US3823391A

US3823391A - System for monitoring remotely related buildings

Info

Publication number: US3823391A
Application number: US00325631A
Authority: US
Inventors: P Worsley; J Baker
Original assignee: Valley Burglar and Fire Alarm Co
Current assignee: Valley Burglar and Fire Alarm Co
Priority date: 1973-01-22
Filing date: 1973-01-22
Publication date: 1974-07-09
Anticipated expiration: 1991-07-09

Abstract

A system for accommodating a simultaneous monitoring of the integrity of a plurality of remotely related buildings from a common observation station, characterized by a plurality of monitoring units each having an integrity monitoring circuit, integrated with one of a plurality of said remotely related buildings for continuously conducting an electrical current, the amperage of which is indicative of building integrity, and an observation circuit located at the observation station common to all monitoring units remotely related to the buildings including circuit means responsive to changes in said amperages for providing intelligence indicative of a changed status of building integrity.

Description

United States Patent [191 Worsley, Jr. et al.

111 3,823,391 July 9,1974

[ SYSTEM FOR MONITORING REMOTELY RELATED BUILDINGS [75] Inventors: Paul R. Worsley, Jr.; Jerry D.

Baker, both of Fresno, Calif.

[73] Assignee: Valley Burglar & Fire Alarm Company 22 Filed: Jan. 22, 1973 21 Appl. No.: 325,631

[52] US. Cl 340/213 R, 340/253 11, 340/276,

12/1969 McGrath 340/213 10/1972 Lee 340/276 Primary Examiner-John W. Caldwell Assistant Examiner-Richard P. Lange Attorney, Agent, or Firm-Huebner & Worrel [57] ABSTRACT A system for accommodating a simultaneous monitoring of the integrity of a plurality of remotely related buildings from a common observation station, characterized by a plurality of monitoring units each having 1 an integrity monitoring circuit, integrated with one of a plurality of said remotely related buildings for continuously conducting an electrical current, the amperage of which is indicative of building integrity, and an observation circuit located at the observation station common to all monitoring units remotely related to the buildings including circuit means responsive to changes in said amperages for providing intelligence indicative of a changed status of building integrity.

11 Claims, 3 Drawing Figures OBSERVATION g STATION 4 I at /a Ls 5 r i t *1 L 3 If 1 5 6 I SYSTEM FOR MONITORING REMOTELY RELATED BUHJDINGS BACKGROUND OF THE INVENTION The invention relates to a system for simultaneously monitoring the integrity of a plurality of remotely related buildings, and more particularly to a system for use in simultaneously monitoring the integrity of remotely related buildings, with respect to intrusion, em-

ploying telephone or hard lines connecting a plurality of monitoring circuits located in mutually remote buildings with a plurality of observation circuits located at a common observation station, which is, in turn, remotely related to the buildings.

Burglar alarms are notoriously old and are commonly employed for detecting unauthorized intrusion of protected premises. Among such systems are'the so-called silent alarms, including closed circuit T.V. monitoring systems, employed in monitoring the integrity of a selected building. Such systems are responsive to an intrusion for providing a warning signal at a remote observation station. Where a T.V. monitoring system is employed a video signal is provided.

Often times, systems of the type heretofore employed are readily subject to being defeated orv rendered ineffective through various techniques, such as crossshorting circuit components, generation of false signals, and even circuit interruption, whereby breaking and entering a thus protected premises can be achieved undetected.

Furthermore, systems heretofore employed often are capable of functioning in only a single mode, and therefore cannot readily undergo a change in modes for accommodating alternate day and night operations. For example, during daylight hours, it maybe desirable to protect only skylights, rear doors, and the like, while at night additional areas of the building must be monitored and thus protected against unauthorized intrusion. Accordingly, monitoring circuits heretofore employed have been duplicated in those instances where dual monitoring functions are required.

It, therefore, is the purpose of the instant invention to provide a highly dependable, efficient, economic and practical monitoring system for use in simultaneously monitoring the integrity of a plurality of remotely related buildings from a common observation station, during both day and night operations.

OBJECTS AND SUMMARY OF THE INVENTION It therefore is an object of the instant invention to provide an improved system for monitoring the integrity of remotely related buildings from a common observation station.

It is another object to provide a simplified, economic, and practical system for simultaneously monitoring the integrity of a plurality of remotely related buildings, the mode of which can selectively be altered for accommodating day and night operations, and is not subject to being defeated through a use of circuit interruption and/or cross shorting techniques. a

It is another object to provide a simplified, economic, and practical monitoring circuit for continuously monitoring the integrity of remotely relate buildings from a common observation station employing color coded lights for indicating circuit condition and status change.

These and other objects and advantages are achieved through the use of a system which iincludes a plurality of remotely related, integrity monitoring circuits, each being disposed within one of a plurality of selected buildings, including circuit means for continuously conducting an electrical current, the amperage of which is indicative of building integrity, and a plurality of observation circuits located at a common observation station and connected with said plurality of monitoring circuits through hard line circuitry, having means responsive to changes in current amperages flowing through the monitoring circuits for continuously providing intelligence indicative of the status of integrity for each of the buildings, as will become more readily apparent by reference to the following description and claims in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view of a system which embodies the principles of the instant invention, depicting a plurality of monitoring units including monitoring circuits coupled with observation circuits located at a common observation station.

