After installing the system to send video from floor level (sat receiver) to my workshop TV in the basement, the basement TV had a lot of noise. I turned off the cordless phone, the wireless router, intercom, floresent lights, tried all four channels. Nothing helped. I then tried reversing the setup, moving the sat receiver to the basement and sending to the TV upstairs. Turned all above back on and the problem was solved. Darned if I know why!
Next I discovered my wireless router no longer was working. The TV transmitter is aimed right at the router located on the second floor. I changed the transmit channel on the router from channel 3 to channel 11. All is well!