US3435413A

US3435413A - Apparatus and method for translating a nondescript signal into a distinctive recordable signal

Info

Publication number: US3435413A
Application number: US462028A
Authority: US
Inventors: Foster E Weld
Original assignee: EW Bliss Co Inc
Current assignee: EW Bliss Co Inc
Priority date: 1965-06-07
Filing date: 1965-06-07
Publication date: 1969-03-25
Anticipated expiration: 1986-03-25
Also published as: DE1462448A1; GB1141712A

Description

March 25, 1969 F. E. WELD 3,435,413

APPARATUS AND METHOD FOR TRANSLATING A NONDESCRIPT SIGNAL INTO A DISTINCTIVE RECORDABLE SIGNAL Filed June 7, 1965 Sheet of 2 I TRANSLATING I I cIRcuIT I 2 I -I.0GIcs /-26 RECORDER I I II I I I 29 I FIG. I I DECODERS /24 I I8 I I I I l I STATION 7 STATION POWER I6 SUPPLY STATION SOURCE 3 I TATION -I I 26 I I 38 46 I I I TRIGGER I I I SWITCH I I I r 32 I I I 'I TRIGGER I I swI'rcI-I I IC+ -I I [42 CODING L I 1 4 I I TRIGGER MATRIX I I SWITCH Z I IC+ 36 I l F ii I I I TRIGGER L I SWITCH I J II .I II II I I: GUN/G GATED /48 I RECORDER I I STEPPING I cIRcuIT SWITCH I I DRIVER I 50 I I INVENTOR.

I FOSTER E. WELD I STEP. swITcI-I I L I I Min/14,2804,

ATTOR NEYS March 25, 1969 F. E. WELD 3,435,413

APPARATUS AND METHOD FOR TRANSLATING A NONDESCRIPT SIGNAL INTO A DISTINCTIVE RECORDABLE SIGNAL Filed June 7, 1965 Sheet W is mm B m @m WE a v 1R tfiw E 3K w M 325; zEo2w F .7 Y YwJ B A a 35m wzinmfifiom m Ow MTV +0 3 1 mm NJ m m 5% N: mmv j 3 mm +0 I J mm S 3 TII, 3 on +0 ATTOR NEYS.

United States Patent 3,435,413 APPARATUS AND METHOD FOR TRANSLATING A NONDESCRIPT SIGNAL INTO A DISTINCTIVE RECORDABLE SIGNAL Foster E. Weld, Newton Highlands, Mass., assignors to E. W. Bliss Company, Canton, Ohio, a corporation of Delaware Filed June 7, 1965, Ser. No. 462,028 Int. Cl. Gllb 5/78; G081) /00 US. Cl. 340-147 12 Claims ABSTRACT OF THE DISCLOSURE Apparatus and method are as disclosed herein for use in translating a nondescript signal representative that a predetermined condition has occurred at a local station into a descriptive pattern of coded recordable pulses. The apparatus includes means, such as a signal generator, for purposes of providing a steady state output signal. A pulse generator serves to provide a train of time spaced pulses. A coding matrix serves to receive the output signal and provide a characteristic pattern of signal pulses at a plurality of output circuits which are representative of a particular local station. A stepping mechanism responds to the generated pulses for purposes of sequentially stepping one step at a time for each generated pulse and from one of the output circuits to the next. A gating circuit responds to the signal pulses and the generated pulses for developing a recordable pulse only upon occurrence in time of a generated pulse in the absence of a signal pulse. This gating circuit is adapted to be connected to a recording mechanism for recording an indication for each recordable pulse.

This invention pertains to the art of recording and, more particularly, to apparatus and method for translating a nondescript signal into a distinctive recordable signal.

The invention is particularly applicable for use in conjunction with fire alarm and police call systems and will be described with reference thereto; although it will be appreciated that the invention has broader applications.

A typical fire alarm system takes the form of a series loop connecting various local fire alarm boxes or stations together in a current carrying series circuit with a central station. A fire alarm call may be sent from each local station to the central station by merely actuating a lever at the local station, which in turn actuates a device for interrupting the current flow in a distinctive manner resulting in a coded signal. The coded signal takes the form of a train of current pulses which are time spaced according to a code representative of the calling local station. The coded signal is transmitted through the series circuit to recording equipment at the central station for recording a mark for each received pulse, with the resultant pattern of recorded marks corresponding to the coded signal and, hence, representative of the calling station.

