A signal receiving apparatus includes a frequency converting circuit, a computing circuit, and a control circuit. The frequency converting circuit is for converting a RF signal to respectively generate a first converted signal and a second converted signal according to a first converting frequency and a second converting frequency. The computing circuit is for computing signal quality parameters of the first converted signal and the second converted signal. The control circuit is for outputting a control signal according to the signal quality parameters of the first converted signal and the second converted signal, wherein the control signal corresponds to the converting frequency of the frequency converting circuit.