wspr-tools

Code for the WSPR protocol

encode.py

python3 encode.py callsign locator power

Currently only simple callsigns and 4-symbol locators are accepted. Power is in dBm. This can be used directly for producing transmission sequences for the Arduino/AD9851 based transmitter below, or as a library to encode the WSPR protocol.

manual.py

python3 manual.py callsign locator power

Used to display the straight-key transmission sequence for a narrow-band frequency shift transmitter. Please refer to my web page on non-standard WSPR equipment for more information.

arduino_ad9851.ino

Arduino program to actually transmit the data generated by encode.py using an AD9851 module.

Note: if you use the square wave output (QOUT1 or its inverse QOUT2), make sure to tune the comparator voltage to achieve a reasonable duty cycle. If followed by a class E amplifier this is about 45% for maximum power output (anywhere near 50% should be OK). I use a DC voltmeter and approximate the duty cycle with V/5, so that a measured 2V reading translates into a 40% duty cycle.

You could of course also take either of the sine wave outputs (ZOUT1, ZOUT2) and amplify or feed directly into a low-pass filter to the antenna.

make_table.py and make_sound.py

Code to support completely analog operation. Run make_table.py and write down the printed table on a piece of paper, making sure to include the horizontal lines after every 9th symbol. I simply fill the indicated squares with a pencil, and the whole message takes three columns on a piece of A4 graph paper.

Then run make_sound.py, which creates the file ticks.wav. This file can be played (by an analog tape player, perhaps?) starting at an even minute. You should have no problem following the beat when keying the message, but if you lose track at some point, the higher tone at the symbol before each 9-symbol block boundary can be used for synchronization.