A filter device provides a wideband passband of a communication device for a RF signal. The filter device includes a first filter circuit in parallel with a second filter circuit. The first filter circuit includes a first notch filter, and has a first notch. The second filter circuit includes a second notch filter in series with a reversal circuit for phase shifting the RF signal filtered by the second notch filter, the second filter circuit having a second notch. The first and second filter circuits form a band pass filter having a passband between a lower cutoff frequency defined by the second notch and an upper cutoff frequency defined by the first notch. The band pass filter provides low insertion loss in the passband, and high insertion loss in an adjacent lower stopband below the lower cutoff frequency and in an adjacent upper stopband above the upper cutoff frequency.

A radio frequency receiver is provided that comprises an antenna, an RF amplifier, at least one down conversion mixer stage and a variable notch filter. The at least one down-conversion mixer stage is arranged to act on signals provided by the RF amplifier and is tuned to a tuned frequency ft which is selected from a plurality of possible tuned frequencies corresponding to a frequency of the RF signal to be received at the antenna. The variable notch filter is arranged to act on signals passing from the antenna to the RF amplifier and has a resonance frequency f.sub.r which is selected from a plurality of possible resonance frequencies such that f.sub.r=f.sub.t in where n is a whole number between 2 and 10. The variable notch filter thereby acts to attenuate signals from the antenna at said resonance frequency.

A noise reduction system for a digital receiver reduces noise in signals received at the digital receiver. The digital receiver includes an input for receiving an analogue signal, analogue signal processing circuitry for processing an analogue signal, and an output for providing the processed signal to a digital signal processor. The noise reduction system is located between the input and the analogue signal processing circuitry, and includes a first component that outputs results of a noise signal identification and a second component that applies one or more counter-measures to the received analogue signal to produce a modified analogue signal. The modified analogue signal has a reduced level of noise compared to the received analogue signal, wherein the noise reduction system is arranged to assess the effectiveness of the one or more counter-measures applied by the second component to determine whether any further counter-measures are required.

An active canceller includes a magnitude estimator, a phase estimator, a tone generator, and a suppressor. The magnitude estimator estimates the magnitude of spurious signals on a channel. The phase estimator estimates the phase of the spurious signals on the channel. The tone generator generates a tone signal based on the estimated magnitude and phase. The suppressor subtracts the tone signal from a channel signal to suppress the spurious signals. The magnitude and phase estimators and the suppressor may operate in the time domain.

A system that incorporates aspects of the subject disclosure may perform operations including, for example, receiving, via an antenna, a signal generated by a communication device, detecting passive intermodulation interference in the signal, the interference generated by one or more transmitters unassociated with the communication device, and the interference determined from signal characteristics associated with a signaling protocol used by the one or more transmitters. Other embodiments are disclosed.

The disclosure provides a narrowband filter coupled to a signal path of a first system. The narrowband filter includes a first frequency converter, an integrator, and a second frequency converter coupled to each other in a sequence. The first frequency converter has a first input terminal receiving an input signal from the first system. The narrowband filter also includes a current generator. The current generator has a first terminal coupled to the input signal, a second terminal coupled to a first voltage, and a control terminal coupled to an output terminal of the second frequency converter. The narrowband filter dynamically adjusts a current being drawn from the signal path of the first system, as to detect and eliminate the frequency band of the unwanted signal generated by an influence of a second system close to the first system.

The disclosure provides a narrowband filter coupled to a signal path of a first system. The narrowband filter includes a first frequency converter, an integrator, and a second frequency converter coupled to each other in a sequence. The first frequency converter has a first input terminal receiving an input signal from the first system. The narrowband filter also includes a current generator. The current generator has a first terminal coupled to the input signal, a second terminal coupled to a first voltage, and a control terminal coupled to an output terminal of the second frequency converter. The narrowband filter dynamically adjusts a current being drawn from the signal path of the first system, as to detect and eliminate the frequency band of the unwanted signal generated by an influence of a second system close to the first system.

In one example, the present disclosure describes a device, computer-readable medium, and method for reducing interference on the frequency modulation (FM) radio broadcast band from the G.fast protocol standard spectrum. For instance, in one example, a method includes delivering broadband service to a customer over a spectrum that overlaps with a frequency modulation radio broadcast band, and applying a notch filter to a target frequency of the frequency modulation radio broadcast band based on a profile that is customized for the customer, wherein the notch filter prevents the broadband service from using the target frequency during the delivering.

A noise reduction system for a digital receiver reduces noise in signals received at the digital receiver. The digital receiver includes an input for receiving an analogue signal, analogue signal processing circuitry for processing an analogue signal, and an output for providing the processed signal to a digital signal processor. The noise reduction system is located between the input and the digital receiver input, and includes a first component that outputs results of a noise signal identification and a second component that applies one or more counter-measure to the received analogue signal to produce a modified analogue signal. The modified analogue signal has a reduced level of noise compared to the received analogue signal, wherein the noise reduction system is arranged to assess the effectiveness of the one or more counter-measures applied by the second component to determine whether any further counter-measures are required.

To provide a communication device that can suppress radio wave interference in communication using a plurality of frequency signals in a simply method, a communication device includes a first communication unit that communicates with a first external device by using a first frequency signal, a second communication unit that communicates with a second external device by using a second frequency signal, and a control unit that controls, when one of the first and second communication units transmits data to a corresponding one of the first and second external devices, the other of the first and second communication units not to receive data.