Hi Alan,
On 9/19/2022 1:01 PM, Alan Altman AG7XS via wsjt-devel wrote:
Greetings,
Thank you for all the great work on creating and improving WSJT-X.
You are probably aware of the ADX transceiver designed by WB2CBA. It is a
simple open source digital HF rig designed for home brewing. We are working on
replacing the Arduino with a RPi PICO. Due to differences in internal
peripherals and timers, it is more complicated to measure the TX frequency in
order to send it to the Si5351 DDS we use.
In rethinking the problem, it occurred to me that WSJT-X must first generate a
digital list or table of tones for each transmission before they are sent to
the sound card and on to the rig as an analog signal.
FT8 signals are not generated from a list of tones. Abrupt frequency
changes from one tone to the next would generate unwanted sidebands with
amplitudes far above those of a properly generated FT8 signal. For
relevant details see Figure 3 and the associated text in our QEX paper
describing the FT4 and FT8 protocols:
https://physics.princeton.edu//pulsar/k1jt/FT4_FT8_QEX.pdf
-- 73, Joe, K1JT
What would greatly simplify the transition to PICO is if the TX audio
frequencies could be sent out over USB in a directly useable format that could
be directly added to the base frequency and on to the DDS. The best solution
for ADX would be the final 0 to 3000 Hz tone frequency value be sent upon start
of TX and each subsequent change in value or at a preset interval until the end
of TX (stop value appended to release TX mode) or some other system if it is
easier to implement on the WSJT-X side. Timing would be controlled by the
WSJT-X. We have been using VOX or CAT control for PTT, but could update that to
CAT only.
In addition if USB CAT polling interval requests could be blocked during TX
periods, that would be even great as it prevent dropouts and data conflicts if
using a USB hub with audio dongle.
73,
Alan
AG7XS
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