Recently, a combined telephone-telegraphy fire or police alarm system has been developed for use by municipalities and takes the form as disclosed in United States patent application, Ser. No. 403,316, filed Oct. 12, 1964, now Patent No. 3,384,714, entitled Combined Telephone-Telegraphy System, assigned to the same assignee as the present invention. That system utilizes the time proven reliability of the typical series connected fire alarm stations. But, in addition to fire or alarm reporting, the system provides voice communication between the calling local station and the central station through the series circuit. The new system also deviates from the typical 3 ,435,413 Patented Mar. 25, 1969 fire alarm system in that when a person lifts a telephone handset at one of the local stations, a complex coded tone frequency alarm signal made up of two distinct frequencies will be transmitted through the series circuit to the central station. At the central station a plurality of frequency decoders serve to decode the complex coded frequency signals, and for each complex signal received two decoders, representative of two different frequencies, will each provide a steady state output potential. A plurality of AND circuits at the central station are each associated with a particular local fire alarm station, and each is connected to a different combination of two decoders. When two decoders connected to a particular AND circuit develop output potentials, then that AND circuit will also develop a steady state output potential representative of its associated local fire alarm station which transmitted the alarm signal. A light associated with each AND circuit will glow when that AND circuit develops an output potential to alert an operator at the central station as to which local fire alarm station transmitted an alarm signal. The operator may then communicate by voice communication with the person initiating the alarm signal for details of the fire, etc.

Many municipalities that desire to convert their typical fire alarm system to a combined telephoned-telegraphy system, as described above, also desire that means be provided for permanently recording which fire alarm station transmitted an alarm signal. In the interests of econ omy, many of these municipalities further desire that any existing recording equipment owned by the municipality for use with a typical fire alarm system be used with the combined telephone-telegraphy system. The steady state output potentials developed by each AND circuit of the new system are nondistinguishable from each other, rendering them nondescript and not easily utilized for actuating recorder equipment normally used with a typical fire alarm system. Accordingly, means are required for translating the nondescript output potential developed by each AND circuit into a descriptive recordable signal representative of the calling local fire alarm station.

The present invention is directed toward apparatus and method for satisfying the foregoing needs of fire alarm systems for translating nondescriptive signals into descriptive recordable signals, taking the preferred form of coded signal pulses which may be utilized for actuating recording equipment, including the type normally used with a typical fire alarm system.

In accordance with the present invention, the translating apparatus includes: a circuit responsive to the occurrence of a nondescript signal for developing a steady state output signal; a pulse generator responsive to the output signal for generating a train of spaced pulses; a coding matrix having an input circuit for receiving the output signal and a plurality of output circuits, and having circuits for providing a characteristic pattern of signal pulses at its output circuits representative of a particular local station; a stepping switch device responsive to the generated pulses for sequentially stepping one step at a time for each generated pulse from one of the coding matrix output circuits to the next; and, a gating circuit responsive to the characteristic signals and the generated pulses for developing a recording pulse only upon the occurrence of a generated pulse and the absence of a characteristic signal pulse.

In accordance with another aspect of the present invention, a method is provided for translating a nondescript signal representative that a predtermined condition occurred at one of a plurality of local stations into coded recordable pulses, comprising the steps of:

(1) Generating a train of time spaced pulses upon the occurrence of a nondescript signal;

(2) Applying a signal upon the occurrence of the nondescript signal to an input circuit of a coding matrix having a plurality of output circuits;

(3) Providing a characteristic pattern of coded signal pulses at the plurality of coding matrix output circuits representative of the local station;

(4) Cycling a stepping switch from one coding matrix output circuit to the next, one step at a time for each generated pulse; and,

(5) Recording an indication on a recording medium only upon the occurrence in time of a generated pulse and the absence of a signal pulse.

By practicing the method described above, a coded pattern of indications will be recorded during each cycle of operation of the stepping switch representative of the local station at which the predetermined condition occurred.

A primary object of the invention is to provide apparatus and method for translating a nondescript signal into a distinctive recordable signal.

Another object of the present invention is to translate a nondescriptive signal representative of a particular one of a plurality of local stations in a fire alarm system into a distinctive recordable signal in the form of coded pulses which may be used by a municipalitys existing recorder equipment for recording a coded pattern of indications representative of the particular local station.

