Abstract: A facsimile signal superposing system for an analog type modulated facsimile signal has been found. The present superposing system has a digital memory storing the pattern to be superposed, and the insertion circuit which has a first input terminal for receiving the original facsimile pattern, a second input terminal for receiving the output of said digital memory, and an output terminal providing the sum of the first and the second input terminal signals. The cells of the digital memory are read one after another substantially synchronized with the original picture signal, thus, a superposed facsimile signal is obtained at said output terminal. The additional pattern to be superposed is, for instance, the date of the facsimile transmission.

Abstract: A carrier is amplitude modulated in an amplitude modulator by a train of unipolar signals which alternately assume a definite voltage level and an arbitrary amplitude of one polarity. Either the carrier before it is modulated or the modulated carrier is phase modulated by the train of unipolar signals. The phase modulation takes place cyclically in that modulated carrier assumes one of predetermined N discrete phases for each occurrence of the unipolar signals. On the receiving side, the received signal is subjected to an envelope detection to extract envelope information.

Abstract: A carrier is amplitude modulated in an amplitude modulator by a train of unipolar signals which alternately assume a definite voltage level and an arbitrary amplitude of one polarity. Either the carrier before it is modulated or the modulated carrier is phase modulated by the train of unipolar signals. The phase modulation takes place cyclically in that modulated carrier assumes one of predetermined N discrete phases for each occurrence of the unipolar signals. On the receiving side, the received signal is subjected to an envelope detection to extract envelope information.