satellite radio receivers for processing both of qpsk modulated signals and - fm signals

摘要

There is provided a low-cost satellite broadcast tuner capable of receiving and processing both a QPSK modulation signal and an FM signal while assuring simple connection of an LNB to the tuner. A single front-end section (30) including an RF stage, a mixer, a local oscillator circuit, an IF stage, an AGC loop is used for both an FM detector (16) and an I/Q quadrature detector, so that both the FM signal and the QPSK modulation signal are received and processed in the single front-end section (30). In the above case, a power of the FM detector (16) for detecting the FM signal is turned off when receiving the QPSK modulation signal, and a power of a local oscillator circuit (21) required for detecting the QPSK modulation signal is turned off when receiving the FM signal. IMAGE