View Full Version : continous ( not pulse) Infrared detetion

06-16-2005, 09:50 PM
· I have a infraredball RCJ-04 , Its infrared signal is continous(not pulse) ,wavelength 950nm
· how can i detect the infrared signal

· could anyone give me a program to detect the continos infrared signal

· thanks for your help

Post Edited (hsiaochung) : 6/17/2005 1:23:02 AM GMT

Loopy Byteloose
06-16-2005, 10:40 PM
The advantage of a pulsed irfrared is that you can identify your signal from a lot of 'noise' that is out there.

If you use a non-pulsed sensor, your robot might chase a lit cigarette or another heat source just because it is the hottest IR spot around.

Are you sure that is what you want?· You can use features in the BasicStamp to create a pulsed signal.· And, though I am not 100% sure how, you might be able to have the BasicStamp recognize a particular frequency from a sensor that doesn't filter to a particular frequency.

G. Herzog in Taiwan

Andy Lindsay (Parallax)
06-17-2005, 12:07 AM
Too bad their Robot Soccer balls aren't continuously pulsed; that would be a much better design.·

The Boe-Bot CMUcam (http://www.parallax.com/detail.asp?product_id=30051)·has some examples at the bottom of the page, one is tracking a colored ball.· As far as the CMUcam would be concerned, an infrared ball would be the same as a bright white ball, so it might work.·

You can also use the detection part of·Parallax' QTI module (http://www.parallax.com/detail.asp?product_id=28108) to detect ambient, DC infrared.· The circuit is simple enough, with a resistor, capacitor, and an IR phototransistor (http://www.parallax.com/detail.asp?product_id=350-00018).· (The phototransistor will work better than a QTI because of its shape.)· IR phototransistors are pretty common, and can be obtained at most electronics outlets.· With this circuit and the RCTIME command, you can measure the ambient infrared intensity, and test to see how far away you can detect the soccer ball.· With an array of these things in·a soccer competition's·controlled lighting environment, it should be possible to discern·its·angle and relative distance.· The question that remains is how good is the range?


Here is TestIrPhototransistor.bs2 (http://forums.parallax.com/attachment.php?attachmentid=38067), a PBASIC Program·you can use with the circuit to measure ambient infrared.· I tested it with a·QTI module.· When I pointed it out the window, the Debug Terminal displayed values below 100 - high infrared.· When I pointed it at the far wall, it displayed higher values (400 to 500 -·lower infrared).· Under the shade of a table, it displayed·even higher values (2000 to 3000 - lower still).· With this kind of response and the low cost of the parts, it's worth testing for range on the soccer ball in controlled lighting conditions.·

' TestIrPhototransistor.bs2

' {$STAMP BS2}
' {$PBASIC 2.5}

IoPin PIN 2

time VAR Word


RCTIME IoPin, 1, time
DEBUG HOME, "Ambient IR = ", DEC5 time


Post Edited (Andy Lindsay (Parallax)) : 6/16/2005 6:01:00 PM GMT

06-17-2005, 04:13 AM
Many BS2 IR Designs want to detect a TV Remote control, which modulates the light. Therefore they use an IR-Decoder (a three lead, IR-frequency sensitive device). You want a true IR-Photo-Transistor to detect un-modulated IR light. It's going to be sensitive to ambient IR though -- like the Sun puts out.

But if that's what you want, that's what's been called out above.

Andy Lindsay (Parallax)
06-17-2005, 05:12 AM
Here's a link to the spec sheet:


06-17-2005, 08:14 AM
· thanks for everyone reply , especially, Andy

· I will try the method that promoted by you