Diversity receiving device and diversity receiving method

A diversity receiving device for receiving, at a first receiving system and a second receiving system, a transmission signal containing first to K-th high-frequency-channel components having mutually different first to K-th central frequencies respectively, K being an integer not less than 2, the diversity receiving device comprising:

• a first receiving circuit that receives, as an input, a first received signal obtained at the first receiving system;
• a second receiving circuit that receives, as an input, a second received signal obtained at the second receiving system;
• a diversity combining unit that combines an output of the first receiving circuit and an output of the second receiving circuit for each same frequency component;
• and
• an oscillation controller;
• the first receiving circuit including:
• a first local oscillator that supplies first to K-th lower-side oscillation-frequency signals having first to K-th lower-side oscillation-frequencies respectively, the first to K-th lower-side oscillation-frequencies being shifted toward lower frequency sides of the first to K-th central frequencies respectively;
• a first frequency converter that performs frequency conversion of the first received signal by using the first to K-th lower-side oscillation-frequency signals, thereby generating first to K-th lower-side low-frequency signals corresponding to the first to K-th lower-side oscillation-frequencies respectively;
• a first signal adder that adds up the first to K-th lower-side low-frequency signals, thereby generating a first addition signal;
• a first channel-component extractor that extracts, from the first addition signal, first to K-th lower-side low-frequency-channel components corresponding to the first to K-th high-frequency-channel components respectively;
• and
• a first channel signal processor that performs signal processing of the first to K-th lower-side low-frequency-channel components, thereby generating first to K-th lower-side low-frequency-channel processing signals corresponding to the first to K-th lower-side low-frequency-channel components respectively to output the first to K-th lower-side low-frequency-channel processing signals to the diversity combining unit;
• the second receiving circuit including:
• a second local oscillator that supplies first to K-th higher-side oscillation-frequency signals having first to K-th higher-side oscillation-frequencies respectively, the first to K-th higher-side oscillation-frequencies being shifted toward higher frequency sides of the first to K-th central frequencies respectively;
• a second frequency converter that performs frequency conversion of the second received signal by using the first to K-th higher-side oscillation-frequency signals, thereby generating first to K-th higher-side low-frequency signals corresponding to the first to K-th higher-side oscillation-frequencies respectively;
• a second signal adder that adds up the first to K-th higher-side low-frequency signals, thereby generating a second addition signal;
• a second channel-component extractor that extracts, from the second addition signal, first to K-th higher-side low-frequency-channel components corresponding to the first to K-th high-frequency-channel components respectively;
• and
• a second channel signal processor that performs signal processing of the first to K-th higher-side low-frequency-channel components, thereby generating first to K-th higher-side low-frequency-channel processing signals corresponding to the first to K-th higher-side low-frequency-channel components respectively, and outputs the first to K-th higher-side low-frequency-channel processing signals to the diversity combining unit;
• the oscillation controller controlling the first to K-th lower-side oscillation-frequencies so that frequency bands of the first to K-th lower-side low-frequency signals become adjacent to one another and controlling the first to K-th higher-side oscillation-frequencies so that frequency bands of the first to K-th higher-side low-frequency signals become adjacent to one another.