This paper describes the development of an adaptive weighted code division multiplexing (AW-CDM) transmission system that includes a new multipath compensator. This system provides “graceful degradation” (variable picture quality with local reception conditions) of TV reception by dividing hierarchical information into spread-spectrum subchannels. Each subchannel has a different priority and, thus, a different threshold. Software simulation for the AW-CDM reveals sound performance under strong propagation. This hierarchical transmission system can be used to detect problems that occur when a digital transmission is in its threshold, thus preventing the abrupt breakdown of digital TV systems.
