×

Diversity combiner

  • US 4,868,890 A
  • Filed: 12/14/1987
  • Issued: 09/19/1989
  • Est. Priority Date: 12/15/1986
  • Status: Expired due to Term
First Claim
Patent Images

1. A diversity combiner for combining two received radio signals having the same frequency and modulation, comprising:

  • a mixer for each of the radio signals;

    a voltage controlled oscillator connected to each mixer;

    an intermediate frequency filter connected to each mixer for generating an intermediate frequency signal;

    a phase comparator connected to each intermediate frequency filter for comparing the intermediate frequency signal with a reference signal and generating an output signal responsive to the phase difference for controlling the voltage controlled oscillator frequency;

    means for determining the logarithm of each intermediate frequency signal amplitude and for generating two respective control voltages in response to said logarithms; and

    a signal weighting and adding circuit common to the two radio signals for forming a weighted aggregate of the two intermediate frequency signals, said weighting and adding circuit including;

    first and second pairs of bipolar transistors, one transistor in each pair receiving one of said two control voltages, and the other transistor in each pair receiving the other of the two control voltages;

    a first converting means for converting one intermediate frequency signal to a first current and a second converting means for converting the other intermediate frequency signal to a second current, said first and second pairs of transistors being responsive to said control voltages to divide each of said first and second currents into first and second components such that the ratio between the first and second components of said first current is at least approximately equal to the corresponding ratio between the components of said second current; and

    a resistor for supplying both the component of said first current which passes through the transistor supplied with the control voltage originating from the same intermediate frequency signal as said first current and the component of said second current passing through the transistor supplied with the control voltage originating from the same intermediate frequency signal as said second current.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×