[mschuster91]

The original v4 RTL-SDR has a 1PPM TCXO. The problem is, the tons of shady clones don't.

As for the GPSDO, that should be easy to solve at least if the host platform is a Raspberry Pi - the SparkFun NEO-M9N board can be connected to the PPS input of the Pi. The problem is, that thing is expensive.

[1] https://www.berrybase.de/sparkfun-qwiic-gps-breakout-neo-m9n...

[BenjiWiebe]

I'm not an interferometry expert, so I don't know what level of precision is required, but usually a GPSDO takes a lot more than a PPS output.

A PPS output makes for very accurate timekeeping over long time scales. A GPSDO is a very stable oscillator that gives you precise frequency.

Disciplining your oscillator with a PPS signal would be much harder than with the typically used 10 MHz signal. And I don't think an RPi would do very good at putting out a highly stable MHz signal disciplined to a PPS input.