Trouble understand IR specification

[timothyjackson]

Dear all:

I'm having a little trouble understanding something

For an IR (IR TX and RX) can someone explain what the following is

Frequency Range (Mhz) = ?
stripe (line) width (Khz) = ?
Modulation Type

many many thanks - tj

 

[dknguyen]

Frequency range would be the frequency of IR light (ie. the wavelength of light) that a RX is sensitive to. For a TX, this is the range of wavelengths it will emit. Neither RX or TX are perfect so they can't emit, or be sensitive to just a single wavelength of light- it's a small band around a center frequency.

Not sure what stripe width is...sounds familliar. It's a width, but you say the units are in kHz?

Modulation is similar to the RX and TX being switched on and off synchronously at a high frequency. That means the RX is only trying to detect light when the TX is sending light. This makes false triggers less likely to happen (like ambient light can sometimes cause a false trigger).

 

[Nigel Goodwin]

I suggest you give more details of what you're trying to do?, so far you're making no sense?.

 

[Sceadwian]

I did a little bit of searching on google and everything I'm finding with a refrence to line width is for infrared spectroscopy. I'm not sure how the receivers work but basically the line width is the sub band of the IR spectrum the specimen absorbs.

 

[timothyjackson]

OK - definatley helping.

Maybe by strip, i mean beam? - Beam width, does that ring any bells (i guess some "measurablity" of how big the IR beam is (thats being transmitted)

Modulation - I understand PWM, yet, what are the types of Modulation - are there different/generic ways to modulate. I.e. if i asked someone to modulate an ir tx and rx with XX(?) modulation?

thanks tj

 

[Nigel Goodwin]

Still not really making any sense - why not explain what you're wanting to do?.

 

[timothyjackson]

aiming to understand 2 things

1 - If IR can be technically specified according to the following factors:

stripe (line) width (Khz) = ?
Modulation Type

&

2 - Exactly what they mean

 

[Nigel Goodwin]

Still makes no sense - IR is just a certain part of the spectrum, do YOU understand your question if it's altered to read:

1 - If BLUE can be technically specified according to the following factors:

stripe (line) width (Khz) = ?
Modulation Type

&

2 - Exactly what they mean

 

[Sceadwian]

LED's IR or otherwise don't send out only one frequency, they send out a thin band around a central frequency, the stripe width is basically the cuttoff above or bellow or center of the primary frequency.