US3448443A - Signaling system - Google Patents

Description

June 3, 1969 F. E. wELD SIGNALING SYSTEM sheet ors Filed July 9, 1965 I1lillllllillmmmwiwfllilIIII!! ATTORNEYS June 3, 1969 F. E. wl-:LD

SIGNALING SYSTEM ors Sheet Filed July 9, 1965 Om .E

ATTORNEYS sheet of 5 June 3, 1969 F. E. WELD SIGNALING SYSTEM Filed July 9, 1965 k 0S om. o m mw @E u mm. w, U TE m mw a L v sa 2956 2.522 ME a omg com of o3 oom .be o H M v n w T m m ,qm @E F 7 m v VL B ml LPP ATTORNEYS F. E. WELD SIGNALING SYSTEM June 3, 1969 Sheet Filed July 9. 1965 INVENTOR.

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vi M2525 mwmn -moa m ATTORNEYS Sheet Filed July 9, 1965 FOSTER E. wELD imq ody ATTORNEYS United States Patent() U.S. Cl. 340-287 13 Claims ABSTRACT F THE DISCLOSURE There is provided a signaling system which includes a plurality of remotely located system transmitters, each including code signaling means, driving means for driving said code signaling means, and control means for activating the driving means; a conventional fire alarm transmitter having normally-closed signaling contacts connected in series with the signaling means of the system transmitters by a conductor extending from a central station; a central station pulse generator for transmitting driving impulses to an activated system transmitter through a pair of conductors extending from the central station; and, a pulse generator controller for energizing the pulse generator when a system transmitter is activated and no conventional lire alarm transmitter has been actuated.

This invention pertains to the art of signaling systems and, more particularly, to an improved signaling system in which transmitter driving impulses are transmitted from a central station to remote code transmitters which transmit coded signal impulses back to the central station to actuate recording or alarm devices in accordance with the coded signal impulses.

'Ihe present invention is particularly applicable as a tire, emergency and/or watch signaling system and will be described with -particular reference thereto; although it will be appreciated that the invention has broader applications.

A signaling system similar to that of the present invention is described and illustrated in my U.S. Patent No. 2,355,934. That system generally includes a plurality of remotely located transmitters, each including a normally open activating switch and a coded cam wheel driven by a ratchet motor for actuating normally closed code signaling contacts; a central station pulse generator for transmitting impulses of alternating positive and negative polarity to an activated transmitter, the positive impulses serving to drive the ratchet motor and the negative impulses serving as signaling impulses in dependence on the active transmitter coded cam wheel to energize a central station alarm or recording device in accordance with the code; and, three conductors extending from the central station with one conductor connected in series with the code signaling contacts and the other two conductors connected to each transmitter ratchet motor through its activating switch.

The driving power for each remote transmitter of the above system is obtained from the pulse generator at the central station. One of the problems of the system described above is that it includes no provisions to permit compatibility with a conventional self-powered re alarm transmitter, i.e., a positive, noninterfering, successive, automatic ground, prewound clockwork driven transmitter such as E. W. Bliss Company, Gamewell Divisions Three Fold Manual or Automatic Master Box, catalog numbers 700() (Manual) and 9000 (Master), Series. It is important that such a system be compatible with conventional self-.powered transmitters since many users of the system may own large quantities of such transmitters and would like to use them in the system. For a system 3,448,443 Patented June 3, 1969 ACe similar to that described above to be compatible with a conventional self-powered re alarm transmitter, provisions should be made to obtain noninterfering signaling operation between the conventional self-powered trans- -mitters and the systems remotely powered transmitters. More particularly, provisions should be made to prevent the pulse generator from transmitting driving impulses to an activated system transmitter until an actuated conventional fire alarm transmitter has completed its signaling operation.

The present invention is directed toward a signaling system similar to that as described above, but which is compatible with conventional self-powered tire alarm transmitters and which includes provisions for obtaining noninterfering signaling operation between the systems transmitters and the conventional self-powered transmitters, thereby overcoming the noted disadvantages, and others, of previous signaling systems.

In accordance with the -present invention the noninterfering signaling system includes a plurality of remotely located, remotely powered system transmitters, each including code signaling means, driving means, such as a ratchet motor, for driving same, and a control means for activating the driving means; a self-powered conventional re alarm transmitter having normally closed signaling contacts; circuit means electrically connecting said signaling contacts in series with the signaling means of the system transmitters and including a conductor extending from a central station; a central station pulse generator means located at the central station for transmitting driving impulses to the driving means of an activated system transmitter through circuit means including a pair of conductors extending from the central station to said system transmitters; and, pulse generator control means located at the central station and coupled to the pulse generator means, the pulse generator control means including circuit means for energizing the pulse generator means only when a system transmitter is activated after a predetermined period of time has elapsed from the last actuation of a conventional alarm transmitter so that non-interfering operation is obtained between the system transmitters and the conventional alarm transmitter.

In accordance wih another aspect of the present invention the pulse generator controller serves to time a predetermined period of time upon actuation of a conventional re alarm transmitter before energizing the pulse generator, the predetermined period of time being greater than the time duration of a closed circuit in the iirst conductor circuit due to closure of the fire alarm transmitter signaling contacts during signaling operation of such transmitter to thereby prevent energization of an activated system transmitter until the re alarm transmitter completes its signaling operation.

In accordance with a still further aspect of the present invention, a detector circuit is provided for the signaling system for energizing a control means of a system transmitter; the detector circuit includes a detector conductor having a relay coil and a bucking coil connected together in series opposition, and a normally open detector switch connected across the bucking coil.

The primary object of the present invention is to provide an improved signaling system having compatibility with a conventional self-powered re alarm transmitter.

Another object of the present invention is to provide a signaling system having provisions for obtaining noninterfering signaling operation between system transmitters and conventional self-powered iire alarm transmitters.

A still further object of the present invention is to provide an improved signaling system utilizing solid state devices, such as transistors, for low current and, hence, power requirements for economically eflicient operation.

These and other objects and advantages of the invention will become apparent from the lfollowing description of the preferred embodiment of the invention as read in connection with the accompanying drawings in which:

FIGURES 1 and 1A are system block diagrams of the preferred embodiment of the invention;

FIGURE 2 is a schematic diagram illustrating a system transmitter;

FIGURE 3 is a schematic circuit diagram of the central station equipment illustrated in block diagram form in FIGURE 1;

i FIGURES 4A, 4B, 4C, 4D and 4E are waveforms of voltage versus time illustrating one aspect `of the operation of the invention;

FIGURES 5A, 5B and 5C are waveforms of voltage versus time illustrating another aspect of the operation of the invention; and,

FIGURES 6A and 6B are waveforms of amplitude versus revolutions illustrating a still further aspect of the operation of the invention.

Referring now to the -drawings wherein the showings `are for the purpose of illustrating a preferred embodiment of the invention and not for the purpose of limiting same, FIGURE 1 is a block diagram illustrating the signalling system and generally includes a plurality of remote transmitters XTR-1 through XT R-7 a pair of conventional fire alarm transmitters A .and B; a pair of transmitter lines TL and LN extending from a central station C; a signal line SL extending from central station C; a detector line DL extending from central station C and including in circuit therewith a pair of detectors 'D and E; emergency relay equipment ER at the central station C and including a ground time delay unit GTD, emergency grounding relay circuitry EGR, transmitter circuit supervisory relay circuitry TSR, emergency connect relay circuitIy ECR, and a direct current voltage supervisory relay circuit DCR; box and transmitter circuitry AR including detector circuit supervisory relay circuitry DSR, alarm supervisory relay circuitry ASR, pulse generator circuitry PGR, transmitter alarm relay circuitry TAR, signal supervisory relay circuitry SSR, and signal alarm relay circuitry SAR; a console recorder CR at the central station C; power supply circuitry at the central station C including an alternating current voltage source F, a battery H, a battery charger I, and three 24 volt D.C. to 110 volt D.C. converters CV-1, CV-Z and CV-3; and, an alarm line AL having in circuit therewith alarm devices AL-I, AL-Z and AL-3.

