Digital field pick-up unit using COFDM scheme

The COFDM (coded orthogonal frequency division multiplexing) modulation scheme is effective for digital transmission under multipath fading conditions. A digital 800 MHz FPU (field pick-up unit) that uses COFDM technology has been developed to enable stable live-TV transmission from moving vehicles. In the experimental COFDM-FPU, compressed digital video/audio data are distributed to 572 carriers within the 9 MHz bandwidth, using the DQPSK (differential quadrature phase shift keying) modulation scheme for each carrier. Field trials have been carried out for comparison with a conventional analogue FM-FPU. The COFDM digital FPU maintains video signal stability even under severe multipath fading conditions, when pictures of the conventional PM-FPU are seriously degraded. This paper describes the first application of the COFDM modulation scheme to the digital FPU that transmits digital signals from a mobile source. It also introduces the main features of this experimental equipment together with the results of the transmission experiments.