Arrangement for carrier wave insensitive modulation - uses special modulating method for simplifying transmitter-receiver unit with modulation index adjusted so that no information is applied to the frequency area within the carrier wave frequency

摘要

A transmitter-receiver unit has a receiver part (1) and a transmitter part (2), which are coupled together by hybrid circuits (4), an oscillator circuit (7) which is common for by transmission and reception, whereby the modulation index is so adjusted that essentially no information is applied to the frequency area within the carrier wave frequency. The modulation index is approximately 1.5. A high pass filter is arranged to filter away the carrier wave band from the demodulated signal in the transmitter.