Instructables

Crude Tracking Device from a GPS And Two-Way Radios

So, I wanted to get a tracking device. As soon as I looked into the market, I realized the prices for one of those things begins at an arm, and goes up to a leg or more! The madness must be stopped! Surely the principles of knowing where something is could be used without paying out the nose for it. After some hair pulling, this idea was born. This took a lot of trial and error before I was able to hammer out what it has become for me today, and for all that, it is just workable enough for my purposes. Therefore, if you can think of a way this concept could be made better, please share! I've built on the shoulders of giants, and I expect you to do the same. This idea belongs to the people! Information is free! Insert an inspiring slogan here!
The nature of this tracking device is extremely limited and technical, but if you can hack it, this really works -- and that in itself is really exciting. The limitations are at times frustrating:

  • The 2-way radios necessitate a linear or nearly linear sight on your tracking device (which in many cases may spoil the whole point anyway).
  • You must be closer to the transmitter than the nominal range of your radios.
  • The tracker can get bulky (think about it -- you're basically lashing together two electronic devices that were originally meant to work separately).
  • This one is the worst limitation: you will need to be able to manually sift through the static garbage that radios usually emit to find the data your GPS is trying to send. If you are a total 1337 h4ck3r, you may be able to write a program that pulls it out automatically and feeds it into Google Earth. (If, incidentally, you do accomplish this, tell me what to do to gain your favor when you take over the world.) Beware! Radio static can get really random, and will even imitate the data you are after, often giving you misleading results.

So far, for all my test runs, this device has about a 60 percent accuracy. Yikes.

To quote, with a slight change, someone who inspired me to think this way: "If you can't modify it, you don't own it!"
Building on that, the lesson I have learned and hope to teach others is that something's label should not limit the way we use it.
 
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LinT11 month ago

Established in 1989, as one of the core
and leading manufactures of wireless 2 way radios.

BFDX is the first group
of wireless communication equipment research and development enterprise to
integrate the hardware, RF, and software in China.

tracy@bfdx.com

pbates1233 years ago
It never ceases to amaze me when I read something like this. The fact that you managed to get anything out of this just blows me away. But Cudo's to you! Wow!

You could improve your transmission rate immensely by placing a couple simple intermediary devices in the circuit. Your radio's are meant to transmit audio not pulses like come out of the GPS and go into the computer. It is shear luck that the computer interprets the spikes/clicks coming from the receiver to the computer. There are a couple of replies that point to the Automatic Packet reporting system which would work and solve a lot of your problems.

This is best way to implement your solution, not using cell phones. Use Dual Tone Multiple Frequency transmission (DTMF) it marries the Serial Digital Data from the GPS to the analog audio transmitted and received and converts it back to Digital to interface to the computer. Follow the links to a device, one of many, that perform this task.

http://www.cmlmicro.com/Products/index.asp?/Products/WTelecom/CMX865A.htm&searchvalue=wlt&setindex=1&gclid=CMa965GWqKkCFcsZQgodvCDpLg

