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How can I determine the IR frequency?

  1. Jun 23, 2008 #1
    Hey, I found this forum on good, so I apoligize for my lack of knowledge, but I am trying to determine the IR frequency of these two IR Text Messengers.
    Theyre designed to only send messages to one another, so is there any way I could test to discover their frequency? Would it be written anywhere on the inside of the device, and if so where and how.
    Thanks so much, and I apoligize if i posted this in the wrong place.
  2. jcsd
  3. Jun 23, 2008 #2


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    To measure the wavelength/frequency of the light you would need a spectrograph.
    In practice the easier way is to look for the cheapest IR diodes in a parts catalogue, thats what they will be using. Generally around 905nm but the wavelength control of these parts is poor so the output will be somewhere around 890-950nm
  4. Jun 23, 2008 #3
    Sorry to ask a stupid question, but whats that in Hurtz?
  5. Jun 23, 2008 #4


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    About 10^16 hz, you don't normally use frequency for visible wavelengths.
    Do you mean the data frequency that the code is sent at rather than the frequcy of the light?
    Thats usually around 100-1000 bits/second, you could get a photodiode and hook it upto an oscillopscope.
  6. Jun 23, 2008 #5
    Oh, ok.
    Truthfully im not 100% sure which I want, but ill forward it to my Professor.
    Thanks so much!
  7. Jun 24, 2008 #6


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    You should also be aware that, if the two devices are designed to only send messages to each other, then the frequency of light being used may not be the key you're looking for. In class, we built IR com-units that sent data in pulses. The frequenc of the light was irrelevant; the receiver was tuned to look for a specific frequency of pulse.
  8. Jun 24, 2008 #7
    Ya. if you're thinking you can 'intercept' transmission or something that's not what you're looking for at all (however, you may be able to jam transmission but just spamming IR in the approximate frequency). To 'intercept' you're talking about cryptography. (Since packets between the two things are encrypted)
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