| 摘要 |
PURPOSE:To obtain a composite envelope detecting output by bringing the envelope detecting output to sample holding, in a diversity receiver, comparing the respective outputs, and selecting the output from a predominant receiver. CONSTITUTION:Intermediate frequency signals IFs, IFb from a receiver are amplified alternately as a time division by a logarithmic characteristic by a switching signal, respectively. Subsequently, said signals are brought to an envelope detection, brought to a DC amplification and applied to sample holding circuits 12a, 12b. A voltage which is brought to sampling by the circuits 12a, 12b is held by capacitors Ca, Cb during a holding period. This sample voltage is amplified through DC amplifiers 14a, 14b, respectively, and an envelope detecting signal is generated. Output levels of the amplifiers 14a, 14b are compared by a comparator 13, and a side of a higher level is selected and applied to an interference detecting circuit 11. Accordingly, to the circuit 11, an envelope detecting output based on an output of the receiver of one predominant side is applied, an interference is detected and a composite envelope output is obtained.
|
