- The Uputronics GPS/RTC Raspberry Pi Expansion Board is a timing receiver featuring an u-blox M8 GNSS chip, priced at £41.99.
- It provides access to raw GNSS messages and correlator data, enabling sub-nanosecond precision for orbit determination and Doppler measurements.
- The board does not include an antenna but works with both high-end and cheap antennas, though better reception comes with a nicer one.
- Assembly on a Raspberry Pi 4 is straightforward with included hardware, but configuring the Pi requires disabling the login shell on the serial port while enabling the hardware serial port.
- The device communicates via UART1 at a default baudrate of 9600, but higher baudrates are recommended to handle data from multiple satellite constellations.
- It supports simultaneous tracking of GPS and Galileo (same frequency), plus one of BeiDou or GLONASS, but not all four at once.
- The expansion board is used as station 1 in the galmon.eu project and can also serve as a precise PPS time source with additional setup.