Simple radio locator

Projects General Guidance
1

Hallo All
I am planning quite a simple project. The aim is to detect a angular position of one device by another device located in the center. To simplify, there is central “master” device which should detect an position (only an angel) of slave device. The resolution can be very poor like +_ 15 deg. The distance shouldn’t be monitored and it won’t be bigger than 10 meters.
I have experience with some optical (IR) sensors, in this case I would install 12 fotosensors on master device (30 deg. each) and on slave device a IR LED. Then I would search for the strongest signal on fotosensor – simple like that.
However in this case I cannot use any foto base solution that why I was thinking about radio transmitter in slave device and 12 radio receivers in master device.
The problem is that I have very poor knowledge in radio devices. Could You advise me what kind of devices as a transmitter and receiver I should use. Is it possible to determinate signal strength simply over analog input (like fotoresistor)?

Thanks in advance for any help.
Best Regards
NiechcialA

2

It is very easy to constrain the emission or detection of light - for example by putting the lights or the detectors in tubes.

I don't think there is any easy way to constrain radio waves sufficiently so that they could be used the way you want.

...R

3

How fancy do you want to get?

Or put a loop antenna on the receiver and rotate it until it gets to a null, that is the traditional approach.

4

Or put a loop antenna on the receiver and rotate it until it gets to a null, that is the traditional approach.
Automatic direction finder - Wikipedia

Along those lines, the built-in "F" shaped antenna on small, single board 2.4 GHz radios like the Pololu Wixel is reasonably directional. As long as the transmitter is in a fixed location and orientation, and there are no nearby reflecting surfaces, the receiver+antenna orientation could be used to get an approximate direction, with an ambiguity of 180 degrees. Pololu - Wixel Shield for Arduino + Wixel Pair + USB cable

5

These ideas relying on RF signal strength all assume that you have got the reception conditions set up so that the signal goes from strong enough to receive, to too weak to receive, as soon as the aerial moves out of alignment. For a transmitter/receiver pair well within their maximum range, that's unlikely to be the case; your radio transceivers don't usually require perfect alignment for them to be able to communicate, even though they have asymmetric aerials.

6

Many radios (like the Wixel) produce a Received Signal Strength Indicator (RSSI) which is a sensitive indicator of the relative orientation of the transmitting & receiving antennas and is thus useful for directional indications. Partly for that reason, RSSI is not a good indicator of distance between transmitter and receiver.