Accurate timestamped samples support on LimeSDR

Projects Lime Suite
1

We are developing a Time Difference of Arrival (TDoA) application, where we need very accurately timestamped samples (less than 10 ns error), synchronized to GPS. Is there a way to have the LimeSDR synchronized with GPS via an internal or external GPSDO?

If an internal GPSDO is possible, would we be able to get the GPS timestamps with some API call to the LimeSuiteNG library, and if so, how would that work? What would be a suitable hardware model for internal GPSDO?

If an external GPSDO is a possible solution as well, how would that work in practice, given that the GPSDO only gives a 10 MHz and a PPS signal (e.g. see Leo Bodnar LBE-1421 GPSDO)? Could we get GPS timestamps in this option seen that no information about the current time is transmitted between the GPSDO and the LimeSDR? Or is there a GPSDO option where more signals are transmitted (if so, which model)?

2

LimeSDR XTRX integrates a GNSS receiver and the new LiteX-based FPGA gateware has a component called LimePPSDO which can be used to provide GPSDO capability.

The LimePSB RPCM board may also be of interest and when used with LimeSDR XTRX provides a complete platform, with integrated OCXO and the possibility to use IEEE 1588 instead for PPS source.