wspr-tools/README.md

# 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
<a href="http://robos.org/sections/radio/wspr/">my web page on
non-standard WSPR equipment</a> 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.