Channel fault or discontinuity detector - uses two different frequency signals transmitted from opposite ends of channel and detector sensing signal issuing from discontinuity

摘要

The appts. for detecting holes in a channel consists of generating a pair of unequal frequency signals and transmitting these from opposite ends of the channel and detecting signals emitted from the holes. A bi-frequency signal generator (11, 12) transmits the signals 400 Hz and 1000 Hz down each end of the channel (1) by aerials (3) and (4). A signal detector (23) is used to locate the source of signals escaping from the channel at the discontinuity (2).