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I was looking to buy an IR receiver to decode my remote control and was looking at a catalogue at http://www.vishay.com/docs/49845/_sg2145.pdf.

On page two the carrier frequency is mentioned as carrier out for the last two modules while for every other module it lists a specific frequency like 38 kHz,etc. Can someone help me understand what it is and if these are different than a regular IR receiver module?

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    \$\begingroup\$ The 38 kHz ones are for signals which are OOK modulated (see en.wikipedia.org/wiki/On-off_keying ) and use a carrier frequency of 38 kHz. These IR receivers will supress/ignore signals with a different carrier frequency. The ones with the carrier output will output the carrier frequency, they might work with a wider range of carrier frequencies. \$\endgroup\$ – Bimpelrekkie Jul 12 '17 at 11:36
  • \$\begingroup\$ so basically, i cant use the modules which output 'carrier out' since they wont be outputting the actual pulses but rather just the carrier frequency? \$\endgroup\$ – thunderbird Jul 12 '17 at 11:58
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    \$\begingroup\$ Nope, you can use these but they might be sensitive to non-38 kHz remotes. The pulses (the modulation) will still come out otherwise these receivers would be pretty useless. But if you're using an 38 kHz remote (I believe 99% of them are 38 kHz) then you'd better use a 38 kHz one. \$\endgroup\$ – Bimpelrekkie Jul 12 '17 at 12:30
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Plainly listed, those two modules are the Learning and Repeater modules. These modules require outputting the entire signal, both the coded pulses and the carrier frequency they are modulated at.

The others strip the modulation and only output the coded pulses, the data.

The normal modules work better with the carrier frequency they are designed for, but they will still be sensitive to some degree to close frequencies. A 38khz module can read 31khz remotes with a lower degree of vision or distance. The error rate can increase though.

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