A The transmitter line TL extends from the positive side of converter CV-l through normally closed pulse generator contacts PGR-1, transmitter circuit alarm relay coil TAR-C, transmitter line terminal TL+ and is looped to define three open transmitter loops 10, 12 and 14, through terminal LN-l, through a high impedance relay coil TSR-C having an impedance on the order of 10 kilohms, back through the transmitter loops 10, 12 and 14, from terminal LN- to terminal TL-, and thence through the central station C to the negative side of converter CV-l. Preferably, the maximum resistance of each loop of the transmitter line is on the order of 400 ohms.

normally closed emergency ground relay contacts EGR-1 to the negative side of converter CV-1. Preferably, the maximum line resistance of signal line SL is on the order of 400 ohms and that supervisory current on the order of 100 milliamperes normally ows through the signa line SL. Y

The detector line DL extends from the positive side of the 24 volt D.C. to 110 volt D C. converter CV-3, through a detector supervisory relay coil DSR-C, and thence through a line current adjusting rheostat RV-3, a 0 to 50 milliampere ammeter 22, detector line terminal DL-|-, and is then looped twice to dene a first detector double loop 24, and is again looped twice to define a second `detector double loop 26, and then extends through detector line terminal DL- to the negative side of converter CV-3. Detectors D and E, respectively associated with the detector loops 24 and 26, are substantially identical and, accordingly, the following description will be made with reference only to detector D.

Detector D includes a detector relay DR having a relay coil 30 and a bucking coil 28 connected together in series opposition so that current normally owing from Adetector line terminal DL+ to detector line terminal DL- through coils 28 and 30 will not energize detector relay DR. The detectors D and E each include normally open detector contacts 34 associated with detector relay IDR and in series circuit with transmitter coils XTR-C of transmitters XTR-3 and XTR-7 across transmitter lines TL and LN. Detector D also includes normally open detector contacts 32 connected across detector relay bucking coil 28. The detector contacts 32 may take any suitable form, such as a bimetallic switch or a manually operated switch, etc. Preferably, the miximum total resistance of the Adetector line DL is on the order of 3,000 ohms and the current normally flowing through the detector line DL is on the order of 40 milliamperes.

The alarm line AL extends from the positive side of the 24 volt D.C. to 110 volt D.C. converter CV-2, through alarm supervisory relay coil ASR-C, normally closed supervisory :alarm relay contacts SAR-C, through a line current adjusting rheostat RV-Z, a 0 to 200 milliampere ammeter 36, through the alarm terminal AL{, through the series connected alarm devices AL-1 through AL-3, and from the alarm terminal AL- to the negative side of converter CV-Z.

Transm tters The transmitters XTR-1 through XTR-7, illustrated in FIGURE 1, are substantially the same and each takes the form, for example, of transmitter XTR-1, illustrated in detail in FIGURE 2. Transmitter XTR-1 includes a driving coil XTR-C of -a ratchet motor 38 including a ratchet wheel 40, a driving pawl 42 magnetically associated with coil XTR-C, a cam carrying shaft 44 extending from ratchet wheel 40 and having mounted thereon a coding wheel 46, a transfer wheel 48, a Geneva gear actuating wheel 50 having a pin 52 extending therefrom for purposes of actuating a Geneva wheel 54, and an off-normal cam wheel 56. The code wheel 46 is provided with a plurality of radially extending cam lobes 58 which serve to engage movable contact 60 of normally closed signalling contacts SL-1 connected in series circuit with The supervisory line SL extends from the junction of i the normally closed pulse generator relay contacts PGR-1 and the normally de-energized transmitter alarm relay coil TAR-C, through a series circuit including normally energized supervisory alarm relay coil SAR-C, normally energized signal supervisory relay coil SSR-C, through a line current adjusting rheostat RV-1, a 0 to 200 milliampere ammeter 1-6, through a signal line terminal SL+, through normally closed signal contacts SL-l through SL-7 of transmitters XTR-1 through XTR-7, respectively, through normally closed signaling contacts 18 and 20 of conventional fire alarm transmitters A and B, respectively, signal line terminal SL, and thence through the signaling line SL. The transfer cam wheel 48 includes a cam lobe 62 extending radially outward therefrom and serves to engage a movable contact 64 of a single pole, double throw transfer switch S-2. Contact 64 is connected to transmitter coil XTR-C. The transfer switch S-2 also includes a stationary contact 66 connected to stationary contact 76 of detector switch S-1 and a second stationary contact 68 connected to a stationary contact 70of detector switch S-l. Detector switch S-1 includes a movable contact 72 connected to transmitter line terminal LN- through the anode to cathode circuit of a diode 74.

vThe Geneva gear cam wheel S4 includes a radially extending cam lobe 78 which serves to engage and displace a movable contact 80 from a stationary contact 82 to a second stationary contact 84 of a single pole, double throw Geneva gear driven switch S-3. Stationary contact 84 is connected to transmitter coil XT R-C and stationary contact 82 is connected to the cathode side of diode 74 in transmitter line LN.

The off-normal cam wheel 56 is provided with a pair of diametrically opposed notched portions 86 and 88 for receiving a cam wiper portion of movable Contact 90 of oi-normal single pole, double throw switch S-4. The switch S-4 also includes a stationary contact 92 connected to. transmitter coil XT R-C and another stationary contact 94 normally in engagement with contact 90 and connected to the movable contact 80 of Geneva switch S-3, through contacts 71 and 75 of a single pole, double throw switch S-5 having another contact 73 connected to the cathode side of diode 74. The detector switch S-1, illustrated in FIGURE 2 as a single pole, double throw switch, may take various `forms either as a. manually operable switch or as normally open relay contacts 34, illustrated in conjunction with detectors D and E in FIGURE 1. Switch S-1 should be double throw type, with connections to contacts of the cam operated transfer switch S-2, as shown by FIGURE 2, whenever the switch S-l may remain in abnormal position for a time longer than the time to transmit the signal. This is necessary in order for the transmitter to stop at the completion of each transmission. For manually operated transmitters, where the starting switch S-l is not likely to be held closed longer than the transmission time of a signal, the switch S-1 may be a single normally open contact and the transfer switch S-2 may be omitted, in which case, contact 76 of S-1 would be connected directly to transmitter coil XTR-C, instead of through contacts 64 and 66 of S-2. A noninterference coil NI-C of a noninterference relay NIR is connected in parallel with transmitter coil XTR-C and is magnetically connected with normally closed noninterference contact NI-1 connected in series circuit in transmitter line TL and in parallel with a diode 96, poled as shown in FIGURE 2.

Central station equipment Reference is now made to FIGURE 3 in which the equipment located at central station C is illustrated in schematic circuit diagram form. For purposes of facilitating the understanding of the invention, the lfollowing description will commence with describing the components shown on the left hand side of FIGURE 3, proceeding to those shown on the right hand side of FIGURE 3.

