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Avoid daylight for IR receipt.

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truvahorse

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What are the methods avoiding daylight interfacing when receive IR signals.

Thanks advance.
 

E

erickki

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truvahorse said:
What are the methods avoiding daylight interfacing when receive IR signals.

Thanks advance.
This is not a software request. Moved here!

erickki
 

toonafishy

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I had this problem with visual light sensors circuit. What I did was built a wheatstone bridge circuit with sensors on two opposite sides of the bridge and two resistors for the other two legs. Since it is a balanced bridge, the output is zero when light hit both sensors. When one sensor received light from my transmitter, the bridge became unbalanced and I detected it. This thing worked great! Completely insensitive to ambient light but detected the modulated light wave easily.
 

GrandAlf

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Toonafishy's is a good idea, but is there anything wrong with using plain old IR filter materal.
 

jk

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normally you use a transimpedance-amplifier with a high-pass-filter. the high-pass-characteristic can be integrated as a feedback path which feeds back a dc to low-frequency current. in this way you can get a rather high dynamic range / and snr for the whole system.
 

flatulent

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The IR plastic material that only passes IR is a good start. The sunlight will cause a constant current to flow which has two effects. One is to put a DC bias on your circuit. The other is to make broad band noise. The cure for both of these problems is to use a pulsing signal for the desired one and at a high frequency. Use a bandpass amplifier in the receive path.
 

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