Radio signal receiving system having means for selectively combining signals from a plurality of receiving sections

Claim 1

A radio signal receiving system having first and second signal receiving section means for providing output signals having substantially equal amplitudes and a signal combiner means coupled directly to outputs of said receiving section means for combining the outputs thereof to provide a combined signal having a substantially constant voltage, said first and second receiving section means being unbalanced with respect to ground, said signal combiner comprising: a first and a second input terminal means for respectively receiving the outputs of individually associated ones of said first and second receiving section means; circuit means having at least a set of first and second receiving terminals and an output terminal, said first and second receiving terminals being connected with two resistors in series, said output terminals being connected to the junction of said resistors; first switching means connected between said first input terminal and said first receiving terminal, second switching means coupled between said second input terminal and said second receiving terminal; third switching means connected between said first and second receiving terminals and interlocked to close when either one of said first and second switching means opens; and means connected to said first and second input terminal means for controlling said first, second and third switching means so that said first and second switching means are closed and said third interlocked switching means is opened in a normal state representing those outputs which are derived from said first and second receiving section means when they are above any one of a predetermined signal-to-noise ratio, a predetermined signal level, and a predetermined pilot signal level and if either of said two outputs is driven out of said normal state, the one of said first and second switching means which receives a signal in the normal state remaining closed with said third switching means closing, while the one of said first and second switching means which receives a signal driven out of the normal state is opened.