Abstract: A method and apparatus to provision a network node such as a network appliance is described.

Abstract: The present invention comprises a circuit having at least not less than three cascade connected phase shift circuits and wherein the phase characteristic of the circuit is determined in such a manner that the phase of the audio input signals is gradually delayed depending on logarithmic increase of frequencies in a range of audible frequencies and a phase delay in a range of 450 degree˜600 degree in total in the range of audible frequencies is caused.

Abstract: A sound reproduction system comprising a digital audio signal input (1), a digital audio signal processor (2, DSP) and a digital audio signal output (3) wherein the digital signal processor (2, DSP) comprises a high pass (HP) filter (21) with a high pass frequency (f), an amplifier (22) for a signal filtered by the HP filter, and a low pass (LP) filter (23) with a low pass frequency (f) for filtering the signal after amplification by the amplifier (22) and for providing an output signal, and the digital processor comprises an establisher (24, 25) for establishing the high pass frequency or the low pass frequency and a matcher (26) for matching the high pass frequency and low pass frequency of the high pass filter and low pass filter respectively to each other.

Abstract: A digital audio signal processing system and method transforms two-channel stereo time-domain data into the frequency domain. Vector operations are performed upon the frequency-domain data by which signal components unique to one of the input channels are routed to one of the output channels, signal components unique to the other of the input channels are routed to another of the output channels, and signal components common to both channels are routed to a third and optionally to a fourth output channel. The frequency-domain output channels are then transformed back into the time-domain, forming an equivalent number of channels of output audio data. The vector operations are performed in a manner that preserves the overall information content of the input data.

Abstract: To improve upon a method of adjusting at least one filter parameter such as the mid-frequency of at least one filter unit provided with a playback system for audio signals, this filter unit being provided in particular for at least one digital equalizer assigned to the playback system, as well as an associated playback system so as to achieve automatic optimization of an acoustically correct bass level boosting, [a] first the acoustic frequency response is determined, [b] then a cutoff frequency below which the sound pressure falls below a sound pressure threshold level based on the average sound pressure is determined, and [c] next the filter parameter(s) of the filter unit is/are adjusted automatically, so that the mid-frequency of the filter unit is just above the cutoff frequency thus determined.

Abstract: A clock generator circuit, comprising: a multi-phase clock signal generator for generating a plurality of clock signals having a same frequency but difference phases according to a reference clock signal; a modulation device for generating a phase modulation signal through Delta-Sigma modulation; and a phase modulator, which is electrically coupled to the modulation device, for selecting one of the clock signals to be a modulated clock signal according to the phase modulation signal.

Abstract: A tone-boost circuit for boosting a range of frequencies of an input signal without “clipping” of the signal is disclosed comprising an amplifier, a limiter, having at least one pre-determined limiter threshold, a first filter and a signal adder, the signal adder adding the output of the first filter with the original input signal. Further modifications include incorporating a second filter for filtering the input signal before being added to the output of the first filter, a third filter for filtering the input signal before amplification and a dynamic implementation of the amplifier. The circuit may be implemented in analogue or digital and is particularly relevant for bass-boost audio circuits.

Abstract: An improvement to inventor's prior art loudspeaker crossover filter invention is described. A substantially flat network input-impedance characteristic across the audible frequency range is provided by the addition of at least one series connected constant resistance network at the input terminals of the crossover filter system. By relaxing certain infinite slope filter parameters, more uniform acoustic polar response of the loudspeaker system is obtained. Specifically, infinite slope methods are used for the upper (higher frequency) band-edge of low-pass and band-pass filters, and optionally, for high-pass filters. Infinite slope characteristics, however, are relaxed for the lower frequency slope of band-pass filters and, optionally, for high-pass filters. In addition, the crossover network uses fewer components than infinite slope crossovers of the prior art.

Abstract: The present invention relates to a method for embedding a watermark into a black and white or color digital image [D(x)]. Basically the inventive method comprises the steps of transforming the digital image using a wavelet transform [WC(y)], transforming a watermark using discrete cosine transform (DCT), integrating the wavelet-transformed digital image with the DCT-transformed watermark [DW(x)+WC(y)] to insert the watermark into the image, and generating the watermarked image using inverse wavelet transform [D(x)?]. For color images, RGB mode is converted into YIQ mode using a conversion matrix and the wavelet transform is applied to the Y-, I-, Q-values. This inventive digital watermarking of a color image is found to be highly robust against lossy compression and other image processing operations, compared to conventionally known methods which are known to be unsuitable for watermarking color images.

