2018-09-22 13:46:58 UTC
Of course, these are filters whose cutoff frequency moves with the first harmonic of the input signal. Probably, all of us have done this with IIR filters but in this application I cannot afford the group delay of IIR filters.
The input can move as much as +/-500Hz each second, relatively smoothly, not suddenly. I have a millisecond to calculate the coefficients for a 1024 tap FIR filter, whose output can show no evidence of switching (jerks, steps, etc).
I would love to use equiripple calculations but I am open to others if they are fast and clean enough.
This application is for an ASIC, I cannot use standard libraries for it except for reference, I expect that I will have to write it myself unless someone knows of a reference or an application that I can use for reference.
Please forgive my ignorance if the answers are obvious, I have not done this before.
Thank you for any help.