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T41 with Polar Modulation
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After learning that Hans Summers was at Dayton Hamvention promoting his QMX which can now operate SSB using Polar Modulation, this got me thinking.
Has anyone considered a T41 using Polar Modulation?
How difficult would the software be to implement? I am sure I can sort the hardware side of things.
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John, G0SDF |
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I skimmed Hans' paper on the topic (what a great read!): It looks doable on the software side -- the T41 has plenty of processing power and the methods look tractable. I worry about two things on the hardware side: The design needed to support the self-calibration routines needs some thinking about too. -------- Original Message -------- On 5/25/25 10:04 AM, John G0SDF via groups.io wrote:
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FWIW Flex's new transceiver (the ) also uses polar modulation (aka EER Envelope Elimination and Restoration) Apparently they hired one of the people behind the out of retirement. They claim 500W with 80% efficiency.
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Of course, the EER radios most of us have heard of are the uSDX and truSDX. Although I am amazed at these little radio, since they are using the same Atmel Atmega328 as the classic Arduino Uno, I've personally avoided them since they have a reputation of splattering. Seems like they can be made to work well but are "fragile". Lots of things can go wrong so they don't work well. I have a lot of respect for programmers who can squeeze the last bit out of a processor but in this case I think it was a great proof of concept that shouldn't have been made generally available.
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Like Oliver I wonde
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On Sun, May 25, 2025 at 11:27 AM, Oliver KI3P wrote:
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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 mode than other MOSFET amps. As proof of this, look at the attached Two-Tone test with that amp. We are getting 36 dBC of separation of the 3rd order IM products compared to the carrier. That is generally considered "Very Good". This is about what Hans reported for his amp with the Polar Modulation. Better than -40dBC is usually considered "Excellent".
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To accomplish the amplitude portion of the Polar modulation would require some hardware changes, if I understand the process correctly. The power supply voltage is varied to accomplish the amplitude modulation in Han's scheme.
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However, the predistortion process would probably be beneficial and does not require more hardware - just some careful measurements.
Regards,
Al
AC8GY
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On 2025-05-25 19:50, Dave VE3LHO wrote:
FWIW Flex's new transceiver (the Aurora [1]) also uses polar*** Since Flex's stuff is totally closed source, it really doesn't matter to me what they do. I just read Hans' article. Amazing! I was thinking - how to use this technique with higher power? The part where you wiggle the frequency of the si5351 is power-independent. That wouldn't change. But what about the AM modulation part? Well, there used to be high power AM rigs... Apparently, the final can run class C. Highly efficient. But you need a *lot* of audio. Where can I find a high power audio amp with good linearity? Yup, the world of hi-fi. Intriguing... - Jerry, KF6VB |
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On Mon, May 26, 2025 at 11:23 AM, jerry-KF6VB wrote:
On 2025-05-25 19:50, Dave VE3LHO wrote:Understood. I'm not planning to shell out >$5K for one when it becomes available either. Thus the "for what its worth". My point was that EER has now broken though to commercial ham equipment. And that they have a proof-of-concept of sorts for EER for much higher power than QMX or (tr)uSDR.
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The interesting issue to me (as I tried to say in my previous post but it got cut off) is the synchronization between phase and amplitude changes. A solvable problem but the calibration routine will be "interesting" |
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On 2025-05-26 12:10, Dave VE3LHO wrote:
The interesting issue to me (as I tried to say in my previous post but*** Indeed. QMX auto-calibrates. It takes a *long* time, but it's totally unattended. Unfortunately, Hans' code is also closed-source. And encrypted! The only open source EER I know of is the (tr)uSDX. Hans' description of what he did is pretty detailed, though. - Jerry, KF6VB Links: |
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