Hello everyone, I want to transmit the co-ordinates and elevation of the ATV (All Terrain Vehicle) to the cockpit. For this I will need a range of about 1.2 mile. What all are the ways to accomplish the data transmission. I want the data transmission to be as lag free as possibe. And also I was thinking to determine the speed of the vehicle using the GPS data. As the vehicle will be running on muddy tracks I thought of using the GPS data to determine the speed. Or I can make the standard speedometer using the reed switch, but will that be feasible, I am concerned about it getting damaged given the conditions.
Most GPS recievers will give you a speed output, so that part is trivial.
The most common solution here for transmitting data that far would be the XBee series of radios. For this distance you should definitely go with a higher power pro model and the 900Mhz frequency. Check out Sparkfun's XBee guide here.
https://www.sparkfun.com/pages/xbee_guide
If you have a GPS that will output a serial signal that the xbee can send that may be all you need. If your GPS uses another standard then an Arduino would be needed to translate.
Help me understand exactly what you want to do... you want to transmit GPS location/altitude data from the ATV to a remote location which could be a mile away?
Bear in mind that GPS is very inaccurate when it comes to altitude, especially while moving. Can be off by hundreds of feet. I think it would be easier, cheaper and way more accurate to use a barometric pressure sensor for altitude. A google search found lots on the subject of Arduino and barometric altimeters.
As far as speed for the ATV itself, just put all your stuff in a nice sealed enclosure and add a couple 7-segment LED displays for your two-digit speed output from the GPS.
Or use a hall-sensor for speed. If I was doing this method (and I might for my dirtbike), I would go to http://www.trailtech.net/enduranceIIkits-atv.html and find my ATV model, click on the "speed sensor" link and buy that cable and the magnet kit. It will come with instructions on how to mount the cable and the magnet to your specific ATV model. On the other end of the cable is just a connector that you can connect to your Arduino to monitor the pulses generated with each rotation of the wheel. You will need to know your wheel circumference to do the right calculations and it's easy to test your accuracy by comparing your speed/odometer with a gps you carry along with you.