Wideband tunable notch cancellation
AssigneeNorthrop Grumman Systems Corporation
InventorsMark Kintis, Xing Lan
Life of this patent
Estimating the term…
Abstract
A system and method for wideband tunable notch cancellation that is passive and does not require feedback or feed forward circuitry. An input spectrum containing interference is split into two signals that are 180 degrees out of phase with each other. The preferred signal is filtered out of the 180 degree out of phase signal using a notch filter while the original signal is sent through a delay line. Then the two signals are summed with a power summer so that the interference signals that are 180 degrees out of phase with those in the original signal are cancelled out and the preferred signal remains. The notch filter is tunable to different preferred signals.
Claims18
A radio frequency receiver comprising:
- a splitter for receiving an input signal comprising a preferred portion of a input frequency spectrum and an interference portion of the input frequency spectrum and splitting the input signal between a first output that provides a first spectrum that is in phase with the input signal and a second output that provides a second spectrum that is 180 degrees out of phase from the input signal;
- a delay line for receiving the first output from the splitter;
- a tunable notch filter for receiving the second output from the splitter and filtering out the preferred portion of the input frequency spectrum and outputting only the interference portion, said tunable notch filter further comprising:
- a first wideband hybrid coupler with an input coupled to the second output of the splitter and first and second outputs;
- first and second band stop filters coupled to the first and second outputs of the first wideband hybrid coupler, each band stop filter having an output;
- and
- a second wideband hybrid coupler with inputs coupled to the outputs of the first and second band stop filters and an output;
- and
- a summer for combining the output of the second wideband hybrid coupler and the delay line such that the interference portion of the input frequency spectrum is cancelled out in the output signal of the summer.
A receiver for performing notch cancellation on a wideband signal, said receiver comprising:
- a power splitter for receiving the wideband signal comprising a preferred portion of a frequency spectrum and an interference portion of the frequency spectrum and splitting the wideband signal between a first output that provides a first spectrum that is in phase with the wideband signal and a second output that provides a second spectrum that is 180 degrees out of phase from the wideband signal;
- a delay line for receiving the first spectrum from the first output of the power splitter;
- a tunable notch filter for receiving the second spectrum from the second output of the power splitter, said tunable notch filter filtering out the preferred portion of the input frequency spectrum and outputting only the interference portion;
- and
- a power summer for combining the output of the tunable notch filter and the output of the delay line such that the interference portion of the frequency spectrum is cancelled out in the output signal of the power summer.
A method for performing notch cancellation on a wideband signal comprising a preferred portion of a frequency spectrum and an interference portion of the frequency spectrum, said method comprising the steps of:
- splitting the wideband signal into a first spectrum that is in phase with the wideband signal and a second spectrum that is 180 degrees out of phase from the wideband signal;
- receiving the first spectrum at a delay line;
- receiving the second spectrum at a tunable notch filter, said tunable notch filter filtering out the preferred portion of the frequency spectrum of the second signal and outputting only the interference portion;
- and
- combining the output of the tunable notch filter and the output of the delay line such using a power summer so that the interference portion of the frequency spectrum is cancelled out in the output signal of the power summer.
Dependencies are inferred from the claim text.