Patent ID: 6965739

Claim:
A communication system in which at least three intermediate frequency subcarrier signals are frequency-multiplexed and transmitted, the at least three intermediate frequency subcarrier signals are frequency-converted into target frequency bands at transmission destination sides, and a signal bandwidth containing all the at least three intermediate frequency subcarrier signals is wider than a signal bandwidth of the target frequency bands, wherein when first and second pilot carriers are to be multiplexed and transmitted together with the at least three intermediate frequency subcarrier signals, frequencies of the at least three intermediate frequency subcarrier signals, a frequency of the first pilot carrier signal, and a frequency of the second pilot carrier signal are determined to obtain a frequency in the target frequency band by adding/subtracting an integral multiple of the frequency of the first pilot carrier signal and in an integral multiple of the frequency of the second pilot carrier signal to/from each of the frequencies of the at least the intermediate frequency subcarrier signals, wherein frequency subcarrier signals of at least three systems is an integral multiple of a predetermined frequency, and a frequency difference between the first pilot carrier signal and the second pilot carrier signal equals the predetermined frequency.