Help with deciding how to build GPS tracker

999iscool

I came across these
http://www.parallax.com/ProductInfo/Accessories/GPSComparisonTable/tabid/831/Default.aspx

and VPN1513 GPS Receiver Module looks pretty promising with a 9 feet anteena. Does it mean it can be used for a longer range?

My project description:

I have several cars that I want to keep track of. I want to know how far they are away from a common starting point, and find the location on Google Map at every 30 seconds of update interval (it would be enough). It is about 2-3 miles range in diamete.

I don't have experience with hardware, but I code a lot, so please help me decide what I need. So far, wifi and mobile data plan seems to be out of question. (I am still reconsidering a mobile data plan...but okay). So let;s keep it using just Radio transmission.

What GPS shield should I purchase? What transmistter (I assume it's going to sit in my home, the starting point) do I need? Do I need any sort of licnese (I live in New York) to use some of those band? I know with radio there will be a lot of noise. How reliable are these combo? I really need it for within 2-3 miles.

Thanks.

Nick Ernst

Hello,
There are a few things that you should consider in the planning of your project. The first is that the VPN1513's antenna does not allow it to be operated at a longer range. The external antenna that it comes with is to help it acquire a signal from satellites. To get around a 2-3 mile radius range around you, you are going to need a transmit and receive unit that we do not carry. We currently have the XBee modules, but even the Pro series with a 60mW antenna only gets around a mile of range with line-of-sight outdoors. To be able to get a long range transmitter like the kind you will need if you do not go the cellular route, then you will most likely need a HAM operator's license. To be sure, I would recommend checking your local laws.

-Nick

Franklin

You might try this radio. http://www.solarbotics.com/product/51750/

Duane Degn

Franklin,

I'd be surprised if that radio would really transmit several miles except under ideal conditions.

I have a pair of XSC XBees which communicated fine about a block away but once I turned a corner and had a bunch of houses between the radios, the two radios could no longer communicate with each other.

The XSC XBees are supposed to have a 14 mile range (or something like that) but again, that range could only be reached under ideal conditions. Under normal city conditions, the range is less than 1/4 mile.

GordonMcComb

What you want to do costs money, and there's a reason for it.

Each vehicle will need a GPS receiver, some kind of processor, and a commercial data transmitter. The GPS and processor you can do with parts from Parallax. The kind of transmitter you need requires licensing, and they're expensive (several hundred dollars each). Look for a VHF or UHF radio; those that work at microwave frequencies cannot be used in a densely populated area like New York with lots of steel and stone structures. The nature of microwave requires very close proximity or line-of-sight in order to work.

You then need an RF data receiver at your location. It doesn't need a license, but it's also expensive. You will then need a processor to read the data coming over the radio and modify it for use on your PC with Google Maps.

Two GPSs, three processors, two RF data transmitters, one RF data receiver. Off the top of my head I think you're looking at $1,000+.

How would getting GPS location reports every 30 seconds be helpful in a city like New York? How far can you go in that amount of time during workday traffic -- a block? You can grow old very quickly watching that on a map!

A cheaper alternative might be to get an GSM SMS cell phone board for each GPS, and text the location to you. Each car will need its own SMS board, which means two cell phone accounts, plus yours (if each is $60, you're looking at $180 a month). Remember that texting isn't always real time. If the service is jammed, quite possible in NYC, text may not go through for minutes or even hours.

What might be easier/cheaper is a service. They've set up everything for you, and lease the equipment. You pay a monthly fee.

-- Gordon

Chris Savage

Years ago I designed a Fleet Management System that used a GSM Module (which also had GPS) to provide Latitude, Longintude, Altitude, Speed and some other data when requested by the Dispatch Center. I am working on a similar project using a newer Janus module, but again, a SIM Card and monthly data service is required for this system. I think I pay $15.00/month for the test system.