Abstract: Method for adapting the concentration of a sample gas in a gas mixture to be analysed by a gas chromatograph assembly, the assembly comprising a sample gas inlet, a secondary gas inlet, a gas chromatograph sensor, a gas chromatograph column, and a gas chromatograph bypass parallel to the column, characterized by a) introducing sample gas through the sample gas inlet, b) introducing secondary gas through the secondary gas inlet, c) mixing the sample gas and the secondary gas to a gas mixture and conducting the mixture via the bypass, d) circulating the mixture in a gas conducting loop comprising the bypass and the sensor, e) repeating steps b), c) and d) without step a) to gradually reduce the concentration of sample gas within the mixture until the concentration reaches a desired predetermined level, f) analysing the mixture by means of gas chromatography employing the column and the sensor.

Abstract: Method for wide range gas detection using a gas detection system comprising a sample gas inlet, a reference gas inlet, a gas modulation valve and a gas analyzer, wherein the gas modulation valve alternatingly connects the sample gas inlet to the gas analyzer during a sample gas time period and the reference gas inlet to the gas analyzer during a reference gas time period, characterized in that the sample gas time period is shorter than the reference gas time period such that the sample gas concentration in the gas analyzer is reduced.

Abstract: Described is a method for quantifying the amount of optically interfering gas impurities in a gas detection system comprising a sample gas inlet, a reference gas inlet, a gas modulation valve, and an infrared absorption gas detector used for analysis of methane or natural gas, wherein the gas modulation valve alternatingly connects the sample gas inlet to the gas detector during a sample gas time period and the reference gas inlet to the gas detector during a reference gas time period. The method includes measuring an infrared absorption for at least two different sample gas concentrations in the gas detector achieved via respective different ratios from the sample gas time period and the reference gas time period, and comparing amplitudes of different measurement signals of the at least two different sample gas concentrations with calibration functions to assess an actual gas impurity concentration in the sampled gas.

Abstract: A gas detection system, comprising a sample gas inlet, a reference gas inlet and a gas modulation valve alternatingly connecting one of the sample gas inlet and the reference gas inlet to a gas sensor, is characterized in that a selective transfer filter is located in the gas flow path connecting the gas modulation valve and the gas sensor.

Abstract: Infrared gas detection system comprising a gas inlet, an infrared gas analyzer connected to the gas inlet and a secondary gas sensor connected to the gas inlet, and an evaluation device evaluating the measurement signals from both the infrared gas analyzer and from the secondary gas sensor, such that a gas is identified only if both the infrared measurement signal and the secondary measurement signal coincide in time.

Abstract: Described is a method for quantifying the amount of optically interfering gas impurities in a gas detection system comprising a sample gas inlet, a reference gas inlet, a gas modulation valve, and an infrared absorption gas detector used for analysis of methane or natural gas, wherein the gas modulation valve alternatingly connects the sample gas inlet to the gas detector during a sample gas time period and the reference gas inlet to the gas detector during a reference gas time period. The method includes measuring an infrared absorption for at least two different sample gas concentrations in the gas detector achieved via respective different ratios from the sample gas time period and the reference gas time period, and comparing amplitudes of different measurement signals of the at least two different sample gas concentrations with calibration functions to assess an actual gas impurity concentration in the sampled gas.

Abstract: Method for wide range gas detection using a gas detection system comprising a sample gas inlet, a reference gas inlet, a gas modulation valve and a gas analyzer, wherein the gas modulation valve alternatingly connects the sample gas inlet to the gas analyzer during a sample gas time period and the reference gas inlet to the gas analyzer during a reference gas time period, characterized in that the sample gas time period is shorter than the reference gas time period such that the sample gas concentration in the gas analyzer is reduced.

Abstract: Infrared gas detection system comprising a gas inlet, an infrared gas analyzer connected to the gas inlet and a secondary gas sensor connected to the gas inlet, and an evaluation device evaluating the measurement signals from both the infrared gas analyzer and from the secondary gas sensor, such that a gas is identified only if both the infrared measurement signal and the secondary measurement signal coincide in time.

Abstract: A gas detection system, comprising a sample gas inlet, a reference gas inlet and a gas modulation valve alternatingly connecting one of the sample gas inlet and the reference gas inlet to a gas sensor, is characterized in that a selective transfer filter is located in the gas flow path connecting the gas modulation valve and the gas sensor.

Abstract: A listening device includes an input transducer, an output transducer, a signal processor, and a feedback cancellation system for estimating acoustic feedback. The feedback cancellation system includes an adaptive FBC filter arranged in parallel to the forward path, an adaptive whitening filter, and a howl detection unit that performs howl detection based on an output of the adaptive whitening filter. The adaptive FBC filter includes a variable FBC filter part and an FBC update algorithm part for updating the variable FBC filter part, the FBC update algorithm part receiving first and second FBC algorithm input signals influenced by the electrical input and the electrical output signals. Further, the feedback cancellation system receives an electrical update signal essentially consisting of the direct part of the electrical input signal and coefficients of the adaptive whitening filter are based on the electrical update signal.

Abstract: A listening device includes an input transducer, an output transducer, a signal processor, and a feedback cancellation system for estimating acoustic feedback. The feedback cancellation system includes an adaptive FBC filter arranged in parallel to the forward path, an adaptive whitening filter, and a howl detection unit that performs howl detection based on an output of the adaptive whitening filter. The adaptive FBC filter includes a variable FBC filter part and an FBC update algorithm part for updating the variable FBC filter part, the FBC update algorithm part receiving first and second FBC algorithm input signals influenced by the electrical input and the electrical output signals. Further, the feedback cancellation system receives an electrical update signal essentially consisting of the direct part of the electrical input signal and coefficients of the adaptive whitening filter are based on the electrical update signal.

