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Apparatus and method for synchronizing a plurality of remote transmission and receiving stations and providing automatic gain control of the synchronizing signal

  • US 5,278,690 A
  • Filed: 06/19/1992
  • Issued: 01/11/1994
  • Est. Priority Date: 05/16/1991
  • Status: Expired due to Term
First Claim
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1. In a cellular radiotelephone system, apparatus for synchronizing a plurality of remote transceiver stations and a base station connected to the remote stations to a common reference signal having a reference frequency;

  • comprising;

    the base station including;

    a first input for receiving an RF radio signal,a second input for receiving a reference signal,a base station splitter connected to the second input for splitting the reference signals into first and second base paths,a base signal combiner circuit connected to the first input and the first base path and operative for combining the RF radio signal and the reference signal into a first RF composite signal,a laser device connected to the base signal combiner circuit and operative for converting the first RF composite signal into an AM composite light signal,a transmitting light fiber link having a first end connected to the laser device,a remote transceiver station connected to a second end of the light fiber link to receive the AM composite light signal of the laser device and including;

    an optical signal received connected to the light fiber link and operative for separating the reference signal from the AM composite light signal for synchronizing operations in the remote station;

    a remote station splitter connected to the optical signal receiver and operative for splitting the reference signal into first, second and third remote paths,RF signal transmission apparatus connected to the optical signal receiver and operative for providing radio signal transmission of RF signal outputs of the optical signal receiver,a first frequency synthesizer connected to the first remote path to accept the reference signal separated from the AM composite light signal and generate a RF carrier signal at a cellular frequency to be modulated by a maintenance signal returned to the base station to indicate status of the remote station,RF signal reception apparatus in the remote transceiver station for receiving cellular telephone radio signals and including a mixer,a second frequency synthesizer connected to the second remote path to accept the reference signal separated from the AM composite light signal and generate a local oscillator signal applied to the mixer for down converting received RF radio signals;

    an RF maintenance receiver connected to the third remote path to accept the reference signal separated from the AM composite light signal and generate a signal frequency to tune the RF maintenance receiver to a control signal frequency generated by the base station for maintaining the remote station;

    a remote signal combiner circuit coupled to the RF signal reception apparatus and the first and second remote paths whereby the remote signal combiner circuit generates a return RF composite signal.a remote optical transmitter connected to the remote signal combiner circuit and operative for converting an output of the remote signal combiner to an AM return optical signal,a second transmitting light fiber interconnecting the remote optical transmitter to the base station,a base optical receiver at the base station connected to the second transmitting light fiber and connected to receiver circuitry at the base station for separating the RF signals from the AM return optical signal, the receiver connected to receive the reference signal from the second base path, and includingan AGC amplifier responsive to an amplitude of the reference signal to adjust an amplitude of the RF signal to compensate for optical losses in the second transmitting light fiber.

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