A signal receiver generates a reference signal that sweeps frequencies of desired channel bands, and then feeds the reference signal to an input terminal of receiver unit via a signet-switching circuit that performs switching of the desired-channel signal and the reference signal. The signal receiver then detects the signal strength present in plural frequencies of intermediate frequencies delivered to an output terminal of the reference signal, and after storing detected signal data in a memory, the signal receiver compares the detected signal data to aimed frequency characteristics. Then, the signal receiver determines tuning voltages of respective tuning circuits so that difference arose from the comparison can be minimized. After determining the tuning voltages, these voltages are delivered to respective tuning circuits, and then switching operation between the reference signal and the desired channel signal is executed before the signal receiver eventually receives the switched signal.