IR link

[dark]

Hi,
Are short distance IR links also prone to atmospheric conditions . I this for a distance of 3feet or so f og or rain wont produce much attenuation . Pleas provide your feedback.

Rgds

 

[ericgibbs]

Hi,
Are short distance IR links also prone to atmospheric conditions . I this for a distance of 3feet or so f og or rain wont produce much attenuation . Pleas provide your feedback.

Rgds

hi,
It depends a lot on the power output of the IR emitter, I guess you are pulsing the emitter.??

Rain is not so bad, Fog can be a problem [ some motor way Fog detector systems work using IR absorption thru the light path]

The worst problems I have found are snow and condensation on the lens/optics.

EDIT:
Look at the graph in this link for the 'best' IR frequencies
https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water

 

[dark]

hi,
It depends a lot on the power output of the IR emitter, I guess you are pulsing the emitter.??

Rain is not so bad, Fog can be a problem [ some motor way Fog detector systems work using IR absorption thru the light path]

The worst problems I have found are snow and condensation on the lens/optics.

EDIT:
Look at the graph in this link for the 'best' IR frequencies
https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water

Hi , thanks for the reply , yes the emitter would be carrier modulated at 40Khz . Ican increase emitter power say the emitter spec provides an intensity spec of 100mW/sr , considering fog atteunation and the closeness of the link at 3~4feet what optical power would be required , any link would be helpful . Please omit snow from the list as there would be shade in line of side but fog would certainly come in between . I am working on a system that would allow known vehicles (with transponder) inside the barrier and deny access to unknown .

 

[ericgibbs]

I would suggest that you use a TSOP 40kHz detector module, the IR Emitter could be a SFH486 type, ensure that the TX and RX are within the same nM region.

 

[magnatro]

the transmission will be prone to disturbances if particulates are present in the ether medium.for 3 meter or so, use more than two IR module in series to increment the power of the IR radiation.

 

[ericgibbs]

the transmission will be prone to disturbances if particulates are present in the ether medium.for 3 meter or so, use more than two IR module in series to increment the power of the IR radiation.

hi,
As I understand the OP, its only 3 to 4 feet.?