What is a decimating filter?
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. Decimation also is known as down-sampling. Decimation filters help you remove the excess bandwidth and reduce the sampling frequency of the signal.
What happens if we violate the Nyquist criteria in downsampling or decimating?
2.1. 6 What happens if I violate the Nyquist criteria in downsampling or decimating? You get aliasing–just as with other cases of violating the Nyquist criteria. (Aliasing is a type of distortion which cannot be corrected once it occurs.)
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.
How does lowpass filtering and decimating improve SNR?
The FFT shows a very clear peak (two with the symmetry). If I naively downsample without filtering, the signal gets aliased and the SNR decreases, which makes sense: I removed relevant information about the sine while keeping the noise unchanged. Then, I applied a lowpass filter to avoid aliasing when subsampling.
What is the difference between decimation and downsampling?
2.1.1 What are “decimation” and “downsampling”? Loosely speaking, “decimation” is the process of reducing the sampling rate. In practice, this usually implies lowpass-filtering a signal, then throwing away some of its samples.
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?