Night depository line security

Claim 2

A line security premise unit having a line connectable to a central station, said unit being capable of transmitting on said line, in response to interrogation signals on said line, coded response signals, said premise unit comprising: a counter; a transmitter for generating a coded pulse signal on said liNe in response to the stepping of said counter; said counter being started in response to the occurrence of each said interrogation signal on said line; and said counter being reset in response to the termination of each said interrogation signal; whereby said coded pulse signals are maintained in synchronism with said interrogation signals.

Claim 3

The premise unit of claim 1 further comprising: an oscillator for generating a periodic series of pulses to trigger said counter, said oscillator starting in response to the occurrence of each interrogation signal on said line.

Claim 4

The premise unit of claim 1 further comprising: a plugboard coder connected between the output of said counter and said line for establishing the code of said pulse signals on said line.

Claim 5

The premise unit of claim 1 further comprising: a counter inhibit circuit responsive to a predetermined state of said counter for stopping the generation of coded information.

Claim 6

The premise unit of claim 4 further comprising: an inhibit disabling circuit being set in response to the termination of said interrogation pulse and being reset after the start of said counter but before said counter reaches said predetermined state.

Claim 7

The premise unit of claim 1 further comprising: a power storage element connected to said line; said counter and transmitter being powered by energy from said storage element; said storage unit being charged by energy from said central station.

Claim 8

A line security premise unit having a line connectable to a central station, said unit being capable of transmitting on said line, in response to and in synchronism with random interrogation signals on said line, coded response signals, said premise unit comprising: a counter; a transmitter for generating a coded pulse signal on said line in response to the stepping of said counter; an oscillator for generating a periodic series of pulses to trigger said counter, said oscillator starting in response to the occurence of each interrogation signal on said line; a counter inhibit circuit responsive to a predetermined state of said counter for stopping the generation of coded information; an inhibit disabling circuit being set in response to the termination of said interrogation pulse and being reset after the start of said counter but before said counter reaches said predetermined state; and a counter reset responsive to the termination of each said interrogation signal on said line.

Claim 9

A line security premise unit having a line connectable to a central station, said unit being capable of transmitting on said line, in response to and in synchronism with random interrogation signals on said line, coded response signals, said premise unit comprising: a counter; a transmitter for generating a coded pulse signal on said line in response to the stepping of said counter; an oscillator for generating a periodic series of pulses to trigger said counter, said oscillator starting in response to the occurence of each interrogation signal on said line; a counter inhibit circuit responsive to a predetermined state of said counter for stopping the generation of coded information; an inhibit disabling circuit being set in response to the termination of said interrogation pulse and being reset after the start of said counter but before said counter reaches said predetermined state; and a counter reset responsive to the termination of each said interrogation signal on said line.

Claim 10

The premise unit of claim 7 further comprising: means for selectively connecting the outputs of said counter to said transmitter to establish the code of said pulse signals on said line.

Claim 11

A synchronized random interrogation line security system comprising: a central unit; a premise unit located remote from said central unit; a line electrically interconnecting said central unit and said premise unit; said central unit comprising: a. a signal generator for generating randomly spaced interrogation signals, said generator having an output connected to said line, b. an alarm signal generator, c. a receiver having an input connected to said line, said receiver being operative to decode pulse signals on said line; d. a reference signal source, e. means timed by said interrogation signal for comparing said decoded signal and said reference signal, and f. means for actuating said alarm signal generator in accordance with the results of said comparison; and said premise unit comprising: a counter; a transmitter for generating a coded pulse signal on said line in response to the stepping of said counter; said counter being started in response to the occurrence of each said interrogation signal on said line; and said counter being reset in response to the termination of each said interrogation signal; whereby said coded pulse signals are maintained in synchronism with said interrogation signAls.

Claim 12

A synchronized random interrogation line security system comprising: a central unit; a premise unit located remote from said central unit; a line electrically interconnecting said central unit and said premise unit; said central unit comprising: a. a signal generator for generating randomly spaced interrogation signals, said generator having an output connected to said line, b. an alarm signal generator, c. a receiver having an input connected to said line, said receiver being operative to decode pulse signals on said line; d. a reference signal source, e. means timed by said interrogation signal for comparing said decoded signal and said reference signal, and f. means for actuating said alarm signal generator in accordance with the results of said comparison; and said premise unit comprising: a counter; a transmitter for generating a coded pulse signal on said line in response to the stepping of said counter; said counter being started in response to the occurrence of each said interrogation signal on said line; and said counter being reset in response to the termination of each said interrogation signal; whereby said coded pulse signals are maintained in synchronism with said interrogation signAls.

Claim 13

The system of claim 9 wherein said premise unit further comprises: an oscillator for generating a periodic series of pulses to trigger said counter, said oscillator starting in response to the occurrence of each interrogation signal on said line.

Claim 14

The system of claim 10 wherein said premise unit further comprises: a plugboard coder connected between the output of said counter and said line for establishing the code of said pulse signals on said line.

Claim 15

The system of claim 9 wherein said premise unit further comprises: a counter inhibit circuit responsive to a predetermined state of said counter for stopping the generation of coded information.

Claim 16

The system of claim 9 wherein said premise unit further comprises: an inhibit disabling circuit being set in response to the termination of said interrogation pulse and being reset after the start of said counter but before said counter reaches said predetermined state.

Claim 17

The system of claim 9 wherein said premise unit further comprises: a power storage element connected to said line; said counter and transmitter being powered by energy from said storage element; said storage unit being charged by energy from said central station.

Claim 18

The system of claim 9 wherein said receiver further comprises a register for storing said decoded pulse signal; and said comparing means are timed by the termination of said interrogation pulse.

Claim 19

The system of claim 9 wherein said central unit further comprises: means responsive to the absence of information on said line for actuating said alarm signal generator.

Claim 20

The system of claim 9 wherein said central unit further comprises: an integrator having a signal input independent of said coded signal and an output connected to said alarm signal generator for actuating said alarm when said integrator output reaches a predetermined value; and the output of said comparison means being connected to said integrator so as to reset said interrogation upon coincidence of said decoded signal and said reference signal.