Sunlight exposing problem

[Dipak Shinde]

Dear Friends I am using vishay make IR receiverTSOP 1738 for the Toll Automation purpose.Our system is totaly outdoor system.I am facing the direct sunlight when expose to IR receiver then efficiency of IR receiver get reduces and i did not received the output.For transmitting the signal we use the panasonic make IR Transmitter LN66A.Pl give me reply as early as possible.

 

[Nigel Goodwin]

Use radio instead! - it's silly trying to use an indoor light system outdoors, particularly as you're probably in a bright country? - although as you haven't bothered filling your location in we can only guess!.

 

[eblc1388]

Are you detecting something passing between the IR emitter and IR sensor for toll calculation purpose?

If so, then the ambient IR would certainly reduce your receiver sensitivity a lot. Under this condition, you can still get a good signal by modulating your IR beam at a low frequency so as to eliminate the relatively slow changing ambient effect.

AC couple your IR receiver signal and pass it through a bandpass filter of the modulation frequency to get a good response.

 

[Nigel Goodwin]

The receiver already uses modulated signals, is AC coupled, and includes AGC circuitry to help against light variations - but is intended for inside use for IR remote control.

I'm presuming he's wanting to transfer data, rather than just break a beam?.

 

[audioguru]

"Toll automation system"?
If your car is towing 9 trailers in series then you must pay 10 times more than a car without a trailer?

He forgot to tell us the range.
He forgot to tell us if the IR transmitter is modulated at 38kHz and in bursts of pulses.
He forgot to tell us the peak current of the transmitter's pulses.

 

[Sceadwian]

IR is a bad idea for outdoor application, though I do think local firefighters/police in some places do use IR signals to change the traffic lights. In order to do this though you need an incredibly bright IR source. Like a 10X10 IR led array, or some other really high powered IR source. To compensate for IR reflected off of a car's body or otherwise bright sunlight you may have to actually put mid value IR shield in front of the receiver and rely on the raw power of the transmitter to get through the filtering.

 

[Dipak Shinde]

Our system scanning the objects 3oo images/ second.Transmitter transmit the siganl when object passes by image processing software computer give the decision how much toll for this vehicle.Pl give me any filter one way reflecting the sunlight or which receiver is compatible for direct sunlight

 

[Sceadwian]

It's not that simple.

 

[audioguru]

Turn off the sun then the circuit will work fine.
Whoever thought of using an IR system in direct sunlight should be .....

 

[Russlk]

Build a roof over the toll area to keep the sun off.

 

[justDIY]

get the detector one of those little umbrellas like they serve in 'girly' drinks.

 

[Oznog]

Well, if you have an IR transmitter and receiver inside of a shroud (like a tube) carefully pointed right at each other then it'll help.

The transmitter probably won't benefit from an IR filter, but the receiver definitely will. That can pick up a lot of wavelengths outside the desired wavelength.

Using infrared outside is nothing new. The traffic light system Sceadwian mentions is called a MIRT and it's used all over. Emergency vehicles have an infrared transmitter that overrides the light and changes it, and does so from some distance too. BTW, very illegal to use and traffic cameras can easily catch the guy using it. TV cameras pick up infrared light too so your car is the one with the strobing light.

 

[tytower]

Would a polarising filter be any good here?

 

[Dipak Shinde]

Dear Friends,
We use IR Receiver TSOP 1738 but vishay discontinued this component.Please suggest the alternative for this compoenent of vihay make or other make.But it is easily available in market.

 

[Nigel Goodwin]

Any IR receiver IC should be fine, try and get one with a similar frequency to the existing one - but generally there seems very little difference between them.

 

[ericgibbs]

hi dipak,

Have a look at schottky optical IR bandpass filters and a Collimator tube for
your IR receiver.


EricG