FIG. 2 is a schematic view of a combined monitoring circuit and an observation circuit electrically coupled into a monitoring unit and employed by the system shown in FIG. 1.

.FIG. 3 is a schematic view, in diagram form, more clearly illustrating the observation circuit depicted in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more specifically to the drawings wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. I a system, generally designated I0, which embodies the principles of the instant invention.

The system 10, as employed, includes an observation station, generally designated 12, and a plurality of re motely related integrity monitoring circuits, generally designated 14.

The observation station 12 is, in practice, located within a fireproof building, or blockhouse, and secured with respect to unauthorized intrusion. Within the blockhouse there is provided a suitable console for simultaneously receiving and supporting a multiplicity of circuit boards, not shown. Each of the circuit boards, as a practical matter, includes a single observation circuit 16 mounted thereon. The circuit I6 is fabricated employing techniques fully understood by those familiar with a fabrication of printed circuits and a use of solid-state devices.

From each observation circuit there is extended a suitable lead which is, in effect, a continuation of a hard line 18, such as a telephone line, employed in coupling the observation circuit with one. of the integrity monitoring circuits to thus form a monitoring unit, designated 19.

Each of the integrity monitoring circuits 14 is located within a selected building, the integrity of which is to be monitored. As a practical matter, the primary function of the system 10 is to determine the instant that any one of a multiplicity of buildings is subjected to unauthorized intrusion. Consequently, the term integrity .components 20 and 22. As a practical matter, the circuit 14 includes leads of copper wires, printed circuits, appropriate switches and the like which extend as a monitoring network throughout the building and located to be broken, activated and the like in response to unauthorized intrusion.

Since monitoring circuits are well known, a detailed description of the specific monitoring circuit employed is omitted in the interest of brevity. However, it is to be understood that the monitoring circuit is continuously conductive and in the event the monitoring circuit is interrupted, or cross-shorted, the resistance of the circuit is varied, whereupon the amperage of the flow of electrical current is varied. Furthermore, the system is coupled at the negative terminal of a 24 volt d.c. source of-electrical potential 23. The positive terminal of the source is connected to ground. Consequently, the system 10 employs so-called single-line circuitry with current flow being directed through each of the observation circuits l6, thence to ground through a hard line 18 and an integrity monitoring circuit 14 for thus completing the circuit through the unit 19.

Each of the variable resistances 20 and 22, illustrated in FIG. 2, is representative of a single portion of the integrity monitoring circuit 14, which is, in operation, employed alternatively for accommodating day and night operations. Consequently, the variable resistance 20 is intended to represent a portion of the circuit 14 employed when the circuit is switched to its normal day mode or during normal operations conducted during daylight hours, while the variable resistance 22 is intended to depict a portion of the circuit employed when the circuit is switched to normal night mode or during operation conducted at night. Of course, the operation of theportion of the circuits designated 20 and 22 are in no way dictated by hours or by daylight conditions, and thus it can be appreciated that the phrases normal day and normal night modes are employed as a matter of convenience in distinguishing between periods when selected circuit portions are employed.

In order to accommodate a switching between the portions of the circuits represented by the variable resistances 20 and 22, there is provided a manually operable switch 24. In practice, this switch is manipulated by personnel within a building for purposes of switching the operation of the system 10 for operation in normal day and normal night modes.

As will hereinafter become more fully apparent, th observation circuit 16 monitors the status of the circuit 14 and thus provides intelligence indicative of changes occurring in the status. Consequently, it is improbable if not impossible for an intruder to defeat the system 10 by switching the circuit between its modes of operation, since each time the mode is changed intelligence indicative of the change is presented by the observation circuit 16 to personnel within the observation station 14.

It is to be understood that each circuit unit 19 includes a monitoring circuit 14 and an observation circuit 16. Since the units 19 can be added and deleted without interrupting the function of the remaining portions of the system 10 and the design and construction of the units 19 are quite similar, a detailed description of a single unit is believed adequate for providing a complete understanding of the instant invention.

Referring now to FIGS. 2 and 3, it is noted that the circuit 16 is coupled with the hard lines 18 at a circuit switch S1, within a block, designated A. This switch is employed for coupling a ring-back circuit 26 with the hard line 18 employed in coupling the

circuits

14 and 16. The purpose of the ring-back circuit 26 is to impose a volt signal on the line 18 so that personnel within a building being monitored by a circuit 14 is provided with a signaling voltage which indicates that the integrity of the line 18 and thee circuit 14 are in tact. Normally, this is performed in the blockhouse, or at the observation station 12 at the time the building is closed.