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

FIGURE 1 is a system block diagram illustrating a plurality of series connected calling stations and a central station;

FIGURE 2 is a block diagram of one embodiment of the present invention; and,

FIGURE 3 is a schematic diagram illustrating in greater detail the preferred embodiment of the invention.

Referring now to the drawings and more particularly to FIGURE 1, there is illustrated in block diagram form one application of the preferred embodiment of the invention as applied to a fire alarm system, which is preferably constructed in accordance with United States application, Ser. No. 403,316, identified previously, generally including a plurality of local

fire alarm stations

1, 2, 3 through N, connected together in series across a central station power supply source 10 through central station equipment 12. The power supply source 10 and central station equipment 12 may be located, for example, at the fire department headquarters and the various local stations 1 through N may be located at desired locations Within the fire alarm system. The several stations 1 through N are connected together in series by means of a single metallic circuit 14 through which direct current flows, in accordance with the arrow i illustrated in FIG- URE 1, having a constant value on the order of 100 milliamperes supply by the power supply source 10. Power to operate each local station 1 through N is obtained from the direct current flow in circuit 14. A pair of encoders are located in each local station and serve, upon lifting of a handset at the station, to develop a pair of frequency signals which are combined and transmitted through circuit 14 as a complex coded tone frequency signal representative of the calling station to the central station 12. A capacitor 16 is connected across the power supply source 10 to prevent the complex coded tone frequency signals from being coupled to the power supply source. The central station equipment 12 includes coupling circuitry 18, which serves to couple received tone frequency signals from the calling local station to decoder circuitry 24 including a plurality of decoders for decoding the complex frequency signal. For each complex frequency signal received, two decoders, representative of the two combined frequency signals, each developing a steady state output potential. The steady state output potentials of decoder circuitry 24 are applied to logic circuitry 26, which includes a plurality of logic AND circuits, each representative of one of the local stations 1 through N. Each AND circuit of logic circuitry 26 is connected to a different combination of two decoders of decoder circuitry 24 and serves when both its decoders develop output potentials to in turn develop a nondescript output potential representative that its associated local station transmitted an alarm signal.

In accordance with the present invention, a translating circuit 28 is provided for translating the nondescript output potentials developed by the AND logic circuits of logic circuitry 26 into descriptive recordable signals for application to a recorder 29. The translating circuit 28 is illustrated in greater detail in block diagram form in FIGURE 2, and generally includes: four

trigger switches

38, 40, 42, and 44; a coding matrix 46; a gated stepping switch driver 48; and, a gating circuit 52. Each trigger switch has an output circuit connected to one of a plurality of input circuits of both the coding matrix 46 and the gated stepping switch driver 48. The coding matrix has a plurality of output circuits connected to the stepping switch 50. The grated stepping switch driver 48 has two output circuits; one connected to stepping switch 50 and the other connected to an input circuit of gating circuit 52. Stepping switch 50 also has an output circuit connected to an input circuit of gating circuit 52, which in turn has an output circuit connected to recorder The AND circuits of logic circuitry 36 are illustrated in simplified form in FIGURE 2 by

switches

30, 32, 34, and 36, which serve when closed to respectively connect 21 C+ voltage supply source to trigger

switches

38, 40, 42, and 44 within translating circuit 28. Switches 30 through 36 may also represent individual local stations of any system in which it is desired to record an indication that a particular station has placed a calling signal, or that a particular condition exists at or is noted by a local station. The calling signal in this instance is merely the closure of a switch, i.e., switches 30 through 36.

Referring now to FIGURE 3, the trigger switches 38 through 44, coding matrix 46, gated stepping switch driver 48, stepping switch 50 and gating circuit 52, as well as the recorder 29 are shown in greater detail in schematic diagram form. Trigger switches 38 through 44 preferably take the form as silicon controlled rectifiers, as shown in FIGURE 2, and will be referred to as such hereinafter.

Switches

30, 32, 34 and 36 serve to respectively connect a C+ voltage supply source with the gates of silicon controlled

rectifiers

38, 40, 42 and 44. The anodes of

rectifiers

38, 40, 42 and 44 are connected together in common with a 13+ voltage source through a normally closed restoring switch 62, which may be manually opened by merely applying force to a spring type contact arm 64 in the direction of the arrow indicated in FIGURE 3. The cathodes of rectifiers 38, 4t), 42 and 44 are connected together in common with a B voltage supply source through

diodes

54, 56, 58 and 60, respectively.

