this is just about exactly the way cable companies did it with their old analog boxes. they had a digital control signal between channels that addressed a box and told it what channels to descramble. a friend of mine *cough* used to have a test box that blocked the control frequency [this case was 107mhz i think, selectable via dip switches for that box brand or cable carrier] and sent its own signal to the box. it would go through each address and activate all channels. eventually it would get to the address of the box connected, sometimes it took a few minutes. if i remember correctly it was a pic sending the codes.