we were hoping to try position-domain DGPS, so that we can keep using lower-cost NMEA modules, as described in the following paper:
“DGPS Enhancement to GPS NMEA Output Data: DGPS by Correction Projection to Position-Domain” <https://doi.org/10.1017/S0373463312000471>
RTCM would be better, since it gives access to individual satellite raw data, enabling observation-domain DGPS. But as you note it’s more expensive and our sensors are meant to be disposable (it’s hard to recover them in the ice).
We’re asking different vendors if we can have one more decimal place in coordinates – just a matter of not truncating or rounding up the output, I guess. I understand it is just garbage for a stand-alone GPS, but we’re hoping to squeeze some precision via DGPS as noted above.