Transmitter/receiver apparatus with common oscillator that changes frequency between transmitting and received operations

• US 5,239,689 A
• Filed: 10/18/1991
• Issued: 08/24/1993
• Est. Priority Date: 10/25/1990
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Fukuda, Kunio
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): VO, NGUYEN THANH
• Application Number:
  US07/779,269
• Time in Patent Office: 676 Days
• Field of Search: 455/75-76, 455/78-79, 455/82-83, 455/85-87, 455/73, 370/29, 370/27, 370/95.1
• US Class Current: 455/86
• CPC Class Codes: H04B 1/50 using different frequencies for the two directions of communication

Abstract

A transmitter/receiver apparatus wherein a sufficiently great difference is assured between frequencies of intermediate frequency signals of transmitting and receiving circuits to assure an improved disturbance preventing performance. An oscillating circuit for oscillating a signal for selection of a channel is provided commonly for the transmitting and receiving circuits. In the transmitting circuit, power is supplied, also in a receiving operation, to a modulating circuit so that it continues a modulating operation, and an output of the modulating circuit is frequency converted with an oscillation output of the oscillating circuit into a signal of a frequency corresponding to a predetermined channel. In the receiving circuit, a received signal of the predetermined channel is frequency converted with the oscillation output of the oscillating circuit into a signal of an intermediate frequency. The frequency of the oscillation output of the oscillating circuit is varied by a predetermined amount between transmission and reception.

Claims

1. A transmitter/receiver apparatus of the TDMA/TDD system, comprising:

a transmitting circuit for transmitting an outgoing FM signal in response to an input signal;

a receiving circuit for receiving an incoming FM signal;

an oscillating circuit provided commonly for transmitting and receiving operations of said transmitter/receiver apparatus for oscillating a signal for selection of a channel;

said transmitting circuit including a modulating circuit to which power and said input signal are supplied in a transmitting operation of said transmitter/receiver apparatus, power but no said input signal being supplied to said modulating circuit in a receiving operation of said transmitter/receiver apparatus;

said transmitting circuit further including frequency converting means for frequency converting an intermediate frequency transmission output signal Sit of said modulating circuit with an oscillation output of said oscillating circuit into a signal of a frequency corresponding to a predetermined channel;

said receiving circuit being of the superheterodyne type wherein a received signal of the predetermined channel is frequency converted with the oscillation output of said oscillating circuit into a reception signal Sir of an intermediate frequency; and

means for varying the frequency of the oscillation output of said oscillating circuit by an amount between said transmitting and receiving operations such that a frequency difference between said signals Sit and Sir is equal to half the difference between the frequency of said signal Sit and the frequency spacing between said predetermined channel and an adjacent channel.

2. A transmitter/receiver apparatus, comprising:

an oscillating circuit provided commonly for transmitting and receiving operations of said transmitter/receiver apparatus for oscillating a signal for selection of a channel;

a modulating circuit;

a first mixer circuit for frequency converting an output signal of said modulating circuit with an oscillation output of said oscillating circuit;

a first multiplying circuit for multiplying an output signal of said first mixer circuit by n which is a value greater than 1 to produce a transmission signal of a predetermined channel;

a second multiplying circuit for multiplying the oscillation signal of said oscillating circuit by n;

a second mixer circuit for frequency converting a received signal of the predetermined channel with an output signal of said second multiplying circuit into a signal of a first intermediate frequency;

an intermediate frequency amplifier to which the first intermediate frequency signal from said second mixer circuit is supplied; and

a demodulating circuit to which an output signal derived from said intermediate frequency amplifier is supplied;

said modulating circuit being supplied, also in a receiving operation of said transmitter/receiver apparatus, with power;

the output signal of said modulating circuit having a second intermediate frequency fit and the frequency of the first intermediate frequency signal being fir, where

space="preserve" listing-type="equation">fit=(fir±

Δ

f)/n

and Δ

f is a predetermined frequency;

the oscillation frequency of said oscillating circuit being varied by Δ

f/n between said transmitting and receiving operations.

3. A transmitter/receiver apparatus according to claim 2, wherein the predetermined frequency Δ

f is equal to a distance between adjacent channels.