[michaelt]

> I'll admit I was a bit disappointed to see that the hardware was just RTL-SDR.

Somewhat surprisingly, if you went back 15-20 years, a lot of what the author is doing in software here would have been done in hardware.

GPS receivers used to market themselves by the number of tracking channels they had, as cheaper receivers might only have the hardware needed to track 6-8 satellites while a more expensive receiver might track 12.

So this software-defined receiver actually implements quite a bit of what would otherwise be hardware. And of course it can track every satellite in view.

The software-defined approach has some powerful benefits - for example, initial satellite acquisition involves calculating cross-correlation between the received signal and various gold codes. Being able to do this in the fourier domain lets you acquire signals pretty fast!

If you want a hardcore DIY GPS receiver, going right down to the transistor level, you'd probably enjoy reading https://lea.hamradio.si/~s53mv/navsats/theory.html - an 1990s era DIY GPS receiver, complete with hand-drawn schematics, hand-drawn PCBs, even a hand-made antenna.

[makomk]

I think even these days, a lot of what the author is doing here is still generally done in hardware for power efficiency reasons - it's just that nowadays, the hardware looks a lot like the software-defined architecture used here with a conversion to digital at the frontend followed by hardware accelerators for doing cross-correlation in the fourier domain. Actually, this kind of approach of implementing the architecture an SDR-based receiver would use as specialised hardware seems to be pretty common in general nowadays.