256 QAM 400 Mb/s microwave radio system with DSP fading countermeasures

A 256 QAM 400 Mb/s system and repeater configuration, using fading countermeasures with digital signal processing (DSP) technologies, is described. A one-chip transversal filter is developed. This large-scale integration chip is used as a fully digital transversal equalizer and a cross-polarization interference canceller offering compactness, low power consumption, and no tuning. An advanced control method called the shift-bit select and the maximum level error method are introduced to improve control response, acquisition and steady performance. The field test confirms good performance of the fading countermeasures with DSP technologies.<>