Infrared Range - LED vs. Module

Discussion in 'General Electronics Chat' started by kapildevkumar a, Sep 21, 2016.

  1. kapildevkumar a

    Thread Starter New Member

    Jun 5, 2015
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    I have tried using an IR transmitter and Receiver. But its range was too small. How can a increase it(like that of in a TV remote)?

    What is the range of IR LED ? By adding a high frequency carrier wave does its range(operating distance) change? If yes how(briefly explain)? What is the need for high frequency carrier wave?
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Yes, modulating the carrier will dramatically increase range. The receiver can be set to be much more sensitive because it is rejecting noise that is not at the carrier frequency.
     
  3. ronv

    AAC Fanatic!

    Nov 12, 2008
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    http://www.vishay.com/docs/82459/tsop48.pdf
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    What range do you need ?
     
  5. kapildevkumar a

    Thread Starter New Member

    Jun 5, 2015
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    In the Range of 10m. How a carrier wave increases its range
     
  6. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    It is not JUST the carrier wave that increases range, it is also a frequency-selective band-pass filter that makes the receiver much more sensitive. Without a carrier frequency, the receiver is very sensitive to "noise" (reflections, sunlight, electrical noise, ...) if you give the receiver circuit very high gain. Alternatively, with a carrier frequency, you can filter out all DC and all other frequencies of IR noise and look only for pulses of the correct frequency of IR, amplify with very high gain and, with that, get amazing range 5 to 7 meters, in daylight.

    Two more things to consider to get that great range is to:
    - use low angle IR emitter to concentrate the energy into a tighter cone.
    - check the datasheet for maximum current at 50% duty cycles which may be quite a bit higher than the standard current rating to get brighter flashes and longer range.
     
  7. wayneh

    Expert

    Sep 9, 2010
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    I re-read my answer and realize, after reading @GopherT 's reply, that I may not have been clear enough.

    Modulating the carrier does not increase the energy in the transmitted beam. In fact it reduces the total energy emitted. (Caveat: The intensity of the individual flashes can be increased because the average power is less than the peak power. This can in fact contribute to a longer range.)

    The greatest increase in range from using a modulated carrier occurs at the receiver. Using modulation increases the signal to noise ratio, allowing the receiver to be many times more sensitive without causing false triggering.
     
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  8. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    If the Tx & Rx are fixed to solid supports 10 m is no problem. One AAC project required 3 Tx's to be side to side with 1 ft. spacing, 3, Rx 30 ft. away with 1 ft. spacing. Tx IR LED's, 15 deg. colminated with plastic lenses so there was no cross talk. As usual, no final feed back from OP.
     
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