Pulse generator A pulse generator PG is connected across battery H and serves to periodically energize pulse generator relay coil PGR-C of pulse generator relay circuit PGR for purposes of periodically opening the normally closed contacts PGR-1 in the transmitter line TL. The pulse generator PG includes generally a bistable multivibrator circuit 100 and a trigger source for driving the multivibrator taking the form of a unijunction relaxation oscillator 102. The multivibrator circuit 100 includes a pair of silicon controlled rectiers Q-2 and Q-3 connected together in ip-op fashion and having their cathode' circuits connected directly to the negative side of battery H and their anode circuits connected to the positive side of battery H throughY resistorsR-4 and R-S, respectively. A smoothing capacitor C-S is connected in parallel across battery H between the battery and the multivibrator circuit 100. The anodes of rectifiers. Q-Z and Q-3 are connected together by a capacitor C-4 and a diode D-l, poled as shown in FIGURE 3, is connected between the junction of the capacitor and resistor R5 to the positive side of battery H. The gates of rectifiers Q-2 and Q-3 are connected together by series connected capacitors C-Z and C-3, having their junctions connected to the negative side of battery H through a load resistor R-3 of the relaxation oscillator 102. The gates of rectifiers Q-2 and Q-3 are also connected to the negative side of battery H through resistors R-6 and R-7 respectively. A Zener diode Z-1, poled as shown in FIGURE 3, is connected between the negative side of ybattery H and the positive side of battery H through a resistor R-8. The junction of the cathode side of Zener diode Z-1 and resistor R-8 is connected to base B-2 of unijunction transistor Q-1 of the relaxation oscillator circuit 102 through a resistor R-2. Transistor Q-1 also has a base B-1 connected to the junction of capacitors C-2 and C-3 of multivibrator circuit 100, and a timing capacitor C-l connected between its emitter and the negative side of battery H. A pair of variable timing resistors 104 and 106 are connected together in series between the emitter of transistor Q-l and the positive side of battery H through resistor R-l and resistor R-8. The emitter of transistor Q-l is also connected to the negative side of battery H through a resistor R-9 connected in Series with normally closed contacts PCR-1 of pulse control relay circuit PCR, normally closed restore switch S-ZB and normally closed relay contacts TAR-1 of transmitter alarm relay circuit TAR. The normally closed contacts TAR-1 are connected in parallel with normally open relay contacts SAR-1 of signal alarm relay circuit SAR. The junction of normally closed relay contacts PCR-1 and resistor R-9 is connected to the junction of variable resistors 104 and 106 through normally open relay contacts PCR-2 of the pulse control relay circuit PCR. The output of pulse generator PG is taken from the anode of rectier Q-3 and is connected to relay coil PGR-C and also to relay coil PCR-C of the pulse control relay circuit PCR through the cathode to anode circuit of diode D-2. The relay circuit PCR is a slow release relay and includes normally open relay contacts PCR-3 connected in series with coil PCR-C across battery H through normally open relay contacts TAR-2 of the transmitter alarm circuit TAR. The relay circuits PCR and TAR also include normally closed relay contacts PCR-4 and TAR-3 connected together in series for purposes as will be described in greater detail hereinafter.

The signal alarm relay circuit SAR includes a relay coil SAR-C in series circuit in the signal line SL, normally open relay contacts SAR-1 connected in parallel with normally closed relay contacts TAR-1, and normally open relay contacts SAR-2 connected from the positive side of battery H to resistor R10 of a ground time delay circuit GTD.

Ground time delay circuit The ground time delay circuit generally includes a unijunction relaxation oscillator and a free runningrelaxation oscillator 107 for driving a silicon controlled rectifier Q-6. The unijunction relaxation oscillator circuit 105 includes a unijunction transistor Q4 having an emitter connected to resistor R-10 through the parallel path including diode D-3 connected in parallel with series connected resistor R-11 and varia-ble resistor RV-4. A timing capacitor C-6 is connected from the emitter of unijunction transistor Q4 to the negative side of battery H through normally closed restore switch S-ZA. Transistor Q4 also has a first base B-1 connected to restore switch S-2A through a load resistor R-12 and a second base B-2 connected to the positive side of battery H through a reverse bias resistor R-13.

The free running oscilator 107 includes a unijunction transistor Q-S having an emitter connected to base B-2 of transistor Q-4 through a capacitor C-7, a first base B-l directly connected to switch S-ZA and a second base B-2 connected to the positive side of battery H through a reverse bias resistor R-14. A timing capacitor C-8 is connected between the emitter and base B--l of transistor Q-S, and is also connected in series with a resistor R-15 to the positive side of battery H. Load resistor R-12 is connected in parallel with a capacitor C-9 across the gate to cathode circuit of a silicon controlled rectiier Q-6 having an anode connected to the positive side of battery H through a pilot lamp PL-4. A diode D4, poled as shown in FIGURE 3, is connected from the anode of silicon controlled rectifier Q-6 to the positive side of battery H, and a Zener diode Z-2, poled as shown in FIGURE 3, is connected across the anode to cathode circuit of rectifier Q-6.

Emergency ground relay circuitry The emergency ground relay circuit EGR includes a relay coil EGR-C connected across battery H through the anode to cathode circuit of silicon controlled rectier Q-6 of ground time delay circuit GTD and the normally closed restore switch S-ZA. Relay circuit EGR also includes normally closed relay contacts EGR-1 in series circuit with signal line SL, normally open relay contacts EGR-2 adapted when closed to connect signal line terminal SL- with signal line terminal SL-land normally open relay contacts EGR-3 adapted when closed to connect transmitter line terminal TL- to ground G.

Direct current supervisory relay circuitry The direct current supervisory relay circuitry DCR includes a relay coil DCR-C connected across battery H, and normally open relay contacts DCR-1 adapted when closed to connect a pilot lamp PL-9 across an alternating current source K.

Transmitter supervision and emergency connect relay circuits The transmitter supervisory relay circuit TSR includes a high impedance current limiting device in the form of relay coil TSR-C connected between transmitter line terminals LN- and LN}, and normally open relay contacts TSR-1 connected to the positive side of battery H through relay coil ECR-C of emergency connect relay circuit ECR. Relay contacts TSR-1 are also connected to the negative side of battery H through a series circuit including normally closed transmitter test switch S-6A, normally closed relay contacts TAR-3, normally closed relay contacts PCR-4, and normally closed restore switch S-ZA. Emergency connect relay circ-uit ECR also includes normally open relay contacts ECR-1 connecting relay coil ECR-C across battery H through normally closed restore switch S-2A, normally open relay contacts ECR-2 connecting transmitter line terminals LN- and TL-, and normally open relay contacts ECR-3 connecting transmitter terminals TL-land LN}-.

Detector line supervisory relay circuitry The detector line supervisory relay circuit DSR includes relay coil DSR-C and normally open relay contacts DSR-1 and DSR-2. As illustrated in FIGURE 1, as well as in FIGURE 3, relay coil DSR-C is in series circuit with detector line DL together with line current adjusting rhetostat RV-3 and milliampere ammeter 22. Nor mally open relay contacts DSR-1 serve to connect a pilot lamp PL-7 across battery H. The normally open relay contacts DSR-2 serve when closed to conduct a relay coil TBR-C of trouble relay circuit TBR across battery H.

Trouble relay circuit The trouble relay circuit TBR, in addition to relay coil TBR-C, also includes normally closed relay contacts TBR-1 and normally open relay contacts TBR-2. Trouble contacts TBR-2 when closed serve to connect a supervisory alarm lamp PL-11 and a trouble buzzer TB across an alterating voltage source L. Also, a switch S-7 is provided having normally closed contacts S-7A and S-7B. Contacts S-7A serve to connect trouble buzzer TB in parallel with lamp PL-11 and contacts S-7B are connected in parallel with relay contacts TBR-2.

