# infrared transmitters

Discussion in 'Electronic Basics' started by Paul Horwood, Apr 26, 2005.

1. ### Paul HorwoodGuest

I wonder if anyone can help me?

I am looking at building a 6 band infrared transmitter.
Now it seems that most infrared beams are modulated via a high signal like
37Khz.

What I want to do is to transmit all the 6 bands at once but on different
infrared frequencies.
The frequencies would be for example:- 935,5 - 937,8 - 927,2 - 948,1 -
934,2 - 928,3 nm (nanometer) .

How can this be done?

Is there a meter that can be used to determin the frequency of infrared
light?

Or is there a calculation that can be done to determin which components I
would need?

Will the standard infrared emitters be capable of narrowed bandwidth like
this?

Paul...

2. ### John SmithGuest

Why this approach? What are the 6 signals you're transmitting? Are they
continuous (analogue) or discrete (digital)? What bandwidth?
After analysing the problem, you might discover another solution e.g. time
division multiplex.

To answer directly, I'm not aware of reasonable cost devices. There probably
are expensive solutions, e.g. using filters, but filters with centre
frequencies as you've shown (and narrow bandwidth as you've shown) will be
costly.

3. ### Bob EldredGuest

You want to multiplex by optical frequencies? There is no simple way to do
this. Standard emitters have way to wide a spectrum. It would require Laser
emitters and even then the wavelengths listed are quite close together.
Furthermore, it would take advanced optical processing, spectrum analysis,
etc. to separate the signals when received. But, why do you want to do
this? Why not multiplex with different modulation frequencies or multiplex
with time division at a single mod. frequency. You need to be more specific
about the information you want to transmit and its bandwidth and one of us
can suggest how you might do it.
Bob

4. ### Paul HorwoodGuest

You want to multiplex by optical frequencies? There is no simple way to do
By the looks of it I would need to use infrared filters over the emitters...
Sounds more complicated than I expected...
Think I will use another system..

Paul...