As a practical matter, it is important to note that circuit 16 includes a lead 29 which serves to conduct current from the source 23 to the circuit while a lead 30 is provided for coupling the circuit with ground. Electrically connected between the

leads

29 and 30 is an RF filter circuit, designated by block B, FIG. 2, which includes a 100,000 ohm resistor 31 and a 0.22 microfarad capacitor 32. Accordingly, the circuit of the unit 19 is protected against an introduction of high voltage RF signal.

Switch S1, FIG. 2, is electrically connected with a circuit block C. As a practical matter, block C includes a current limiting and transient filter circuit through which high voltage transient signals are clipped whereby the circuit 16 is protected from excessive current loads. As a practical matter, block C includes a 6.4 kilohm resistor 28, connected in series with the switch S1, employed in limiting current flow through the circuitry for thereby affording a degree of protection thereto.

Block C also functions in a protective and transient filter function. This circuit, as best shown in FIG. 3, is a parallel circuit having the voltage from the source 23 applied thereto, through the lead 29, and includes a 5.6 volt Zener diode 34 provided for clipping high voltage transient signals to that level, as well as a pair of 0.22 microfarad capacitor 36. The capacitors serve to filter pulse signals of RF frequency as well as pulse signals of relatively long pulse durations.

Immediately following block C, as illustrated in FIG. 2, are blocks D, E, F and G, which collectively serve to detect changes in the condition of the circuit of the unit 19. In practice, the circuit of block D includes an electrically energizable lamp 44, preferably yellow, the circuit of block E includes an electrically energizable lamp 46, preferably green, the circuit of the block F includes electrically energizable lamp 48, preferably white, while the circuit of block G includes an electrically energizable lamp 50, preferably red.

The

lamps

44, 46, 48 and 50 have one terminal connected to ground through a switch S2 and are energized for indicating a condition of the circuit of the unit 19. Such an indication serves as intelligence related to the integrity of the building being monitored. Each of the circuits of blocks D, E, F and G, in turn, are coupled with a status-change block, designated H, through leads 52, 54, 56 and 58, respectively. Within the circuit of the block H there is included another electrically energizable lamp 60, preferably blue in color. This lamp is energized upon a change in the amperage of the cur rent flowing through the unit 19.

Accordingly, it should be apparent that the blocks D, E, F and G serve as current detection stages and detect current changes for the current flowing through the unit 19. In practice, the blocks D, E, F and G are con nected through a common lead 62 with the current limiting and transient signal filter circuit of block C. Thus, a current path is provided simultaneously to all of the blocks D, E, F, and G from the circuit 14.

Each of the current detection stages, or blocks D, E, F and G, is provided with a signal pick-off circuit, generally designated 64. Each of the pick-off circuits, in turn, includes a lead 66 through which a potentiometer 68 is connected with the lead 29, FIG. 3. Each of the potentiometers is provided with a wiper arm 70 and a resistor 72 relative to which the wiper arm 70 is adjustable. For reasons well understood, the current delivered through the wiper arm 70 can be varied simply by repositioning the wiper arm relative to the resistor.

Each of the wiper arms 70 is, in turn, coupled electrically to the base of an NPN transistor 74, all being similarly biased. As a practical matter, the transistors employed are of the type designated 2N2923, each having a negative voltage applied to its emitter while ground potential is applied to its collector. As a practical matter, current limiting resistors 76 are interposed between the wiper arms 70 and the base of the transistors 74, of blocks D, E and F for adjustment and protective purposes.

The collectors of the transistors 74, within the circuits of blocks D, E and F are connected to ground through kilohm resistors 78, while the emitters thereof are connected directly with the -24 volt d.c. source of potential, through leads 80 electrically connected with the lead 29.

It should therefore be readily apparent that each of the transistors 74 is forward biased by a voltage pickedoff by an arm 70 and applied to the base thereof. However, once the current established through the resistor 76 drops to a preselected level, the biasing voltage applied to the base of the transistors 74 is removed whereupon the transistor ceases to conduct between the source 23 of electrical potential and ground. Thus, the circuits 64, in effect, continuously monitor the current flowing through the circuit 14 and are responsive to voltage signals of selected values applied to the bases of the NPN transistors 74.

Turning now to the first current detecting stage or circuit of block C, FIG. 3, it is noted that the lamp 44 also is connected with the negative dc. voltage through an SCR 82. The SCR is configured to be fired by a gatinng signal, at ground potential, directed through a directional diode 84 and applied to its gate. False triggering of the SCR diode 82 is prevented by a filter circuit, generally designated 86, whiich includes a one kilohm resistor 88 and a 0.22 microfarad capacitor 90. The circuit of block D is set to respond to a current of 0.75 ma (milliampere) or less flowing through hard lines 18. As a practical matter, this current is no more than carrying current for the phone line. Accordingly, this circuit functions in the event the circuit 14 is opened by an intruder.

Once the voltage of the signal applied to the base of the transistor 74 is dropped to a selected low level, the transistor 74 is switched-off, i.e. ceases to conduct.

