What are the useful techniques in the process of FIR filter?5.8G Frequency microwave sensor module

　　FIR tricks center on two things 1) not calculating things that don't need to be calculated, and 2) "faking" circular buffers in software.

　　How to skip unnecessary calculations?

　　First, if your filter has zero-valued coefficients, you don't actually have to calculate those taps; you can leave them out. A common case of this is "half-band" filter, which have the property that every-other coefficient is zero.

　　Second, if your filter is "symmetric" (linear phase), you can "pre-add" the samples which will be multiplied by the same coefficient value, prior to doing the multiply. Since this technique essentially trades an add for a multiply, it isn't really useful in DSP microprocessors which can do a multiply in a single instruction cycle. However, it is useful in ASIC implementations (in which addition is usually much less expensive than multiplication); also, some newer DSP processors now offer special hardware and instructions to make use of this trick.

Read recommendations:

How to test and implement FIR filters?

MF58 glass packaging NTC heat -sensitivity resistance.Radar Microwave Induction Sensor Switch manufa

HW-M10-1 microwave sensor module

PIR Lens 2814

HW8004 Night light microwave sensor module，PIR sensor module