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From: Jan Panteltje <alien@comet.invalid>
Newsgroups: sci.electronics.design
Subject: Re: Ir remotes
Date: Mon, 20 May 2024 12:37:41 GMT
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On a sunny day (Mon, 20 May 2024 11:50:22 +0200) it happened Lasse Langwadt
<llc@fonz.dk> wrote in <v2f6cv$3tvoi$1@dont-email.me>:

>On 5/20/24 09:15, Don Y wrote:
>> On 5/20/2024 12:01 AM, Don Y wrote:
>>> My understanding is that Ir remotes modulate an Ir "carrier" signal
>>> in a particular pattern to express a particular "code" corresponding to
>>> the key pressed/held.
>>>
>>> And, that different "chipsets" use different carriers and encodings.
>>>
>>> Is there a front-end that is tuned to the particular carrier
>>> in the receiver?  Or, is all of this done "digitally"?
>>>
>>> I.e., with a fast-enough (Ir) photodetector, should I be able to
>>> decode ANY signal from ANY "remote"?
>> 
>> And, before anyone mentions the obvious, I've already looked at lircd
>> which is the reason behind this post; why do they claim they can handle
>> ALMOST all remotes?  Is this a limitation of their hardware implementation?
>> Or, timing problems in the way they try to process the raw video signal?
>
>afaik almost all use a 30-50kHz carrier, nominally something like 38kHz,
>I think the common IR receivers have build in bandpass filter, so it is 
>just a matter of interpreting bits (there's a few common protocols)
>
>
>I know that B&O (used to?) be an exception with a 455kHz carrier, I'm 
>guessing because someone clever many decades ago thought to use an AM IF 
>filter

 https://panteltje.nl/panteltje/pic/ir_pic/
  used it to control my cable modem.
But I also have a Chungop SRM403E remote that can learn codes from other remotes.
In fact many remotes can learn codes from other remotes,
I have an other Chinese one that can.
Makes life sometimes easier, now you only need one remote for say 3 different devices.