Scanning apparatus for detecting and analyzing supervisory and signaling

Abstract

Scanning apparatus for monitoring 88 telephone subscriber lines to detect the on hook or off hook condition of the lines and to detect and count dial pulses. A multiplexing arrangement produces a sample of the incoming signal on each subscriber line in a recurring sequence. The apparatus includes a memory for storing an indication for each subscriber line as either on hook or off hook, a memory for storing the most recent sample for each subscriber line, a memory in association with a counter for storing dial pulse count information for each subscriber line, and a memory in association with a timer for storing timing information for each subscriber line. The multiplexing arrangement and the memories are coupled to a decision section of an arrangement of logic decision blocks which analyze each sample together with the stored data associated with the same subscriber line. Depending upon the particular combination of information presented to the decision section one of several end-state flip-flops is set. Depending upon which end-state flip-flop is set a subroutines section of logic elements updates the contents of the memories. If appropriate, the subroutines section causes an output buffer to report a change in the status of a subscriber line to an on hook or off hook condition and causes another output buffer to report a count of the number of dial pulses for a dialed digit after all the pulses for the digit have been counted.