69results about "Limiting amplitude of digital/coded signals" patented technology

An apparatus and method of automatically compensating audio volume in response to a channel change. The method includes generating a gain value to adjust a level of an input audio signal by comparing an average level of the input audio signal with a predetermined input / output level curve, adjusting an audio volume of the input audio signal by applying the generated gain value to the level of the input audio signal, and adjusting a dynamic range of the audio signal having the adjusted audio volume.

Sound pressure level limiter with anti-startle feature for audio systems are disclosed. The anti-startle feature may be implemented with a delta incident detector for detecting delta acoustic incidents that exceed a predetermined acoustic startle boundary, a delta limiter for determining an anti-startle gain, and an amplifier to apply the anti-startle gain to the input signal. The delta incident detector may detect delta incidents based on an estimated true SPL delivered by a transducer to a predetermined datum point. The estimated true SPL may be determined by based on a measured receiving frequency response of the transducer. An SPL limiter may also determine an SPL gain in response to detecting an SPL acoustic incident that exceeds a predetermined SPL threshold, and an amplifier may apply the SPL gain to the input signal to reduce it below the threshold.

A digital clipper is highly oversampled to decrease aliasing and increase accuracy. The difference between the clipper's input and output is then downsampled and added to the delayed, unclipped signal at 1x sample rate to achieve clipping. Filters operating at 1x can be placed in series with the downsampled differentially-clipped signal to achieve overshoot compensation, bandlimiting of the clipped signal, and other goals.

The invention discloses a pick-up device and method. The pick-up device comprises a digital signal processor, at least one microphone, multiple amplifiers and multiple analog-digital converters. Each microphone is used for receiving an audio signal and sending the audio signal to the amplifier corresponding to the microphone. Each amplifier is used for amplifying the received corresponding audio signal and sending the amplified audio signal to the analog-digital converter corresponding to the amplifier. Each analog-digital converter is used for converting the received corresponding audio signal into a digital signal and sending the digital signal to a digital signal processor. The digital signal processor is used for receiving the digital signals sent by the analog-digital converters, confirming the digital signals where clipping is not conducted from the received digital signals, and confirming output signals according to gain values corresponding to the digital signals where clipping is not conducted. The pick-up device can have good pick-up performance in various pick-up scenes.

A method and apparatus for limiting the absolute magnitude of an audio signal. The method may include firstly variable-gain reducing the gain of an audio signal, and then secondly variable-gain reducing the gain of the audio signal faster than the first variable-gain reduction, thereby limiting the absolute magnitude of the audio signal to a threshold. The first variable-gain reduction may include variable-gain reducing the gain of the audio signal in a first stage, and the second variable-gain reduction may include variable-gain reducing the gain of the audio signal in a second stage that reduces the gain faster than the first stage. The second variable-gain reduction may include delaying the audio signal, finding a peak among the delayed audio signal, calculating a fast gain from a found peak, and modifying the delayed audio signal with the calculated fast gain.

A grounding switch is described which operates properly even in the presence of negative voltages on a signal line. The grounding switch uses isolated field effect transistors that have their substrates tied to different voltages. The isolated field effect transistor has gate voltage and substrate voltage which can be pulled down to negative voltage when the signal line has a negative voltage allowing the switch to remain open even with a negative voltage.

A class D amplifier (1) comprises an input unit (11) for receiving a digital input signal (Vin), a pulse shaping unit (12) for producing pulse shaped signals in dependence of the input signal (Vin), a comparator unit (13) for comparing the pulse shaped signals and producing a comparator signal, a driver unit (14) for producing driver signals in dependence of the comparator signal, a switching output unit (15) for producing a pulse width modulated output signal (Vout) in dependence of the driver signals, and a feedback unit (16) for feeding the output signal (Vout) back to the pulse shaping unit (12). The input unit (11) comprises a clipping control unit (10) for controlling the duty cycle of the pulse width modulated output signal (Vout).

