Inter-unit digital signal transmitting method, digital signal transmitter and receiver equipment, digital signal transmitter, and digital signal receiver

摘要

Digital signal transmitter/receiver equipment includes a first transmitter/receiver unit that handles digital signals and a second transmitter/receiver unit connected to the first transmitter/receiver unit via a transmission line to subject a digital signal to both a modulation/demodulation process and a frequency conversion process. The object is to suppress the signal attenuation due to a cable connecting the first transmitter/receiver unit to the second transmitter/receiver unit. Each of the first and second transmitter/receiver units includes a first frequency-shift modulation unit that sets the frequency of the digital signal transmitted between the first and second transmitter/receiver units to a value lower than an intermediate frequency at a frequency conversion processed by the second transmitter/receiver unit, and a second frequency-shift demodulation unit for demodulating the digital signal subjected to a frequency-shift modulation.