What is it?
Its a receiver for a fixed frequency on a shortwave bands (versions from 136kHz to 18MHz available).
The fixed frequency correspons to the receive WSPR frequency on a particular band.
Why did you make it?
To be able to receive and upload WSPR spots 24 hours a day without tying up my HAM transceiver.
WSPR is a great tool to be able to check out the HF propagation at your specific location and this is a really easy and low cost way of starting to receive WSPR.
This is aimed to be a Plug-and-play product that you need to do zero work with.
However, if you do want to tweak it or change the frequency for use in another application etc, the schematic and software is open source.
What makes it special?
Instead of tying up your transceiver, you will use this extremely low power device that can be powered directly from the USB port of your computer.
It is always tuned to the WSPR frequency for the given band. You plug in an antenna at one end, connect the Audio out port to your computer sound card, then power it and you are good to go.
The narrow band-pass filter at the front of the receiver gives it good rejection of strong signals. You will be able to pick up weak WSPR signals even if the band is full of strong signals for example when there is a contest going on on the band.
This can be challanging for some receivers.
For a really low "always-on" setup you might want to use a Raspberry Pi as the computer. The receiver only consumes 0.35W!
My plan is to be able to receive all HAM bands from 2190m to 2m with this type of receiver and I will release new frequency versions from time to time. If you want a specific frequency let me know in a message. Different Bands need different band-pass filters internally.
These are the fixed WSPR Receive frequencys that are used for the different band versions:
Documentation page here.