A transmitter includes: a limiter performing clipping in which an amplitude part at a level higher than an amplitude level based on a predetermined clipping level is clipped from an input signal, separating the input signal into an input signal after the clipping, which contains a predetermined out-of-band component, and a clip signal clipped from the input signal through the clipping, and outputting the input signal after the clipping and the clip signal; a high-pass filter subjecting the clip signal inputted from the limiter to high-pass filtering for blocking an in-band component contained in the clip signal while passing an out-of-band component contained in the clip signal, which is opposite in phase to the out-of-band component contained in the input signal after the clipping; an adder performing an addition process on the out-of-band component received from the high-pass filter and the input signal after the clipping received from the limiter; and an amplifier performing power amplification on a signal outputted from the adder, and outputting the amplified signal.

An apparatus and method of automatically compensating audio volume in response to a channel change. The method includes generating a gain value to adjust a level of an input audio signal by comparing an average level of the input audio signal with a predetermined input / output level curve, adjusting an audio volume of the input audio signal by applying the generated gain value to the level of the input audio signal, and adjusting a dynamic range of the audio signal having the adjusted audio volume.

The invention relates a method and apparatus for protecting electro dynamic transducer from heat overload. In an embodiment of the invention, the voice coil of an electro dynamic transducer is protected by measuring the power of the input audio signal. When a predetermined power limit is reached by the input audio signal, the power of the input audio signal is reduced.

A class D amplifier (1) comprises an input unit (11) for receiving a digital input signal (Vin), a pulse shaping unit (12) for producing pulse shaped signals in dependence of the input signal (Vin), a comparator unit (13) for comparing the pulse shaped signals and producing a comparator signal, a driver unit (14) for producing driver signals in dependence of the comparator signal, a switching output unit (15) for producing a pulse width modulated output signal (Vout) in dependence of the driver signals, and a feedback unit (16) for feeding the output signal (Vout) back to the pulse shaping unit (12). The input unit (11) comprises a clipping control unit (10) for controlling the duty cycle of the pulse width modulated output signal (Vout).

The present invention provides an apparatus and method of automatically compensating audio volume in response to a channel change. The method includes generating a gain value to adjust a level of an input audio signal by comparing an average level of the input audio signal with a predetermined input / output level curve, adjusting an audio volume of the input audio signal by applying the generated gain value to the level of the input audio signal, and adjusting a dynamic range of the audio signal having the adjusted audio volume.

A class D amplifier (1) comprises an input unit (11) for receiving a digital input signal (Vin), a pulse shaping unit (12) for producing pulse shaped signals in dependence of the input signal (Vin), a comparator unit (13) for comparing the pulse shaped signals and producing a comparator signal, a driver unit (14) for producing driver signals in dependence of the comparator signal, a switching output unit (15) for producing a pulse width modulated output signal (Vout) in dependence of the driver signals, and a feedback unit (16) for feeding the output signal (Vout) back to the pulse shaping unit (12). The input unit (11) comprises a clipping control unit (10) for controlling the duty cycle of the pulse width modulated output signal (Vout).

A peak level of amplitude of transmission signals in a multi-carrier communication system or the like is to be effectively suppressed. A transmission data generating unit generates digital transmission data from original data by an OFDM system. A limiter of a peak suppressing unit limits a level of transmission data using thresholds. A subtractor subtracts output data of the limiter from the transmission data to generate differential data. A subtractor suppresses the peak level by subtracting the differential data from transmission data whose timing is coordinated by delay units. A transmitter unit converts the transmission data whose peak level is suppressed into analog transmission signals, further converts their frequency, amplifies their power, and transmits the frequency-converted and power-amplified signals to a radio line via an antenna.

Improved methods and devices for processing low-frequency audio data are provided. A bass extraction process may involve applying low-pass filters to received audio object signals, to produce extracted low-frequency audio signals. The bass extraction process may be performed prior to a process of rendering audio objects into speaker feed signals. A bass management process may involve routing the extracted low-frequency audio signals to the one or more speakers capable of reproducing low-frequency audio signals.

