Abstract: Apparatus for reducing interference in a first signal caused by a second signal. Before the signals are transmitted, the first signal is tested to determine how much interference can be tolerated. During portions of the first signal which can tolerate a large amount of interference, the amplitude of the second signal is increased. During portions of the first signal that can only tolerate a small amount of interference, the amplitude of the second signal is decreased. The average amplitude of the second signal is large enough to provide an acceptable bit error rate or signal to noise ratio, yet small enough not to substantially corrupt the first signal. In one embodiment, the technique is employed to allow transmission of additional data on a television channel.