I bought a couple of RF wireless PIR sensors for home security but I am currently trying to figure out how to make these communicate with my arduino ver RF. I already have some RF receivers but I am not sure how these devices actually encode data.
What information do you have about the sensors?
To do what you want, you will need to determine what the data format is that the sensor sends.
This isnt an easy task.
If you have a CRO, then pulling a sensor apart and trying to find the data line to the internal transmitter
would be a good start.
Almost all of them use the simple 2272 or 2262 style of encoding.
The RCSwitch library has an advanced example that detects the protocol and the timing.