Historically, the only way to implement TPBT was using 2 IFs with fixed filters and adjustable LOs. I don't know of any instances of that, but would love to know what radios implemented TPBT before the Icom 7300.

I've got about 2/3 of the math coded up in Octave. I've got signals at 5 MHz, 30 Hz below and 50 Hz above, two filters 500 Hz wide with 50 Hz of overlap and a 50 Hz wide filter. Filters are trapezoids with 10 Hz wide skirts on each side. KISS.

Everything is being specified in the frequency domain for convenience. I'm not using any of the Octave packages. Just doing the basic math by hand. This for the simple reason I know the operations a *lot* better than I know Octave/MATLAB. I can count 8 different DSP software packages I used over the years. I spent far more time fixing bugs in DSP software or writing new codes than actually using it.

I am unlikely to make things minimum phase as they should be or make the huge number of figures needed to explain it all.

My goal is an analog version of TPBT using a single fixed IF.

Reg

Edit: This is every bit as tedious as I expected. Octave is crashing while using a 56 GB memory allocation when I'm only part way through the calculations. So I have to go back and reorganize to create, plot, use and delete the series as I go through that nightmare task list I laid out earlier. I'm not happy with 2 Hz for only 1 second, so I want to make the series longer. I'd really like 10 seconds, but that will be an overnight "tape to tape" job on this machine as it's only 16 GB of DRAM and 64 GB of swap.