Are there any devices that do radio telemetry of up to a mile that are very small and use little power? (I'm not familiar with this area at all)
Basically I want to do a project while revolves around getting the position of a moving object(moves < 50mphs) over a distance of several hundred meters(but maybe up to 1 mile or so in extreme conditions). I can attach a device to the object but it needs to be small as possible(except possibly the antenna).
My method was going to use triangulation by having 2 other fixed devices that listen to a signal produced by a device on the remote object. Essentially they would listen for the device sending a pulse wave of known freqency and calculate the dopler shift(well, just the time it takes to get the next pulse). I'm not sure if this is very accurate though as I need to know precisely where the object is(up to inches atleast but cm or mm is much better).
I think the method probably isn't great due to the low speeds involved but I'm not sure. I think that the object will end up showing no movement at all due to round off errors and such.
This is basically like wildlife telemetry where I want to get the position of an animal very precisely and then plot its movements. I'm just not sure if what I want is practical and not to sure about where to start. Are there IC's that essentially do what I want?
Oh, I was thinking that I could have multiple fixed "observation" devices that could monitor the signal then in the software I could compute some average triangulation from them all. I'm not so woried about the fixed devices as the can be as large as needed(well, practically only several pounds or so).
I was also thinking that maybe RFID might work too but I have no idea as I don't know anything about it(not sure the distances it works over but I doubt it can be used for what I want). Lasers for accuracy are ofcourse out of the question. I'd also have to worry about atmospheric effects too but I suppose I can worry about efficiency once I get on the right track.
Oh, and I think GPS is probably out of the question too because of the accuracy I need and because I really need something that is virtually fail proof(not going to cause problems when a cloud goes by or something like that or the object goes under a tree).
Any Ideas?
Thanks, Jon