Therefore, a gating signal is applied from ground to the gate of the SCR diode 82 causing that diode to fire. Thereupon a circuit is completed through the lamp 44, between ground and the source of negative potential so that the lamp 44 thus is energized. Enerization of the lamp 44, of course, indicates that a current through the circuit 14 is reduced to a level indicating that an open condition for the circuit 14 exists. This indication serves as intelligence warning of the presence of an intruder within the building being monitored.

The circuit of block E is quite similar to that of block D and is employed for indicating that the circuit 114 is set in a normal night mode, indicated through the ener gization of the lamp 46, preferably green in color. This circuit includes an NPN transistor 92, the base of which is connected with the collector of the NPN transistor 74 through directional diode 94. The collector of the transistor 92 is connected to ground thorugh a 10 kilohm resistor 96, while the emitter is connected to the source of negative voltage through ohm resistor 98.

The lamp 46, as before mentioned, has one terminal thereof connected to ground through the switch S2, while the other is connected to the source of negative voltage through still another NPN transistor 100. The emitter of the transistor 100 is connected to the source of negative voltage 23, also via the resistor 98. The base of the transistor 100 is connected between the collector of the transistor 92 and the resistor 96 through a directional diode 102. In practice, the potentiometer 68 of the pick-off circuit 64 within the circuit of block E is so set that when the circuit l4 is switched to its normal night mode a current of 0.8 ma. to l.l5 ma. is present through the resistance 72. This causes a forward biasing voltage to be applied to the base of the transistor 74 so that it is switched on or rendered conductive. Once the transistor 74 is switched on, ground potential is removed from the base of the transistor 92 causing it to switch off. Once the transistor 92 is switched off, ground potential is applied to the base of transistor 100 for thereby switching it on. Hence, once the transistor 74 of the pick-off circuit 64 is switched on by switching the circuit 14 to its normal night mode, the transistor 92 is rendered non-conductive so that ground potential is applied through resistance 96 and the diode 102 for switching the transistor 100 on. As the transistor 100 begins to conduct, this heavier current causes the voltage drop across the resistance 98 to increase. This voltage drop serves to reverse bias the transistor 92 further aiding in the connduction of the transistor 100. As a practical matter, this results in speeding the switching of the transistor 100 so that the lamp 46 is rapidly switched on once the transistor 74 is switched on.

Thus, it is readily apparent that when the circuit 14 is set in its normal night mode, th green light 46 remains energized so that personnel within the observation station 12 are continuously aware of the condition of the unit 19.

Turning now to the third current detecting circuit of block F, it should readily be apparent that this circuit is substantially the same as the circuit of block E. However, it also is important to note that the circuit of block F includes an NPN transistor 104, the base of which is connected between the collector of the transistor 74 of the pick-off circuit 64 and ground potential through a directional diode 106. The collector of the transistor 104 is connected to ground through a 15 kilohm resistor 108 and the emitter thereof is connected to the negative potential through a 100 ohm resistor 110.

An NPN transistor 112 is connected at its collector with one terminal of the non-grounded terminal of the lamp 48 while the emitter thereof also is connected with negative potential through the resistor 110. The base of the transistor 1 12 is connected between the collector of the transistor 104 and the resistor 108 through a diode 114. This circuit serves to provide intelligence indicative of the normal day mode operation an operates in substantially the same manner as the circuit of the second current detecting stage of block E. However, it is important to note here that when the threshold voltage, established by the adjustment of the potentiometer 68 of the pick-off circuit 64, is reached the current flow attains a value of 1.15 ma. Thus,. when the voltage attendant 1.15 to 1.40 ma, as seen through the potentiometer 64, is applied to the base of the transistor 74, the lamp 48 is energized as the transistor 112 is switched on as a result of a biasing signal being delivered to the base thereof through a diode 1114.

It is important to herenote that a PNP transistor 115 is coupled at its collector with the base of the NPN transistor 92 while the emitter thereof is connected to ground potential. The base of the PNP transistor is connected with ground and with the non-grounded terminal of the lamp 48 through a suitable biasing resistor network, not designated. Once a current path is established through the lamp 48, the transistor 115 is permitted to switch on, whereupon transistor 92 becomes forward biased and transistor 100 is thus maintained in a reverse biased condition for thus assuring that the lamp 46 remains de-energized so long as the lamp 48 is energized.

Turning now to the circuit off block G, it is noted that the lamp 50 is connected with the negative voltage source 23 through an SCR 116 which is switched on in response to a gating signal applied to the gate thereof when the current through the pick-off circuit 64 attains a level 1 of 1.4 ma., normally experienced at any time a cross-short occurs. The gating signal is derived from the emitter of the NPN transistor 74 through a current limiting resistor 120 connected thereto. The transistor 74 is connected to ground at its collector, through 4.7 kilohm resistor 122, while the emitter thereof is connected to the lead 29 through a 1 kilohm resistor 124. A filtering circuit 126 is connected between the input to the gate of the SCR 116 an the lead 29 for preventing an application of false signals to the gate of the SCR 116. The filter circuit 126 includes 0.22 microfarad capacitor 128 and 1 kilohm resistor 130 arranged in circuit parallel.