Abstract: A circuit and method provides for the protection of transducers from over excursion, particularly for the protection of transducers for audio loudspeakers. A frequency dependent excursion limiter circuit has an initial summing stage followed by a shaping filter stage. A clamping function is provided at the summing stage, or at a separate stage between the summing stage and the shaping filter stage, for clamping the driving signal at a predetermined maximum voltage if the driving signal exceeds the predetermined maximum voltage level. The shaping filter stage provides a frequency response shaping function based on a predetermined frequency response shaping criteria which is related to the frequency dependent excursion limits of the transducers being protected from mechanical overload. An inverse shaping filter function is provided at the initial summing stage by providing feedback from the shaping filter stage, thus eliminating the need for a separate inverse shaping filter circuit before clamping.

Abstract: A driver control circuit (10) that enhances a steep crossover slope while permitting selective shaping or adjusting of its in-band frequency response with a minimum number of components. The driver control circuit includes a signal connector (16) for connecting with a source of audio signals (12); a speaker connector (18) for connecting with a speaker (14); and a frequency passing circuit (20) coupled between the signal connector (16) and the speaker connector (18) for passing a selected range of frequencies of the audio signals to the speaker (14) and for attenuating other frequencies. The frequency passing circuit (20) includes components forming a traditional low-pass or high-pass filter network and a resistive component (R1) connected in parallel across the second series mounted component of the low-pass or high-pass filter network.

Abstract: For a phase-locked loop, disclosed is a method (and corresponding apparatus) for reducing electromagnetic interference caused by a clock signal produced by a voltage controlled oscillator, the method comprising: generating a control signal having a first type, e.g., sinusoidal, of slight variation in magnitude relative to a nominal magnitude value thereof; and providing the slightly varying control signal to a voltage-controlled oscillator (“VCO”) to obtain a clock signal exhibiting a second type, e.g., sinusoidal, of slight variation in frequency relative to a nominal frequency value thereof. The slight variation is non-negligible.

Abstract: A circuit for providing a variable amount of bass control on an input signal dependent on a signal level of the input signal includes a high-pass filter, a variable impedance shunt connected to the output of the high-pass filter, and a signal level detector for controlling the variable impedance shunt. Depending on the signal level, the variable impedance shunt varies the Q value of the high-pass filter so that at low signal levels, the Q value is at its maximum while at high signal values, the Q value is lowered.

Abstract: An SC filter with intrinsic anti-alias function for adjustably decreasing or increasing the amplitude of audio signals in a predetermined frequency range. The SC filter includes a filter module having an RC network with at least one frequency-response-determining RC member whose resistor component R is realized in SC technology. The SC filter also includes a setting means connected to the filter module such that its setting determines the frequency response of the SC filter. The setting means also renders possible a neutral setting in which the effective audio signal path of the SC filter circumvents the filter module so that no decrease or increase of the amplitude of individual frequency portions takes place. An anti-alias low pass filter unit is connected into the audio signal path when the setting means is not set to the neutral setting and the anti-alias low pass filter unit is not located in the audio signal path when the setting means is set to the neutral setting.

Abstract: A driver control circuit (10) that enhances a steep crossover slope while permitting selective shaping or adjusting of its in-band frequency response with a minimum number of components. The driver control circuit includes a signal connector (16) for connecting with a source of audio signals (12); a speaker connector (18) for connecting with a speaker (14); and a frequency passing circuit (20) coupled between the signal connector (16) and the speaker connector (18) for passing a selected range of frequencies of the audio signals to the speaker (14) and for attenuating other frequencies. The frequency passing circuit (20) includes components forming a traditional low-pass or high-pass filter network and a resistive component (R1) connected in parallel across the second series mounted component of the low-pass or high-pass filter network.

Abstract: The present invention relates to an active analog filter including a differential amplifier, an output of which provides a filtered signal and a non-inverting input of which is connected to a median potential between supply potentials of the amplifier, a first series association of a first fixed resistor and a first variable resistor between an input terminal of a signal to be filtered and an inverting input terminal of the amplifier, a second series association of a second fixed resistor and a second variable resistor between the output of the amplifier and its inverting input terminal, and a third variable resistor in series with a filtering capacitor, between a midpoint of one of the series associations and the median potential.

Abstract: A self-tracking bandpass filter (1) comprises a controllable filter (10) having a signal input (11) for receiving a signal (&phgr;) to be filtered, a bandpass output (13) for providing a bandpass signal (SBP) having a center frequency (f0), and a control input (15) for receiving a control signal (SC); and a control unit (20) coupled to the control input (15) of the controllable filter (10), adapted to generate the control signal (SC) in such a way that the center frequency (f0) of the bandpass characteristic (HB) of the controllable filter (10) is substantially equal to the frequency (f) of the input signal (&phgr;).

