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'[OT] dual channel IR'
2009\02\11@234921 by alan smith

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Do the standard crop of IR recievers (30,33,36KHz etc) have the ability to distiquish between the frequencies?  I want to have two channels of IR going at the same time, and essentialy right next to each other or will they get confused? In other words, will they only pass the carrier the rec is tuned to?


     

2009\02\12@000252 by M. Adam Davis

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You'd have to do some tests, it depends primarily on the receiver.
Still, I think you'd be better off with wider separation.

-Adam

On Wed, Feb 11, 2009 at 11:49 PM, alan smith <spam_OUTmicro_eng2TakeThisOuTspamyahoo.com> wrote:
> Do the standard crop of IR recievers (30,33,36KHz etc) have the ability to distiquish between the frequencies?  I want to have two channels of IR going at the same time, and essentialy right next to each other or will they get confused? In other words, will they only pass the carrier the rec is tuned to?
>
>
>
> -

2009\02\12@004723 by William \Chops\ Westfield

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On Feb 11, 2009, at 8:49 PM, alan smith wrote:

> Do the standard crop of IR recievers (30,33,36KHz etc) have the  
> ability to distiquish between the frequencies?  I want to have two  
> channels of IR going at the same time, and essentialy right next to  
> each other or will they get confused?

They have a sort of "average" exponential sensitivity roll-off from  
their center frequency, usually as show in some nice graph in the data  
sheet  (for instance, if I read it right, the TSOP11.. series  
sensitivity drops off 3bB at fzero/7 from the target frequency.)  
So... as much separation as possible is a good idea.  (I know that the  
IRRC plane contingent manages to get by with more than one setup at  
opposite ends of the usual spectrum (30 and 40kHz?)

OTOH, I know someone tried to use 38kHz Sharp GP1UE261xk detectors as  
a drop-in replacement for 36kHz detectors that were discontinued by a  
supplier, and had it not work (You can buy the 38kHz sensors cheap!  
here: http://www.2dkits.com/zencart/index.php?products_id=8 )

BillW

2009\02\12@035306 by Mike Harrison

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On Wed, 11 Feb 2009 20:49:19 -0800 (PST), you wrote:

>Do the standard crop of IR recievers (30,33,36KHz etc) have the ability to distiquish between the frequencies?  I want to have two channels of IR going at the same time, and essentialy right next to each other or will they get confused? In other words, will they only pass the carrier the rec is tuned to?
>
>
>      

The passband is usually pretty wide - using 2 different ones to discriminate different signals is
almost certainly not going to work unless they are something like 455K and 36K

2009\02\12@143626 by Brendan Gillatt

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alan smith wrote:
> Do the standard crop of IR recievers (30,33,36KHz etc) have the
> ability to distiquishbetween the frequencies?  I want to have two
> channels of IR going at the same time, and essentialy right next to
> each other or will they get confused? In other words, will they only
> pass the carrier the rec is tuned to?
>

The leakage will be absolutely atrocious. If you can be sure of the
orientation of the transmitter you could try using the same frequency of
modulation but polarizing the two beams at right angles to each other.

- --
Brendan Gillatt | GPG Key: 0xBF6A0D94
brendan {a} brendangillatt (dot) co (dot) uk
http://www.brendangillatt.co.uk
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