An arrangement comprising apparatus for the sending and receiving of information by phase shift carrier transmission

摘要

924,647. Phase shift radio signalling. TELEFONAKTIEBOLAGET L. M. ERICSSON. Feb. 23, 1961 [Feb. 23, 1960], No. 6767/61. Drawings to Specification. Class 40 (5). In a phase shift telegraphy system the signals are preceded by a short carrier burst phase shifted by 90 degrees from the signal phase reversals and the output of the signal phase detector is rectified by a full wave rectifier so that a pulse is produced from the latter only during the short starting burst which indicates the start of a signal. Alternatively, one of the two inputs to the signal phase detector may be shifted through 90 degrees and applied with the other input to a second phase detector, this producing a pulse output only during the start carrier burst. A reference oscillator of equal frequency is used at the receiver for demodulating the carrier pulses, and synchronizes with the latter, but does not lock in phase with the " start " signal, due to its short duration.