Hello Kickin,
Kickin>>The problem I am having is getting a suitable transmitter/receiver that will work up to a range of up to 40 miles (if base is static). The only thing I can think of is equiping each tracking unit with a mobile phone. When the base station phones, the mobile will automatically be 'picked up' and the current GPS data sent via audio.<<
Ok... Lets look at the facts...
There will be NO WAY ANY RF signal will go 40 miles way in the VHF region (lets say above 50 MHZ). A 144 MHZ signal running 40 watts of power will go about 15 to 20 miles on the average. If nothing is inbetween them, it can go further...But don't count on it. 15 to 20 miles is EXTREMELY EXTREMELY good. Radio communication is one of my specialties.
Rule #1... VHF is LINE of SIGHT... if you cannot visually see the other person...you will start running into trouble. Thus,if you are within about 4 to 5 miles of each other, you may be able to communicate spottedly.
Rule #2....HF is NOT line of sight...But you have another problem... The antenna being long enough, and what time of day you are using it.
Basically said the answer is no... You must use some other method than Radio signal...OR use a Repeater to transfer the data. And using the Repeater is NOT a guarantee of 100 percent 40 mile range...
Using Cell phones, may be the SUREST way to receive GPS data on location, because of the number of Service repeaters. And they already have them set up! <g>. How you transmit that data is up to you...But the faster the transmit, the less reliable on the receiving end. And when going through Cell phones, I would suggest keeping your Baud at 1200 and below... preferably 300 or below. And if you could... about 45 or so. The slower buad rates will be easier to test and work with...until you have established positive and reliable communication.
Dwayne
Kickin >>Do you think this will be the only feasible method of communication? Something without the cost of hundreds of 10 second calls would be nice :-)
Thanks for any info :-)<<
You have some huge problems...
1. Line of sight.
2. Power of transmitter.
3. obsticles as you encounter them. (will kill your signal).
4. Antenna length for proper and max signal output.
Sometimes those 10 second calls are really nice....especially if they are reliable and the system is already set up for you...
Dwayne
Ability to Fly:
Hurling yourself towards the ground, and missing.
Engineers that Contribute to flying:
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