Squeelling Communication / Control

[Clyd3]

I'm kinda new to the whole R/C thing, and I was wondering about a slightly more creative way of doing things...
I want to control a robot, or tell it what to do, by transmitting different pitches of sound in the range of 4000Hz to 8000Hz.
Dont worry to much about how the robot itself moves, just that I need a way to transmit the sound (not much of a problem), and receive a minimum of four pure pitches in the range, for forwards, backwards, left and right.

So, to simplify the circuit, lets just make a board with four LEDs on it to start off. Wait! Rather 5, one for power (i often forget to turn on circuits).
So how can I get the right LED to light up when it hears the right pitch sound?
I'll play the sound directly from the computer for now, so we don't have to worry about the mic circuit until later (so we'll just plug the current circuit in where the speakers would plug in).
Lets power it with a 9V battery, chuck in a 16F628 for later and viola!
Gimmie a suggestion please!

 

[Nigel Goodwin]

Well the idea is very 1960's, and it wasn't a very good technique back then either!.

Far better to use a digital system, particularly as you're using a PIC anyway.

But if you really want to detect audio tones you can use a PLL to do so, I think the NE567 is the usual tone detector PLL chip?. Use one for each tone you want to detect.

 

[Clyd3]

Thanks a lot Nigel,
Sounds good!
I will proceed to the constuction phase immediately!
You see, I'm after style now, not effectiveness!
I'll put more features in with more pitches soon, and I'll keep the more important parts in RF for greater efficiency.
I'll post a link to a video of what I've made as soon as I make it...
My SciFi cross Gamer mind can picture quite a lot of noise!
The only cheesy part is that I can only send one command over sound at a time, as far as I know. So I'll do other stuff with RF.

 

[audioguru]

You are using frequencies that are a multiple of each other. Distortion of the signal will cause harmonics which will give your pitch detectors false outputs.
Touchtone (DTMF) for telephones is an audio tone signalling method that uses frequencies not related for no false outputs. :lol:

 

[Clyd3]

I was just reading up on that with testing in sound stuff with a 2kHz square wave thingy, thanks for the confirmation!!!!!!