Guy Lavoie
Active Member
I was going through some posts about IR codes on the ADI forum and came across this very informative post by our now deceased friend Jon Armstrong. This information is handy when learning IR codes with the Ocelot and other similar devices:
The most common IR carrier frequency is 38KHz used by the NEC protocol family. Sony, Zenith and Pioneer are at 40 KHz, ReplayTV and Philips at 36 KHz and Mitsubishi at 33 KHz. Most of these will probably work fine at the default frequency but you decrease range as you deviate father from the proper frequency.
The most common Dish models, RCA, GE, Proscan, Scientific Atlanta set top boxes, and older Panasonic and Technics us ~58 KHz.
There are some cable STB's made by Jerrold that use no carrier frequency, they just switch the IR led on and off like a flashlight and the Ocelot can't learn or generate these commands.
Then there are a number of exceptions. RCA brands some Pioneer equipment, as do others that rebadge other manufacturers equipment. Sony and Kenwood have a few models that use 455KHz, that cannot be learned but can be generated by IR-Max IF you have a Pronto file.
Bang and Olufsen also use a 400+ KHz carrier frequency, as do a few other European manufacturers.
Usually, this seems important until you get your gear working but as Guy has pointed out you can decode Pronto hex and it is quite simple to calculate. All learned commands start out with 0000 and you will see something like 0000 0067 ... the second term 0067 is, when converted to decimal, ~4 x the wavelength in uSec.
To convert to decimal 6 x 16 + 4 = 103 and 103/4 = ~25. To get frequency in KHz divide 25 into 1000 or 1000/25 = 40 KHz.
-Jon
The most common IR carrier frequency is 38KHz used by the NEC protocol family. Sony, Zenith and Pioneer are at 40 KHz, ReplayTV and Philips at 36 KHz and Mitsubishi at 33 KHz. Most of these will probably work fine at the default frequency but you decrease range as you deviate father from the proper frequency.
The most common Dish models, RCA, GE, Proscan, Scientific Atlanta set top boxes, and older Panasonic and Technics us ~58 KHz.
There are some cable STB's made by Jerrold that use no carrier frequency, they just switch the IR led on and off like a flashlight and the Ocelot can't learn or generate these commands.
Then there are a number of exceptions. RCA brands some Pioneer equipment, as do others that rebadge other manufacturers equipment. Sony and Kenwood have a few models that use 455KHz, that cannot be learned but can be generated by IR-Max IF you have a Pronto file.
Bang and Olufsen also use a 400+ KHz carrier frequency, as do a few other European manufacturers.
Usually, this seems important until you get your gear working but as Guy has pointed out you can decode Pronto hex and it is quite simple to calculate. All learned commands start out with 0000 and you will see something like 0000 0067 ... the second term 0067 is, when converted to decimal, ~4 x the wavelength in uSec.
To convert to decimal 6 x 16 + 4 = 103 and 103/4 = ~25. To get frequency in KHz divide 25 into 1000 or 1000/25 = 40 KHz.
-Jon
