Carrier frequency for IR codes

[rapo]

Hello everyone,

In the past I've made with an atmega32 an infrared decoder and emitter and it worked for some IR protocols (like NEC, Sony) but now I want to improve it to work for air conditioning devices. The decoder/emitter is working for some AC devices (I've tested on two types) but not on all devices. The decoder/encoder is meant to be like an universal remote because is not dependent on protocol, is saving only the time stamps of the code and reproduce them so theoretically it should work.
My question is : How much can vary the carrier frequency? Usually is 38 kHz but I read somewhere, I don't remember where that I could be 430-440 kHz. If the carrier frequency is of hundreds of kHz the decoder/encoder must be redesigned.

 

[sky_123]

IR carrier frequency is approx 38kHz but it is not critical at all. The receiver doesn't check the frequency. It is filtered via analog means. The range may change slightly.

If the carrier frequency is of hundreds of kHz the decoder/encoder must be redesigned.

Is this a guess? Hundreds of kHz is unusual/unrealistic for usually-encountered IR remote controls. It would be approx 30-40kHz.

 

[rapo]

I've read on a website that on AC devices the carrier frequency could be 430 kHz(on some devices not on all). I want a second opinion to be sure, because I don't have an oscilloscope now to measure exactly. It's true that this frequency needs special hardware and it's not proper for cheap remote controls but remote controls from AC devices are having long codes to be hard to be decoded (I don't know the reason for this).

 

[edpalmer42]

Hello everyone,

In the past I've made with an atmega32 an infrared decoder and emitter and it worked for some IR protocols (like NEC, Sony) but now I want to improve it to work for air conditioning devices. The decoder/emitter is working for some AC devices (I've tested on two types) but not on all devices. The decoder/encoder is meant to be like an universal remote because is not dependent on protocol, is saving only the time stamps of the code and reproduce them so theoretically it should work.
My question is : How much can vary the carrier frequency? Usually is 38 kHz but I read somewhere, I don't remember where that I could be 430-440 kHz. If the carrier frequency is of hundreds of kHz the decoder/encoder must be redesigned.

A few brands do use high carrier frequencies for their IR remotes. I've heard that Bang & Olufsen and some Kenwood equipment use 455 KHz. I don't think that there's anything special about air conditioners that would make high frequencies desirable. It seems to be more of a company standard.

If you're not aware of it, check out http://www.hifi-remote.com/forums/ . They have an amazing amount of info on remote controls and codes.

Ed