Consequently, once the current through the potentiometer 68 of the pick-off circuit 64 reaches the level of 1.4 ma., the transistor 74 of the pick-off circuit 64 is caused to conduct in response to the voltage level of the signal applied to the base thereof through a wiper arm 70. As the transistor 74 conducts, the gating signal is delivered, via the resistor 120, to the gate of the SCR 116 whereupon a current path is established through the lamp 50, between its grounded terminal and the source 23, whereupon the lamp 511 is energized. Since the lamp 50 propagates light of the color red, once current flow through the circuit 14 reaches a high level indicating a cross short. Thus, an observer at the observation station 12 is provided with intelligence indicative of the cross-short condition for the circuit 14. Such a condition normally indicates an interruption of building integrity caused through intrusion.

It is important to appreciate that monitoring personnel at the observation station 12 should be apprised of prior changes in circuit condition, even though such personnel were not aware of such a change at the instant it occurred. To achieve this there is provided a status-change circuit stage, block H, which responds to each change in the condition of the circuit and provides intelligence in the form of light of a blue color emanating from lamp 611 which is connected between ground and the negative voltage source 23 through SCR 134. A gating signal for the SCR 134 is derived through a PNP transistor 136, the collector of which is connected with the lead 29 through a 15 kilohm resistor 138 while the emitter thereof is connected to ground. The base of the transistor 136 is biased to a non-conducting mode through a resistor 140 connected between the base and ground potential. Thus, the resistor 136 normally is biased to its non-conducting state.

Also coupled to the base of the transistor 136 is a plurality of detection leads 142, 144, 146 and 148 which extend from connections established between the voltage source 23 and each of the

lamps

44, 46, 48 and 50, respectively. Accordingly, it is to be understood that once a current flow is established through any of the lamps 44 through 50, the leads 142 through 148 serve to apply a negative voltage to the base of the transistor 136 for switching this transistor to its conducting state, by overcoming the biasing signal applied to the base through the resistor 140.

As a practical matter, each of the leads 142 through 148 includes therein, in series, a 2.2 microfarad capacitor 149 and a 1 kilohm resistor 149R so that the nega tive signal derived through the connection of the leads with the lamps 44 through 50 applies a switching signal to the base of the resistor 136 for a period determined by the time constant of the capacitor 149 and the series connected resistor 149R. As a practical matter, a filter circuit 150, which includes a 1 kilohm resistor 152 and a 0.22 microfarad capacitor 154, is provided for preventing a firing of the SCR 134 through an application of a false signal.

It should, therefore, be apparent that once the transistor 136 is caused to conduct in response to a nega' tive signal applied to its base, a gating signal is applied to the SCR 134, whereupon the current path between ground the the source 23, through the lamp 60, is established for energizing the lamp to provide light of a blue color. This lamp thus serves to indicate that a change in circuit conditions has been experienced.

ln addition to energizing the lamp 60 an audible signal generator 156 is connected with the circuit 116 at pin P. Pin P, in turn, is connected between the SCR 134 and the lamp 60 so that when the SCR 134 is caused to conduct a negative voltage is applied to the pin. This signal is then applied to the signal generator so that an audible signal, as well as a visual signal, is provided at each change in a set condition which is indicative of a change which has occurred in the integrity of the building being monitored by the circuit 14. As a practical matter, a current limiting resistor 158 is interposed between the SCR 134 and the pin P.

Of course, once intelligence has been provided at the observation station 12, circuit monitoring personnel must be afforded an opportunity to reset the circuit of the unit 19. This is achieved through the reset switch S2 which, through an NPN transistor 160 interrupts flow of current through the lamp 60 and to the audible Signal generator 156. I

In practice, the emitter of the NPN transistor 160 is coupled with the negative voltage source 23, through the lead 29, while the collector thereof is connected between the lamp 60 and the SCR 134. Accordingly, a current path established through the transistor 160 causes a current to bypass the SCR 134, permitting the SCR to reset to its non-conducting state. As a practical matter, a pair of directional diodes 162 are connected in series between the SCR 134 and the collector of the NPN transistor 160 in order to assure that the SCR 134 is afforded an opportunity to reset in the presence of the transistor 160 in its conductive state.

Normally, the transistor 160 is biased to a nonconductive state through a 10 microfarad capacitor 164 and a'current limiting resistor 166. HoweverQit is noted that the resistor 166 also is connected through a directional diode 168 and a current limiting resistor 170 to a pole, designated 172, of the switch S2. It is to be understood that the switch S2 is a single pole double-throw switch normally open between the pole 172 and ground, while being closed between the

lamps

44, 46, 48 and 50 and ground. However, in order to reset the circuit and thus clear intelligence from the observation circuit 116, the switch S2 is manipulated so that the circuit is opened between the lamps 44 through 50 and ground while a circuit is completed from ground to the base of the transistor 160 via resistors 166 and 170. Of course, a completion of the circuit between the pole 172 and ground causes ground potential to be applied to the base of the transistor 160 for overcoming the negative bias of the capacitor 164. Of course, the capacitor 164 is permitted to charge through a directional diode 174. The pin P also is connected with the pole 172, through the resistor 170 and a directional diode 176. Accordingly, ground potential is applied between the resistor 158 and the pin for removing the negative voltage applied thereto through the transistor 160 as the pole 172 of the switch S2 is grounded. As a practical matter, a directional diode 178 is interposed between the pin and the collector of the transistor 160 in order to prevent a negative voltage from being applied to the collector from the pin.