Abstract: A listening device system includes two listening devices, each having its own separate housing. The first device includes an input transducer housed within the housing for converting an input sound to an electrical input signal which includes a direct and an acoustic feedback part, and a feedback cancellation system. The feedback cancellation system includes an adaptive FBC filter including a variable FBC filter part, and an FBC update algorithm part for updating the variable FBC filter part. The FBC update algorithm part receives first and second input signals influenced by the electrical input and the electrical output signals. The second listening device includes an input transducer housed within its housing producing an electrical update signal essentially consisting of the direct part of said electrical input signal. The update signal is conveyed from the second device to the first device, where feedback cancellation parameters are adjusted based on that signal.

Abstract: A hearing aid system includes an input transducer, an output transducer, and an electrical signal path between them. The signal path includes a signal processing unit. An electrical feedback cancellation path is formed between the output side and the input side of the signal path and subtracts an estimate of acoustical feedback from a signal on the input side of the amplifier part, the electrical feedback cancellation path including an adaptive filter for providing a variable filtering function. A probe signal generator generates a probe signal characterizing an acoustical feedback path, the probe signal being fed to the adaptive filter of the electrical feedback cancellation path. A second input transducer is located at a position where the acoustical signal is substantially free from acoustic feedback from the output transducer, and the adaptive filter uses a signal derived from the second electrical input signal to influence its filtering function.

Abstract: The invention regards a scheme for generating a probe noise signal to be used in an anti feedback system of an audio system. The audio system comprises e.g. a microphone for capturing an audio signal, an audio signal processor for adaptation of the audio signal and a receiver for generation of an audible signal. According to an embodiment of the invention, a noise signal is injected into the audio signal path between the microphone and the receiver and used for estimating acoustical feedback, the noise signal being generated by the following steps: converting a digitized audio signal to the frequency domain, in order to obtain a series of magnitude and phase values, changing the phase values such that the phase of the resulting signal becomes less correlated, preferably substantially un-correlated, to the original signal, converting the magnitude and phase back to a time domain signal using the changed phase values. The invention may e.g. be used in a hearing aid, a headset or a pair of headphones.

Abstract: The invention concerns in a first aspect an audio system comprising a microphone, audio signal processing means, an output transducer and means for detecting a possible feedback tone and the corresponding frequency of the feedback tone in the audio system between the output transducer and the microphone. According to the invention means for counteracting feedback are provided. Further, means are provided for changing the phase of the audio signal at a given frequency. In a further aspect, a binaural hearing aid system comprising first and second hearing instruments according to the first aspect, each hearing instrument comprising transceiver circuitry allowing an exchange of signals between the two hearing instruments, and wherein the binaural hearing aid system is adapted to provide that a phase change introduced in the first audio signal by a controller of the first hearing instrument is or can be introduced in the second audio signal of the second hearing instrument via said transceiver circuitry.

Abstract: The invention concerns in a first aspect an audio system comprising a microphone, audio signal processing means, an output transducer and means for detecting a possible feedback tone and the corresponding frequency of the feedback tone in the audio system between the output transducer and the microphone. According to the invention means for counteracting feedback are provided. Further, means are provided for changing the phase of the audio signal at a given frequency. In a further aspect, a binaural hearing aid system comprising first and second hearing instruments according to the first aspect, each hearing instrument comprising transceiver circuitry allowing an exchange of signals between the two hearing instruments, and wherein the binaural hearing aid system is adapted to provide that a phase change introduced in the first audio signal by a controller of the first hearing instrument is or can be introduced in the second audio signal of the second hearing instrument via said transceiver circuitry.

Abstract: The invention concerns an audio system comprising a microphone, audio signal processing means, an output transducer and mans for detecting a possible feedback tone and the corresponding frequency of the feedback tone in the audio system between the output transducer and the microphone. According to the invention means for counteracting feedback are provided. Further, mans are provided for changing the phase of the audio signal at a given frequency.

Abstract: The invention relates to a hearing aid system with an electrical feedback cancellation path, for compensating acoustic feedback between an output transducer and an input transducer by subtracting an estimate of the acoustical feedback from a signal on the input side of the amplifier part, the electrical feedback cancellation path comprising an adaptive filter for providing a variable filtering function. The invention further relates to a method of compensating acoustic feedback in a hearing aid system and to its use. The object of the present invention is to provide an alternative scheme for estimating the acoustical/mechanical feedback in a hearing aid. The problem is solved in that the hearing aid system comprises a second electrical input signal consisting essentially of the direct part of said first electrical input signal (i.e.

Abstract: The invention regards a scheme for generating a probe noise signal to be used in an anti feedback system of an audio system. The audio system comprises e.g. a microphone for capturing an audio signal, an audio signal processor for adaptation of the audio signal and a receiver for generation of an audible signal. According to an embodiment of the invention, a noise signal is injected into the audio signal path between the microphone and the receiver and used for estimating acoustical feedback, the noise signal being generated by the following steps: converting a digitized audio signal to the frequency domain, in order to obtain a series of magnitude and phase values, changing the phase values such that the phase of the resulting signal becomes less correlated, preferably substantially un-correlated, to the original signal, converting the magnitude and phase back to a time domain signal using the changed phase values. The invention may e.g. be used in a hearing aid, a headset or a pair of headphones.

Abstract: A hearing aid with anti feed back system, the hearing aid including a signal path from at least one input transducer to an output transducer, a signal processing unit, acoustic environment detection capability, and a parameter generator that generates input to the setting of signal processing parameters to be used in the signal processing unit based on either manual input or from the results of acoustic environment detection, and an alert signal generator that generates an alert signal to the anti feed back system whenever one or more preselected input to the generation of signal processing parameters undergoes changes.