Abstract: A signal receiving system, a band detection method for a multi-carrier signal and a demodulating apparatus thereof. Each carrier of the multi-carrier signal has a plurality of symbols respectively corresponding to a plurality of time. The band detection method includes: defining a scan area range according to a full band range of the multi-carrier signal; obtaining a reference symbol corresponding to each of the symbols according to time and frequency offset values in the scan area range; performing an operation on each of the symbols and corresponding reference symbol to obtain calibration information of each carrier of the multi-carrier signal; tuning the full band range of the multi-carrier signal according to the calibration information thereof.

Abstract: A device and a method for detecting a guard interval (GI) of an orthogonal frequency division multiplexing (OFDM) signal are provided. The device includes a signal transforming unit and a GI determining unit. The signal transforming unit receives the OFDM signal and sets a predetermination GI to provide a first frequency-domain symbol and a second frequency-domain symbol. The GI determining unit receives the predetermination GI, the first frequency-domain symbol and the second frequency-domain symbol to determine a phase difference between the first frequency-domain symbol and the second frequency-domain symbol and determines the GI of the OFDM signal according to the phase difference.