GB1358355A - Automatic telegraphy monitoring device - Google Patents

Abstract

1358355 Television monitoring arrangement T OHSAWA and M KARITA 29 June 1972 [3 July 1971] 30586/72 Heading H4F [Also in Division G4] A broadcasting monitoring device detects an audio or visual start and stop signal and between these signals filters the audio signal into predetermined frequency ranges, integrates and converts to a digital value the signal into each range and then codes and stores the values. The signals may be radio or TV and may be broadcast or transmitted by cable. The audio start signal is preferably two 20 nS duration pulses separated by and followed by a 20 nS portion of no signal inserted into the audio signal (Fig. 1, not shown) and the stop signal may be similar but with 10 nS duration. The visual signals are preferably white horizontal bars at predetermined positions on an otherwise black frame (Fig. 5, not shown). The system of Fig. 3 uses audio start and stop pulses on a TV signal. The audio signal is extracted from the audio detector 10 of a television receiver TV and is fed to start detector circuit A, stop detector circuit B and gate G. In start circuit A, the signal is band pass filtered at 13s at the frequency corresponding to 20 nS pulses and is shaped and rectified at 14s. The detection circuits comprise gate 15s, clock 16s, mark and space timing circuit 17s, 18s respectively and pattern detector 19s. These detect the start signal and when the full, correct start pattern has been received, an output is generated which sets bi-stable 20 and enables gate G. Stop circuit B functions in an identical manner; its output setting monostable 21 which resets bi-stable 20 and closes gate G. The audio signal passing through G is divided into channels 1 to n by filters 22. The signals are integrated at 23 to a level determined by Schmidt trigger 24 which then resets the integrator and supplies a pulse to counter 25. The counts in counters 25 after the stop signal are representative of the energy in each frequency channel and are characteristic of the signal. They are read into register D and then transferred by a pulse from monostable 21 into store E. When the start and stop pulses are video signals, the horizontal sync. pulses are integrated during each frame. When the integrated voltages exceeds a threshold, the arrival of the video voltage associated with the white bar opens a gate and the audio signal is again fed to the filter, integrator and counter circuits.