Subject: Re: Common IR remote control frequencies
Date: Thu, 24 Oct 2002 22:02:30 +0000
NNTP-Posting-Date: 24 Oct 2002 21:03:46 GMT
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?
>> 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.
In my first attempt, I used just a photodiode, and re-transmitted the signal
intact, but the problem was the circuit could not differentiate between
ambient light and a modulated carrier.
Searching for IR Repeater circuits on the internet, a lot of these use a
demodulator like TSOP1738, wire it to a repeater, then reinsert a carrier.
If you can think of a work around, I'd be glad to hear about it.