It all depends on what your transmitter sends. You talk about an encoder how is this connected?
Some do use serial but others do not. Please look at the spec of your transmitter to see.
I was thinking about HT12E > www.ipic.co.jp/Pdffiles/ht12e.pdf
It has 8 address pins and 4 data pins (for buttons for example) and has on output pin to transmitter.
My transmitter: TLP434A > HTTP 301 This page has been moved
My receiver: RLP434 > www.rfphone.com/files/rlp434.pdf
I can not find info what that transmitter sends and if I can use serial.