Signal Indicator?

I'm trying to make a simple transmitter/receiver setup to use in airsoft to keep track of the distance (not worried about direction right now) between me and whatever the transmitter is planted on. The transmitter can send out a steady signal or pulses, and the only problem I have is how it will show the distance. I have a line of LEDs that I want to set up so that more light up the closer I get to the transmitter, but I don't know how to rig the setup so that it displays signal strength (I would think that the closer you are the stronger the signal). Does anyone have any idea how I can do this or perhaps better alternatives that accomplish the same thing?

rickharris7 years ago
Possibly signal strength isn't the best parameters to measure. That would be affected by several things, your direction from the transmitter, things in the way, other people moving about.

If you get your tx to send out a digital signal to each receiver and you receiver immediately returns the signal the home base can measure the time difference between the signals to assess the distance the signal travelled.

Bearing in mind that radio waves travel at the speed of light - 3 x 10^8 then this time lag will be small for the short distances you are looking at but not impossible to measure.

Another possibility might be to use video cameras mounted up high to see where everyone is - there are programmes out there to interpret the video picture.


pyrorower (author)  rickharris7 years ago
So what you're saying is to have two sets of a transmitter/receiver combination, and have mine send out a pulse, then when it receives the pulse, the other pair will "reply" with a pulse. Then when mine receives the "reply" it calculates the time delay and estimates the distance. That could work out well if I can manage to build the circuit boards I need for that and do the necessary programming. Perhaps instead of electromagnetic signals I could use sub-audible sound (the pitch of which we cannot hear) since it carries well through many materials and it will allow mroe room for error with the programming. I don't think the video camera is an option simply because I don't have a good place to mount it.
jeff-o7 years ago
Wow, tricky question.  I think the best way to go about this is using GPS modules.

The transmitter would consist of a GPS module, a microcontroller of some sort, and a radio.  The microcontroller would poll the GPS module at regular intervals for the position data, then transmit it to your receiver.

The receiver would have a similar setup, with a GPS module, controller and radio receiver.  Possibly also an LCD screen.  After all, if it's this complex already, an LCD is not so hard to add on!

Best of luck...  hopefully someone has done something similar already, and you can borrow from their work.