Method for transmitting signals via a narrowband channel

摘要

Method for transmitting signals containing information on the radio path via a narrowband signal channel. The signal containing the information is fed at the transmitting end to a mixing unit to which the signal of the local oscillator of the transmitting end is fed. In the mixing unit, a mixing product is formed from the information signal and the local oscillator signal, its frequency range being essentially lower than the frequency range of the information signal which is to be transmitted. The mixing product signal is used as the modulation signal of the radio transmitter with which both the signal of the aforementioned modulation signal containing the information and precise information on the frequency and phase of the local oscillator signal are transmitted. At the receiving end, the demodulated modulation which is to be transmitted is separated with a bandpass filter and the signal obtained is fed to the mixing unit of the receiving end to which the signal containing information on the frequency and phase of the local oscillator of the transmitting end is also fed. A mixing product which corresponds in terms of its information content and frequency to the original information signal of the transmitting end is formed in the mixing unit from the aforementioned signals which are fed into it.