RF indicator for home surveillance project

This is my 1st. Rf hobby project
I'm working on a home surveillance project using a 1.2 mhz wireless video/audio
transmitter/reciever, motion sensor and video camera. the transmitter will only be powered
up when the cam is filming and the reciever will be on all the time.
what I need is a simple cheap way of.
when the reciever is recieving it will give me a output I can use to turn on a LED or use
for a input to a micro controller.I'm not sure if the RF signal could be use to say switch
a transisitor.
thanks for any help or advice