Radio station system

• US 4,231,116 A
• Filed: 11/24/1978
• Issued: 10/28/1980
• Est. Priority Date: 03/27/1978
• Status: Expired due to Term

• Current Assignee: Hitachi Denshi Kabushiki Kaisha, Hitachi, Ltd.
• Original Assignee: Hitachi Denshi Kabushiki Kaisha, Hitachi, Ltd.
• Inventors: Sekiguchi, Nobuo, Fujiwara, Yukinari, Kaneko, Yoichi, Toya, Mitsuo
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US05/963,431
• Time in Patent Office: 704 Days
• Field of Search: 325/17, 325/18, 325/20, 343/179, 343/181, 331/1 A, 331/58, 363/1, 363/157
• US Class Current: 455/87
• CPC Class Codes: H04B 1/50 using different frequencies for the two directions of communication

Abstract

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.

Claims

1. In a radio station system for transmission and reception of signals from a modulation signal source utilizing multichannel transmission and reception frequencies of the type comprising a transmitter and receiver wherein a multi-frequency signal source is supplied with a channel designation input to produce the local reference frequency signal for the receiver and the transmission frequency signal for the transmitter and wherein the difference between the transmission and reception frequencies is made equal to the intermediate frequency with respect to respective channels, the improvement which comprises means for directly utilizing a variable frequency output of said multifrequency signal source and said local reference frequency signal, said variable output being responsive to said channel designation input to select channel frequencies, means for producing a fixed frequency output from said multi-frequency signal source, means responsive to said fixed frequency and said modulation signal for producing a modulated carrier wave having a frequency twice said intermediate frequency, means for shifting the frequency of said variable output by the frequency of said carrier wave, and means for utilizing said freuqency shifted output to determine said transmission frequency.

2. The radio station system according to claim 1 wherein said multi-frequency signal source comprises a synthesizer which supplies the output of a reference oscillator as the carrier wave of said modulated wave.

3. The radio station system according to claim 1 wherein said modulated wave producing means comprises a modulator for modulating the fixed frequency output of said multi-frequency signal source with the modulation signal source output and a frequency multiplier connected to receive the output of said modulator to produce said carrier wave.