Alarm supervisory relay circuit The alarm supervisory relay circuit ASR has, as illustrated in FIGURE 3, a relay coil ASR-C connected in series circuit in alarm line AL together with line current adjusting rheostatv RV-Z, ammeter 36, alarm devices AL-l, AL-Z and AL-3 across the output circuit of converter CV-2 through normally closed relay contacts SAR-3 of the signal alarm relay circuit SAR. The alarm signal relay circuit ASR also includes normally -open relay contacts ASR-l and ASR-2. Relay contacts ASR-1 serve when closed to connect a pilot lamp PL-6 across battery H, through normally closed relay contacts SAR-4 of signal alarm relay circuit SAR. The relay contacts ASR-2 serve when closed to connect relay coil TBR-C of trouble relay circuit TBR across `battery H. A switch S-S includes normally closed switch contacts S-SA and S-8B, and normally open switch contacts S-8C and S-8D. Switch contacts S-SC when closed serve to short circuit normally closed contacts SAR-3 in alarm line AL to prevent transmission of current from converter CV-2 through the alarm circuit, if desired. When switch contacts S-SA and S-SB are opened, causing contacts S-SC and S-SD to become closed, a pilot lamp PL-12 will be connected across battery H. In addition to the foregoing, the trouble relay coil TBR-C may be energized upon closure of normally open relay contacts SSR-1 or relay SSR. As illustrated in FIGURE 3, contacts SSR-2 serve when closed to connect pilot lamp PL-3 across battery H.

General operation During the operation of the signaling system, supervisory current on the order of milliamperes normal-ly ilows through signal line SL, supervisory current on the order of 4() milliamperes normally flows through the detector line DL, supervisory current on the order of 10 milliamperes normally ows through the series circuit including transmitter lines TL and LN, and alarm supervisory current on the order of 100 milliamperes normally ilows through alarm line AL. The transmitter line supervisory relay coil TSR-C connecting transmitter terminals LN+ to LN- is normally energized by the l0 milliampere current iowing through the coil, whereby its magnetically associated relay contacts TSR-1 are normally open, as shown in FIGURE 3. The l0 milliampere current owing through the transmitter line is insuicient to energize transmitter alarm relay coil TAR-C, therefore transmitter alarm relay contacts TAR-2 are open and relay contacts TAR-1 are closed, as shown in FIGURE 3, short circuiting timing capacitor C-1 in pulse generator PG. Thus, the pulse generator PG is normally inoperative and the transmitters XTR-1 through XTR-7 are normally deactivated.

Reference is now made to detector D in the detector line DL illustrated in FIGURE 1. The current normally owing through the detector line DL flows through coils 28 and 30 of detector relay DR in opposing directions. Upon closure of detector contacts 32 in response to an alarm condition, such as a smoke detection, heat detection, or the like, coil 28 will become short circuited and the detector relay DR will become energized, whereby its associated contacts 34 will become closed. With relay contacts 34 closed transmitter coil XT R-C of transmitter XTR-3 will be connected directly across terminals TIH- and LN-, thereby short circuiting the high impedance relay coil TSR-C. The current flowing through the transmitter line will then increase in value sufficiently to energize transmitter alarm relay coil TAR-C.

The transmitter alarm coil TAR-C may also be energized by connecting movable contact 72 to stationary contact 76 of detector switch S-l, illustrated in FIGURE 2. With contact 72 in electrical engagement with stationary contact 76 current will flow from the positive side of converter CV-1 through normally closed pulse generator relay contacts PGR-1, transmitter alarm relay coil TAR- C, transmitter line terminal TL-l, through transmitter coil XTR-C, movable contact 64 to stationary contact 66 of transfer switch S2, stationary contact 76 to movable contact 72 of detector switch S-l, and through transmitter line terminal TL- to the negative side of converter CV-1. In this manner, transmitter supervisory relay coil TSR-C will be short circuited, whereby the current flowing through transmitter line TL will increase sufficiently in value to energize transmitter alarm relay coil TAR-C.

When transmitter alarm relay coil TAR-C becomes energized (see FIGURE 3), its normally closed relay contacts TAR-1 will become opened, thereby removing the previous short circuit path across timing capacitor C-1 of pulse generator PG. Current will tiow from the positive side of lbattery H, through resistors R-8, R-1, variable resistors 106 and 104 to charge capacitor C-1. Referring now to the waveforms of voltage versus time in FIG- URES 4A through 4E, it will be noted that at time to relay coil TAR-C is energized, as illustrated by waveform VTAR C in FIGURE 4A. When relay coil TAR-C becomes energized, capacitor C-l will commence charging in accordance with the voltage waveform V04, illustrated in FIGURE 4B, toward the peak point voltage Vp, having a waveform as illustrated by the dotted line in FIG- URE 4B, of unijunction transistor Q-l. After a period of time t1 in accordance with the RC time constant determined by the values of resistors R-8, R-1, variable resistors 106 and 104 and capacitor C-1, the voltage V04 across capacitor C-1 will attain the level of the peak point voltage Vp, whereupon the emitter of transistor Q-l will become forward biased and the dynamic resistance between the emitter and base B-l will decrease to an eX- ceedingly small value so that the capacitor C-l will discharge through the emitter to base B-1 and load resistor R-3. The voltage developed across load resistor R-3 when capacitor C-1 discharges will be sucient in magnitude to trigger the bistable multivibrator circuit 100. Each time that silicon controlled rectifier Q-3 is conducting current, both relay coil PCR-C and relay coil PGR-C will become energized. When relay coil PGR-C becomes energized, normally closed contacts PGR-1 will open presenting an open circuit in the transmitter line TL. This will de-energize transmitter coil XTR-C and pawl 42 will, in a conventional manner, displace the ratchet wheel 40 one step in the direction shown by the arrow in FIGURE 2. When the ratchet wheel has moved one step the movable contact 64 of transfer switch S-2 will electrically engage stationary contact 68 deactivating the detector switch circuit; however, the movable contact 90 of off-normal switch S-4 will engage stationary contact 92 thereby maintaining electrical circuit connection between transmitter lines TL and LN through coil XTR-C.

With reference to the waveforms illustrated in FIG- URES 4C through 4E, it will be noted that when capacitor C-1 is discharged after completing a charging period for a time shown by t1, the pulse generator PG energized the pulse generator relay coil PGR-C, as indicated by the first pulse P-1 of the voltage waveform VPGR C, illustrated in FIGURE 4C. Also in FIGURE 4D it will be noted that when the pulse generator relay coil PGR-C is energized the transmitter coil XTR-C is de-energized, as evidenced by the waveform VXTR C. Also, in the event that upon the first step of the ratchet wheel 40 the code wheel signal contacts SL-l are opened, the Signal alarm relay coil SAR-C will be de-energized, as evidenced by the waveform VSAEC in FIGURE 4E.

When the pulse control relay coil PCR-C becomes energized its contacts PCR-2 and PCR-3 will become closed, and its normally closed contacts PCR-1 will become open. When the transmitter alarm relay coil TAR-C becomes de-energized upon opening of pulse generator contacts PGR-1, its contacts TAR-1 will close, but will not short circuit the timing capacitor C-1 because contacts PCR-1 are still open due to the slow release characteristic of relay PCR. C-1 will therefore immediately start to recharge toward the peak point voltage Vp of unijunction transistor Q-1; however, the charging path for capacitor C-1 will not include variable resistor 104 which becomes short circuited upon closure of contacts PCR-2, but rather includes resistors R-S, R-1, variable resistor 106, now closed contacts PCR-2 and resistor R-9. The RC time constant of the new charging circuit is much shorter than that of the RC time constant when variable resistor 104 is in the charging circuit. Thus, after a period of capacitor charging, evidenced by the time t2, which is much shorter than t1, the voltage CC 1 across capacitor C-1 will attain a level equal to the peak point voltage Vp of unijunction transistor Q-l, whereupon the capacitor will again discharge through the emitter to base B-l of the transistor to develop a second trigger voltage pulse across load resistor R-3. This trigger pulse voltage will be sucient to change the state of multivibrator so that silicon controlled rectier Q-3 -becomes nonconductive and silicon controlled rectifier Q-Z becomes conductive. Thus, pulse generator relay coil PCR-C will be de-energized as its previous current path through the anode to cathode circuit of rectier Q-3 has been removed. The relay contacts PGR-1 in the transmitter line TL will become closed and relay coil TAR-C will become energized. When relay coil TAR-C becomes energized its normally open contacts TAR-2 will become closed maintaining relay coil PCR-C energized since the time for its relay contacts PCR-3 to become open is of longer duration than the time required for relay contacts TAR-2 to become energized when rectifier Q-3 becomes nonconductive. Thus, the relay coil PCR-C is normally energized during the pulsing operation of the signal system so long as relay coil TAR-C becomes energized immediately following closure of normally closed pulse generator contacts PGR-1.

