Hi All, first post.

I have an idea for a hobby type project that I wish to build, but since I have little knowledge of electronics, I am lost on how to start - what I need etc.

The project idea is simple. I want to build a portable handheld device that shows direction and distance of a small transmitter.

The idea comes from me an my gf getting sick of trying to find each other in those big super stores when we go.

So each would have a little "tracking bug" type item and a little receiver with an lcd screen that points at the other tracking bug and gives distance. Maybe also the tracker could be built into the display unit.

I would guess the maximum distance it would need to work would be about 600-700ft (200-250m). ie The furtherest you could be away from each other in one of those huge Wal-mart/Target type places.

I have seen lots of FM transmitters and receivers but don’t know if these would work or even be able to transmit / receive at that distance.

1. So is this a reasonable possibility for me to build something like this?
2. How much would it cost?
3. Is there a better way to do this?
4. Is it legal to transmit radio like this in the USA

Thanks for your time


Adrian

 

Building something like you describe would be very difficult for a beginner, or even a professional for that matter. If something like this would be inexpensive to make I am sure they would already be on the market.

 

Instead of trying to track using radio signal strength, etc., design a device that can determine it's own position (like a sort of GPS). Then, it could transmit it's location data to the other unit(s) digitally. GPS itself may have the accuracy/resolution you need. You might have problems with the GPS receiver being shielded from the satellites' signals by the metal structure of the building, though. I don't really know much about the current generation of GPS, however.
Jeff

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Nothing is impossible for the man who doesn't have to do it himself - Weiler's Law

 

You could just pass a simple multiple choice test, get an amateur radio license, and use a 2M handheld to exchange much more than position. A set of FRS walkie talkies might also work for you. No license or test is required.

 

You could use one of those 120db emergency screamers (audio) and let your friend locate you (once your hearing recovers...)

oh, probably not legal. Definitely inconsiderate.

 

Your supposed to stick with the g/f.... even when they spend forever looking at pants and shoes...... Trust me..... I know these things

 

Don't get too close to your g/f in a big store or she will catch you looking at all the other girls.

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Uncle $crooge

 

You can still do it if you are skillful , walk behind her

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Superman returns..

 

How about holding the purse while they go try something on...

 

Sunglasses.

 

You may find what you need in amateur radio publications. A bit of detail -

A. Foxhunting is one of numerous Radio Direction Finding activities that are part of amateur radio. The amateur license helps you deal with the licensing of the transmitter.

B. APRS - Automatic Position Reporting System is part of amateur radio. In one arrangement a base station with a computer transmits a query to a station - which is another transceiver equipped with some intelligence as well as a GPS. The remote, presumably mobile/portable station responds with the GPS position and possibly other information.

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stevez

 

That is not a trival application as others have already stated. Direction detection is somewhat simpler but distance is a real challenge. GPS is the only pratical way I can think of and this would not be a cheap or easy project for either the sending unit or receiving unit.

Lefty

 

Then the other girls can't see you winking at them.

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Uncle $crooge

 

Here's a GPS module from Parallax, about $70US. The text says that it's good for outdoors, so it may not work too well inside. Also, Navsync seems to have some interesting products.
Jeff

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Nothing is impossible for the man who doesn't have to do it himself - Weiler's Law