Resistors

55, 57, 59 and 61 are connected between the gate and cathode of

rectifiers

38, 40, 42 and 44, respectively, and each resistor serves in combination with a load resistor 68 within the gated stepping switch driver 48 as a voltage divider to prevent excessive voltage between the gate and cathode of its associated rectifier.

The gated stepping switch driver 48 includes a pulse generator 72 taking the form of a relaxation oscillator 73 and a bi-stable multivibrator 75, connected across load resistor 68. Relaxation oscillator 73 takes the form of a unijunction transistor 74 having a first base B1, a second base B2 and an emitter 76 connected with one end of resistor 68 through resistors 78 and 80. A timing capacitor 82 is connected between the emitter 76 and a B- voltage supply source. Base B2 is connected to the 13+ voltage supply source through a current limiting resistor 84 and base B1 is connected to the B voltage supply source through an output resistor 86.

Bi-stable multivibrator of pulse generator 72 is connected across the output resistor 86 of relaxation oscillator 73 and includes a pair of silicon controlled rectifiers 88 and 90 connected together in push-pull fashion, with their anodes being directly connected together through a capacitor 92. The gate of rectifier 88 is connected to the gate of rectifier 90 through a pair of series connected capacitors 94 and 96. The anode of rectifier 88 is connected with the B+ voltage supply source through a current limiting resistor 98. The cathodes of the rectifiers 88 and 90 are directly connected to the B- voltage supply source. The gates of rectifiers 88 and 90 are connected to the B voltage supply source through current limiting

resistors

102 and 104, respectively. The output of the relaxation oscillator 73 is coupled to the input of the bi-stable multivibrator 75 by means of a current limiting resistor 106 connected between the junction of the series connected capacitors 94 and 96 and the junction of base B1 of unijunction transistor 74 and output resistor 86.

The anode of rectifier 90 is connected to the base 108 of a germanium power transistor 110 within gating circuit 52 through a pair of series connected

resistors

112, 114, also located within gating circuit 52. The emitter 116 of transistor 110 is connected to the B-] voltage supply source through a diode 118, poled as shown in FIG- URE 3. A resistor 120 is connected between the B+ voltage supply source and base 108 of transistor 110 and a diode 122 is connected between the B- voltage supply source and the collector 124 of transistor 110. Diode 118 and resistor 120 together serve to prevent false turn-on of transistor 110. Diode 122 serves as a surge suppressor to limit the induced voltage in marking magnet coil 126. The power transistor 110 serves as a relay for energizing a recorder marking magnet coil 126 of recorder 29 connected across diode 122. The recorder marking magnet coil 126 serves, when energized, to actuate a suitable marking arm 128 to print a mark 130 or make a perforation, if desired, in a suitable recording medium 132 driven by a suitable motor 134 at constant speed in the direction indicated by the arrow in FIGURE 3.

Stepping switch 50 includes a stepping switch magnet coil 136 connected between the anode of rectifier 90 and the B voltage supply source, and when energized by anode current of rectifier 90 serves to actuate a ratchet motor 138. A diode 140, poled as illustrated in FIGURE 3, is connected across magnet coil 136 of stepping switch 58 and serves as a surge suppressor to limit the induced voltage across coil 136. Ratchet motor 138 includes a ratchet wheel 142 mounted on a rotatable shaft 144 driven by a spring biased ratchet pawl 146 which is pivotally mounted to a support 148 and spring biased by a spring 150. Each time magnet coil 136 is energized, pawl 146 is withdrawn from engagement with ratchet wheel 142 and each time the coil is de-energized the pawl 146 drives the ratchet wheel 142 one step by spring power from spring 150 so that shaft 144 rotates one step at a time about its axis in the direction of the arrow illustrated in FIG- URE 3. A contact wiper 152 having three equally spaced

contact wiper arms

154, 156 and 158 is mounted on shaft 144. The

contact wiper arms

154, 156 and 158 are electrically connected to the junction of

resistors

112 and 114 of gating circuit 52 through a common output circuit 164.

