FT8 on Dhiru's Notebook

Inbuilt band-hopping in WSJT-X 3.x

Sat, 18 Oct 2025 00:00:00 +0000

WSJT-X 3.x has inbuilt support for band hopping!

RX results from an experimental version of DDX:

This is super useful for monitoring FT8 traffic on multiple bands.

Fri, 17 Oct 2025 00:00:00 +0000

This code generates a .wav file which emulates a fully-populated FT8 band!

This .wav file can then be played with rpitx on actual air (well on a dummy load) for receiver testing purposes.

rm mixed.wav; sox -m *.wav mixed.wav

sox mixed.wav -r 48000 sampleaudio.wav

Now play sampleaudio.wav using rpitx.

I have tested rpitx on Raspberry Pi Zero 2W TX'ing @ 14.074 MHz.

Mon, 29 Sep 2025 00:00:00 +0000

On an AMD64 machine:

1 second using the fast decode settings.

We were able to get the MSHV's FT8 engine to work on Android, thanks to the work done by https://github.com/sannysanoff/SDRPlusPlusBrown folks.

Around ~4.5 seconds to decode the same file.

This is why we can't really have full-blown realtime FT8 decoder(s) on Android just yet!

Idea: But we can surely use this full-blown FT8 decoder in our FT8 Decoder app which has no realtime requirements!

Tue, 15 Apr 2025 00:00:00 +0000

I am posting an early design sketch of a 2m WSPR beacon.

25 MHz HCI 0.5ppm TCXO powering the Si5351 module instead of the 26 MHz TCXO. If this fails, we can use a 10 MHz OCXO instead (a bit out of spec but works fine).
Tokmas CID10N65F GaN FET might work @ 144 MHz as the 'final'. If not, use Mitsubishi RD15HVF1-501 MOSFET as backup.
2SK3475 as the driver with variable DC bias at the gate
The whole VCC to this amplifier will be PTT switched
Ideally, we would want to keep the driver stage linear but the final stage as switched (Class C/D) Alternate: Perhaps by DC coupling the Si5351 input to 2SK3475, we can avoid the need for DC gate bias
The "RFC" (bifilar coil still needed?) part will need to be figured out for VHF!

Results: To be built and tested soon!

Thu, 13 Feb 2025 00:00:00 +0000

The Easy FT8 Encoder can be accessed here.

In the near future, we want to add the K1JT's original FT8 encoder functionality as well.

Update: FT8Play is crazy good!