ABSTRACT
Multirate signal processing usually means the handling of a data stream at more than one sampling rate for improving the performance of some signal processing tasks. Two basic operations are encountered here:
1. Decimation (downsampling) or sampling rate reduction 2. Interpolation (upsampling) or sampling rate increase
The reasons why the data rate of a certain signal is changed are many, but to mention a few:
Providing compatibility between a data stream and a processor Improving the computational effi ciency of a certain processor Eliminating the need for high-order antialiasing fi lters while using simple low-cost ADCs Reducing the quantization noise of ADCs through oversampling Making it possible to deal with signals of different bandwidths at the same time Reducing the storage capacity required to save a data stream Reducing the required lengths of narrow-band digital fi lters by decimating the input data rate Reducing transmitting channels occupation
Whatever the reason is for changing the sampling rate either upwards or downwards, it should be possible to bring it back after processing to its original rate without causing any serious errors to the data.