Coding matrix 46 may be of any suitable type capable of performing the operation to be described hereinafter, but preferably comprises a first plurality of ten conductors 160, vertically arranged in FIGURE 3, overlying and in perpendicular relationship to conductors 162, horizontally arranged in FIGURE 3. Conductors 160 are each connected with one of the output contacts or terminals 2 through 11 of coding matrix 46. One of the

wiper arms

154, 156 and 158 is, at the beginning of a cycle of operation of the stepping switch 50, in electrical contact with terminal 1 of the stepping switch. The horizontally arranged conductors 162 at

terminals

166, 168 and 169 respectively serve as input circuits for the cathodes of silicon controlled

rectifiers

38, 40, 42 and 44. Coding matrix 46 is prearranged by means of a plurality of diodes 163 to provide a characteristic pattern of signals at its

output terminals

2, 3, 4, 5, 6, 7, 8, 9, 10 and 11 in accordance with the positioning of the various diodes. Thus, for example, it will be noted, with respect to the uppermost horizontal conductor 162, that a diode connects terminal 166 with output terminal 3 and another diode connects terminal 166 with output terminal 7. In this manner, as contact Wiper 152 is sequentially stepped from terminals 1 through 11 current flows from input terminal 166 to the common output circuit 164 only when the contact wiper engages output terminal 3 or output terminal 7. This is representative of a

code

2, 3, 4. Similarly, it will be appreciated with reference to the next lower horizontal conductor 162, a plurality of diodes connect terminal 168 with each of the

output terminals

2, 5, 6, 7, 8, 9, 10 and 11, but not with output terminals 3 and 4. This is representative of

code

1, 2. Similarly, it will be noted that the next lower horizontal row of diodes provides a characteristic pattern of signals at output terminals 2 through 11, representative of

code

4, 1, 2. Thus, it will be appreciated that the coding matrix 46 provides a different characteristic pattern of signals at its output terminals for each of the calling stations, represented in FIGURE 3 by

switches

30, 32, 34 and 36.

The shaft 144 of the stepping switch 50 is provided with a cam 170 having three cam lobes 172 thereon ex tending radially outward with respect to shaft 144 and spaced equi-distant with respect to each other. A cam follower 174 rides on cam 170 as shaft 144 rotatesand serves to operate a double pole, double throw switch 176. Switch 176 is provided with a pair of movable contacts 178 and 180, illustrated in FIGURE 3, in their normal position with cam follower 174 located on cam lobe 172. Switch 176 also has a stationary contact 182 for engagement with movable contact 178 and is electrically connected to the junction of resistor 84 and the B+ voltage supply source. Switch 176 also has a stationary contact 184 in electrical contact with movable contact connecting a capacitor 186 in series with the B- voltage supply source to the B+ voltage supply source through resistor 68 and diode 188, poled as illustrated in FIGURE 3, for charging the capacitor 186. The switch 176 has another stationary contact 190 connected to the junction of resistors 78 and 80, and serves when electrically connected with movable contact 180 to provide a discharge circuit for capacitor 186 through resistor 78.

Operation The operation of the translating circuitry 28, illustrated in FIGURES 1, 2 and 3, commences with receipt at the central station 12 of a coded complex frequency alarm signal made up of two different distinct frequencies transmitted by one of the local calling stations 1 to N. The coded complex frequency signal is applied through coupling circuitry 18 to decoder circuitry 24, where two decoders, representative of the two combined frequencies, each develops a steady state output potential. The two steady state potentials are applied to logic circuitry 26 wherein one AND logic circuit responds to the two potentials and in turn develops a steady state potential representative of one of the calling stations, for example, station 1. For purposes of simplifying the explanation of the invention, the AND logic circuit is illustrated in FIGURE 3 by switch 30, which when closed provides a positive nondescript steady state potential from the C+ voltage supply source, representative of station 1. Thus, with switch 30 closed, a positive potential will be applied to the gate of silicon controlled rectifier (trigger switch) 38 from the C+ voltage supply source, thereby forward biasing the rectifier which then conducts current through its anode to cathode circuit from the 13+ voltage source, through normally closed restoring switch 62 to the input terminal 166 of coding matrix 46. Capacitor 186 will have been previously charged in accordance with the polarities, illustrated in FIGURE 3, by current flow from the B+ voltage supply source to the capacitor through diode 188 and resistor 68 to the B voltage supply source. It is to be understood that the 13+ voltage supply source represents the positive side of a direct voltage supply source and the B- voltage supply source represents the negative side of the same voltage supply source. With rectifier 38 forward biased and conducting, current will also flow from the 13+ voltage supply source through the anode to cathode circuit of rectifier 38, diode 54, and through the load resistor 68 to the B- voltage supply source. Accordingly, capacitor 82, which is connected in parallel with resistor 68 through resistors 78 and 80, will charge according to the polarities indicated in FIGURE 3. When the voltage across capacitor 82 rises to the peak point voltage, approximately one-half of the value of the B+ voltage supply source, of transistor 74, its emitter 76 will become forward biased and capacitor 82 will discharge through the emitter 76 to base B1 of transistor 74 and output resistor 86. A positive voltage pulse will appear across output resistor 86. Thereafter, the capacitor 82 will again charge and discharge through transistor 74 and resistor 86 at a rate according to a RC time constant determined by the values of capacitor 82 and resistor'80.

