SparkFun Forums 

Where electronics enthusiasts find answers.

Tips and questions relating to the GPS modules from SFE
By jag28
Im working on a a battery powered GPS project that i need to run as long as possible. Say an hour or less per day total, aiming at several months duration. Also i need it to work for about every application as a general use GPS system for whatever i think of doing with it, but its primary use that it must do well is track a car from under it or in a nonmetalic bumper. It would be nice to have a nice GPS unit to just have rather something lacking , though im also not sure i need to spend a ton on one since it seems they are releaseing new and better ones all the time that i could just buy a new one in a year or 2 and replace the old.

Which GPS do I choose. I know its a complicated thing based one wha ti need it to do exactly. But i thought maybe some of u guys have experience with them and could give some insite. The ones that have my eye right now are the ETek EB-85A, and u-blox Antaris 4 and 5.

Noticeing some pretty large price differences btwn some of these modules. And maybe with chips? Is it cheaper to build the module or to just take the module option and run with it.

Another issue im having is trying to figure out based on the data sheets what the real power consumtions are. See some in mW which seem way lower than they end up being on the module data sheets. Maybe its for just a single chip when they cite the mW? Also the biggest thing is, are they calculating in the antenna current usage as well? Seems like the antenna is typicaly around 10-15mA? and thats a big chunk to ignore. Ive noticed most of the antennas ive seen seem to be relativly the same in performance, though i havnt really bothered to look into them too much yet. Any sudgestions there would be great as well.

Ive no real hands on experience with any of these GPS's so i have nothen to compair with. The Lassen IQ seems cheap and good power consumption only 12 channels. I understand the purpose of the channels but what i dont know is how big a difference they really make in a real world situation in comparison to others. Plus i assume each of these perform differnt based on brand/firmware used.

Ive looked for some sort of comparison chart or graph or list of these differnt modules and or chipsets but have found nothing.

Thanks for the help
By jag28
So ive been looking around at GPS/antennas some more. Active and passive antennas. I see active ones use power, and are typically for external antennas. But i guess what id be useing is a passive one, and i need to know if the current consumption (if there is any) of one of these is already calculated into the datasheet info on the differnt GPS modules. Exactly how all that works/calculated would be a big help. Thanks