| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem of a conventional digital broadcast receiver that has a limitation of its miniaturization due to its large circuit scale because frequency conversion is executed twice in the conventional configuration where a receive digital broadcast signal is frequency-converted into an intermediate frequency signal, quadrature detection is executed at the intermediate frequency, and obtained I, Q signals are given to a digital modulation signal system. SOLUTION: In the digital broadcast receiver of this invention consisting of a tuner section that applies quadrature detection to a received digital broadcast signal and outputs I, Q signals and of a digital modulation signal processing system that receives the I, Q signals to execute digital demodulation and error correction, the digital modulation signal processing system outputs an amplitude control signal to the tuner section so that the amplitude of the I, Q signals given to the digital modulation signal processing system is kept constant, the tuner section keeps the output amplitude of the I, Q signals constant on the basis of the amplitude control signal outputted from the digital modulation signal processing system and applies quadrature detection to the received digital broadcast signal without converting its frequency into an intermediate frequency so as to realize a stable and suitable reception characteristic and the miniaturization of the circuit scale.
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