Relaxation oscillator 102 will continue to oscillate so long as TAR-2 contacts are closed by energization of relay coil TAR-C after each opening and then closure of relay contacts PGR-1. When the transmitter XTR-1 completes its cycle of operation, the transfer switch contacts S-2 and ofi-normal switch contacts S-4 and the detector switch contacts S-1 will be in the positions illustrated in FIGURE 2. This will occur at a time when the controlled rectier Q-3 in the pulse generator is conductive and PGR1 is holding the transmitter line open. When Q-S next becomes nonconductive and PGR-C becomes de-energized, PGR-1 will close the transmitter line which now includes the high resistance coil TSR-C. The value of the current flowing in transmitter line TL will then return t0 its normal value on the order of l0 milliamperes. Thus, relay coil TAR-C of transmitter alarm relay circuit TAR will not become energized by the current iiowing therethrough and its contacts TAR-1 will close and its contacts TAR-2 will open. Failure of TAR to close its contacts TAR-2 will allow the slow release relay PCR to release. Its contacts PCR-3 and PCR-2 will then open and its contacts PCR-1 will close. Accordingly, the timing capacitor C-1 in the unijunction relaxation oscillator 102 of pulse generator PG will become short circuited and the pulse generator will cease to operate.

Operation of the coding mechanism When the pulse generator PG is transmitting a train of time spaced voltage pulses, as evidenced by the waveform VXTR C in FIGURE 4D, the transmitter coil XTR-C in transmitter XTR-1 will alternately become energized and de-energized. Each time transmitter coil XTR-C of transmitter XTR-1 (see FIGURE 2) is energized and then deenergized, ratchet motor 38 will step one step. If the code wheel signaling contacts SL-1 are closed by a cam lobe 58 during the period when transmitter alarm relay coil TAR-C is energized, then current will ow through the signal line SL to maintain the signal alarm relay coil SAR-C energized. However, if during this period a cam 1 1 lobe 58 does not maintain switching contacts SL-1 closed, then no current will ow through the signal line SL and, hence, the .signal alarm relay coil SAR-C will be deenergized. The waveform of the voltage across signal alarm relay coil SAR-C may take the form, for example as that illustrated in FIGURE 4E, from which it will be noted that a code of two pulses, a space and then a third pulse has been transmitted from transmitter XTR-1 to thecentral station. The console recorder CR, which may take various forms, is responsive to the energization and de-energization of relay coil SAR-C to print a code corresponding with waveform VSAR C, Thus, with reference to FIGURE 3, it will be noted that when coil SAR-C is energized its associated relay contacts SAR-2 will be open, as shown, and when the coil becomes de-energized the contacts SAR-2 will close to energize the console recorder CR.

Noninterference operation with conventional transmitters During the operation of the signaling system illustrated in FIGURE l, it is possible that one of the conventional tire alarm transmitters A or B will have been actuated to commence transmitting coded signal impulses to the central station C when one of the transmitters XTR-1 through XTR-7 is activated by an automatic or manual closure of contact 72 with contact 76 of detector switch S-1 (see FIGURE 2). Transmitters A and B are conventional standard re alarm transmitters and preferably take the form of positive, noninterfering, successive, automatic grounding, prewound clockwork driven transmitters, such as E. W. Bliss Company, Gamewell Divisions Three Fold Manual or Automatic Box, catalog 7000 (Manual) and 9000 (Master), Series. For purposes of simplicity, the transmitters may be schematically illustrated as including normally closed switches 18 and 20, which upon actuation of the transmitter will open and close the signal line SL in accordance with a predetermined code representative of the transmitting re alarm transmitter. Thus, for eX- ample, if transmitter A has been activated a code wheel mechanism within the transmitter will open and close switch 18 to interrupt the 100 milliampere current normally owing through signal line SL in accordance with a predetermined code representative of transmitter A. Each time switch 18 is opened, the signal alarm relay coil SAR-C in the transmitter signal line SL will become deenergized and its associated relay contacts SAR-2 will become closed to energize the console recorder CR. Thus, the console recorder CR willrecord a visual representation of the code transmitted by transmitter Ato the central station C.

If normally closed signaling contacts 18 of transmitter A are open whne transmitter XTR-1 becomes activated, then relay coil TAR4C will become energized due to the activation ofptransmitter XTR-1 and signal alarm relay coil.SAR-C will be de-energized due to the interruption of'. current flow through the signal line SL upon opening of contacts 18. With relay coil TAR-C energized its normally closed contacts TAR-1 will become open, but timing capacitor C-1 will not be permitted to charge since a short circuit across the capacitor will be completed through relay contacts SAR-1 which close upon de-energization of relay coil SAR-C. Upon the next closure of signal contacts 18 of transmitter A, relay coil TARC will still be energized since transmitter XTR-1 will still be activated, but relay contacts SAR-1 will become opened thereby providing an open circuit path across capacitor C-1 which will now commence to charge through the circuit including the positive side of battery H, through resistors R-S, R-l, Variable resistors 106 and 104, as illustrated by the waveform VC 1 in FIGURE 5C. However, before suicient time has elapsed for the voltage VC 1 across capacitor C-1 to attain the peak point voltage VP of unijunction transistor Q-1, the signaling contacts 18 of transmitter A will again open, whereby the capacitor will again be short circuited and will discharge through resistor R-9, normally closed contacts PCR-1, normally. closed restore switch S-ZB and closed contacts SAR-1.0i relay SAR to the negative side of Abattery H..Thus, the pulse generator PG will not commence operation. Referring now to the waveform illustrated :in FIGURE B of the voltage VSAR C across relay coil SAR-C, it-will be noted that contacts 18 of transmitter A have alternatelyr opened and closed the signalline SL to transmit three pulses or breaks to the central .station- C, the last break of which is elongated by contacts 18 remaining open'for the time shown by t3. TheV time vt1 required for v'capacitor C-1 to charge to the peak point voltageVp of transistor Q-1 is adjusted by means of variable resistor 104 sot-that it is greater than time t4, the time of closure-of contacts 18 vduring signaling operation. Thus this period t4wma'y be referred to as a test period duringv which the ycentral station C will test the signal line SL to determinewhether it should permit the pulse generator PG to begin operavtion and thereby permit transmitter XTR-1 to transmit coded signal impulses to the central station, or instead to permit a conventional transmitter, such as transmitter A, to complete its transmission of coded signal impulses; After the test period t4 has terminated, the remaining impulses transmitted from transmitter A will take the form of coded signal impulses representative'of transmitter'Al and these coded signal impulses will be recorded by console recorder CR in the manner describedV previously. After the transmitter A has completed transmitting its coded signal impulses to the central station C, and providing the transmitter XTR is still activated, i.e., transmitter alarm relay coil TAR-C is still energized, the timing capacitor C-1 will charge to the peak point voltage Vp of unijunction transistor Q-l, in the manner described previously with reference to FIGURES 4A and 4B, so that transmitter XTR-1 will transmit its coded signal impulses to the central station C.

