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Range finder using RF and an arduino?

One of the projects I've been spit-balling for a very long time requires me to be able to build some sort of range finder (if I'm using the correct term).

Basically, I would like to create a "finder" unit and a "hider" unit[s]. My thought would be to us RF of some sort, so the "hider" unit will spit out a certain frequency, that the "finder" will pick up and react to (in this case, speed up the blinking of some LED's and turn some servo's to set levels).

This doesn't need to be exact. So long as I can detect a decent range so I have a cold, warm, warmer, and on fire points to use, it'll do the desired deed. Price is another factor, as I would like to keep this around the ballpark of $30 per unit. 

Thanks in advance!! 

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rickharris2 years ago

What you want to do is quite hard.

to range find the distance from a transmitter using RF you would need to know when the transmitter produced it's pulse. the measure the time to reception - This would be very hard to do in practical terms.

I guess you could use a microprocessor - Send the transmission time with the pulse then compare with the current time at the receiver. Few it any simple micro processors have the accuracy you would need.

DoctorWoo (author)  rickharris2 years ago

Just to ensure I'm following: when you say accuracy, you're referring to the timing of the pulses, which is needed for this to run, right?

Going even a touch more stupid: is there anyway to make it so the finder is always listening for the pulse, and just change the pulse rate of the hider unit?

DoctorWoo (author)  DoctorWoo2 years ago

Just figured out how stupid my second question was...I did do more digging, and found this (https://hackaday.io/project/1259-Hide-and-Seek). Although it does break the price limit I was trying to keep in, I think I could reverse engineer the core into a hide-and-seek concept that would only relay basic distance (and maybe direction) to the finder unit.

You can use the same sort of system sown in this video. But rather than using it to have a robot follow the frequency output you have a set of indicator LEDs.

DoctorWoo (author)  mpilchfamily2 years ago

Figures Ben Heck would have something up his sleeve for this. I'll have to give that a good look at. Thanks!