Does anyone have any info or schematics regarding how to build a vehicle tracker?

The device will need to be fitted/removed covertly to the outside of the vehicle. All I need it to do is work like a compass so I have a reciever in my car which points me in the rough direction of the tracking unit.

Anyone?

 

A couple months ago Circuit cellar ran an article about building a GPS system with a Cell Phone module designed for vehicle tracking. You could call it up and it would tell you its GPS coordinates.

A system used to track animals is a simple radio transmitter that broadcasts a repetative signal and a directional antenna. You just turn the antenna while listening to the signal; when the antenna is pointed strait at the transmitter the signal is the strongest.

Brent

 

That's mostly fiction - it's a very difficult thing to try and do!.

'bmcculla' has pointed out the most effective way of vehicle tracking, with a GPS receiver and phone transmitter on the vehicle. For a simple 'tracking' system, you could leave out the phone and have it permanently broadcast it's location via a small transmitter.

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PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Tracking the location of a cell-phone has entered the public realm
here in the UK an Europe, (no idea if u can do it elswhere but presume so)
Various sites offer the service for a fee
www.Childlocate.co.uk
is one example, I single them out as they are/were offering a free 30 day or 5 location requests plus free text messages. Accuracy does vary depending on network coverage between 100 and 500 meters.

 

In the States we have Lojac and ON Star..Lojac is a commercial vehicle locator, mostly for recovering stolen vehicles..On Star is a General Motors accessory package on the high end vehicles..It will locate a vehicle , it can even send a signal to it to unlock the doors (after owner verification)..

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gerty

 

The "compass" thing is quite a complicated and inaccurate system. It can be done with a phased array, but unless the array is quite large the error can swamp any sense of direction. Also reflections & obstacles will probably make the signal too incoherent to get a direction on. This is assuming you have a sophisticated design to do the job.

What can be done reliably is just a simple amplitude. With some experience, you can waive the antenna and get a sense of the direction, along with the change in amplitude as you move around. It can still be confused by terrain, reflections, and obstacles. They used this for tracking collars for bears, etc for a long time, but I think they've all been replaced with digital GPS locators by now.