Noninterference operation with system transmitters When transmitter XTR-1 becomes activated by closure of switch contact 72 with contact 76 of detector switch S-1 (see FIGURE 2), current will ow from the transmitter line terminal TL+ through transmitter coil XTR-C, transfer switch S-Z, contacts 76 and 72 of switch S-l, to the transmitter line terminal TL-, as previously described. Current will also flow through noninterfe'rence coil NI-C in parallel with transmitter goil XTR- C, whereupon the noninterference coil will also become energized and its associated normally closed contacts NI-l will become opened. This places diode 96 inthe transmitter 'lin'e circuit to prevent current flow beyond transmitter XT R-l to transmitters XTR-2 to XTR-7. Similarly, when the ratchet motor 38 steps one step, contact 90 will engage contact 92 of off-normal switch S-4 and, thus',l current will no longer be permitted to flow from transmitter line terminal LN- throughthe path from the cathode s ide of the diode 74,`through contacts 82 and 80 of switcli'S-Z, through switch S-S when closed, and contacts 94 and 90, of switch S-4. Diode 74, therefore, serves to block cur-A rent flow from a'previous transmitter, i.e., fone closer to the central station than transmitter XTRfl, through the path including terminal LN-,th'rough the diode74 to terminal TL- and, thence, to the negative side of converter CV-1. Transmitter XTR-1 will transmit its coded signal impulses to the central station C without inter ference from either a preceding or a. succeeding transmitter until such time that contact is againplaced in electrical engagement with contact 94'l of off-normal switch S-4. With reference to FIGURE 2, it will be noted" that upon a half revolution of cam shaft 94 the wiper portion of contact 90 willvv be received by notch 88y in the'of-normal cam wheel 56 so that the movable contact 90 becomes engaged with stationary contact 94 to'thereby short circuit diode 74. This will permit a preceding transmitter toy commence operation and since in this position the olf-normal switch prevents current from owing 13 through the transmitter XTR-C, as well as a noninterference coil NI-C, contacts Nl-l will close to short circuit diode 96 to permit a succeeding transmitter to commence operation.

Types of transmitter operation i The signaling system of the present invention may include separately or in combination various types of signaling transmitters, such as, for example, manual lire alarm transmitters, automatic fire alarm transmitters, supervisory alarm transmitters, and watch report station transmitters. Whereas these transmitters generally take the form as illustrated in FIGURE 2, they, nevertheless, operate in somewhat different manners. That is, a transmitter for a manual iire alarm should transmit four rounds of coded signal impulses for each operation, with each round constituting one-half revolution of cam shaft 44 of the ratchet motor 38 (see FIGURE 2). During each operation of a manual fire alarm transmitter the coded signal impulses transmitted to the central station will include a presignal representative of the nature of the transmitter signal, followed by a coded signal representative of the particular activated transmitting alarm box or transmitter. For the manual tire alarm transmitters, the presignal and the following box number signal will be the same for each transmitted signal round.

For automatic tire alarm transmitters, such as for heat or smoke detectors, sprinkler alarms, etc., the transmitter will transmit five rounds and then stop until the alarm condition has been restored to normal. The transmitter will then transmit one more round when the alarm condition has been restored to normal. The presignal transmitted for the first five rounds will be representative of an alarm condition and the presignal transmitted for the sixth round will be representative of a normal condition.

For supervisory alarm transmitters, such as for power ot, valve closed, pressure low, etc., the transmitter will transmit one round with a presignal representative of an abnormal condition. When this condition is again normal, the transmitter will transmit one more round with a presignal representative of restoration to normal condition.

For watch report stations the transmitters will each transmit one round for each opeartion of the station. The presignal will indicate that the signal is a watch report and will be the same for each operation of the transmitter.

Geneva gear switch operation In the previous section of the description of operation it was mentioned that the various transmitters may transmit various rounds of signal impulses to the central station C. Referring now to FIGURE 2, it will be noted that when movable contact 71 engages contact 73 of switch S-S, the Geneva gear switch S-3 will be inelfective, as is the case when it is desired that the cam shaft 44 turn one-half revolution and then stop during which a presignal of an alarm condition may be transmitted followed by a station identifying signal. If at a later time the condition has been restored to normal, the switch contact 72 will be displaced to engage contact 70 either manually or automatically, as desired, and the transmitter XTRHC coil will become energized through movable contact 64 to stationary contact 68 of transfer switch S-2, stationary contact 70 and movable contact 72 of detector switch S-1.

Reference is now made to FIGURE 6 which illustrates a waveform of amplitude versus revolutions, showing the closure pattern of contacts 90 and 92 of olf-normal switch S-4 throughout the transmission of six rounds R-1 through R-6 of coded signal impulses from transmitter XTR-1 to the central station C. If it is desired that transmitter XTR-1 transmit ve uninterrupted rounds of coded signal impulses to the central station C and then stop until the condition noted by the transmitter XTR-1 has been resored to normal before transmitting the last round R6, then the Geneva switch S-3 is activated by connecting contact 71 to contact 75 of switch S-S. The Geneva gear 54 and its arrangement with pin 52 on Geneva gear actuating wheel 50 is well known to those skilled in the art and may be arranged so that cam lobe 78 will actuate Geneva switch contact 80 once per revolution, or some desired multiple of revolution of shaft 44 and maintain contact 80 in engagement with contact 84 until pin S2 again engages one of the teeth of the Geneva gear. With reference to FIGURES 6A and 6B, the Geneva gear, for example, may be arranged to actuate switch arm 80 at a time corresponding with 150 of angular revolution of cam shaft 44. Switch contact 80 may be maintained in engagement with switch contact 84 until contact 80 rides off cam lobe 78 at, for example, 870 of the angular revolution of cam shaft 44. This function is illustrated in FIGURE 6B, which illustrates the period of closure of the Geneva switch contacts 80 and 84. So long as Geneva switch contacts 80 and 84 are in engagement, the otfnormal switch S-4 will be short circuited and, hence, each time the pulse generator PG transmits a driving pulse to energize transmitter coil XTR-C the ratchet wheel motor 38 will be operative to step one step at a time without hindrance of the off-normal switch contacts, as described in the previous descriptions of operation. When the Geneva gear 54 is actuated again at, for example, 870 of angular revolution of shaft 44, the Geneva gear switch contact 80 will return to engage contact 82 whereby the off-normal switch S-4 will no longer be short circuited. This function can, 'for example, take place during the period that round R-5 of the signal impulses are being transmitted from the transmitter XTR-1 to the central station C. Upon the completion of signal impulses of round R-S the off-normal switch will again provide an open circuit path for the transmitter coil XTR-C which will not be energized again until the detector switch S-1 is returned to its normal condition, i.e., with switch contact 72 in engagement with switch contact 70.

