Radio transmitter-receiver

Abstract

The present invention relates to a radio transmitter-receiver and its object is to provide a frequency diversity communication device which can synthesize two carrier waves by one demodulation circuit without requiring any means for changing over the carrier waves and judging the receiving conditions. The present invention achieves this object by the following means. The two carrier waves are received at the same time, and they are respectively converted by a frequency converter to intermediate frequencies whose center frequencies in modulation are the same, to be demodulated. Thereby, a circuit for selecting the carrier wave becomes unnecessary and only one demodulation circuit is necessary since the carrier waves are synthesized before demodulated. In order to remove beat occurring in the intermediate frequencies of the receiver through the above means, the transmitter performs frequency conversion with the same polarity for the two carrier waves by a baseband signal except a transmitting signal. The present invention realizes a small-sized and low-priced radio transmitter-receiver having a frequency diversity function and widens the utilization range of radio communication.

Dependencies are inferred from the claim text.