Each positive voltage pulse developed across resistor 86 will be applied to the gates of rectifiers 88 and 90 through coupling capacitors 94 and 96, respectively. The first voltage pulse will forward bias both rectifiers 88 and 90, but rectifier 88 will not remain conductive since resistor 98 limits the anode current of rectifier 88 to a value less than the required holding current. Rectifier 90, however, will remain conductive because series connected

resistors

112, 114 and 120 in parallel with the stepping switch magnet coil 136 provides anode current for rectifier 90 of a value greater than that of the required holding current.

When rectifier 90 is conducting, capacitor 92 will charge through resistor 98 and the anode to cathode circuit of rectifier 90. When the next pulse is received from out-put resistor 86, rectifier 88 will again become momentarily forward biased and conductive to thereby discharge capacitor 92, producing a negative voltage pulse at the anode of rectifier 90 causing rectifier 90' to become reversed biased. Thus, rectifier 90 will be conducting and then non-conducting, respectively, under control of alternating pulses developed by relaxation oscillator 73, whereby pulse generator 72 will develop a train of equally time spaced voltage pulses as long as rectifier 38 is conducting.

Each time rectifier 90 is conducting, current will flow from the B+ voltage supply source through stepping switch coil 136 to the B voltage supply source through the anode to cathode circuit of rectifier 90. This will energize coil 136 causing pawl 146 to be pivoted in a clockwise direction, as viewed in FIGURE 3, against the resistance of spring 150. Upon de-energization of coil 136, when rectifier 90 becomes reversed biased, pawl 146 will be resiliently biased by spring 150 to step the ratchet wheel 142 one step by spring power. Thus, each time pulse generator 72 energizes coil 136 there will result, upon the subsequent de-energization of coil 136, a one step movement of contact wiper 152. In this manner, contact wiper 152 will sequentially step one step at a time from contact terminal 1 to contact terminal 12.

When wiper arm 154 of contact wiper 152 is stepped from contact terminal 1, as shown in FIGURE 3, to contact terminal 2, cam follower 174 will ride olf cam lobe 172 whereby the double pole, double throw switch 176 will be displaced from the position as illustrated in FIGURE 3 so that movable contact 178 engages stationary contact 1'82 and movable contact 180 engages stationary contact 190. The engagement of movable contact 178 with stationary contact 182 short circuits restore switch 62 preventing turn-off of rectifier 38 for the duration of a complete cycle of wiper arm 154 from terminal 2 through terminal 11. The engagement of movable contact 180 with stationary contact 190 serves to discharge capacitor 186 through resistor 78.

Transistor 110 of gating circuit 52 serves as a relay for recorder marking magnet coil 126, and is forward biased by anode current of rectifier 90. Each time rectifier is conducting, a sufficiently negative potential will exist on base 108 of transistor with respect to that existing on emitter 116 thereby forward biasing transistor 110. Thus, current will flow from the 13+ voltage supply source, through diode 118, the emitter 116 to collector 124 of transistor 110, and thence through marking magnet winding 126 to the B voltage supply source, thereby energizing winding 126. Energization of marking magnet winding 126 causes marking magnet arm 128 to record a mark on the recording medium 132.

