 Most remote controls use their own coding, transmitting from 8 to 100 or more pulses, fixed or Rolling code, using OOK or FSK modulation.Also, transmitters or receivers can be "universal", meaning they are able to work with many different codings.In this case, the transmitter is normally called a "universal remote control duplicator" because it is able to copy existing remote controls, while the receiver is called a "universal receiver" because it works with almost any remote control in the market.