Broken signal line operation During the operation of the signaling system it is possible that signaling line SL will become broken, presenting an open circuit for a duration greater than that of an open circuit interval of the coded signal impulses transmitted from a transmitter to the central station C. When an open circuit is present in the signaling line SL, signal alarm relay coil SAR-C will become de-energized and its normally open relay contacts SAR-2 will become closed to energize the ground time delay circuit GTD. The time delay afforded by the unijunction relaxation oscillator is increased by the free running oscillator circuit 107, the operation of which is well known to those skilled in the art, which serves to momentarily drop the peak point voltage of unijunction transistor Q-4, allowing peak point current to be supplied from capacitor C-6 rather than through the circuit including resistors RV-4 and R-11. After the time delay has expired capacitor C-6 will discharge through the emitter to base B-1 of unijunction transistor Q-4 to develop a trigger pulse across resistor R-12, which when applied to the gate of silicon controlled rectifier Q-6 will cause the rectier to become forward biased and conductive. Current will then ow from the positive side of battery H, through relay coil EGR-C of emergency relay circuit EGR and also through lamp PL-4 to energize the lamp, through the anode to cathode circuit of silicon controlled rectifier Q-6, and through the normally closed restore switch S-2A to the negative side of battery H. The emergency ground relay contacts EGR-1 will thus become open and the contacts EGR-2 and EGR-3 will become closed, whereby signal line terminals SL- and SL-lare connected together and transmitter line terminal TL-, i.e., the negative side of converter CV-1, is connected to ground G. Thus, as is conventional in the use of signaling systems of the type described in this patent application, the negative side of the power supply has been grounded upon a broken signal line to permit broken line operation from the signaling contacts of the transmitters through the ground connection to complete the signaling line circuit. The emergency ground relay coil EGR-C will remain energized until it is de energized by a momentary opening o'f restore switch S-ZA.

Broken transmitter line operation During the operation of the signaling system it is possible that an open circuit due to a break will occur in the transmitter line circuit, whereby the normally energized transmitter supervisory relay coil TSR-C in the transmitter line circuit will become de-energized. Normally open contacts TSR-1 will become closed to connect the emergency -connect relay coil ECR-C across battery H, through closed switch S-6A, the normally closed contacts TAR-3 and PCR4, and through the normally closed restore switch S-2A. Thus, relay coil ECR-C will be energized and its associated lamp PL-S will also be energized to present a visual indication to an operator that the transmitter line is broken. Also, the normally closed contacts ECR-1, ECR-2 and ECR-3 of the emergency connect relay ECR will become closed connecting transmitter line terminal TL+ to terminal LN-iand terminal LN- to terminal TL-, as well as connecting the relay coil ECR-C directly to the restore switch S-ZA, thereby providing lockup circuit for the relay coil ECR-C so long as restore switch S-ZA is closed. The normally closed contacts PCR-4 and TAR-3 of the pulse relay control circuit PCR and the transmitter alarm relay control circuit TAR, respectively, serve to prevent energization of relay coil ECR-C during normal signal transmission of the signal system. Further, the transmitter test switch S-6A serves to prevent energization of emergency connect relay coil ECR-C when it is desired to test the operation of the transmitters, i.e., upon opening of switch S-6A. It should be noted that normally closed contacts TAR-3 and PCR-4, as well as normally closed switch S-6A may serve to prevent energization of relay coil ECR-C, but will not de-energize the coil if it had previously become energized and then locked up through contacts ECR-1. After relay coil ECR-C has been energized it can be de-energized only by momentarily opening of restore switch S-2A.

Detector line alarm operation The detector line starting relays in the normally closed detector supervisory circuit DL are two coil, single pole, double throw relays with the two coils, i.e., 28 and 30, connected in series opposition so that when both coils are energized by current ow therethrough the energization of the coils will oppose each other and the associated relay contacts 34 will be open. If for some reason during the operation of the signaling system the detector line DL has a broken circuit in its series path, the detector supervisory relay coil DSR-C will become de-energized and its normally open contacts DSR-1 and DSR-2 will become closed. Thus, the pilot lamp PL-7 will become energized at the central station presenting a visual indication of the disruption of the detector line. Current will ilow from the positive side of battery H through the trouble relay coil TBR-C, the now closed detector supervisory contacts DSR-2 to the negative side of battery H. Thus, the trouble relay contacts TBR-1 will become opened and the normally closed contacts TBR-2 will become closed, whereby trouble indicating lamp PL-11, as well as the trouble buzzer TB, will become energized presenting -visual and audible indications to an operator of trouble within the system. The operator upon noting that lamp PL-7 is energized will be aware that the trouble noted is that of a break in the circuit of the detector line DL.

Signal supervisory relay circuit operation During the operation of the signaling system it is possible that a break will occur in the signaling line SL, whereupon the signal supervisory relay coil SSR-C will become de-energized, causing its associated relay contacts SSR-1 and SSR-2 to become closed. Upon closure 0f contacts SSR-1 and SSR-2 the signal supervisory alarm lamp PL-3 will become energized and the trouble coil TBR-C will become energized causing trouble lamp PL- 11, as well as trouble buzzer TB, to be energized. Thus, an operator will be provided with visual and audible indica tions of a trouble condition in the system, and upon observing the various lamps he will note that lamp PL-3 is energized, indicative that the troubleV condition is a break in the supervisory line SL.

Alarm supervisory relay circuit operation The alarm supervisory relay coil ASR-C is normally energized vby the milliarnpere current flowing through the alarm circuit. If for some reason the alarm circuit is broken, the coil ASR-C will become de-energized whereby its associated relay contacts ASR-1 and ASR-2 will become closed, and in a manner similar to that as described hereinabove, the pilot lamp PL-6, `as well as the pilot lamp PL-ll and trouble buzzer TB, will all become energized providing an operator with audible and visual indications of the trouble condition existing in alarm line AL. To prevent a trouble indication when the alarm circuit is open by a signal repeated into it, the normally closed relay contacts SAR-4 of relay SAR are connected in series with normally open contacts ASR-1 of relay coil ASR so that pilot lamps PL-6, PL-11 and trouble buzzer TB will not become energized during an alarm transmission. The trouble buzzer TB may be silenced by closure of switch contacts S-7B and opening of contacts S-7A. When the relay trouble coil TBR-C is restored to its normal condition, the buzzer will again sound and can be silenced by restoring the switch S-7 to the position as shown in FIGURE 3, i.e., closure of contacts S-7A and opening of contacts S-7B. In the event that alarm transmission over the alarm circuit AL is not desired, the switch S-8 may be thrown to its alarm silencing position, i.e., closure of contacts S-SC and S-SD and opening of contacts S-8A and S-SB. This will cause pilot lamp PL-lZ to be energized and the now closed contacts S-SC will short contacts SAR-3 of the signal alarm relay coil SAR so that signals will not be repeated into the alarm circuit. The pilot lamp PL-12 will be maintained energized by contacts S-SD of the switch until the switch is restored to its normal position.

Direct current relay alarm circuit operation During the operation of the signaling system it is possible that battery H will fail, and, accordingly, the norrnally energized relay coil DCR-C of the direct current relay DCR will become de-energized, whereby its associated contacts DCR-1 will close. With contacts DCR-1 closed, pilot lamp PL-9 will become energized from an alternate current supply, such as indicated at K, providing a Visual indication of the failure of the battery voltage.

In accordance with a lpreferred embodiment of the invention, the values and types of components illustrated in the drawings are found in Table I.

