MULTI-RATE FILTER STRUCTURES AND SINGLE CHIP DSP PERFORMANCE
MJD BISHOP · 2024
Multi-rate filter structures are powerful building blocks in a Digital Signal Processing (DSP) toolkit particularly when used to implement decimation and band selection functions prior to detection processing or interpolation prior to digital to analog conversion.'While equivalent filter specifications can be met by single-stage designs, the computational effort required often imposes Eundesirable restrictions on the attainable throughput.Thus even though the control complexity of multi-rate filters is greater (than that of single-stage filters, if the control complexity and data organisation requirements of the multi-rate filter can be implemented, increased throughputs will be obtained through their use.This paper gives performance data for multi-rate filters implemented on the Motorola DSP 56001 processor.Typical throughputs for both finite impulse response (FIR) and wave digital filter (WDF) decimators are given and contrasted with equivalent single-stage design.Comments on the mechanisation of both multi-rate structures and filter kernels on the DSP 56001 architecture are also made, as it is by the careful exploitation of the processor architecture that high performance is obtained. FILTERING REQUIREMENTS AND ALGORITHMSContemporary signal processing systems take analog signals, filter them, perform detection processing, and often output a derived analog signal.A generic "detection" system is shown in figure 1. sigma-delta converters are used for both analog to digital and digital to analog conversion, with a programmable Digital signal Processor (DSP) used to implement the band selection and detection process.