348results about "Limiting amplitude" patented technology

The present invention is directed to a method and system for automatic calibration of an acoustic system. The acoustic system may include a source A / V device, calibration computing device, and multiple rendering devices. The calibration system may include a calibration component attached to each rendering device and a source calibration module. The calibration component on each rendering device includes a microphone. The source calibration module includes distance and optional angle calculation tools for automatically determining a distance between the rendering device and a specified reference point upon return of the test signal from the calibration component.

Loudspeakers can be damaged by high drive signals. One reason for this damage is an excess vibration displacement of the coil-diaphragm assembly. This invention describes a novel method for limiting this displacement by a signal processor. In the present invention, a low frequency shelving and notch filter is used to attenuate low frequencies according to a prediction of the loudspeaker displacement. A novel method for calculating coefficient values for a digital implementation of the low frequency shelving and notch filter according to the predicted displacement is described.

An arrangement and method for converting an input signal z(t) into a mechanical or acoustical output signal p(t) comprising an electro-magnetic transducer using a coil at a fixed position and a moving armature, a sensor, a parameter measurement device and a controller. The parameter measurement device identifies parameter information P of an nonlinear model of the transducer considering and the saturation and the geometry of the magnetic elements. A diagnostic system reveals the physical causes of signal distortion and generates information for optimizing the design and manufacturing process of this transducer. The controller compensates for nonlinear signal distortion, stabilizes the rest position of the armature and protects the transducer against mechanical and thermal overload.

An arrangement and method for converting an input signal into a mechanical or acoustical output signal by using a transducer and additional means for generating a desired transfer behavior and for protecting said transducer against overload. Transducers of this kind are for example loudspeaker, headphones and other mechanical or acoustical actuators. The additional means comprise a controller, a power amplifier and a detector. The detector identifies parameters of the transducer model if the stimulus provides sufficient excitation of the transducer. The detector permanently identifies time variant properties of the transducer for any stimulus supplied to the transducer. The controller provided with this information generates a desired linear or nonlinear transfer behavior; in particular electric control linearizes, stabilizes and protects the transducer against electric, thermal and mechanical overload at high amplitudes of the input signal.

The present application relates in one aspect to a method of controlling diaphragm excursion of an electrodynamic loudspeaker. The method comprises dividing the audio input signal into at least a low-frequency band signal and a high-frequency band signal by a band-splitting network and applying the low-frequency band signal to a diaphragm excursion estimator. The instantaneous diaphragm excursion is determined based on the low-frequency band signal. The determined instantaneous diaphragm excursion is compared with an excursion limit criterion. The low-frequency band signal is limited based on a result of the comparison between the instantaneous diaphragm excursion and the excursion limit criterion to produce a limited low-frequency band signal which is combined with the high-frequency band signal to produce an excursion limited audio signal.

The present invention is directed to a method and system for automatic calibration of an acoustic system. The acoustic system may include a source A / V device, calibration computing device, and multiple rendering devices. The calibration system may include a calibration component attached to each rendering device and a source calibration module. The calibration component on each rendering device includes a microphone. The source calibration module includes distance and optional angle calculation tools for automatically determining a distance between the rendering device and a specified reference point upon return of the test signal from the calibration component.

Microelectromechanical RF and microwave frequency power limiter and electrostatic protection devices for use in high-speed circuits are presented. The devices utilize an airbridge or a cantilever arm including a contact pad positioned operatively adjacent to an electrically conductive and substantially planar transmission line. When the power level in the transmission line exceeds a particular threshold, the airbridge or cantilever arm yields due to force between the contact pad and the transmission line, directing undesired power away from active devices. This characteristic can either serve as a method by which to limit the amount of power passing through the transmission line to a determined value or as a method by which to protect devices along the transmission line from damage due to large electrostatic bursts.

