On Thu, 6 Dec 2001 22:12:44 EST, PICLIST@MITVMA.MIT.EDU wrote:
>Hi, I have an IR xmitter sending the string "1234567890abcxyz"=
 over my
>setup. (F628 - PWM 40khz carrier, RB2 TX 1200 baud).
>The receiver is a F84 hooked to an LCD with the RX hooked=
 directly to a
>GP1U26x module.
>The strange part is I have the two units 3 feet apart on my=
 bench, when
>xmitting on a straight line of sight, I get about 60% errors in=
 the string.
>
>However, when I place my hand directly in front of my two diode=
 emitters,
>I get 100% accuracy everytime ? Could somebody explain this or=
 possibly
>a solution ?
>Thanks,
>Kevin
>

Possibly your transmitter is powerful enough that it's swamping=
 the receiver photodiode or amplifier?

Putting your hand in front of the emitters blocks/scatters enough=
 of the signal that the receiver gets a reflected or attenuated=
 IR signal and that doesn't swamp the reciver circuit.

I've seen this happen before when directing a handheld=
 transmitter directly at a receiver from a foot or so away. Maybe=
 try reducing your transmitter LED current or only use one LED?

Matt Pobursky
Maximum Performance Systems

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