Accordingly, it should be appreciated that once the switch S2 is manipulated so that the circuit between the lamps 44 through 50 and ground is interrupted, while the circuit between the base of the transistor 16,0 and ground is completed, the

SCRs

82, 116 and 134 as well as NPN transistors 100 and 112 are switched to a nonconducting mode for resetting the circuit and turning off the audible signal generator. Of course, once the circuit is interrupted between the pole 172 and ground, by returning the switch S2 to its normal condition, ground potential is again applied to each'of the lamps by' the switch S2.

In practice, the capacitor 164, upon an opening of the circuit at the switch S2 between the pole 172 and ground discharges for a period of one second for biasing the SCR 134 to an off condition through the transistor 160. The circuit is now prepared for reactivation in accordance with its normal mode of operation.

OPERATION It is believed that in view of theforegoing description, the operation of the system will be readily understood and it will be briefly reviewed at this point.

With the circuit fabricated in the aforedescribed configuration, intelligence is provided at the observation 1 station 12 in accordance with the color of light emanating from the circuit lamps 44 through 60. This intelligence is depicted as follows:

The unit 19 is particularly suited for use where the opening and closing times of buildings to be monitored are known by monitoring personnel at the observation station, since the precise operation requires that the premises be opened and closed within a minimal time period. The open or closed, that is the night or day modes for the unit, are indicated by the green and white lights and are set by a manipulation of the switch 24 at the premises. A change between green and white lamps indicates the manipulation of the switch 24, while an energization of the red and

yellow lamps

44 and 50 indicate intrusion in the building. Of course, any change in the condition of the circuit is indicated by an energization of the blue lamp and a tone derived from the audible signal generator 156. By manipulating the switch S2 the circuit can be set to clear or extinguish lights from the board, while a manipulation of the switch 81 provides a ring-back signal to the premises being monitored indicating the integrity of the circuit.

When the green light is energized, it is to be understood that a current of .8 to 1.15 ma is flowing through the hard lines 18 and the monitoring circuit 14. A current of this level causes a suitable voltage to be applied to the base of the transistor 74 causing this transistor to be rendered conductive so that, in effect, transistor 74 is caused to cconduct with a resulting conductive state being imposed on the transistor causing the lamp 46 to be energized.

In the event the switch 24 is manipulated for establishing a day mode on the monitoring circuit 14 an increase in the current flow through the hard lines and the circuit 14 is experienced, whereupon the transistor 74 of the pick-off circuit of the block F is rendered conductive so that the transistor 1 12 is caused to conduct, in response to transistor 104 being rendered nonconductive as groundpotential is removed from the base thereof. As the transistor 112 conducts, the lamp 48 is energized for providing an output of light, white in color. As a practical matter, it is desirable to maintain the lamp 46 in a de-energized condition. Accordingly, the PNP transistor 115, normally maintained in a reverse bias state, is provided with its collector being connected to the base. of the NPN transistor 92 while the emitter thereof is connected to ground potential, as aforedescribed. The base of the PNP transistor 115, while being connected to ground,'also is connected between the collector of the transistor 112 and the lamp 48 so that as a current flow through the lamp 48 is established the biasing voltage applied to the base of the transistor 115 is removed, causing the transistor to conduct for applying a reverse biasing voltage, at ground potential, to the base of the transistor 92. Therefore, it can be appreciated that so long as the lamp 48 is energized, the lamp 46 is biased to its off condition.

In the event the circuit to ground it interrupted, at the monitoring circuit 14, the transistor 74 is rendered non-conductive, through a removal of voltage from the base thereof, while the SCR 82 is responsively caused to conduct for energizing the yellow lamp 44.

Similarly, in the event the circuit 14 is cross-shorted the increase in voltage applied to the base of the tran sistor 74 causes this transistor to conduct to apply a gating signal to the SCR 116, whereupon the SCR 1116 is rendered conductive for thus energizing the red lamp 50. Of course, a current flow established through any of the lamps 44 through 50 results in a gating signal being applied to the SCR 134 for thereby energizing the blue lamp 60. As a consequence, a switching signal is applied to the base of the PNP transistor 336. The intelligence thus provided at the observation station can now be noted and appropriate actions taken.

The switch S2 is then closed to ground the pole 172 and for removing ground potential from the lamps. Thus the switching circuits are permitted to reset for extinguishing intelligence provided by the radiation from the lamps and the signal generator 156. The switch S2 is then reset to its normal position for grounding the opposite pole thereof, whereby the unit 19 is prepared for a subsequent monitoring operation.