A monolithic integrated circuit (IC), and method of manufacturing same, that includes all RF front end or transceiver elements for a portable communication device, including a power amplifier (PA), a matching, coupling and filtering network, and an antenna switch to couple the conditioned PA signal to an antenna. An output signal sensor senses at least a voltage amplitude of the signal switched by the antenna switch, and signals a PA control circuit to limit PA output power in response to excessive values of sensed output. Preferred fabrication techniques include stacking multiple FETs to form switching devices. An iClass PA architecture is described that dissipatively terminates unwanted harmonics of the PA output signal. A preferred embodiment of the RF transceiver IC includes two distinct PA circuits, two distinct receive signal amplifier circuits, and a four-way antenna switch to selectably couple a single antenna connection to any one of the four circuits.

A pulse-width modulation (PWM) amplifier is adapted to a class-D amplifier in which an analog input signal is subjected to integration, pulse-width modulation, and switched amplification, wherein a glitch elimination circuit eliminates noise from a pulse-width modulated signal, from which a high pulse signal and a low pulse signal are isolated such that each pulse is delayed by a dead time at the leading-edge timing thereof. When both of them are simultaneously set to a high level, one of them is reduced in level. In response to the occurrence of clipping, an integration constant applied to an operational amplifier is automatically changed from a primary integration constant to a secondary integration constant. When the clipped state is sustained for a prescribed time, an inversion pulse is compulsorily introduced into the pulse-width modulated signal.

Low-frequency bandwidth extension in the form of dynamic electrical equalization may be applied to loudspeakers so long as the excursion capability of their drive units as well as velocity limits of any port(s) or excursion limits of any associated passive radiator(s), and the power limits of the drive units are not exceeded. The bandwidth extension maximizes low-frequency bandwidth dynamically such that excursion is fully utilized over a range of drive levels, without exceeding the excursion limit. Additional limiting control is available for port air velocity or passive radiator excursion, and loudspeaker drive unit electrical power. The system applies to open back, closed box, vented box, and more complex box constructions consisting of combinations of these elements for loudspeaker designs using design parameters appropriate to each system.

This invention relates to the mechanical protection using digital processing and a predictive estimation of instantaneous displacement of the voice coil in a loudspeaker transducer.The invention solves the problem of limiting the coil displacement of the transducer by applying a look-a-head based linear or non-linear predictor and a controller operating directly on the displacement signal in order to finally convert back into the incoming signal domain.

Loudspeakers can be damaged by high drive signals. One reason for this damage is an excess vibration displacement of the coil-diaphragm assembly. This invention describes a novel method for limiting this displacement by a signal processor. In the present invention, a low frequency shelving and notch filter is used to attenuate low frequencies according to a prediction of the loudspeaker displacement. A novel method for calculating coefficient values for a digital implementation of the low frequency shelving and notch filter according to the predicted displacement is described.

A system and method for prioritizing multiple audio sources and balancing them in a single combined output in a handheld device. Audio sources are sensed and combined with the level of each source subject to adjustment by an attenuator / amplifier. A priority logic unit controls the attenuator / amplifier associated with each source. the level of each source being combined is adjusted on the basis of the character of the sources being combined and a set of programmed rules. For example, if source A is a high priority source (e.g. a telephone ring or other alert tone) and source B is a lower priority source (e.g. a music program) then the sound management system may lower the volume on source B combine with source A and output the result. Alternatively, source A may be raised in volume, combined with source B, and then output. In one embodiment, the sound management system is integrated with a palm sized handheld computer system.

An audio device, for example a wireless communications handset, including a sound transducer (410) coupled to a compensated audio signal output of an audio compensator (450), a mismatch detection circuit (430) having a first input coupled to the compensated audio signal output of the audio compensator (450), the mismatch detection circuit (430) having a second input coupled to the sound transducer (410), the mismatch detecting circuit having an output corresponding to a mismatch between a reference electrical impedance of the sound transducer and an actual electrical impedance of the sound transducer, a compensation estimator (440) having an input coupled to the output of the mismatch detection circuit, the compensation estimator having an audio compensation output coupled to a compensation input of the audio compensator.

