Universal IR Remote Controllers
Nowadays it is no surprise to find 4 or 5 different remote control units in an average living room. TV, Stereo set, DVD player, VCR, Settop box and a Satellite receiver are among the most popular devices and each and every one of them has a unique remote control unit. No wonder that people want to control all these devices with one single universal remote control unit.
Two major types of universal remote controllers exist: Learning controllers and Lookup Table controllers.
A combination of both types in one controller is also possible.
Both types have their own advantages and disadvantages.
Learning Universal Remote Controllers
This type of universal remote controllers has the ability to learn new codes. Usually you must align it head to head with the original remote controller and then press a special sequence of buttons on both controllers. The universal remote controller sees the patterns transmitted by the original remote controller and stores them in its memory. Later it can play back the learned patterns when you press the keys on the universal remote controller.
One of the biggest advantage of this approach is that the universal remote controller can learn codes of brand new remote controllers, which didn't exist yet when the universal remote controller was created.
Lookup Table Universal Remote Controllers
A lookup table universal remote controller uses lookup tables to simulate the original controllers (what a surprise!).
In order to program the universal remote controller you need to enter a special 3 or 4 digit code which can usually be found in a little booklet that came with the universal remote controller.
This code is internally translated into a protocol, and all keys of the universal remote controller are mapped to their corresponding commands.
The major disadvantage of this sort of universal remote controllers is that devices which are younger than the universal remote controller are probably not supported by it, simply because the universal remote controller manufacturer can not implement something which doesn't exist yet.
Upgradable software in the universal remote controllers would be the best solution so that the manufacturer of the universal remote controller can implement new remote controllers.
BTW: I'm not aware of the existance of those upgradable universal remote controllers.
You'll have to ask the manufacturer of your universal remote controller about the 3 or 4 digit code you'll have to enter to simulate one of your original remote controllers, not me, nor the manufacturer of the original remote controller! Only the manufacturer of your universal remote controller can tell you what code to use to simulate your original remote controller, if it is supported at all.
Original remote controllers do not use 3 or 4 digit codes to identify the protocol and key mapping. Only the lookup table universal remote controls use them, and they are manufactured by totally different companies which are in no way related to the original remote controller manufacturer.