Harris has been producing the RF-5000 series HF transceivers since about
1990 with DSP IF. Bandwidth can be selected from 340hz to 6khz. AGC,
syllabic squelch, AM/SSB modulation and demodulation is also done in
DSP. The roofing filter in this series is only 8khz wide and the
receiver performance is fantastic!
Mike

wrote:
There's a number of commercial amateur transceivers that have
DSP in the audio stages but do any have DSP in the IF before the
detector/AGC?

73 Don K6LTS
address in QRZ database