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Subject: Re: Common IR remote control frequencies
Date: Fri, 25 Oct 2002 03:52:41 +0000 (UTC)
NNTP-Posting-Date: Fri, 25 Oct 2002 03:52:41 +0000 (UTC)
User-Agent: tin/1.5.14-20020926 ("Soil") (UNIX) (Linux/2.4.19 (i686))
Michael A. Terrell wrote:
> anc wrote:
>> I believe that a common frequency for the carrier used in IR controls is
>> 38KHz and that certain satellite receivers use 115KHz for the carrier. The
>> TSOP 1738 is a 3pin IR receiver that will decode a 38kHz modulated carrier.
>> What would happpen if an IR control using 115KHz was aimed at this device.
>> Would it strip off the carrier leaving the control
>> pulses or would filtering in the TSOP1738 prevent any output?
There would be no output at all.
>> I am looking to design a universal IR repeater. The problem is getting a
>> receiver to accept all carrier frequencies.
> Why demodulate and remodulate them? Use a detector to see if it is
> modulated above a set frequency and use the output to control
> transmission. This way, your signal already has the right modulation
> and timing.
The problem is that enviromental noise may be high.
Fluorescants spew out lots of noise in the same broad range as remotes.
Simple repeaters may reduce the signal-noise greatly.
Some simple approach like a bandpass from the IR reciever, from 5Khz-500Khz
and something to amplify and AGC it down to the range of the LED might
be most compatible.
Is this for a one-off, or production?
http://inquisitor.i.am/ | mailto:email@example.com | Ian Stirling.
"An enemy will usually have three courses open to him. Of these he will
select the fourth." -- Helmuth von Moltke
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