A method for limiting peak-to-average power of a signal transmitted from a power amplifier. The method comprises: applying a pulse-shape filter to a first signal, thereby generating a second signal being a filtered version of the first signal; and outputting the second signal for transmission from a power amplifier. The method further comprises: applying each of a plurality of predictor filters to a respective instance of the first signal, each predictor filter approximating the application of the pulse-shape filter to the first signal based on a different respective set of filter coefficients, and each thereby generating a respective third signal. The method also further comprises determining an indicator of amplitude of each of the third signals, selecting the indicator corresponding to the largest of those amplitudes, generating a modifier based on the selected indicator, and using the modifier to limit the first signal prior to applying the pulse-shape filter.

A system and method for enhancing the real and / or perceived bass band of an audio signal is disclosed. A computationally simple yet effective bass band enhancement system for use in consumer electronics applications is disclosed. An audio processing system including bass enhancement functionality for use in a mobile audio system is disclosed.

A method and apparatus for limiting the absolute magnitude of an audio signal. The method may include firstly variable-gain reducing the gain of an audio signal, and then secondly variable-gain reducing the gain of the audio signal faster than the first variable-gain reduction, thereby limiting the absolute magnitude of the audio signal to a threshold. The first variable-gain reduction may include variable-gain reducing the gain of the audio signal in a first stage, and the second variable-gain reduction may include variable-gain reducing the gain of the audio signal in a second stage that reduces the gain faster than the first stage. The second variable-gain reduction may include delaying the audio signal, finding a peak among the delayed audio signal, calculating a fast gain from a found peak, and modifying the delayed audio signal with the calculated fast gain.

Example embodiments provide a process that includes one or more of receiving an audio signal at a feedback compressor circuit, determining how much to attenuate the audio signal when a power level of the audio signal exceeds a threshold power level, combining the audio signal with an auxiliary attenuation signal from an auxiliary attenuation source and a compressed attenuation signal from the feedback compressor circuit to create a combination signal, and generating an audio output signal of the feedback compressor circuit based on the combination signal.

Systems and methods for amplitude compressing a digital signal. An input signal is divided into frames having a first and second sets of samples. The samples in the second set are also in a subsequent frame. Peak values are determined for the first and second sets. One or more slopes are calculated based on the peak values. The slopes are used to define a scale factor which is applied to the first set to produce the output signal. For example, if the first peak value exceeds an amplitude threshold, first and last samples in the first set to exceed the amplitude threshold are found. Slopes are calculated for each of three regions of the first set demarcated by the first and last samples. In each region a slope is selected. These slopes along with an initial scale factor are used to calculate the scale factor.

Methods and apparatus in a near-field communication system, in which a modulated signal received in a Reader is clipped by applying upper and lower clip levels. After clipping, the modulated part of the signal corresponds to a greater portion of the overall signal, and thus the requirements placed on an analogue-to-digital converter for the clipped signal are reduced. In a first mode of operation, prior to or at the start of reception of the load-modulated signal, the clip levels may be set in a feedforward manner on the basis of preset values or a detected change in the overall signal; in a second mode of operation, once the clipped signal is available, the clip levels may be set in a feedback manner on the basis of the clipped signal.

A limiting circuit includes an input transconductance stage, an output transconductance stage, a feedback transconductance stage, first and second resistive loads, and a level limiting circuit. The input transconductance stage is operably coupled to convert an input voltage signal into an input current signal. The first resistive load is operably coupled to convert the input current signal and a feedback current signal into an intermediate output voltage signal. The output transconductance stage is operably coupled to convert the intermediate output voltage signal into an output current signal. The second resistive load is operably coupled to convert the output current signal into an output voltage signal. The feedback transconductance stage is operably coupled to produce the feedback current signal based on the output voltage signal. The level limiting module is operably coupled to limit at least one voltage level of the feedback transconductance stage.

