Determining distance and direction of transmitter.

[kyclopas]

The transmitter and receiver communicate on the same frequency. The devices are stationary at time of measurement. Range can be up to 150 meters from each other. Possible obstacles (E.g ceilings/walls). Must be as portable as possible. Low power / not constantly on.

I would like to measure the distance and direction/angle to the transmitter as accurately as possible.

Is there a transmitter/receiver/antenna combination that can be used to provide info that a microcontroller can use effectively for display and calculation?

Thanks

 

[BradtheRad]

Radio enthusiasts have 'foxhunting' competitions to track down a hidden transmitter.

The receivers can be homebrew designs. They need not be the same brand or manufacturer as the transmitter.

Link to "FOXHOUND" RADIO DIRECTION FINDER KIT. Explaining how it works, and how to construct:



Normally you aim a directional antenna from side to side, while reading the signal strength.

However if you really intend that all devices are stationary, then you might consider VOR beacon signals as airports use. These indicate both direction and distance. Your transmitter will need to be more sophisticated if you go this route.

 

[kyclopas]

Moving the antenna while the device is stationary is acceptable. But I need distance and direction. The transmitter and receiver have to be portable (about weight of a cell phone?). And the maximum effective range is about 150 meters. Can a VOR beacon be made the size of a cellphone?

 

[FvM]

You can't determine the distance of a transmit-only device by a single receiver.

You need either a triangulation with multiple receivers or a distance measurement methode, e.g. time-of-flight.

 

[BradtheRad]

There are pet locator systems which you might look into.

You carry the main unit. It is a transmitter/receiver with antenna.

The sender is small enough to attach to a collar. It is idle until it detects a call from you. Then it sends a radio signal.

You move the antenna from side to side, to find the strongest signal.

Range is several hundred feet, depending on what is intervening.

One of the better ones I looked at requires that you obtain a ham operator's license.

 

[D.A.(Tony)Stewart]

FvM is correct if you want accurate azimuth detection you need triangulation. For accurate Range (distance) you need precision clock reference (OCXO) for RF like < 0.0001 ppm that you cannot afford, so signal strength is a crude approximation. THis is what I have used for HF tracking of rocket telemetry and VLF tracking of Navy transmitters etc. But to find a transmitter in an arrow tip for hunting, >100MHz band in license free area (ISM band somewhere)

You might consider a FM burst above 100MHz just that is in band your FM radio to broadcast short range, strong enough to detect short range but low enough not to interfere with others.

BradtheRad's solution is best but requires you move to find locate direction and then move towards direction with increasing signal strength ( ambiguity with mirror image on direction of antenna)

 

[BradtheRad]

Are you permitted to use GPS?

That would be the obvious method.

 

[biff44]

I would do what these guys do:
https://www.radargolf.com/

 

[D.A.(Tony)Stewart]

I would do what these guys do:
https://www.radargolf.com/

I beleive those guys use the RFID technology, where you must move around to find it within 20~100ft best case then it will echo back a weak harmonic of the fundamental tuned signal. using a tuned resonator and rf diode.

So if you intend to be mobile and go find it, and are blind.. it will give a stronger signal when you get closer, but will not tell you how to get there.