Getting Started with GPS

[greywanderer012345]

   I've been looking around on DigiKey and other sites to see how expensive adding GPS capabilities to a robot down the line would be. I found plenty of modules for ~$35USD, which is about what I expected since many devices ~$100 have them built in.

   I want to know what else is required to get started with adding GPS to my projects. Do I need to buy some kind of service, or is that basically included with the purchase of the module? Any device I've bought with GPS does not require any type of monthly payment for the service or anything, so I'm curious about this.
 
  Also, other than modules, kits are often sold for $100-$300 or so. Are these kits required, or just tools to simplify development? What protocols or other software-side concepts should I be familiar with before starting to experiment with GPS?

   I am a seasoned amateur C/C++ and Java programmer, and I have built and experimented with a few of the robot tutorials on this site, all using AVR MCUs, building my own boards. I am not familiar with any communication protocols, and I have not experimented with UART or USB.

  I'm planning to be able to invest the time and money for bigger projects like this about a year from now, and I would like to have the tools and experience to take advantage of that. Thank you for any help.

[Soeren]

Hi,

Adding a little white space here and there makes a post so much more readable (and raises the number of people who actually read a post to the end )

I want to know what else is required to get started with adding GPS to my projects. Do I need to buy some kind of service, or is that basically included with the purchase of the module?

When you have bought a (standard GPS) module, there's nothing extra to pay. Nobody will even know that you receive the signals.
There might be a license fee for some of the combined products that uses other means to up the precision of the GPS, but not for a regular GPS.

Also, other than modules, kits are often sold for $100-$300 or so. Are these kits required, or just tools to simplify development?

It's just like when you buy a kit or a "break out board", stuff that makes it easier or quicker - the module is all you need (and the datasheet of course).

What protocols or other software-side concepts should I be familiar with before starting to experiment with GPS?

Not before, but you'll have to learn the NMEA protocol as you go, as this is the basic protocol all GPS'es use, but that's not different from learning to communicate with eg. an external RTC (although there's more commands and such. I don't think anyone have the entire NMEA in the head
Read all about it in the following first two links and download the PDF in the third.

http://en.wikipedia.org/wiki/NMEA_0183#Application_layer_protocol_rules
http://www.gpsinformation.org/dale/nmea.htm
http://www.sparkfun.com/datasheets/GPS/NMEA%2520Reference%2520Manual-Rev2.1-Dec07.pdf

I am not familiar with any communication protocols, and I have not experimented with UART or USB. I'm planning to be able to invest the time and money for bigger projects like this about a year from now, and I would like to have the tools and experience to take advantage of that.

All you need is the module itself, its datasheet and the above 3 links, time to spend and a regular supply of your favorite beverage


For robot navigation in limited spaces, I wouldn't trust a regular GPS - they can be off more than 50m and even modules using a range of methods to increase the precision to 1m may still be too "loose" for being the only (or primary) nav instrument on-board.

[greywanderer012345]

Thanks.

Yea, I definitely am not planning on relying on GPS for accuracy. I was thinking of altering an R/C airplane to return if it flies out of range. Then, furthering that to essentially a simple UAV.

[greywanderer012345]

When you have bought a (standard GPS) module, there's nothing extra to pay. Nobody will even know that you receive the signals.

Ah, the wording you used made me reinvent my assumptions about how GPS works. I assumed there was some type of communication sent from the module. It makes sense that it only receives information. Now my curiosity is peeked. I will have to start integrating this.

[Webbot]

If it helps - WebbotLib supports NMEA output from GPS modules