God bless Yankee ingenuity !!!
Xellers3 years ago
This is nice, but it's much easier and cheaper to use an inexpensive ($30) pay as you go phone and then install a java applet that will transmit the location of the phone at a regular interval....
B.F.L.M4 years ago
This is all really interesting. Great job! If you hook-up the recieving speaker to another microphone (w/good quality) and connect that to another gps with a built-in map (after disabling THAT gps' 'location data stream') so that it would use the other gps' coordinates to map it out so you dont need google earth? What if you brodcasted the signals via AM frequency (is that illegal?). Please let me know
                  thanks>
V-Man737 (author)  B.F.L.M4 years ago
Thanks, that sounds useful! Unfortunately, it seems the signal coming to the receiver is so full of static that if my laptop can't interpret it automatically (which it can't), neither could a map-GPS. If anyone reading these comments knows someone who is skilled in computer programming + signal-to-noise optimization, perhaps a solution to this problem would be on the tip of his/her brain.
As for broadcasting, especially AM band, it shouldn't be illegal if you're using a blank channel and a friend who has a license. Most truck drivers have a CB radio license, which is sufficient for AM broadcasting. I'm not sure how that would improve the signal, but if you try it and the signal is improved, definitely please let me know.
yusuf7864 years ago
Hey Dude This Is So Cool...! Well I Was Thinking To Make One Like This. Hey Is There Any Other Way Which Is Much Easier & Cheaper To Make A Tracking Device...? If Yes Please Let Me Know. I Also Would Like To Know If I Can Make An Device That Would Tell Me Where The Object Is...? Im Not Sure How To Explain...Anyway Great Tutorial...!!!!
V-Man737 (author)  yusuf7864 years ago
Thank you for your interest!
If there was a cheaper and easier way to make a tracking device, I would love to hear about it. But as far as I know, this is the epitome of cheap and easy in the world of tracking devices. As such (cheap and easy), the reliability could use a little work, in my opinion. I hope someone improves on it to where the data can be automatically interpreted by the laptop instead of having to cull over the raw data with your own eyes. That would make this easier!
Hmm...Okies Hope That You Make More GadGets...! Im WaiTing hehe
angervent5 years ago
This is insane man. Great job,  I can totally see the steam punk set up.  Or maybe a modern movie/tv with the "hacker kid " who whips this up in 30 seconds. Anyway,  I got a couple spare walkie-talkies, any other Brilliant ideas?
V-Man737 (author)  angervent5 years ago
The "related" sections on Instructables often ring up interesting projects. This one caught my eye as one you'd probably like.
danielemur5 years ago
Great instructable! rather than using the walkie-talkies to transmit gps data could you use them to send video?
V-Man737 (author)  danielemur5 years ago
Thanks! I'd imagine it to be possible in theory, but the radios had a borderline effectiveness rate at about 1200 baud (appx. 1 Kbps (kilobyte, 1000), and video usually requires something like several Mbps (megabytes, 1,000,000). If you had a radio that you could manually modulate up in the hundreds-of-Megahertz range, I'd say it's definitely possible.
Pics or it didn't happen. :D
V-Man737 (author)  Kryptonite5 years ago
So far it hasn't, and I'm not about to drop everything to attempt it.
frasierman5 years ago
Wait... can't you use an old cell phone... or am I just stupid?
V-Man737 (author)  frasierman5 years ago
Probably not an old phone. But, as someone else here mentioned, Mologogo offers software for web- and GPS-enabled phones (which are now available in the pay-as-you-go market). I'd recommend going with that if you want to do this the easy way. Some companies offer you a phone for free with a contract. This website offers everything you'd need to track down your prey on the go. Of course, this instructable is for those who have a couple of extra hand-held radios and want to do it that way.
V-Man737 (author)  V-Man7375 years ago
Also, according to the Mologogo FAQ, you'll need a data plan contract, so make sure to make those bytes count! Definitely a rich man's solution. (Rich meaning having a steady income)
ve3bow5 years ago
Ham radio operators have developed a very nice system for this, and you will find lots great project ideas too.
It is called the Automatic Packet Reporting System
http://aprs.org/
V-Man737 (author)  ve3bow5 years ago
If one already has a HAM license, that would work much better!
V-Man737 (author)  V-Man7375 years ago
A Picture is in order...

"Hey Bubblegummer, where am I?"
"Uh... At your house."
"That's right! Wow, this system actually works!"
"Heh."
"Okay, now where am I?"
"Uh... At your house."
"This is SO AWESOME!!!!!!!1"
GPS-HAM.jpg
mcastles5 years ago
I gave you a five cause I think yours is much more complex than mine, to fathom an idea like this would definitely use some good thought. : )
dchurch245 years ago
How do you transmit the location? I was thinking of doing a similar thing and using an Arduino to translate the lon/lat to morse - that way I could get further away and still interperete the break in static.
This explains it well
<http://en.wikipedia.org/wiki/Automatic_Packet_Reporting_System#Technical_Information>
In its most widely used form, APRS is transported over the AX.25 protocol using 1200 baud Bell 202 audio frequency-shift keying(AFSK) on frequencies located within the amateur 2-meter band.
David
V-Man737 (author)  dchurch245 years ago
The location is transmitted as GPS output into the radio's microphone input, much the same way your voice is turned into radio waves via the microphone. So, the transmission is only as good as the radios are. The second radio interprets it and puts it out as electronic signals where its speaker would be. Those are sent into the computer.
ltkenbo5 years ago
Just a idea, but wouldn't a more interference free way to do this be to use a cell phone? Maybe have one where when you call it would answer so you could call it and check the location.
mologogo...put a cheapo prepaid phone in a box (with mologogo)...under a car...
NojiRatz5 years ago
You make me proud, V-Man
V-Man737 (author)  NojiRatz5 years ago
Yay! Thanks! Now make me proud and post up some Instructables!
ipodgeek5 years ago
Interesting tracking system you made there. You did a good job and it looks like you did a good bit of work to get this thing to work. Quick question, can the program Earth Bridge track cellphone numbers and tell you where you are located?
V-Man737 (author)  ipodgeek5 years ago
Thank you! I am quite sure Earth Bridge has no access to cell tower data to triangulate one's cell phone position, as I've seen police do in CSI. I think it'd be awesome to be able to tap into that network in that way, but I think the only people who can are the cell phone companies and governmental agencies.
bernard1925 years ago
Very good idea, although like you said, it will be limited by the range of the walkies. But definitely a very interesting concept. Quick question though, do you think it would work if you got a headset to plug into the transmitter, cut off the plug part of it, and solder the wires to that? That way, the transmitter won't be permanently deformed. Or would there be too much noise, or voltage? Just a thought.
V-Man737 (author)  bernard1925 years ago
That is a very good point. The radios I used had normal jacks to plug into. The reason I didn't use that is because my focus was on decreasing weight and bulk, and my mad scientist within couldn't resist tearing off the microphone. I think if I had really thought that part through, and didn't care so much about weight and size, I would have just done the external plug thing. Good observation!