Nippon Hoso' Kyokai

Hideki Suganami

Toshiyuki Takegahara

Satoru Koizumi

Yoshiharu Hoshino

Yutaka Tanaka

Takeshi Kimura

Kaoru Watanabe

Taiichiro Kurita

Taiji Nishizawa

Kazumasa Enami

Haruo Okuda

Kozo Kameda

Yoshimichi Otsuka

Shoichi Suzuki

Masaru Kanazawa

Kazuhiko Shibuya

Yasuaki Kanatsugu

Minoru Honda

Ryoichi Yajima

Hisakazu Kato

As to a differential code (DPCM) transmission system for an input signal as such as an audio signal, in case higher frequency components thereof are dominant, every another samples of the input signal are alternately into two groups, in each of which differential coding effected, so as to maintain a dynamic range in higher frequency range; in case no frequency components exceeding one fourth of the sampling frequency are contained in the input signal, successive 3 MSB's having a pattern '1, 0, 1' or '0, 1, 0' are corrected into '1, 1, 1' or '0, 0, 0' respectively; and in case 2 symbols of a tertiary code converted from 3 bits of a binary code are transmitted and restored, peripheral bit arrangement of a matrix having rows consisting of the first symbols of the converted tertiary codes and columns consisting of the second symbols thereof are allotted such as Gray codes are obtained, while an inner 2.times.2 matrix of a 4.times.4 matrix formed by inserting a new threshold level between two threshold levels provided for detecting the tertiary code is allotted with bits relating to bits arranged at adjacent positions, so as to reduce the bit error rate of the restored binary code.

Differential code transmission system

A signal transmission system for high definition television that can handle a second television signal which is superior in quality to a first television signal such as an NTSC (National Television System Committee) television signal. The transmitting end of the system transmits a first television signal including a video signal, audio signals, etc., through a main transmission line, as well as a third television signal including a high definition components obtained as the difference between the second and the first television signal through an auxiliary transmission line. The receiving end of the system receives and synthesizes the first television signal transmitted through the main transmission line and the third television signal transmitted through the auxiliary transmission line to produce the second television signal.

Signal transmission system for high definition television

A differential code (DPCM) transmission system for an audio signal, in case higher frequency components thereof are dominant, every another samples of the input signal are alternately into two groups, in each of which differential coding effected, so as to maintain a dynamic range in higher frequency range; when a near instantaneously compressed DPCM signal is transmitted, coding errors caused by the compression are corrected by varying the difference between samples in response to the comparison between a locally decoded signal and the original signal; when the frequency components exceeding one fourth of the sampling frequency are contained in the input signal, successive 3 MSB's having a pattern '1, 0, 1' or '0, 1, 0' are corrected into '1, 1, 1' or '0, 0, 0' respectively; and in case 2 symbols of a tertiary code converted from 3 bits of a binary code are transmitted and restored, peripheral bit arrangement of a matrix having rows consisting of the first symbols of the converted tertiary codes and columns consisting of the second symbols thereof are allotted such as Gray codes are obtained, while an inner 2.times.2 matrix of a 4.times. 4 matrix formed by inserting a new threshold level between two threshold levels provided for detecting the tertiary code is allocated with bits relating to bits arranged at adjacent positions, so as to reduce the bit error rate of the restored binary code.

Differential coding system

A method and system for multiplexing additional audio information in the form of pulse code modulation (PCM) audio signals onto a television signal. The PCM audio signal is time multiplexed into scanning retrace intervals of the video signal. At a receiver, the bit error rate of the decoded PCM audio signal is compared with a threshold so as to switch the audio output from the PCM audio signal to a conventional FM demodulated audio signal when the bit error rate exceeds the predetermined threshold. In this way, the benefits of both PCM audio and FM audio can be obtained by utilizing the higher immunity of FM signals in low signal-to-noise ratio environments, while the high fidelity PCM audio signal is utilized when the signal-to-noise ratio environment is relatively high.

Method and system for transmitting and receiving PCM audio signals in

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Tokyo, Japan

Hideki Suganami