Why is decimation used?
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 decimation rate?
Decimation is a term that historically means the removal of every tenth one. But in signal processing, decimation by a factor of 10 actually means keeping only every tenth sample. This factor multiplies the sampling interval or, equivalently, divides the sampling rate.
What is an interpolation filter?
“Upsampling” is the process of inserting zero-valued samples between original samples to increase the sampling rate. “Interpolation”, in the DSP sense, is the process of upsampling followed by filtering. (The filtering removes the undesired spectral images.)
How do you downsample a signal?
Downsampling. The idea of downsampling is remove samples from the signal, whilst maintaining its length with respect to time. For example, a time signal of 10 seconds length, with a sample rate of 1024Hz or samples per second will have 10 x 1024 or 10240 samples.
What is interpolator & decimator?
Decimation and interpolation are the two basic building blocks in the multirate digital signal processing systems. The decimator is utilized to decrease the sampling rate and interpolator to increase the sampling rate.
What is the purpose of interpolation?
Interpolation is a statistical method by which related known values are used to estimate an unknown price or potential yield of a security. Interpolation is achieved by using other established values that are located in sequence with the unknown value.
How does a polyphase filter work?
A polyphase quadrature filter, or PQF, is a filter bank which splits an input signal into a given number N (mostly a power of 2) of equidistant sub-bands. These sub-bands are subsampled by a factor of N, so they are critically sampled.
What is a decimation filter and how does it work?
Thus, the burden of design can be pushed onto the decimation filter. The most important role of a decimation filter is to decrease the sampling rate by discarding every few samples. Presented in this article is a quick overview of decimation filters, along with their operation and requirements.
What is the decimate-by-4 mode?
For example, a decimate-by-4 mode would mean (total samples)/4, while all other samples are effectively discarded. The ADC must also contain a numerically controlled oscillator (NCO), plus a filter and mixer component that is used as a companion to the decimation function.
What is decimatedecimation in ADC?
Decimation is a method of observing only a periodic portion of the ADC samples, while ignoring the rest. The result is to reduce the sample rate of the ADC. For example, a decimate-by-4 mode would mean (total samples)/4, while all other samples are effectively discarded.
What is “decimation” and “downsampling”?
“Downsampling” is a more specific term which refers to just the process of throwing away samples, without the lowpass filtering operation. Throughout this FAQ, though, we’ll just use the term “decimation” loosely, sometimes to mean “downsampling”. 2.1.2 What is the “decimation factor”?