The recorder 29 will record a predetermined code, such as 2, 3, 4, as illustrated by the marking 130 in FIGURE 3, by the use of the diode coding matrix 46. A diode 163 is placed in circuit connection between terminal 166 and matrix output terminal 3 and another diode 163 is placed between terminal 166 and matrix output terminal 7. When contact iwiper arm 154 engages contact terminal I 3, or terminal 7, the B+ voltage supply source is connected to the base 108 of transistor 110 through the diodes 163, the common output circuit 164, and resistor 114. Each such connection applies a positive voltage pulse of suflicient magnitude to the base 108 of transistor 110 to reverse bias the transistor, preventing energization of recorder marking magnet winding 126. Thus, each such connection serves to cancel a time coincident recording pulse received from pulse generator 72, leaving a space between adjacent marks 130. As wiper arm 154 is sequentially stepped one step at a time from terminal 1 to terminal 12, a characteristic pattern of marks 130, according to

code

2, 3, 4, will be recorded on recording medium 132.

At the completion of the recording cycle, i.e., the completion of sequential stepping of wiper arm 154 from terminal 1 through terminal 12, cam follower 174 will ride up a cam lobe 172, whereby the double pole, double throw switch 176 will return to the position as illustrated in FIGURE 3. Contact wiper arm 156 will then be positioned in contact with terminal 1 and contact wiper arm 154 will then be positioned in contact with terminal 12. Even if switch 30 had been momentarily closed, the current would continue to flow from the B+ voltage supply source through the rectifier 38 to maintain energization of the pulse generator 72. When the double pole, double throw switch 176 is returned to the position as shown in FIGURE 3, current will flow to recharge capacitor 186 in accordance with the polarity indicated in FIGURE 3. The charging of capacitor 186 will act as a momentary short circuit across rectifier 38, causing de-energization of rectifier 38 and consequent deenergization of pulse generator 72. The diode 188 in the charging circuit of capacitor 186 serves to prevent false triggering of the pulse generator 72 by discharging capacitor 186 when rectifier 38 becomes deenergized.

When capacitor 186 becomes fully charged, the translating circuit 28 will be in condition to begin a new cycle of operation.

I claim:

1. Apparatus for translating a nondescript signal representative that a predetermined condition occurred at a local station into a descriptive pattern of coded record able pulses and including means responsive to the occurrence of said nondescript signal for providing a steady state output signal, means responsive to said output signal for generating a train of time spaced pulses, a coding matrix having an input circuit for receiving said output signal and a plurality of output circuits, said coding matrix including means for providing a characteristic pattern of signal pulses at its output circuits representative of a particular local station, stepping means responsive to said generated pulses to sequentially step one step for each generated pulse from one of said output circuits to the next, and gating means responsive to said signal pulses and said generated pulses for developing a recordable pulse only upon occurrence in time of a generated pulse and the absence of a signal pulse, said gating means adapted to be connected to a recording means for recording an indication for each said recordable pulse.

2. Apparatus as set forth in claim 1 wherein said means for providing an output signal includes a silicon controlled rectifier having a gate, an anode and a cathode and adapted to connect via its anode-cathode circuit a voltage supply source with the input circuit of said pulse generating means for energization thereof upon conduction of said rectifier.

3. Apparatus as set forth in claim 2 including normally closed restoring switch means in said anode-cathode circuit for disconnecting said voltage supply source from said anode-cathode circuit to cause turnolf of said rectifier resulting in de-energization of said pulse generating means.

4. Apparatus as set forth in claim 3 including normally open switching means in circuit parallel with said restoring switching means, said normally open switching means being closed for short circuiting and thus disabling said restoring switching means during the period of sequential stepping of said stepping means.

5. Apparatus as set forth in claim 4 including cam means which cycles said stepping means, and cam follower means operatively connected to said normally open switching means for closing said switching means during the period that said stepping means sequentially steps across said output circuits of said coding matrix.

:6. Apparatus as set forth in claim 2 including means for de-energizing said pulse generator means after a cycle of operation of said stepping means across said output circuits of said coding matrix.

