Before implementing the entire system shown in Multirate Processing:
Introduction, we recommend you design a system that
consists of a cascade of filters FIR 1 and FIR 2 without the
sample-rate compressor or expander. After verifying that the
response of your two-filter system is correct, proceed to
implement the complete multirate system and verify its total
response. At first, use fixed compression and expansion
factors of
Compressed-rate processing
In order to perform the processing at the lower sample rate, implement a counter in your code. Your counter will determine when the compressed-rate processing is to occur, and it can also be used to determine when to insert zeros into FIR 3 to implement the sample-rate expander.
Some instructions that may be useful for implementing your
multirate structure are the add and bcc (branch conditional)
instructions. You may also find the b
(branch) instruction useful. The conditional fields that can be used with bcc can be found on page 1-7 of the 55x Mnemonic Instruction Set.









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