A method and apparatus for limiting the absolute magnitude of an audio signal. The method may include firstly variable-gain reducing the gain of an audio signal, and then secondly variable-gain reducing the gain of the audio signal faster than the first variable-gain reduction, thereby limiting the absolute magnitude of the audio signal to a threshold. The first variable-gain reduction may include variable-gain reducing the gain of the audio signal in a first stage, and the second variable-gain reduction may include variable-gain reducing the gain of the audio signal in a second stage that reduces the gain faster than the first stage. The second variable-gain reduction may include delaying the audio signal, finding a peak among the delayed audio signal, calculating a fast gain from a found peak, and modifying the delayed audio signal with the calculated fast gain.

An audio driver comprising a distortion detection unit coupled between an amplifier and a loudspeaker and configured to detect a distortion signal generated by the loudspeaker while the loudspeaker is being used to deliver an audio signal from the amplifier. A distortion compensation unit configured to compensate for the distortion signal without interfering with the audio signal.

The invention discloses an audio amplitude limiting method and system, and belongs to the field of digital audio signal processing and audio amplitude limiting, and the method comprises the steps: calculating an average gain value corresponding to each frame of digital audio signal according to a digital signal of a preset frame length after the digital audio signal of the preset frame length is obtained; and processing the digital audio signal with the preset frame length according to the calculated average gain value to obtain an amplitude-limited digital audio signal. Under the condition that the amplitude of the audio signals lower than the threshold value is not changed, the amplitude of the audio signals exceeding the threshold value is limited within the set threshold value range, truncated distortion is not generated, and high real-time performance is achieved. And the quality of the digital audio signal is ensured, and better experience is brought to a user.

The invention provides a concept for combined dynamic range compression and guided clipping prevention for audio devices. An audio decoder for decoding an audio bitstream and a metadata bitstream related to the audio bitstream according to the concept includes an audio processing chain including a plurality of adjustment stages including a dynamic range control stage for adjusting a dynamic range of the audio output signal and a guided clipping prevention stage for preventing clipping of the audio output signal; and a metadata decoder configured to receive the metadata bitstream and to extract dynamic range control gain sequences and guided clipping prevention gain sequences from the metadata bitstream, at least a part of the dynamic range control gain sequences being supplied to the dynamic range control stage, and at least a part of the guided clipping prevention gain sequences being supplied to the guided clipping prevention stage.

An apparatus and method for preventing an acoustic shock of a portable terminal are disclosed. The apparatus includes a transceiver gain determining unit including a table of gain values for sound signals in each of one or more call modes, configured to output a particular gain value corresponding to a particular call mode; a reference value determining unit configured to receive the gain value from the transceiver gain determining unit, monitor a change in the gain value, and determine a predetermined reference energy value based on the change in the gain value; and an output level adjusting unit configured to receive an input signal, compare the input signal with the predetermined reference energy value, and adjust the level of the input signal to output an output signal.

A transmitter includes: a limiter performing clipping in which an amplitude part at a level higher than an amplitude level based on a predetermined clipping level is clipped from an input signal, separating the input signal into an input signal after the clipping, which contains a predetermined out-of-band component, and a clip signal clipped from the input signal through the clipping, and outputting the input signal after the clipping and the clip signal; a high-pass filter subjecting the clip signal inputted from the limiter to high-pass filtering for blocking an in-band component contained in the clip signal while passing an out-of-band component contained in the clip signal, which is opposite in phase to the out-of-band component contained in the input signal after the clipping; an adder performing an addition process on the out-of-band component received from the high-pass filter and the input signal after the clipping received from the limiter; and an amplifier performing power amplification on a signal outputted from the adder, and outputting the amplified signal.

A digital and / or analog signal processing system and method for auditory enhancement and hearing conservation includes providing an audio signal with high intensity peaks, clipping the audio signal by limiting peak power to produce a clipped signal, and amplifying the clipped signal.