7. Apparatus as set forth in claim 6 wherein said deenergizing means includes a capacitor, a capacitor discharge circuit, two position switching means having a norm-a1 first position in which said capacitor is connected across the anode-cathode circuit of said rectifier, and a second position in which said capacitor is connected across said discharge circuit for discharging said capacitor, means for operating said two position switching means in response to said generated pulses whereby upon the first step of said stepping means said switching means is in its second condition and upon completion of said stepping means across the output circuits of said coding means the switching means is returned to its normal first position, whereby as said capacitor charges it effectively short circuits the anode-cathode circuit of said rectifier causing turnoff thereof and de-energization of said pulse generating means.

8. Apparatus is set forth in claim 7 including cam means which cycles with said stepping means, and cam follower means operatively connected with said two position switching means for positioning said switching means in said second position during the period that said stepping means sequentially steps across said output circuits of said coding matrix.

9. A method of translating a nondescript signal representative that a predetermined condition occurred at a local station into coded recordable pulses and recording said pulses, the method comprising the steps of: generating a train of spaced pulses upon the occurrence of said nondescript signal, applying a signal upon the occurrence of said nondescript signal to an input circuit of a coding matrix having a plurality of output circuits, providing a characteristic pattern of signals representative of a particular local station at said output circuits, cycling a stepping switch sequentially from one said output circuit to the next, one step at a time, for each generated pulse, recording an indication on a recording medium only upon the occurrence of a generated pulse and the absence of a characteristic signal, whereby for each cycle of operation of said stepping switch a characteristic indication pattern is recorded on said recording medium represent-ative of the particular local station.

10. A method of translating a nondescript signal representative that a predetermined condition occurred at a local station into coded recordable pulses and recording said pulses, the method comprising the steps of: developing a steady state output signal upon the occurrence of said nondescript signal, applying said output signal to a coding matrix, developing a characteristic pattern of signal pulses representative of said local station at a plurality of output terminals of said coding matrix, generating a train of spaced pulses upon the occurrence of said nondescript signal, cyclically stepping a switch arm one step at a time for each generated pulse sequentially from one output terminal to the next, and actuating a recorder to record on a recording medium an indication only upon the occurrence of a generated pulse and the absence of a characteristic signal, whereby for each cycle of sequential stepping of said switch arm a characteristic pat tern of indications is recorded representative of a particular local station.

11. In central station equipment means adapted for use in receiving coded station identifying frequency signals from a plurality of local stations and including a like plurality of means each associated with a local station for developing a steady state nondescript output signal when its associated local station transmits a coded frequency signal, the improvement comprising: means for generating a train of spaced pulses, a coding matrix having a separate input circuit associated with each of said calling stations and a lurality of output circuits, stepping means responsive to said generated pulses for sequentially stepping one step at a time for each generated pulse from one of said output circuits to the next, said coding matrix having means for providing a different characteristic pattern of signal pulses at its output circuits for each said local station, means coupled to said output circuits via said stepping means and responsive to said signal pulses and said generated pulses for developing a recording pulse only upon the occurrence of a generated pulse and the absence of a signal pulse, and recording means responsive to said recording pulses for recording an indication for each recording pulse, whereby for each cycle of operation of said stepping means a characteristic pattern of indications is recorded representative of which local station transmitted a coded frequency signal.

12. In a telegr-aphy system having a plurality of local stations and a central station connected togther in a series circuit and adapted to be connected across a power supply source for maintaining current flow in said series circuit, each said local station including means for transmitting a coded frequency signal to said central station via said series circuit, a plurality of means at said central station each associated with one of said stations for developing a steady state nondescript output signal when its assocated station transmits a coded frequency signal, the improvement comprising: means responsive to said output signal for generating a train of spaced pulses, coding means responsive to said output signal for providing at a plurality of output circuits a different characteristic pattern of coded signal pulses for each said local station, stepping means responsive to said generated pulses for sequentially stepping one step at a time for each generated pulse from one of said output circuits to the next, gating circuit means coupled with said stepping means and responsive to said signal pulses and said generated pulses for developing a recording pulse only upon the occureuce 11 12 of a generated pulse and the absence of a signal pulse, References Cited and recording means responsive to said recording pulses UNITED STATES PATENTS v for recording an indication for each said recording pulse, whereby for each cycle of operation of said stepping 3,206,545 9/1965 Kennedy et a1 1794 3,327,060 6/1967 Hogan 179-5 means a characteristic pattern of indications is recorded 5 representative of which station transmitted a coded frequency Signal DONALD J. YUSKO, Primary Examiner.