It is reasonably well known that the Locosys GT-11 used the SiRFstar II and Locosys GT-31 used the SiRFstar III.
What hasn't been so clear is what GPS chip was used in the GW-52 and GW-60; perhaps the SiRFstar IV or something like the MediaTek MT3318? The MediaTek theory originates from PMTK messages being spotted in the GW-52 and GW-60 firmwares.
I decided to do some digging and was somewhat surprised to discover the MediaTek references are actually strong evidence that a MediaTek GPS chip is NOT being used by the GW-52 or GW-60. Yeah, I know... sounds crazy, right?
I've written it all up for anyone interested - logiqx.github.io/gps-guides/detective.html
I took this photo after writing the article.
TLDR - The GW-52 and GW-60 are probably using the SiRFstar IV and in all likelihood SDOS is derived from the SiRFDrive / SiRFNavIII features. The same is probably true for SDOP on the GT-31 when you look at the product timelines.
