Patent ID: 8036624

Claim:
A method for continuously and automatically frequency tuning a variable lobe filter structure (VLFS) to an inserted signal to allow tracking of the inserted signal to match a dynamically changing amplitude slope of a second signal using an offline process for improved interference cancellation system performance, the method comprising: a) forming a first broadband RF lobed filter having a quiescent null proximate to and offset above a center frequency of an imaginary broadband RF lobed tuning filter; b) forming a second broadband RF lobed filter having a quiescent null proximate to and offset below the center frequency of the imaginary broadband RF lobed tuning filter; c) detecting a level of RF energy output from the first broadband RF lobed filter as a first broadband RF lobed filter output; d) detecting a level of RF energy output from the second broadband RF lobed filter as a second broadband RF lobed filter output; e) calculating an error signal by subtracting the first broadband RF lobed filter output value from the second broadband RF lobed filter output value; f) integrating the error signal to generate a control voltage; g) dynamically adjusting the delay time T, via the generated control voltage, to control a lobe bandwidth of the first and second broadband RF lobed filters, an imaginary nulling RF lobed filter and the imaginary broadband RF lobed tuning filter; h) forming a more narrowband RF lobed filter orthogonal to the imaginary broadband RF lobed nulling filter in its quiescent state, i) skewing the narrowband RF filter lobe to implement a corrective amplitude slope of the inserted signal, thereby improving the performance in the improved interference cancellation system; and (j) repeating steps (a)-(i).