Author Topic: save me from the ambient light!  (Read 1066 times)

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Offline nishantTopic starter

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save me from the ambient light!
« on: March 18, 2009, 12:07:46 PM »
hey,
i am using normal transmitter reciever pairs for a line tracer that im building.....the main problem we r facing is that the ambient light is saturating our trans reciever pairs.....can ne1 suggest an effective way to shield off the ambient light so that our sensors read only from the floor?pleez i request urgent solution!
thank you fer your time!! ;D

Offline superchiku

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Re: save me from the ambient light!
« Reply #1 on: March 18, 2009, 12:29:19 PM »
by emitter receiver u mean????????????/

if its infrared then as i suggested u on ur other post...it wont work outdoors..u have to either use ldr or u have to use sum other ways to track the line
JAYDEEP ...

IT AND ROBOTICS ENGINEER

"IN THE END IT DOESNT EVEN MATTER"

Offline nishantTopic starter

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Re: save me from the ambient light!
« Reply #2 on: March 18, 2009, 12:42:58 PM »
yup,i did mean infrared pair......

Offline Soeren

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Re: save me from the ambient light!
« Reply #3 on: March 18, 2009, 12:53:19 PM »
Hi,

i am using normal transmitter reciever pairs for a line tracer that im building.....
I have to ask too... What have you got? (Component numbers and/or datasheets would be helpfull).


the main problem we r facing is that the ambient light is saturating our trans reciever pairs.....
No IR sensor can totally reject ambient light, since ambient light contains infrared.
The IR emitter shouldn't have no saturation problems from ambient.


can ne1 suggest an effective way to shield off the ambient light so that our sensors read only from the floor?pleez i request urgent solution!
Don't know who "ne1" is, please use the Spell Check button before the Post button!

First line of defense should be physically shielding (with IR opaque material) as much as possible, perhaps move the sensors closer to the floor if possible.
When you can't get more from the mechanical methods, you have to adjust the current through the sensing element (assuming it's a photodiode or -transistor), to keep a sensible biasing according to unresolved ambient IR.
If the light is varying too much to keep up a functional bias, a closed circuit bias control could be used to really increase the dynamic range.

But ante up - throw some type numbers in the pot.
No type numbers => no qualified answers.

Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline paulstreats

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Re: save me from the ambient light!
« Reply #4 on: March 18, 2009, 12:57:23 PM »
when you say drowning out, do you mean completely saturating the reading?

If its not saturated, you can take 1 reading with the transmitter switched off (this is the ambient reading) then take a 2nd reading with the transmitter switched on (ambient + detection reading). Take the first reading off the second reading and the result is only light thats being reflected. This does require a way to turn the emitters on and off(transistor or mosfet).

If you mean the ambient light is saturating the entire scope of the device, then its likely that your amplifying stage is wrong.

Are you also sure that it is the ambient light? if you have the output from the ir reciever straight into an adc port then it will appear that way. the problem would be needing a voltage/potential divider stage first.

 


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