Appreciation

First of all, many thanks to Roman for this brilliant WSPR project! The world has never seen a WSPR beacon on such an inexpensive and small hardware ;-).

Simply ingenious is the controller-controlled oscillator, which can be modulated to milliherzts - the heart of the beacon and the project!

As Roman writes in his project description: "It doesn't require any hardware - Pico board itself only."

With this fork, the first transmission of the beacon can be triggered by a button. And then, after the first transmission ends, it is repeated every 4 minutes controlled by the internal RTC of the Pi Pico. The interval for the following transmission can be configured.

Dhiru: This fork adds FT8 support.

Hardware Setup

NEW (Updated): Add a button between Pin 21 (GP16) and Pin 23 (GND) on the Pico board.

The antenna connects to Pin 9 (GP6) on the Pico board.

Bringing Pico 2 beacon on air

Step 1: Configure the FT8 message (char *message = "CQ K1TE FN42";) to send in the WSPRbeacon/WSPRbeacon.c file.

Step 2: Compile the project and copy the pico-wspr-tx.uf2 file to the Pico board.

mkdir -p ~/repos

cd ~/repos

git clone --recursive https://github.com/raspberrypi/pico-sdk.git

export PICO_SDK_PATH=$HOME/repos/pico-sdk

cmake .; make -j4

./picoload.sh pico-wspr-tx.uf2  # optional

Step 3: Power the Pico board

Step 4: Wait for the start time of the next FT8 transfer window. Press the button to start the next broadcast.

Step 5: Use the WSJT-X software to check if the transfer is within the valid transfer window. If necessary, repeat the start procedure.

TODO

https://www.raspberrypi.com/documentation/pico-sdk/high_level.html#group_pico_aon_timer

Use this instead of RTC (hardware_rtc) which is unavailable on RP2350.

Amplifier?

https://github.com/kholia/HF-PA-v10/tree/master/IRFP-Hacks-v5-SMD is a pretty rugged amplifier design for getting 1W to 30W RF output on all HF bands!

In a pinch, you can also try the 2W Amplifier 1-930MHz module that is available on Amazon, and other places.

Demo

Free power (Solar System)

• Connect a 6v solar panel to the CN3791 module.

• Connect a 18650 cell to the 1S BMS (using B+ and B- pads).

• Connect the 1S BMS to the CN3791 module (using P+ and P- pads).

• Connect the load (the beacon system) to the CN3791 module.

References

• https://www.wavecom.ch/content/ext/DecoderOnlineHelp/default.htm#!worddocuments/ft8.htm

• https://github.com/kgoba/ft8_lib

• https://github.com/Jochen-bit/pico-WSPR-tx (We have used this fork)

• 100 LED solar garden light teardown (with schematic)