Thanks everybody!
Richard, the Quadnet keyword was enough to help me find the software (which is super useful) and also several other projects by people who've built analog all pass filters of varying complexity.? These, along with the Quadnet software, have been very helpful as I try to get my head around this.? With careful component selection, some of these designs are claiming better than 70dB of opposite sideband suppression!? For reference, here they are:
W6JL's 10 pole phasing receiver
YU1LM's 8 pole phasing transceiver
WA5BDU's 6 pole receiver, adapted from EMRFD (PowerPoint)
The Scientist and Engineers Guide to DSP is a resource I've stumbled across before, but thanks to Geoff for refreshing my memory!? There's definitely some good reading in there, and it looks like I'll have to finally go find a copy of EMRFD to call my own.? I had wondered if it would be possible to put together a simple monoband SSB rig patterned after the QCX, but for sideband.? From what I've found today it looks possible, though I'm still not sure how to get 45dB of sideband rejection out of a third order all pass filter.? i suppose I'll have to read on to find out!
Cheers,
John VA7JBE
