Scratch-built GPS


[stok] built this GPS receiver from the ground up. The GPS module he got off of eBay dumps NMEA 0183 data. He combined that with an old Nokia LCD and a PIC microcontroller. I like this project because it shows that you can build devices that the general public assumes are really complex.

20 thoughts on “Scratch-built GPS

  1. Actually, the really complicated stuff like acquisition, tracking, bit sync, and the navigation solution are all in the GPS module purchased from eBay. The stuff he added just acts as an interface between the GPS module and the user. I wouldn’t say that he “built” a GPS device any more than I’d say adding peripherals constitutes building a PC.

  2. Yeah, chad is right. This is still a cool hack, replicating the function of very expensive devices on the hella-cheap, but what he built isn’t a GPS “receiver”. I’ve worked with GPS technology in a project before and done some research on it, and I dare say the hardware and programming sophistication required for building a full-featured receiver from scratch is probably out of the reach of most hobbyists. And even if you could do it, it’d be easier and cheaper to just buy a commercial OEM module like in the link. (The Lassen iQ, for example, is like $45 for a module plus $12 for an antenna.)

  3. Someone else has a gps decoder built using one single chip, a pic:

    Now, he just hasn’t shared the code for it. I bet someone else can make it from scratch like this. Hell, other then the resisters and crystal, you can get the pic and lcd (a nokia screen I mean) for free.

    Now, get at it. I would like going geocaching today!…

  4. “Receiver” has a very specific technical meaning. It refers to the receiving (hence the name) of signals of some kind and is usually (but not always) paired with demodulation of some kind. This, in addition with the mathematical post-processing to turn the demodulated signals into position fixes (the real hard part), is the “dirty work” you hand-wavingly dismissed.

    This isn’t a peer-reviewed journal or anything, but some basic application of technical terminology would be nice. So what if the marketoids want to refer to something in a nice package a “receiver”? Guess what, those incorporate receiver functions. The guy in the link did not scratch-build a receiver, he’s displaying the output from one.

    Even if you want to argue about the “receiver” terminology, the “scratch-built” part of the headline is dead wrong, since he bought the little black box to do all the “dirty work”, as you put it.

  5. Need a question answered please. I am looking for a miniture gps system that can fit into a 1 1/2″ wide x 3″ long MP3 player. does anyone have a miniture gps system or the plans to help me build on that will fit inside those dimensions???? {Please help} Thanks Norman

  6. I don’t think you can turn off the GPS enabled on your phone if you cant do it through any of the system menus. You would either need specialized software blah blah. In any case, if someone REALLY wanted to find you, they can triangulate your location depending on what signal strength received from the different cell towers.

  7. Hi,
    How are you?
    I connected Gps (GM-R500) to AVR MCU and set the Buad rate in AVR to 4800.
    I programmed AVR to show the “NMEA” sentences in LCD but the data that
    i saw in LCD wasn’t correct.I don’t know why?
    Should i use invertor between AVR and GPS?
    How should i set the clock frequency in AVR MCU?
    Please guide me in this project.

  8. i ma really impressed to see this sort of appliation being developed.what i want is how to interface a gps receiver to pic microcontroller so that the NMEA messages can be decoded and displayed on to the lcd .i want these longitudes and latitudes to be stored to the external memory connected to the pic which can be later on seen via uploading it to the pc.please help me with the codes in C.and how to proceed.thanking you
    my mail id is

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