Abstract: To improve the aural sensation from an input signal of an audio reproduction system a bandwidth extension device can be used.

Abstract: A crossover network for partitioning by frequency and electrical audio signal from an amplifier into a plurality of frequency bands for presentation to respective drivers or transducers. Such a crossover network couples the respective transducers in a parallel fashion thereby locking the in-phase relationships of signals presented to the respective transducers. The present facilitates a smooth transition between high and low frequencies without creating an abrupt crossover region wherein the phase relationships interject distortion.

Abstract: The invention is an audio compression system for reducing distortion arising primarily from excessive loudspeaker excursion. For a given input audio signal, the maximum signal magnitude (or envelope, energy or power) level above which the loudspeaker will begin to distort is dependent upon the frequency content of the signal. In this invention, the input audio signal is filtered and the magnitude (or envelope, energy or power) level of the filtered signal is compared to a single, constant threshold level. The input audio signal is subsequently compressed only if the magnitude (or envelope, energy or power) level of the filtered audio signal exceeds the threshold value. In one embodiment, the filter has a frequency response which models the excursion response of the loudspeaker in question, and which can be obtained analytically for various types of loudspeakers.

Abstract: A split-band clipper which generates less distortion, minimizes or reduces the occurrence of all IMD, or at least will minimize and reduce the occurrence of widely space IMD, and reduce the quantity of harmonic distortion caused by clipping of bass frequencies.

Abstract: In a power amplifier, a control device employing a dual ganged potentiometer is connected in the feedback circuits of successive amplifier stages to increase the gain of the front end stage while simultaneously reducing the gain in a subsequent stage when the control is turned down. A distortion circuit, such as a tube compression circuit, is coupled between the stages. When the control is turned down, the compression circuit is activated at a lower level that effectively reduces the output power of the second stage. Presence and resonance controls may be provided to tailor high and low frequency damping factor of the second stage and function until the compression circuitry is activated. A ripple reduction filter is provided in a filtered supply for the drivers in the second or power amplifier stage.

Abstract: A speaker excursion control circuit for driving relatively small diameter speakers at their maximum output while assuring minimum distortion of acoustical output from such transducers detects signals which may cause over excursion and dynamically controls the amplitude of signals applied to the power amplifier coupled to the speakers. In one embodiment of the invention a single state-variable filter is employed with a voltage controlled amplifier controlled by a low pass output of the state-variable filter to provide the speaker signal control. In another embodiment, a pair of state-variable filters are employed with the first of such filters defining a model for the speaker cone excursion and providing control output signals to a second state-variable filter which dynamically shifts its filtering characteristics causing increased signal attenuation when the control signals indicate that speaker over excursion may occur.

Abstract: An audio crossover system having two crossover networks, one suited to the auditory preferences of women and the other to the auditory preferences of men. The former attenuates mid-range frequencies more than high-range frequencies and attenuates low-range frequencies still more. The latter attenuates mid-range frequencies more than low-range frequencies and attentuates high-range frequencies even more than those in the mid-range.

Abstract: A telephone privacy device includes first and second connectors that are mateable with a telephone handset and a telephone base, respectively. The handset includes a microphone, and the device includes a variable amplifier that allows the user to amplify the microphone signal to a desired level prior to sending it on to the base. A signal strength display allows the user to monitor the amplitude of the amplified microphone signal. A side tone suppression circuit generates a side tone suppression signal in response to the amplified microphone signal. This side tone suppression signal is used to reduce excessive side tone from the telephone base. An adjustable gain amplifier amplifies the speaker signal supplied by the base for the handset speaker.

Abstract: Electronic crossover audio systems and methods in accordance with the invention provide flat frequency response and the feeling of three-dimensional music reproduction with a well defined image of the placement of various instruments, the vocal source across the sound stage, and a distinct impression of good depth of feel. A four submodule crossover module capable of serially chaining and having a fourth submodule for front and rear center monaural outputs provides infinite segmentation and modification of incoming audio frequency signals as well as provides for center monaural submodules to supply lifelike musical performances with superior clarity in a three-dimensional imaging.

Abstract: A powered loudspeaker system has a cabinet. The cabinet has at least one electroacoustical transducer and a power amplifier coupled to the electroacoustical transducer. Dynamic equalization circuitry coupled to the power amplifier provides a predetermined desired dynamic equalization for the electroacoustical transducer in the cabinet when normally positioned in a listening room.

