Yes, that seems like a more modern approach, and since I'm planning on using a Teensy anyway, per Jack's (W8TEE) recommendations (and I think he mentioned this filter application too), the whole blooming enchilada could go in one box.
Now, a question might be how does this all this integrate with the QCX? It already has audio filtering, doesn't it?
OK, so at this point I have to separate out all these ideas. Here's where we are...
My first project was the digital AGC. A 328 can't do the math fast enough, so I moved to a 32-bit ARM device. Jack suggested a 4-something Teensy, I picked up a 3.6 from my local store to work on. That work continues.
Then I heard the talk about external encoders, and Jens asked rhetorically about about max encoder speed, and I figured I could add a buffer/driver to the digital AGC mod to support fast spin. I'm waiting to hear if he's interested.
Then Jerry asked about a programmable clock generator for a SCAF, which is easily doable, but it would need a CAT interface to link it with the QCX to automate it. I'm interested in doing a CAT interface unit for the QCX (for multiple units, actually, though I'd have to build an antenna switching unit to make it useful).
But if I'm going Teensy for the AGC, then the ARM can handle digital audio filtering without the need for the SCAF in the first place.
So, for now...
I'll keep working on the digital AGC (nicknamed "DAGLO" for "Digital Audio Gain Limiter/Optimizer") in the various configurations I had spoken of, and when I get more solid input from the customer base out here, figure out what else to add. It seems like the ACX+ would be the best host for a built-in solution, replacing the volume control with a second handwheel encoder/push button, at least. If folk are interested in my tuning spin-buffer idea, that could go into an external unit, along with other features.