In view of the foregoing, it should be apparent that the circuit of the instant invention provides a practical solution to the perplexing problem of electronically monitoring the integrity of remotely related buildings.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the illustrative details disclosed.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

l. A system for simultaneously monitoring the integ rity of a building from a remotely related observation station, comprising:

A. an integrity monitoring circuit, characterized by means imparting thereto a selectively variable resistance of two predetermined values, disposed within a selected building including means for continuously conducting therethrough an electrical current at a selected one of two amperages, each amperage being indicative of normal building integrity and dictated by the resistance of the circuit; and

B. an observation circuit located at an observation station remotely related to said building and connected with said monitoring circuit including amperage-monitoring circuit means characterized by a color-coded lamp responsive to the selected amperage of the current conducted through the monitoring circuit for providing intelligence indicative of normal building integrity, and circuit means including a plurality of color-coded lamps responsive to changes in the selected amperage for selectively energizing said color-coded lamps for thereby providing intelligence indicative of abnorma] building integrity.

2. A system for simultaneously monitoring the integrity of a plurality of remotely related buildings from a common observation station comprising:

A. a plurality of remotely related monitoring circuits each being situated within one of a plurality of remotely related buildings;

B. a plurality of observation circuits located at a common observation station remotely related to said buildings, each including,

1. a plurality of electrically energizable lamps for propagating light of mutually distinct colors,

2. a plurality of solid state switching circuits, each being electrically connected with one of said lamps, and

3. a plurality of solid state switching devices, each being electrically connected with one of said solid state switching circuits and responsive to an electrical signal at a predetermined voltage applied thereto for switching the solid state switching circuit connected therewith to a conductive state for electrically energizing the lamp connected with the switching circuit;

D. a plurality of hard lines connecting said plurality of observation circuits with said plurality of monitoring circuits, each being adapted to conduct a current of electrical energy, the amperage of which is determined by the integrity of one of said buildings;

E. a plurality of pick-off means, each being connected with one of said monitoring circuits and with one of said hard lines for applying electrical signals at said predetermined voltage to selected solid state switching devices included within said one monitoring circuit in accordance with the am perage of said current; and

F. selectively operable means for verifying the integrity of said plurality of hard lines.

3. The system of claim 2 wherein the value of said amperage is minimized in response to an opening of said monitoring circuit, and is maximized in response to a cross-shorting of said monitoring circuit.

4. The system of claim 2 wherein each of said solid state switching devices is an NPN transistor, the collectors thereof being connected with said switching circuits.

5. The system of claim 4 wherein said plurality of lamps are connected in parallel with respect to each other and each of said pick-off means includes a potentiometer connected with one of said NPN transistors in a manner such that the resistor thereof is connected between a hard line and a source of negative electrical potential and the wiper arm thereof is coupled with the base of the NPN transistor connected therewith.

6. The system of claim 5 wherein said observation circuit further includes an electrically energizable status-change lamp, adapted, when energized, to propagate light of a color differing from said mutually distinct colors, circuit means connected with each of said switching circuits and with said status-change lamp, responsive to each conductive state imposed on said plurality of switching circuits by said plurality of switching devices for energizing saaid status-change lamp.

7. The system of claim 6 further comprising an audible signal generator connected with said circuit means and responsive to an energization thereof for generat- 9. in a system for remotely monitoring the integrity of a selected building indicated by the amperage of a flow of an electrical current, the improvement comprising:

A. a monitoring circuit situated within a selected building including circuit means foor maintaining an electrical current established at a selected amperage in the monitoring circuit, said amperage tance of the circuit, whereby said indicator lamps are selectively energized to provide intelligence indicating change in building integrity.

10. The improvement of claim 9 wherein said source of electrical potential comprises a source of negative beiing dictated by the resistance of the circuit and 15 correspondingly indicative of building integrity; and

B. an observation circuit located at a station remotely related to said building and connected with said monitoring circuit for continuously monitoring the amperage of the flow of electrical current in said monitoring circuit, including,

1. a plurality of color-coded, electrically energizable indicator lamps, each being responsive to an electrical current flowing through the lamp for propagating light of a predetermined color,

2. a plurality of solid state switching devices, each being connected in series between a source of electrical potential and one side of one of said indicator lamps adapted to switch to a conductive state in response to an electrical switching signal applied thereto for establishing a flow of electrical current through the indicator lamp connected therewith, and

3. circuit pick'off means connected with said monitoring circuit and with said plurality of solid state switching devices for selectively applying electrical switching signals to said solid state switching devices in response to changes in the amperage of the electrical current established in said monitoring circuit, in response to changes in the resis- 24 v. electrical energy and said pick-off means includes a plurality of NPN transistors, the emitter of each being connected with said source of electrical potential and the collector thereof being connected with one of said solid state switching devices, and a plurality of potentiometers, each being connected in series with the base of one NPN transistor of said plurality of NPN transistors and said monitoring circuit.

