Reddit mentions of GlobalSat BR-355 BR-355 Serial GPS Receiver

The SiRF III chipset was (is?) pretty popular. I've used this particular one for projects. It's just the chipset with an antenna and a long cable. Speaks 2.8v serial @ 4800 baud. I think that manufacturer has serial (over usb) versions.

Most GPS devices will be serial (actual serial, serial over usb or serial over bluetooth) and use the NMEA protocol which should work with damn near anything. If you want it to work over TCP/IP, grab gpsd. Many linux applications that use GPS are designed to use gpsd.

They don't really exist in that format, or if they do, they're extremely expensive and specialized. GPS is unidirectional, meaning a GPS device knows its own position, but can't transmit that position back to anything else without another component, typically a cell radio or something like that. While [a GPS receiver around the size of a quarter is feasible] (https://www.amazon.com/GlobalSat-BR-355-Serial-GPS-Receiver/dp/B000VUFGF8) , the data that such a receiver gathers is useless without some way of storing it (for later analysis) or sending it back to you (for real time analysis). Likewise, the power consumption of most GPS devices is far greater than what a quarter-sized battery could provide for a week. The transmitter part takes up quite a bit more space and a ton more battery life, which just compounds the issue.

Most GPS units are geared towards outdoor enthusiasts, and therefore aim to get as accurate track coverage as possible (thereby reducing battery life). If all you needed was a point location every couple hours or something, the battery life becomes less of an issue, but you'd still need the transmission component and to know how to connect them together to do what you want.

So, in short, relax your requirements for size, battery life, and portability and you may be able to piece something together (with a considerable degree of know-how, considering these things aren't just a single component).