Hitachi, Ltd.

Hitachi Denshi Kabushiki Kaisha

Mitsuo Toya

Yoichi Kaneko

Yukinari Fujiwara

Nobuo Sekiguchi

A vehicle radio telephone system includes, in addition to a handset associated with a telephone set, a wireless microphone detachable from the telephone set and a telephone receiver comprising a speaker contained in the telephone set. When a driver drives a vehicle, the wireless microphone is placed near the driver's mouth so that the driver can transmit and receive without handling the handset.

Mobile radio telephone system

A mobile data receiving system for a mobile communication system is disclosed. A clock signal for a digital phase synchronization loop circuit used for receiving digital data such as a dial number is obtained by multiplying or dividing the frequency of the output signal of a highly-stable oscillator for generating a reference frequency for a frequency synthesizer. Also, noise which is generated by the operation of the digital phase synchronization loop circuit is prevented from deteriorating the performance of the transmitter-receiver by the use of a matching circuit located between the frequency multiplier or divider and the digital phase synchronization loop circuit.

Mobile data receiving system

In a radio station system utilizing multi-channel transmission and reception frequencies of the type comprising a transmitter and a receiver wherein the frequency difference between the transmission and reception frequencies is made to be equal to an intermediate frequency, there is provided a source of multi-frequency signal which determines the multi-channel transmission and reception frequencies. The output of the multi-frequency signal source is utilized directly as a local oscillation signal of the receiver and the frequency of the output of the multi-frequency signal source is shifted by a modulated wave having a frequency twice the intermediate frequency and the frequency shifted output is utilized as the transmission frequency.

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Fujisawa, Japan

Mitsuo Toya