Frequency multiplexers and demultiplexers based on the SAW chirp Fourier transformer combined with digital signal processing

Several existing and planned satellite communications systems depend on frequency demultiplexers and multiplexers able to isolate narrow band carriers. To achieve high selectivity, digital signal processing (DSP) is the preferred method. The paper demonstrates how the SAW Chirp Fourier Transform (CFT) can be used as a preprocessor for the high selectivity DSP processor to reduce the on-board power consumption. The requirements to the SAW chirp components and the choice of SAW technology are discussed. The technology status in terms of power consumption for the supporting analog components, IF amplifiers and mixers, A/D converters, and for the DSP hardware is given. The power consumption for the SAW CFT based demultiplexer is estimated and compared to the estimate for an implementation with a fixed anti-aliasing filter combined with DSP