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I had a conversation with Hans about this, and it was our feeling that it was probably not worth the extra overhead and additions to the hardware, since the K9HZ amp is running in a much more linear

That's a nice program!? I've been using Octave in my DSP experiments.? Usually, Matlab code will run in it with little modification.? I've designed filters in it to run on the Teensy, but I never

Bob Where did you get with this? I just ordered 500V, 630V or 1kV instead. LCSC always have good pricing, rather than Mouser and DigiKey. Most caps at LCSC were around 3-20 cents pre-tariff, I always

FWIW Flex's new transceiver (the Aurora ( https://www.flexradio.com/aurora/?srsltid=AfmBOooHr-uT5LeSvoQ8J0Vefce37bc6MbigUR3oa64vpQUmLMLW3Qq6 ) ) also uses polar modulation (aka EER Envelope

I made the plots using Python matplotlib library which is heavily inspired by Matlab, so I'm not surprised you thought that! I switched from Matlab to Python about 15 years ago when I got sick of

I saw the inconsistency in the coefficient array sizes and six of the init functions but then saw that the coefficient arrays seemed specially structured for this type of dual use.? I figured it was

Here's the missing second plot -- much better!

I'll investigate this too, thanks for all the great advice! I'm testing each of the transmit DSP steps individually. I've found another issue -- the number of taps in the initialization of

A picture is worth a thousand words. This uses half the bandwidth as in my earlier post!? And cleaner upper sideband as well. Greg mentioned to me the other day that applying the Hilbert filter at a

Ok.? But the coefficient from in v50 labeled 90 and 0 don't follow that pattern.? And all of the +/- 45 degree coefficients I've seen are the same but reversed.? That's a limited set though so I'm

It appears they are +/-45.? The 90 deg case only has one set of coefficients for I (an odd number) plus a simple delay line for Q.? And every other coefficient is zero.

I think it's on topic.? While the current v66-9 Hilbert coefficients are labeled +/-45 degrees, I speculate that they're actually +90 and 0 degrees.? The label doesn't really matter, but

Hi - I hope this is not off-topic.? The basic question is why +/-45 deg phase shift?? I was raised with 90 deg plus delay (as is in the OA_F32 library).? What is the advantage of +/-45?? Bob * *

I need smallest code to accommodate all of the features I've added.? And I can't use LTO because I need to prioritize heap.? LTO prioritizes stack.

I know of one oddity when you compile with "smallest code".? If you have a Serial.printf statement with a float, weird things will happen.? Integers are OK. There may be other oddities. -- 73 Greg

That's a possibility.? Stack is always tight but it's tighter when compiled with Faster with LTO than with Smallest Code and the latter is the one that crashes.? I assumed it crashed due to a memory

Maybe that pushed the stack over the edge?? Maybe there is some stuff you can temporarily remove from the stack to see if that is the case. -- 73 Greg KF5N

Exactly my thought.? So, I remove the DMAMEM keyword from the decimate state array in my version of the software and it crashed on PTT.

Or perhaps the Hilbert filter needs refined.? Here is an image from the setup mentioned in my previous post with the current v66-9 Hilbert filter: And here with the old Hilbert filter which is a tad

Eyeballing it, the noise hump is about 15 kHz wide.? So you should be able to open up the T41 filter all the way to 6kHz? and see more of the noise in the audio spectrum. I've never seen that