Method for transmitting audio-frequency channels with a carrier frequency system in two-wire grouped frequency mode

摘要

In this method, the useful transmission bands are in the 12-28 kHz frequency range for one direction and in the 32-48 kHz frequency range for the other direction. A pilot frequency outside the useful transmission band, for which the 60 kHz carrier is used, is transmitted only in one direction and evaluated in one terminal station. In this terminal station, both the receive and the transmit signal are controlled in the +/- 4dB range. The other terminal station therefore has no control devices. IMAGE