Matsushita Electric Industrial Co., Ltd.

Yukio Sugimoto

Toyoshi Fukumura

Makoto Okamasa

Sukeichi Miki

Shin Fukuda

Mamoru Kaneko

Shuichi Ninomiya

Toyota Noguchi

Tadafumi Nishimura

Kenjiro Nakayama

Michio Okamoto

A time divided digital signal transmission system includes a transmitter for converting plural analog signals to digit signals, generating multiplexed time divided signals from the digital signals, and transmitting the multiplexed time divided signals by a digital data transmission circuit. The system further includes a receiver for receiving the multiplexed time divided signals, demultiplexing the multiplexed time divided signals so as to thereby obtain the original digital signals and converting the original digital signals back into the original analog signals. The system is arranged to effectively utilize both synchronizing signals and clock signals for the analog to digital conversion and the digital to analog conversion in the system.

Time divided digital signal transmission system

A short wave broadcasting receiver which can receive accurately and stably the desired station is formed with a local oscillator which comprises a variable frequency oscillator, reference frequency oscillators, premixers and band pass filters, frequency converter and an 1F amplifier. By adding a frequency counter unit comprising a frequency counter block and digital display block, the received frequency can be digitally displayed stably and correctly by using a cheap low speed frequency counter.

Radio receiver employing premixing and digital display

A record reproducing system comprising a displacement detection type cartridge and a reproducing circuit for converting the output signal of the displacement detection type cartridge into audio signals. Either the displacement detection type cartridge or a pre-amplifier in the reproducing circuit is provided with a temperature sensitive resistive element so that temperature compensation with respect to the output-temperature characteristic of the displacement detection type cartridge may be effected at either the displacement detection type cartridge or the reproducing circuit.

Temperature compensating reproducing system

A compatible discrete four-channel (CD-4) stereophonic reproducing system which comprises a detecting circuit for detecting a sub-channel signal. A control means detects an over-deviation of the sub-channel signal and deactivates a noise elimination switching circuit connected in a stage following the detecting circuit when the over-deviation signal appears, thereby preventing an output from being transmitted from the detecting circuit to succeeding stages. A distortion reducing circuit is also provided. This circuit is responsive to an output of said control means for attenuating at least a high frequency band of an output of the switching circuit for a predetermined time period, this period being longer than the period for which the over-deviation signal appears. Consequently, the noise produced by various causes can be effectively eliminated.

Discrete four-channel disc reproducing system

There is provided a four-channel stereophonic reproducing system wherein each muting circuit comprises a limiter for limiting the carrier level of a frequency-modulated signal to a predetermined level, a control circuit actuated by the output of the limiter and a switching circuit controlled by the control circuit, whereby when the carrier level of the frequency-modulated signal decreases, the detected output of the sub-channel signal including a large amount of noise components is blocked by the muting circuit.

Four-channel stereophonic reproducing system for reproducing discrete

In a four-channel stereophonic reproducing system of the type in which a first, second, third and fourth audio signals are reproduced from two stereophonic composite signals which are respectively comprised of a left side signal consisting of a main channel signal composed of the sum of the first and second audio signals and a sub-channel signal obtained by frequency modulating or phase modulating the difference between the first and second audio signals, and a right side signal consisting of a main channel signal composed of the sum of the third and fourth audio signals and a sub-channel signal obtained by frequency modulating or phase modulating the difference between the third and fourth audio signals, a detector circuit for detecting each sub-channel signal is followed by a filter circuit for eliminating undesired higher frequencies whereby to eliminate higher audio frequencies including increased noise components to improve the S/N ratio, and at the same time a phase correction circuit is provided in the reproducing section for each main channel signal to correct for any phase distortion due to the filter circuit whereby to ensure a greatly improved separation.

Growing community of inventors

Katano, Japan

Yukio Sugimoto