TABLE I Component: Component value or type Capacitor C-1 microfarads-.. 20 Capacitor C-2 do 0.047 Capacitor C-3 do 0.047 Capacitor C-4 ldo.. 0.33 Capacitor C-S do 0.33 Silicon controlled rectifier Q-Z i CZOF Silicon controlled rectifier Q-3 C20F Unijunction transistor Q-1 2N2646 Zener diode Z-1 volts 12 Diodes D-l, D-2, D-3, D-4 (0.5 amp.)

volts-.. 200 Resistor R-1 kilohms 4.7 Resistor R-2 do 1.0 Resistor R-S ohms 33 Component-Continued Component value or type Resistor R-4 kilohms 22 Resistor R-S ohms-- 470 Resistor R-6 do 330 Resistor R-7 do 330 Resistor R-8 do 470 Resistor R-9 do 33 Variable resistor 104 kilohms-.. 200 Variable resistor 106 do 100 Battery H (D.C.) volts-.. 24

Output voltage of converters Cv-l, CV-z, Cv-s (DC.) d 110 vRelay coil PCR-C ohms. 600 Relay coil PGR-C do 480 Relay coil TAR-C do 480 Relay coil SAR-C do 120 Relay coil SSR-C do- 120 Relay coil DCR-C do 480 Variable resistor RV-1 do- 1000 Relay coil ASR-C do 120 Relay coil DSR-C do 480 Relay coil TBR-C do 480 Resistor R- kilohms 1.2 Variable resistor R-4 megohms-- 3 Resistor R-11 do.. 1 Timing capacitor C-6 microfarads 2O Unijunction transistor Q-4 2N2646 Resistor R-13 kilohm-.. 1 Resistor R-12 ohms-- 33 Capacitor C-7 microfarad-.. 0.001 Resistor R-lS kilohms-.. 100 Capacitor C-8 microfarad-- 0.01 Resistor R-14 kilohm-- 1 Unijunction transistor Q-S 2N2646 Capacitor C-9 microfarad-- 0.01 Silicon controlled rectier Q6 2N2323 Zener diode Z-2 Volts 39 Relay coil EGR-C ohms-- 480 Relay coil TSR-C kilohms 10 Relay coil ECR-C ohms-- 480 Transmitter coils XTR-C do 1600 Detector relay coil DR 'do.. 70 Battery H (D.C., 12 cell) .volts.. 24

Although the invention has been shown in connection with a preferred embodiment, it will be readily apparent to those skilled in the art that various changes in form and arrangements of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim:

1. A non-interfering signaling system comprising:

a plurality of remotely located, remotely powered system transmitters, each including code signaling means, driving means for driving said code signaling means, and control means for actuating said driving means;

a self-powered conventional lire alarm transmitter having normally closed signaling contacts; circuit means electrically connecting said signaling contacts in series with the signaling means of said system transmitters and including a signal line conductor extending from a central station;

a central station pulse generator means, located at said central station for transmitting driving impulses to the driving means of an activated system transmitter through circuit means including a pair of conductors extending from said central station to said system transmitters; and,

pulse generator control means located at said central station and coupled to said pulse generator means, said pulse generator control means including circuit means for energizing said pulse generator means only when a system transmitter is activated after a predetermined period of time has elapsed from the last actuation of a said conventional alarm transmitter so that non-interfering operation is obtained between said system transmitters and said conventional alarm transmitter. 2. A signaling system as set forth in claim 1 wherein said pulse generator control means includes circuit means for timing said predetermined period of time upon actuation of a said conventional fire alarm transmitter before energizing said pulse generator, said predetermined period of time being greater than the time duration of a closed circuit in said signal line conductor circuit due to a closure of said re alarm transmitter signaling contacts during signaling operation to prevent energization of an activated system transmitter until said conventional lire alarm transmitter completes its signaling operation.

3. A signaling system including rst, second and third conductors each defining a loop extending from a central station;

at least one system transmitter having drive means and code signaling means driven by the drive means;

control means for said system transmitter for connecting said system transmitter drive means across said rst and second conductors;

pulse generator means for developing a train of time spaced impulses for transmission through said first and second conductors to energize said system transmitter drive means;

said code signaling means of said system transmitter being connected in series circuit with said third conductor for transmitting coded signal impulses to said central station upon energization of said pulse generator;

said third conductor being connected with a conventional tire alarm transmitter including a normally closed signaling switch being connected in a series circuit with said third conductor, said signaling switch upon actuation of said tire alarm transmitter opening and closing said series circuit in accordance with a predetermined code; and,

pulse generator control means for energizing said pulse generator means when said system transmitter is activated by said control means and no said conventional tire alarm transmitter is actuated,

4. A signaling system as set forth in claim 3 including timing means for timing a predetermined period of time upon actuation of said system transmitter and means responsive to the termination of said predetermined time to energize said pulse generator, said predetermined time being greater than the time duration of a closed circuit interval in said third conductor series circuit due to closing of said conventional lire alarm signaling switch during signaling operatori to thereby prevent said pulse generator from beng energized until said conventional tire alarm transmitter completes its signaling operation.

5. A signaling system as set forth in claim 4 including a rst normally closed switch deactivating said timing means when no said system transmitter is activated and permitting activation of said timing means when a said system transmitter becomes activated.

6. A signaling system as set forth in claim 4 including a second normally open switch deactivating said timing means when said third conductor circuit is open and permitting activation of said timing means when said circuit is closed.

7. A signaling system as set forth in claim 4 including a first normally closed switch deactivating said timing means when no said system transmitter is activated and permitting activation of said timing means when a said system transmitter becomes activated, and a second normally open switch deactivating said timing means when said third conductor circuit is open and permitting activation of said timing means when said circuit is closed.

8. A signaling system as set forth in claim 3 wherein said pulse generator includes a bistable multivibrator circuit and a relaxation oscillator circuit for developing a train of time spaced trigger pulses for triggering said multivibrator from one state to the other state, said oscillator 19 circuit including a timing capacitor and a capacitor charging circuit for charging said capacitor for a predetermined time toa predetermined voltage at which time said capacitor discharges and said oscillator develops a said trigger pulse;

said pulse generator control means including circuit means for preventing said timing capacitor from charging-toward said predetermined voltage when no vsaid system Itransmitter is activated and to permit said timing capacitor to charge when a said system 'transmitter becomes activated. 9. A signaling system as set forth in claim 8 wherein said pulse generator control circuit includes a iirst norrnally closed switch short circuiting said timing capacitor, said switch being open when a said system transmitter is activated to permit said timing capacitor to charge.

10. A signaling system as set forth in claim 9 wherein a'normally de-e'nergized relay coil magnetically associated with said rst switch is connected in series circuit with said Virst `conductor, said first and second conductors being connected together in series circuit through a high impedance current limiting device so that current flowing through the series circuit of said iirst and second conductors is normally insuicient to energize said relay coil, said system transmitter control means adapted to short circuit said high imperdance device to thereby increase said current sufficiently to energize said relay coil, whereby 'said irs't switch will become opened permitting said .timing capacitor to charge to said predetermined voltage and thereby trigger said multivibrator.

11. A signaling system as set forth in claim 9- including a second normally open switch connected in parallel with said rst switch, said switch being closed to prevent said capacitor from charging whenever an open circuit exists in said third conductor series circuit.

12. A signaling system assetA forth in claim 11 wherein a normally energized relay coil magnetically associated with said' second switch is connected in series circuit with said third conductor so that upon an open circuit in said third conductor said relay coil will become de-energized and its associated second switch will become closed to prevent said timing capacitor from charging.

13. A signaling system as set forth in claim 3 wherein said control means includes a relay having a pair of relay contacts connected in series with said driving means between said rst and second conductors and a pair of relay coils connected together in series opposition, said relay coils being connected in series With a detector loop conductor having Adirect current normally owing therethrough, and one of said relay coils being connected in parallel -with -a normally open detector switch which when closed short circuits the said one coil, whereby the other of said relay coils will become energized to close said pair of relay contacts to thereby complete a circuit with said driving means across said rst and second conductors.

References Cited UNITED STATES PATENTS 2,355,934 8/1944 weld 3404-295 2,492,043 12/1949 Holmes 340-287 2,997,665 s/1961 syn/an 328-206 2,699,541 1/1955 ward 340-293 THOMAS B. HABECKER, Prmmy Examiner.

CHARLES M. MARMELSTEIN, Assistant Examiner.

U.S. Cl. X.R.

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