Thread Starter


Joined Nov 9, 2008
I need a schematic of the conditions for the tracking device ......

there will a transmitter which transmits signal with a certain frequency and the receiver consists of a buzzer which gives sound as it receives the signals coming from the transmitter and this sound increases its intensity when the signal strength coming increases....


Joined Jul 9, 2011
What's the maximum distance between transmitter and receiver? Do you want it to function indoor and outdoor? through walls? in all dimensions? in which environment?



Joined Jul 9, 2011
When you say it should be working inside a building, I imagine you mean through walls too. So we can forget about ultrasound and light.

I don't think there will be an easily available schematic to build such a device.
Question is, is this a stationary device or will it be moved around?


Joined Jul 9, 2011
As you can see nobody has such a circuit, otherwise someone would have responded already.
The two most common approaches are signal strength measurements of the received signal and signal delay measurements as for GPS. The latter you won't be able to built. That leaves signal strength.

I would probably try to experiment with those cheap 315MHz transceiver ICs which have built-in RSSI.

However there several issues with indoor tracking:

I have no idea what frequency is best suited, RF is absorbed and scattered in buildings, especially concrete structures. I think depending on the building structure and transmitter position you may even obtain totally misleading information.
The antenna position also has to be always the same when the receiver is moving, since changing its angle will change received signal strength too...

I had some circuit examples, but they where big circuits and AM and there is certainly a limit to your transmitter antenna size, for an AM transmitter for example it would be much too big. What is the maximum transmitter size? What item is it going to be attached to?

Did you consider a commercially available device?

Otherwise there is some experimenting involved in this.


Joined Sep 20, 2005
You could also try sweeping the area with a directional antenna. Doing it from multiple places should get you the idea where the device is, but if it is a concrete building and not just drywalls you will have much trouble getting any sense of the readings.

Of course if it is a stationary installation with just the device moving, you could use some kind of machine learning to teach the system how to manage the signal reflections. Solving it all could do for a nice diploma thesis :)