[ooterness]

There's simpler options if all your equipment is in the same building, but yes, GPS-disciplined oscillators are a really great way to sync up clocks anywhere in the world to within a few nanoseconds. That said, it doesn't really help here because a) nanoseconds not picoseconds and b) the RTL-SDR doesn't have anywhere to plug it in.

[toomuchtodo]

Please forgive the silly question, but can the RTL-SDR receive the GPS signals software defined and process for timing?

[civilitty]

No, it's not enough to know when samples from different SDRs were taken, they must all be taken within a very small interval (tens of picoseconds in OP's example). What the SDRs really need is an electrical signal called a "trigger" that tells them to read their sensors at that exact moment which is what GP meant by plugging them in. You can use a second GPS enable device to generate that trigger but synchronizing those triggers using time of flight is very hard.

[touisteur]

Maybe you can bruteforce time correlation by shifting every source slightly, trying a yuge number of shift combinations and seeing which combination gives the 'best' (most correlated) output on a known signal? I've done that for many out-of-sync systems, and since I've started using GPUs in the two Os I've become obsessed with brute force methods :-)

[kawfey]

It is possible - https://www.rtl-sdr.com/rtl-sdr-tutorial-gps-decoding-plotti...