Abstract: This invention relates to a method and apparatus for reducing adjacent channel power in wireless communication systems. More particularly, the present invention is directed to a system for digitally and adaptively pre-distorting a signal that includes applying a correction to the signal before it is applied to the input of an amplifier such that the correction is equal and opposite to anticipated distortion produced by the amplifier. Thus, the correction and the amplifier distortion cancel one another resulting in a system with an overall linear transfer characteristic. In these circumstances, the adjacent channel power is desirably reduced.

Abstract: In a cable network for delivering a personal communications service (PCS) and cable television (CATV) service, return service applications, e.g., a pay per view service, are also provided on a return cable band provided by the cable network. In accordance with the invention, the return service applications utilize subbands unused by the PCS in the return cable band, thereby unaffecting the PCS. The broadband noise in the subbands normally accompanied by the PCS is filtered out using a tunable filter whose passband is adjustable to coincide with one of many PCS signal bands being used in the return cable band.

Abstract: A feedback loop coupled to a tuned circuit applies to an input of a comparator circuit arrangement a control voltage signal which is a function of the instantaneous current in the tuned circuit. The loop is employed to adjust the timing at which the comparator arrangement applies voltage-refresh pulses to the tuned circuit in response to a reference voltage signal supplied by an external clock. The timing at which the pulses occur is such that the current in the tuned circuit remains in phase with the reference voltage signal. Two like tuned circuits driven 90.degree. out of phase provide the rotating magnetic field characteristic of magnetic bubble, field-access memories.