The TruePosition GPSDO board used in telecom equipment is a cheap solution to have a GPS controlled frequency reference. It is usually available on eBay for cheap. EEVblog has a buch of forum topics around it, so it is quite well understood.
It is a standalone GPSDO in the sense that it implements all GPSDO functions, it needs a GPS antenna and has outputs for 10MHz and 1PPS.
However, it is not standalone in the sense that it needs a little bit (or a lot, if you are so inclined) control. At the very minimum it needs a startup command sent via its serial interface to boot. Once booted, it will work all right, but there are a lot of other function that can be controlled, like position survey, satellite data, time, etc.
So since everyone seems to be doing it, I also decided to build my own GPSDO based on the TruePosition boards. I used a cheap STM32 BluePill board for controlling, a 128x64 bitmap LCD and buttons for user interface and yes, it even has a case and built-in power supply!
This was actually a learning project for me with STM32 in the Arduino environment. So the quality of the code reflects this at some places :-)
The hardware was design with KiCAD.
Once I tidy up the design documentation a bit I will release the blueprints and the software. Until then watch this place and look at the teaser pictures below.
