For a specific project like this, I always learn best by seeing the application and then learning why things are the way they are, so I would start with some schematics (or at least block diagrams) for GPS receivers and some information on the GPS signal standard itself.
GPS signal is very low level, so you'll be getting amplifiers and filters and it's high frequency so you'll need to downcovert at least once before you can sample it... but it's also very well understood and documented. Look around for some DIY GPS frontend projects, take a look at some well fleshed out datasheets with block diagrams for their GPS systems, and then maybe pick up and take apart a cheap active antenna.
Videos could also be a good option to get an idea of how mixers and these sort of RF-specific components work, and there's a number of people on the forums with tutorials of various sorts. Just on the last page of this forum I came across w2aew's videos and they cover a lot of the basics of how primary building blocks work and demonstrating them on the bench, but from the opposite approach and another excellent resource would be Shahriar's videos on TheSignalPath - in taking apart, fixing, or examining RF gear, he goes through how they operate and demonstrates them in experiments - a more top-down approach to learning about things, but it's full of great insight.
There are many resources available and many approaches depending on how you like to learn. I'd say that for this application, if you have access to a spectrum analyzer, it would be really helpful in evaluating the circuit as you design it, though it's probably not useful in the early planning steps.