Abstract: A multiple amplifier system comprises a sound source, a power source, an electronic crossover network for dividing an audio signal from the sound source into a plurality of frequency ranges. Each of the divided audio signal is amplified by an individual power amplifier and fed to a corresponding speaker. A superposing circuit is connected to the sound source and the power source for superposing the audio signal from the sound source and power from the power source. The superposed signal is applied to the electronic crossover network through a lead.

Abstract: A sound field offset device having two channels, each of which includes a frequency selection filter for dividing a stereophonic input signal into two frequency bands by a given frequency falling within an audio frequency, at least one digital filter for performing sound field offsetting within a lower frequency band, and at least one loudspeaker assembly for a higher frequency band having a sharp directivity pattern and capable of defining an area to which acoustic power is emitted. This device allows a sound field to be offset in a cost effective and simple manner, by improving the frequency characteristic of a sound field space and by clarifying the sense of locality of acoustic images.

Abstract: The disclosure relates to devices for the measurement of signals in the field of wideband phenomena. More precisely, a device is disclosed for the processing of electrical signals coming from a derivative type of sensor designed to measure an electrical or magnetic field, currents, surface charges or other derivative variables, said processing including the computation of the primitive of the part of said signal having a spectral frequency higher than a low frequency f.sub.1, the device comprising:means for the electronic integration of said signal, from a frequency f.sub.2 higher than said low frequency f.sub.1 ;compensation means amplifying and integrating said signal between the frequencies f.sub.1 and f.sub.2. FIG. 2 .

Abstract: In a mixer there is a plurality of preamplifiers followed by a plurality of tone control groups connected to a plurality of voltage followers to which a series of active filters is connected, for selecting frequency bands of signals. Then a plurality of adders is connected to the seried of filters for mixing the signals in each frequency band selected by the filters and for sending the mixed signal to a plurality of line amplifiers and final amplifiers, with which loudspeakers are connected. The preamplifiers, the tone control groups, the voltage followers, the series of filters, the adders, the line and power amplifiers and the loudspeakers are connected so as to form a plurality of circuits, all of them equal to each other.

Abstract: Apparatus for reducing distortion in a peak limited audio siganl. The amount of low-frequency spectral energy in the input audio signal is determined for a peak limited signal and used to control low-frequencies in the output audio signal. Identical low-pass filters with cut-off frequencies of 2.2 kHz are used; one passing a peak limited signal, the other a non-peak limited signal. When no noticeable low-frequency spectral energy is present in the peak limited (clipped) signal, the peak level is controlled below 2.2 kHz, without distortion, by a VCA and above 2.2 kHz by a clipper. When low-frequency spectral energy is present, the VCA reduces gain on each low-frequency wave to prevent uncontrolled safety clipping.

Abstract: An isolator circuit for an audio system has an operational amplifier provided between a signal source and an amplifier. A capacitor and a resistor connected in series are connected between each input of the operational amplifier and the signal source. A buffer amplifier is provided between the capacitor and the resistor of each input line of the operational amplifier.

Abstract: An electronic audio signal amplifier and loudspeaker system comprises a preamplifier circuit, a plurality of L electronic crossover networks, a plurality of M output amplifiers and an associated plurality of M loudspeaker assemblies. The electronic crossover networks conjugate an input signal into at least low, mid and high frequency bands which do not overlap for broadcast form at least three loudspeaker assemblies particularly designed for such broadcast and for alleviation of intermodulation distortion. The system delivers an omnidirectional sound at equivalent acoustic energy to listeners over the entire audible spectrum with limited intermodulation distortion. A center channel loudspeaker assembly of the system comprises first and second ported chambers, the second chamber being filled with a sound-absorbent material to attenuate acoustic energy at certain frequencies broadcast from a woofer of the assembly.

Abstract: An audio processing module (20) capable of virtually infinite segmentation of the audio frequency spectrum. The module (20) comprises a first submodule (22), a second submodule (24) and a subwoofer module (28). The first and second submodules (22, 24) are substantially identical, each containing a high pass signal path (112), a high pass band signal path (114) and a low pass band channel (116). A mixed input/output port (29) provides a means for serial chaining of multiple modules.