A method and apparatus is described for controlling conduction between two nodes of an integrated circuit via a stack of FETs of common polarity, coupled in series. In an RF Power Amplifier (PA) having appropriate output filtering, or in a quad mixer, stacks of two or more FETs may be used to permit the use of increased voltages between the two nodes. Power control for such RF PAs may be effected by varying a bias voltage to one or more FETs of the stack. Stacks of three or more FETs may be employed to control conduction between any two nodes of an integrated circuit.

An apparatus for and method of extending the dynamic range of a RF communications receiver. The invention provides a mechanism for controlling the gain of both the LNA and down conversion mixer in the front end portion of an RF receiver. Both the LNA and the mixer are adapted to have both low and high gain modes of operation. The control mechanism typically comprises a two bit gain control that places both the LNA and mixer in one of four operating gain mode states. The selection of the most appropriate operating gain mode state, is preferably determined in accordance with various metrics such as the received levels of the desired signal, levels of interference signals, bit error rate and receiver RSSI.

A voltage supply circuit comprises a voltage control circuit for outputting a bias voltage control signal according to a set value based on a bias voltage of a sensor and a voltage generation circuit for generating the bias voltage to be applied to the sensor based on the bias voltage control signal.

A monolithic integrated circuit (IC), and method of manufacturing same, that includes all RF front end or transceiver elements for a portable communication device, including a power amplifier (PA), a matching, coupling and filtering network, and an antenna switch to couple the conditioned PA signal to an antenna. An output signal sensor senses at least a voltage amplitude of the signal switched by the antenna switch, and signals a PA control circuit to limit PA output power in response to excessive values of sensed output. Preferred fabrication techniques include stacking multiple FETs to form switching devices. An iClass PA architecture is described that dissipatively terminates unwanted harmonics of the PA output signal. A preferred embodiment of the RF transceiver IC includes two distinct PA circuits, two distinct receive signal amplifier circuits, and a four-way antenna switch to selectably couple a single antenna connection to any one of the four circuits.

Methods and systems for thermal protection of a voice coil of a loudspeaker. The method involves driving the loudspeaker based on an input signal received at an input terminal and monitoring both a voltage applied to the voice coil and a current flowing through the voice coil. From the monitored voltage and current, an estimate of temperature of the voice coil and an estimate of power dissipation in the voice coil is determined. The method includes estimating the voice coil resistance based on the monitored voltage and current and at least the estimate of temperature is determined based the estimate of resistance. A gain control signal for modulating a gain applied to the input signal is generated as a function of both the estimate of temperature of the voice coil and the estimate of power dissipation in the voice coil. This means that high power dissipation, which would over long periods lead to overheating, can nevertheless be permitted when the voice coil temperature is low enough, while at high voice coil temperatures any gain modulation applied for thermal protection can be reduced if the power dissipation level drops.

The clamp circuit clamps an input voltage at prescribed higher and lower clamp voltages which are stabilized under a temperature fluctuation. Transistors Q12 and Q14 are switched on in their linear region. In a lower voltage clamp circuit 18, an Vin detecting circuit 20 outputs Va1 by level-shifting Vin by Q13 and voltage-divides by series resistance circuit 23 the level-shifted Vin, while a reference voltage generating circuit 21 outputs Vr1 by level-shifting 0 V by Q15 and voltage-divides by series resistance circuit 25 the level-shifted voltage. Q11 is switched on, when a comparator 22 determines that Va1 descends and goes across Vr1. Here, Q12 is of the same characteristics as Q14, while Q13 is of the same characteristics as Q15. Further, the resistance of the circuits 23 is the same as that of the circuit 25. The higher voltage clamp circuit 19 is similar to the circuit 18.

A loudspeaker protection system includes a filter arrangement for defining one or more frequency bands of an audio signal, controllable amplifier / attenuator combinations coupled to the filter arrangement, and a processing arrangement coupled to control the amplifier / attenuator combinations, such as to determine audio power in at least one of the frequency bands representing relevant loudspeaker protection information used for selective audio power control in the at least one frequency band. This system has the features for a fast and / or slow thermal protection, as well as for a cone excursion protection, all for a loudspeaker in such a system.

