding to the F2-pulse modulated carrier transmitted from
the premises 10 over the power lines 19 to the monitoring station.
Consequently, the monitoring station cannot now be armed to respond
to intrusion alarm signals from these premises.
The instruction alarm signal received by the receiver 30 at the
monitoring station also causes panel 32 to produce on line 71 a
signal that is applied to the transmitter 22 to cause the latter to
transmit a pulse-modulated carrier over the power lines 19 back to
the premises 10 which, after being decoded, produces an
intermittent flashing of the light emitting diode 29. This is a
visual signal to the custodian that there is a door or window open
at these premises.
When all the doors and windows have been closed, the custodian
closes the key plug switch 38, 39, and the system will become armed
as to these premises, as described.
When such arming takes place, the "alarm" signal on line 71 is
removed and the transmitter 22 at the monitoring station sends a
continuous carrier signal over the power lines 19 back to the
premise 10. This carrier, after being decoded, is applied to the
light emitting diode 29 to provide continuous illumination, which
tells the custodian that the system is armed as to these premises
and that no intrusion alarm condition exists there.
If, after the monitoring station has been armed as to these
premises, an intrusion alarm signal is transmitted to the receiver
30 at the monitoring station, it will produce on line 71 a pulse
modulation control signal to cause the light emitting diode to
flash on and off again.
When the custodian wants to "disarm" the system as to intrusion
alarm signals originating at these premises 10 (such as at the
beginning of a work day in an industrial plant), first he closes
the key plug switch 38, 39 to again apply the F2 modulation to the
carrier that is transmitted from the premises 10 over the power
lines 19 to the monitoring station 20. The resulting output signal
at terminal 8 of the F2 decoder 54 in the key receiver 21 energizes
the sequential relay so as to remove the power for the circuits in
panel 32 that signal the police, the automatic dialer and the
audible alarms in the event of an intrusion alarm. Then the
custodian removes the key plug from the key jack.
DOOR OR WINDOW ALARM TRANSMITTER - FIG. 3
FIG. 3 illustrates schematically a door/or window alarm transmitter
at the protected premises 10 in FIG. 1. There may be a single
transmitter for all doors and windows to be monitored at these
premises, or a single transmitter for all windows and a single
transmitter for all doors there, as shown in FIG. 1, or various
other combinations of transmitters for different windows and doors
at these premises.
This transmitter complies with the current F.C.C. requirement that
the broadcast interval be not longer than 1 second, and followed by
a silent period of 30 seconds or more.
In FIG. 3 the transmitter is shown under the control of three
series-connected sensor switches 80, 81 and 82, each associated
with a respective door or window, and each closed whenever that
door or window is closed. Any desired number of such
series-connected sensor switches may control a particular alarm
transmitter.
The sensor switches are connected in series between ground and the
base of transistor Q1, whose emitter is grounded and whose
collector is connected directly to the base of a second transistor
Q2. The emitter of Q2 is connected directly to the positive
terminal of a battery B and also is connected to the base of Q1
through a resistor 83.
The collector of Q2 is connected through a series-connected diode
84 and capacitor 85 to the base of Q1. A resistor 86 is connected
between ground and the juncture between diode 84 and capacitor
85.
The collector of Q2 is connected to the input of an encoder
modulator 87 whose output is connected to an R.F. oscillator 88
coupled to a broadcast antenna 89.
In the operation of this transmitter, as long as all of the sensor
switches 80, 81 and 82 remain closed, both transistors Q1 and Q2
will remain off.
Whenever any one of the sensor switches 80-82 is opened, the base
current of transistor Q1 turns on, causing current to flow from the
collector to the emitter of Q1. This turns on the base current in
transistor Q2, and the resulting emitter-collector current in Q2
operates the encoder modulator 87 so that the antenna 89 broadcasts
a coded, amplitude-modulated radio signal that identifies this
window/door alarm transmitter at these particular protected
premises. Preferably, the carrier frequency of this radio signal is
about 300,000,000 Hz, and the modulation signal frequency is in the
supersonic range. This radio signal will be picked up by the
receiver 30 at the monitoring station (FIG. 1).
This coded signal transmission lasts only 1 second or less each
time. During this 1 second or less, the capacitor 85 will become
charged through diode 84 enough to turn off the base current in Q1,
thereby turning off Q1 and then turning off Q2. Capacitor 85
discharges through resistor 86, and the time constant provided by
these circuit elements is such that Q1 and Q2 remain off for thirty
seconds or more. At the end of this period, transistors Q1 and Q2
will turn on again (if one of the sensor switches 80-82 is still
open) for the 1 second-or-less on interval, and then they will turn
off again for the 30-second-or-more off period. During this off
period, a repeated opening and closing of any of the sensor
switches 80-82 will have no effect. Instead the transmitter will
remain off for the full period of 30 seconds or more, so as to
insure compliance with the F.C.C. requirement mentioned
hereinbefore.
The receiver 30 at the monitoring station includes suitable
circuitry for retaining the intermittently-broadcast signal during
the alarm transmitter's off periods.
It is to be understood that various modifications may be made in
the system disclosed without departing from its essential
principles.
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