[Elecraft] Transmit Equalizers and FT4/8

[Andy Durbin]

" the tones used CAN be much lower than 1500 Hz. I have worked station that were down to 200 Hz. And the the tones can go as high as the sending stations transmitter will allow, typically less than 2.7-2.8 KHz.

The transmitted signal frequency is the suppressed carrier frequency plus the modulation frequency.  The presence of a signal at 200 Hz, or 4,000 Hz, in your receive waterfall  is not in conflict with the transmitter modulation frequency being in the range 1,500 to 2,000 Hz.

If you have an open mind you may learn something from this paper -

https://www.dropbox.com/s/85aoc937kz235iq/FT8%20audio%20harmonics%20draft%20d%20k3wyc.pdf?dl=0

Pay particular attention to the Part 2 - Discussion of WSJT-X split mode.

73,
Andy, k3wyc