An impedance matching apparatus has: a storing portion 70 for previously storing, for plural positions which can be taken by a movable portion of a variable impedance element, allowable power values respectively corresponding to the plural positions of the movable portion; and an abnormality determining portion 80 for determining an allowable power value based on the present positions of the movable portion supplied from position detecting portions 41, 42 and the allowable power values stored in the storing portion 70, for comparing the allowable power value with an input power value, and for determining that it is abnormal when the input power value is larger than the allowable power value. Accordingly, the calculation load during the matching operation can be reduced.

A piezoelectric device is provided with a sound source IC, an amplifier for amplifying a sound source from the sound source IC, a piezoelectric speaker for generating sound based on a drive signal from amplifier, an MPU for performing a predetermined control process on the drive signal, a memory for storing temperature dependency information about the piezoelectric constant (d14) and Young's modulus E of the piezoelectric speaker, and a temperature sensor for detecting an ambient temperature. MPU has correcting unit, compares a detected result of the temperature sensor with the temperature dependency information, and performs temperature correction on the drive signal serving as an acoustic signal based on a compared result. The piezoelectric speaker outputs the acoustic signal temperature-corrected by correcting unit. Thus, it becomes possible to realize various piezoelectric devices, such as a piezoelectric speaker system, capable of preventing various input information from fluctuating even when there is a change in usage environmental temperature.

An apparatus comprising at least a first microphone with a first acoustic sensitivity to provide a first microphone signal and a second microphone with a lower second acoustic sensitivity to provide a second microphone signal, that apparatus furthermore comprises a signal processor that is built to process the first microphone signal to be recorded and / or transmitted and an overload detector to detect an overload of the first microphone signal and wherein the signal processor in case of a detected overload is built to process the second microphone signal to substitute the first microphone signal to be recorded and / or transmitted during the time period in which the overload of the first microphone signal is detected, which apparatus furthermore comprises at least a first speaker built to receive a first speaker signal and transform it into acoustic sound, in a speaker mode of the first speaker, while the apparatus is built to use the first speaker as second microphone, in a microphone mode of the first speaker.

An audio peak limiter in which the lower sideband of the modulation distortion spectrum is canceled. The peak limiter is realized by multiplying the input signal by a control signal. The Hilbert transform of the control signal is multiplied by the Hilbert transform of the input signal and the outputs of the two multipliers are added. This cancels the lower sideband of the modulation process. Various filters can be added to eliminate aliasing in digital realizations, to band-limit the output signal, and to control peak overshoot.

An arrangement and method for converting an input signal z(t) into a mechanical or acoustical output signal p(t) comprising an electro-magnetic transducer using a coil at a fixed position and a moving armature, a sensor, a parameter measurement device and a controller. The parameter measurement device identifies parameter information P of an nonlinear model of the transducer considering and the saturation and the geometry of the magnetic elements. A diagnostic system reveals the physical causes of signal distortion and generates information for optimizing the design and manufacturing process of this transducer. The controller compensates for nonlinear signal distortion, stabilizes the rest position of the armature and protects the transducer against mechanical and thermal overload.

An apparatus for and method of extending the dynamic range of a RF communications receiver. The invention provides a mechanism for controlling the gain of both the LNA and down conversion mixer in the front end portion of an RF receiver. Both the LNA and the mixer are adapted to have both low and high gain modes of operation. The control mechanism typically comprises a two bit gain control that places both the LNA and mixer in one of four operating gain mode states. The selection of the most appropriate operating gain mode state, is preferably determined in accordance with various metrics such as the received levels of the desired signal, levels of interference signals, bit error rate and receiver RSSI.

The presence or absence of a speaker connected to an output terminal of an audio system is determined based on the electro-generator properties of the speaker. The audio system includes an output amplifier coupled to the output terminal. The method includes driving the output amplifier with a predetermined drive signal sufficient to produce a predetermined speaker excursion if a speaker is connected to the output terminal. The output amplifier is then isolated from the output terminal. A signal at the output terminal is sensed after the output amplifier is isolated. The sensed signal is compared with a predetermined reference for determining whether a speaker back-EMF is present. A speaker detection signal is generated indicating absence of a speaker if the back-EMF is not present.