JPS57202148A - Code transmission system - Google Patents

Abstract

PURPOSE:To transmit analog information together with digital information, by generating one pulse to one CMI code rule error and reproducing the original analog signal by introducing the pulse train to a pulse frequency demodulation circuit. CONSTITUTION:An input analog signal 103 is converted into a PFM signal 123 at a modulator 105 at transmission side 50. An interface circuit 106 is operative with the leading of the signal 123 and generates only one pulse 121 with the CMI rule error with the same width as the period of a clock 102 synchronized with a data 101. A CMI coder 104 generates the CMI rule error only once to a transmission circuit 51 when this one pulse is received. At a reception side 52, a CMI composite circuit 114 detects the CMI code rule error and generates one CMI rule error detection pulse 122, and after the pulse width is adjusted with a monostable multivibrator circuit 116, the pulse is restored to the original analog signal 113 at a PFM demodulation circuit 115.