For knock filter theory, perhaps this document from 1995 can shed some light?
EDIT: I've also discovered most of the meanings behind the spreadsheet I had posted earlier in the thread:
http://www.gearhead-efi.com/Fuel-Inj...ll=1#post85161
I found a Delphi patent for a programmable knock filter here:
https://patentimages.storage.googlea.../US5594649.pdf
The phrasing in this patent document perfectly jives with the spreadsheet. As such, the descriptions and units are as follows:
SBST = Software-based Self-test? Internal GM test routine?
FIRST STAGE (Bandpass Filter)
FREQ = Frequency (kHz)
GAIN = Gain (multiplier)
Q = Q Factor
COMP GAIN = Compressor Gain (ratio of input power to output power beyond threshold)
LPCF = Low-pass Filter Cutoff Frequency (Hz)
NOISE CHANNEL
GAIN = Gain (multiplier)
OFFSET = DC Offset Voltage (mV)
ITC = Increasing Time Constant (ms)
DTC = Decreasing Time Constant (ms)
IGN = ???
AOT = ???
ID RES K Ohms = Resistance value used to ID filter on ID pin (kOhms)
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