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What is decimation filtering?
Decimation is the process of reducing the sampling frequency of a signal to a lower sampling frequency that differs from the original frequency by an integer value. This lowpass FIR filter is an anti-aliasing filter followed by an M-fold decimator. The decimator passes every Mth sample and discards the other samples.
Why do we need decimation filter?
The most immediate reason to decimate is simply to reduce the sampling rate at the output of one system so a system operating at a lower sampling rate can input the signal. For example, if you double the sample rate, an equivalent filter will require four times as many operations to implement.
What is interpolation and decimation filters and why we need it?
• Decimation. – Reduce the sampling rate of a discrete-time signal. – Low sampling rate reduces storage and computation requirements. • Interpolation. – Increase the sampling rate of a discrete-time signal.
Which filter is present in decimator?
Digital Filters 4.66, is a high-order decimation filter that allows decimation by factors up to 1024.
Which is the best filter to use for decimation?
To implement the filtering part, you can use either FIR or IIR filters. To implement the downsampling part (by a downsampling factor of “M”) simply keep every Mth sample, and throw away the M-1 samples in between. For example, to decimate by 4, keep every fourth sample, and throw three out of every four samples away.
When to use decimation before or after downsampling?
However, since the original signal has components up to 10 kHz, you must lowpass-filter the signal prior to downsampling to remove all components above 5 kHz so that no aliasing will occur when downsampling. This combined operation of filtering and downsampling is called decimation.
How much computation is required for a fir Decimator?
A simple way to think of the amount of computation required to implement a FIR decimator is that it is equal to the computation required for a non-decimating N-tap filter operating at the output rate. 2.4.2 How much memory savings do I gain by using a FIR decimator?
What is the correct order of decimation in multirate?
Decimate in order from the largest to smallest factor. In other words, use the largest factor at the highest sampling rate. For example, when decimating by a factor of 60 in three stages, decimate by 5, then by 4, then by 3. The multirate book references give additional, more specific guidance.