I have been working with Mike Johnshoy, KB2ML, on the sBitx 64 bit development. For straight keying I use a test setup of the DUT transmitting at low power into a dummy load with another receiver (K3) monitoring the signal with a short test antenna (a jumper lead clipped onto a PL259 center) located on the dummy load.. The audio is recorded in Audacity and the waveform analyzed by a Python program that detects peaks, times signal and spaces and does some statistics on the results. I drive the DUT with an external keyer to produce a string of perfectly spaced dits. Here is what the 64 bit code waveform looks like in Audacity for dits at 40 wpm.

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and here are the stats for this sample:

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73
??? Bob? KD8CGH

BTW in tests the zBitx delay was the default 50.

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73
??? Bob? KD8CGH

Bob, with the sBitx we seem to have much better results.? ?Have you tested the sBitx with the same setup?

Thanks for your work!

Gordon KX4Z

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zBitx test rerun at 15 wpm with delay 600.

stats

Number of dits 12
Number of spaces 12
Average Pulse Duration: 0.084414 seconds
Standard Deviation of Pulse Durations: 0.011073 seconds
Average Space Duration: 0.074662 seconds
Standard Deviation of Space Durations: 0.004133 seconds
Cycle length: 0.159076 seconds
dot/sp: 1.130622

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73
??? Bob? KD8CGH

zBitx test rerun at 40 wpm with delay 600. I start recording before sending see the an issue with the first dit in both zBitx 600 delay tests.

stats

Number of dits 23
Number of spaces 23
Average Pulse Duration: 0.045027 seconds
Standard Deviation of Pulse Durations: 0.005587 seconds
Average Space Duration: 0.039543 seconds
Standard Deviation of Space Durations: 0.003505 seconds
Cycle length: 0.084570 seconds
dot/sp: 1.138701

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73
??? Bob? KD8CGH

Thanks Gordon

I used the same setup for both the sBitx and the zBitx. Same dummy load, receive antenna, K3, Audacity and Python program. The first excellent results posted in the first post were from the sBitx with 64 bit software.

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73
??? Bob? KD8CGH

zBitx 40 wpm, 150 delay. again looks reasonable except for first dit.

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73
??? Bob? KD8CGH

Lee

See the first post for waveform at about 15 wpm with delay 50 and post 117502 for the same speed with delay 600.

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73
??? Bob? KD8CGH

We could make that work in a pinch, but I bet we can get this better!!! ? it’s not yet really clear yet why this isn’t as good as the sBitx , which has the same number of processors ??????

Has anybody tried Ron’s system for putting a processor dedicated to the transmission?

Gordon kx4z?

Gordon

?? The sBitx performance above was seen with the 64 bit code. A lot of work went into making it work well. Someone will have to repeat that effort or just use the developed code.

? Also, the Pi 4B has four Cortex-A72 cores running at 1.8 GHz with 2-8 GB of SDRAM. The Pi Zero 2 has four Cortex-A53 cores running at 1 Ghz with .5 GB of SDRAM.

? All that said - the zBitx already has a very capable second processor in the Pi Pico that I think is just loafing along now. Several people have implements entire SDRs with the Pico. However, using a second processor to manage real time tasks would be a major revision of the circuitry.

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73
??? Bob? KD8CGH