Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Lasse Langwadt Newsgroups: sci.electronics.design Subject: Re: Ir remotes Date: Mon, 20 May 2024 11:50:22 +0200 Organization: A noiseless patient Spider Lines: 28 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Mon, 20 May 2024 11:50:23 +0200 (CEST) Injection-Info: dont-email.me; posting-host="a75d9c77c2cedba5e73953b84cdb6c19"; logging-data="4128530"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19Lrlol0jYDVf8Jrd/Reeb5+Ga1q9Cy0ec=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:MSnYzj4SzHHHVyTM0cKHB38FGEs= In-Reply-To: Content-Language: en-US Bytes: 2252 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