Abstract: A biamplified speaker system wherein each speaker enclosure contains amplifiers and an electronic crossover network is powered by its own power supply. A preamplified audio signal is fed to each speaker enclosure for reproduction by a tweeter and a pair of bass drivers. The power amplifiers receive their frequency band of equalized signals from the electronic crossover. The power amplifiers utilize a MOSFET power output stage with the MOSFETs bolted directly to the heat sinks. One power amplifier drives the tweeter, another drives the woofer. The electronic crossover utilizes a modified 24-dB/oct design to divide up the preamplified signal into the frequency bands to be supplied to the tweeter and bass drivers, as well as to compensate for the characteristics of the drivers, in order to provide a flat frequency response curve for the entire speaker.

Abstract: Electronic crossover modules and systems in accordance with the invention employ a set of crossover channels in each module together with internal input interconnections which enable input signals to be serially intercoupled but cutoff points to be separately adjustable. Each module comprises two independently settable, variably interconnectable high pass channels and a third low pass channel which also is independently settable, and which can receive signals from the first two channels and/or a different module and also transmit signals to a different module. Using the available input interconnections and a frequency multiplier control in the first channel, great versatility in bi-amp and tri-amp with two channel and/or four channel operation is achieved.

Abstract: In an adjustable power fader device for a loudspeaker system with at least four speakers right and left channel input signals are received by respective power fader circuits. Each power fader circuit has a variable resistor connected across its input terminals and a series of at least two speakers across its output terminals. The sliding terminal of the variable resistor is connected via a capacitor to the mid point of the series of speakers, one of which has good low pitch sound reproduction. The two sliding terminals of the respective power fader circuits are movable together and the level of audio signals applied to the loudspeakers is accordingly adjusted.

Abstract: A loudspeaker system includes at least two loudspeaker drivers, together with an electrical crossover network having filter circuits with at least two separate mutually exclusive frequency passbands. The filter circuits comprising the crossover network each possess brick-wall amplitude responses, i.e., passbands with very high band-edge amplitude vs. frequency response slops, on the order of 100 dB/octave in the better embodiments. The high passband band-edge slopes, which are realized by the inclusion of transmission zeros in the separate crossover filter transfer functions, takes together with further appropriate crossover filter transfer function synthesis causes the separate loudspeaker drivers comprising the loudspeaker system to function independently of one another in their contribution to total system acoustic output.

Abstract: An audio crossover filter which automatically tunes the crossover frequency according to the content of the program audio which is being filtered.

Abstract: A frequency band filtering circuit and phase shift free crossover network comprising at each crossover frequency range between band pass filters a low-pass filter means characterized by a transfer function that decays at a second or higher order function of frequency and a high-pass filter means characterized by a transfer function that rises as a second or higher order function of frequency and wherein the respective pair of transfer functions sum to unity. By employing circuit filters characterized by high order polynomial transfer functions that sum to unity, the combination of sharp roll-off and excellent frequency separation is achieved without introducing phase distortion when the signals are recombined or summed.

Abstract: A method and apparatus for improving the accuracy in locating psychoacoustic images in plural channels of related audio signals. Signals are cross-fed from one channel to another in an out-of-phase relationship with respect to the signals in the other channel. The phase relationship is such that it has not more than a single maximum with respect to frequency. Cross-feeding is limited to frequency components less than a predetermined value in the range of 1,000 to 5,000 Hertz. The overall gain of each of the audio channels in the frequency range of approximately 100 to 1,000 Hertz is greater when a signal is applied to that channel only, than when the signal is applied to both channels. When the same signal is applied to both channels, a dip in gain occurs for frequencies in the range of approximately 200 to 900 Hertz. Above the dip, the gain is relatively flat and below the dip, the gain increases gradually.

Abstract: A peak limiter is described which employs the Hilbert transform. Effectively distinct processing occurs for low frequency and high frequency signals and harmonic distortion results only when the limiter is excited by high frequencies.

Abstract: In sound generating systems, it has been ascertained that various factors cause spurious, audible emanations when transducers of reasonable size and cost are driven in complex motions characteristic of typical high fidelity audio reproduction. In a typical system in which different transducers are used for different frequency ranges, the spurious emanations are reduced by change of amplitude or frequency or both, without affecting transducer performance, to levels at which they are substantially inaudible. Means are coupled to each speaker in a multispeaker system for compensating for mass, compliance and damping. Further, crossover means are provided for introducing opposing signal components in a crossover range between two adjacent range speakers such that opposing signal components are acoustically cancelled in the composite output.

Abstract: A multiband analog audio processor is described which provides low peak-to-r.m.s. ratios. A distributed crossover configuration is described which, in the presently preferred embodiment, employs bandpass filters with embedded clippers for high frequency processing. Circuits for improved distortion performance of the distributed crossover configuration is also described. An economical series/parallel crossover configuration with favorable summation properties is also set forth.