Hi!

By reading the message: "ir_detect" by "Berkin kartal" in this forum, I saw a answer "ir eye unit outs nothing if source is not pulsating, "

I'm using an AT89c52 with all the INTs avaible.

How can the IR receiver "know" if the source is pulsating? It's because I want to make a soccer robot for the "RoboCupJunior".

At first, I used the "narrow band-pass filter" but it didn't work well, because the Visible light ball is always moving in the play ground. The ball is a 102Hz red light source. But if the ball is moving, the frequency it received may not be 102Hz, and the circuit is too complicated.

So I give up using the "narrow band-pass filter". But it is the most important sensor for the robot, so...

Without the narrow bp, I'm trying a more simpler way for the ball detection: a photo-resistor (voltage divider), a comparator (LM339). I think this is the easiest way to maintain the highest performance, by a simple circuit. But anyway, the performance is STILL NOT VERY GOOD BECAUSE THERE ARE TOO MANY VISIBLE LIGHT SOURCE IN THE PLAYGROUND.

Now I want to know: how a circuit detect the light source whether the source is "pulsating" or not (whether 102Hz or not). Most of the time the light source in the play ground is not "pulsating", but the ball. So if I can get a curcuit about "how to detect a pulsating source", then I can make the sensor. CAN ANYONE HELP ME WITH THIS?

I am only a high school student in Macau, China, and I use English as my second language, so, I cannot express my meaning well...and also, I can't spend too much money on buying the "well-done modules", SO ALL THE SENSORS I MADE MUST BE AS SIMPLE AS POSSIBLE.

Thanks for your help!

Stanley Lio