11. The improvement of claim 9 further comprising:

A. an electrically energizable status-change lamp adapted to respond to an electrical current flowing therethrough for propagating light of a predetermined color;

B. further solid state switching means connected in series with said source of electrical potential and said status-change lamp adapted to switch to a conductive state in response to an electrical signal applied thereto for establishing a flow of electrical current through the status-change lamp;

C. further pick-off means including a circuit connected with each indicator lamp and said further solid state switching means for applying an electrical signal to said further solid state switching means in response to each flow of electrical current established through said plurality of indicator lamps for thereby establishing a flow of electrical current through said status-change lamp whereby said status-change lamp is energized concurrently with the energization of each indicator lamp; and

D. circuit means connected with said status-change lamp for maintaining said flow of electrical current through the status-change lamp for periods of determinable durations.

Claims

1. A system for simultaneously monitoring the integrity of a building from a remotely related observation station, comprising: A. an integrity monitoring circuit, characterized by means imparting thereto a selectively variable resistance of two predetermined values, disposed within a selected building including means for continuously conducting therethrough an electrical current at a selected one of two amperages, each amperage being indicative of normal building integrity and dictated by the resistance of the circuit; and B. an observation circuit located at an observation station remotely related to said building and connected with said monitoring circuit including amperage-monitoring circuit means characterized by a color-coded lamp responsive to the selected amperage of the current conducted through the monitoring circuit for providing intelligence indicative of normal building integrity, and circuit means including a plurality of color-coded lamps responsive to changes in the selected amperage for selectively energizing said color-coded lamps for thereby providing intelligence indicative of abnormal building integrity.

2. A system for simultaneously monitoring the integrity of a plurality of remotely related buildings from a common observation station comprising: A. a plurality of remotely related monitoring circuits each being situated within one of a plurality of remotely related buildings; B. a plurality of observation circuits located at a common observation station remotely related to said buildings, each including,

3. a plurality of solid state switching devices, each being electrically connected with one of said solid state switching circuits and responsive to an electrical signal at a predetermined voltage applied thereto for switching the solid state switching circuit connected therewith to a conductive state for electrically energizing the lamp connected with the switching circuit; D. a plurality of hard lines connecting said plurality of observation circuits with said plurality of monitoring circuits, each being adapted to conduct a current of electrical energy, the amperage of which is determined by the integrity of one of said buildings; E. a plurality of pick-off means, each being connected with one of said monitoring circuits and with one of said hard lines for applying electrical signals at said predetermined voltage to selected solid state switching devices included within said one monitoring circuit in accordance with the amperage of said current; and F. selectively operable means for verifying the integrity of said plurality of hard lines.

3. circuit pick-off means connected with said monitoring circuit and with said plurality of solid state switching devices for selectively applying electrical switching signals to said solid state switching devices in response to changes in the amperage of the electrical current established in said monitoring circuit, in response to changes in the resistance of the circuit, whereby said indicator lamps are selectively energized to provide intelligence indicating change in building integrity.

7. The system of claim 6 further comprising an audible signal generator connected with said circuit means and responsive to an energization thereof for generating an audible signal concurrently with the energization of said status-change lamp.

8. The system of claim 7 further comprising selectively operable means for simultaneously de-energizing said lamps and terminating the generation of said audible signal.

9. In a system for remotely monitoring the integrity of a selected building indicated by the amperage of a flow of an electrical current, the improvement comprising: A. a monitoring circuit situated within a selected building including circuit means foor maintaining an electrical current established at a selected amperage in the monitoring circuit, said amperage beiing dictated by the resistance of the circuit and correspondingly indicative of building integrity; and B. an observation circuit located at a station remotely related to said building and connected with said monitoring circuit for continuously monitoring the amperage of the flow of electrical current in said monitoring circuit, including,

10. The improvement of claim 9 wherein said source of electrical potential comprises a source of negative 24 v. D.C. electrical energy and said pick-off means includes a plurality of NPN transistors, the emitter of each being connected with said source of electrical potential and the collector thereof being connected with one of said solid state switching devices, and a plurality of potentiometers, each being connected in series with the base of one NPN transistor of said plurality of NPN transistors and said monitoring circuit.

11. The improvement of claim 9 further comprising: A. an electrically energizable status-change lamp adapted to respond to an electrical current flowing therethrough for propagating light of a predetermined color; B. further solid state switching means connected in series with said source of electrical potential and said status-change lamp adapted to switch to a conductive state in response to an electrical signal applied thereto for establishing a flow of electrical current through the status-change lamp; C. further pick-off means including a circuit connected with each indicator lamp and said further solid state switching means for applying an electrical signal to said further solid state switching means in response to each flow of electrical current established through said plurality of indicator lamps for thereby establishing a flow of electrical current through said status-change lamp whereby said status-change lamp is energized concurrently with the energization of each indicator lamp; and D. circuit means connected with said status-change lamp for maintaining said flow of electrical current through the status-change lamp for periods of determinable durations.