Abstract
Digital transmission signals are distorted by multi-path fading in a mobile radio channel. It is a severe problem especially when they are transmitted at high bit rate such as HDTV digital signals. OFDM (Orthogonal Frequency Division Multiplexing) is a modulation scheme which can mitigate the adverse effect multi-path fading by distributing the transmission data into a large number of carriers of a low bit rate modulation. In order to transmit the compressed HDTV digital data and reduce the degradation due to multi-path fading, we have developed a multi-level OFDM modem, which adopted 16DAPSK (Differential Amplitude Phase Shift Keying) modulation scheme for each OFDM carrier. This paper describes the features of the experimental 16DAPSK-OFDM modem and discusses the aspects of mobile digital FPU (Field Pick-up Unit) of the HDTV digital signals.
