DATA SIGNALLING SYSTEMS

• US 3,882,492 A
• Filed: 04/17/1973
• Issued: 05/06/1975
• Est. Priority Date: 04/17/1973
• Status: Expired due to Term

• Current Assignee: David J. Mcsorley, Jaye D.E. Croos
• Original Assignee: David J. Mcsorley, Jaye D.E. Croos
• Inventors: McSorley, David J., De Croos, Jaye
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Lange, Richard P.
• Application Number:
  US05/351,882
• Time in Patent Office: 749 Days
• Field of Search: 340/413,412,408,213.1,150,151,223,163
• US Class Current: 340/518
• CPC Class Codes: G08B 25/14 Central alarm receiver or annunciator arrangements

Abstract

In a security alarm signalling system in which a signal may be transmitted from any one of a number of remote stations to a central receiving station, the receiving station includes a multiple input encoder responsive to a change of state on any one of its inputs for presenting a coded output representative of the number of the input on which the change of state has occurred, and a digital display device including means for scanning the coded output to obtain a digital readout of the said number and thereby, in use, identifying the associated remote station.

Claims

1. A receiver for use in a security alarm signalling system in which a predetermined number of remote stations are each connected to a central receiving station by respective pairs of wires, each remote station being identified by a different predetermined number, and the receiver including a multiple input encoder, each input of said encoder being connected, when in use, to a respective pair of wires from one of the numbered remote stations, and the receiver also including a multiple input binary store;

gating means connected between the outputs of said binary store and corresponding inputs of said encoder;

scanning means for periodically scanning the inputs of said encoder, said scanning means including enabling means for periodically enabling each of said gating means in turn;

said encoder including means responsive to a change in the signal level on any one of its inputs for generating a cOded output signal representative of the number of the remote station to which the input is connected, and a digital display device including means for converting the coded output into a digital read-out of said number; and

means responsive to the presence of a signal in said encoder for inhibiting the enabling means until the signal has been encoded and read out on the display device.

2. A receiver according to claim 1 in which the digital display device includes a counter, and the receiver further includes an oscillator for feeding pulses to the counter in response to a detected change of signal level on one of the inputs to the encoder, a coincidence detector connected to compare the output of the encoder representing the number of the remote station associated with the change of signal level with the number present in the counter, and inhibiting means connected to receive an output from the coincidence detector when the two numbers being compared are equal for inhibiting the supply of pulses to the counter such that the final number displayed by the counter represents the number of the remote station.

3. A receiver according to claim 1, further including a clear line indicator connected to receive an energising signal from a control circuit whenever a change in signal level has been detected at one of the encoder inputs, and means for inhibiting operation of the indicator whenever an alarm signal is present at one of the inputs to the encoder whereby the indicator distinguishes between the display of a number in response to the appearance of an input signal and the display of a number in response to the disappearance of an input signal.

4. A receiver according to claim 2, in which the digital display device further includes a printer for printing the said input number displayed by the counter.

5. A receiver according to claim 2 in which the encoder includes a diode matrix of perpendicular coordinate lines, the output of each gating circuit being connected to the junction of a respective pair of diodes in the matrix such that an output is obtained from the corresponding pair of coordinate lines which intersect at the junction, the two coordinates together representing the two digits of the numbered input line to be displayed.

6. A receiver according to claim 2 in which the counter includes means for hunting synchronously for each of the pair of coordinates.

7. A receiver according to claim 2 in which the counter comprises a pair of electromagnetic decade counters arranged to give a two digit decimal output display, a first of the decade counters hunting for the least significant coordinate and the second decade counter hunting for the most significant coordinate of the number to be displayed.