64 results about "Narrowband noise" patented technology

Reduction of noise in a device having a console with one or more microphones and a source of narrow band distributed noise located on the console is disclosed. A microphone signal containing a broad band distributed desired sound and narrow band distributed noise is divided amongst a plurality of frequency bins. For each frequency bin, it is determined whether a portion of the signal within the frequency bin belongs to a narrow band distribution characteristic of the source of narrow band noise located on the console. Any frequency bins containing portions of the signal belonging to the narrow band distribution are filtered to reduce the narrow band noise.

In an adaptive filter for cancelling common-mode noise in digital subscriber loops, a narrowband noise estimator is used to detect one or more noisy frequency bands of the common mode signal and derive therefrom a first noise estimation signal. A wideband noise estimator derives from the remainder of the common mode signal a second noise estimation signal. The first and second noise estimation signals are subtracted from the differential signal, The wideband noise estimator comprises a bandstop filter for removing the frequencies detected by the narrowband noise estimator, an analog-to-digital converter for digitizing the bandstopped signal, and an adaptive filter for deriving the second noise estimation signal from the digitized bandstopped signal and, in the process, compensating for phase and gain differences, especially attributable to the interference being injected at different points along the length of the channel.

A system and method for removing narrowband noise from an input signal in which notch filters having notch frequencies corresponding to the noise are dynamically adjusted in accordance with a detected noise spectrum. The method may be applied to telemetry systems for implantable medical devices such as cardiac pacemakers to result in improved noise immunity.

A system and method for receiving telemetry data from implantable medical devices such as cardiac pacemakers with improved noise immunity is disclosed. Ambient noise levels and signal strength are monitored and used to adaptively adjust the detection sensitivity of the receiver. Filtering of the received signal is performed to remove both broadband and narrowband noise. Removal of narrowband noise is accomplished with notch filters that are dynamically adjusted in accordance with a detected noise spectrum.

This invention is used in communications, for example, in expanded signal spectrum broadband communication systems. The technical effect of this invention consists in an enhanced narrow-band interference suppression factor and almost complete elimination of the effect displayed by a powerful narrow-band interference or a group of narrow-band interferences in a limited frequency band. A noise signal formed in the frequency band (F0, F1) in the transmission channel of a broadband communication system is power-modulated by a given modulation technique at a modulation frequency Fmod<<(F1−F0) and passed through a propagation medium, in which a narrow-band interference is superimposed thereon; received in the receiver; filtered in the frequency band (F0, F1); amplified, and divided into two signals. One of the signals is obtained by amplifying the filtered signal and limiting the amplitude thereof, and the other signal is the filtered signal or a signal linearly amplified without altering the shape thereof. The two signals obtained are then multiplied; the resultant signal is filtered in the frequency band [ΔFnar, (F1−F0)]; and the envelope of the signal obtained by filtration in the frequency band [ΔFnar, (F1−F0)] is separated in order to be subsequently demodulated and to give an information signal.