1209 results about "All-pass filter" patented technology

A hermetic terminal for an active implantable medical device (AIMD), includes an RF distance telemetry pin antenna, a capacitor conductively coupled between the antenna and a ground for the AIMD, and an inductor electrically disposed in parallel with the capacitor and conductively coupled between the antenna and a ground for the AIMD. The capacitor and the inductor form a band pass filter for attenuating electromagnetic signals through the antenna except at a selected frequency band. Values of capacitance and inductance are selected such that the band pass filter is resonant at the selected frequency band. In an alternative form, the band pass filter is coupled in series with the telemetry pin antenna for attenuating MRI signals of a selected frequency band.

A slice and offset circuit is provided that uses a digital integrator in the feedback loop of the offset cancellation circuitry. A slice circuit receives an indication of a desired slice voltage and supplies a signal to specify the slice level, which is combined with a sensed offset level of the amplifier. The feedback loop includes a low pass filter that receives the combined signal indicative of the offset and the slice level. The low pass filter includes the digital integrator circuit that includes an up / down counter that counts in a direction determined according to a digital signal having a ones-density indicative of a value of the combined signal with respect to a reference signal, thereby generating a feedback signal that cancels offset and adjusts for slice.

A multi-channel acoustic cancellation system 40 with, for example, stereo speakers and a pair of microphones in the transmitting and receiving rooms (11 and 21) has time varying all-pass filters (45, 47) in the signal path between the microphones (13, 15) in the transmitting room (11) and the speakers (27, 29) in the receiving room (21) to provide decorrelation.

A digital group delay compensation system comprising a digital allpass filter that is utilized in an implementation phase; and a system that generates coefficients for the allpass filter used in the implementation phase such that the overall performance of a system is measured and optimized in a calibration phase.

A method and apparatus for reducing cross-talk in an oximeter. The oximeter includes a band pass filter. The amount of cross-talk through the band pass filter is estimated. Based on this estimate, the corner frequencies of the band pass filter are adjusted when it is designed to minimize the cross-talk. In one embodiment, a calibration mode is performed when a sensor is attached to the oximeter. In the calibration mode, the signals are measured with first only the red LED on and then with only the IR LED on. Any signal measured in the off channel is assumed to be a result of cross-talk from the other channel. The magnitude of the cross-talk is determined as a percentage, and subsequently the percentage is multiplied by the actual signal and subtracted from the other LED signal as cross-talk compensation.

Systems and methods for canceling static and dynamic DC offsets by combining a digital DC offset correction scheme with an analog DC offset correction scheme. A feedback-based digital DC offset correction scheme provides different adjustment levels for a plurality of discrete gain states and the analog DC offset correction scheme operates in different cancellation modes dependent on a frame structure. A digital DC offset correction scheme collects DC offset control information and provides adjustment levels. In addition, a negative-feedback based switchable high pass filter has a plurality modes of operation, where one mode of operation includes an all-pass filter.

Resistance in parallel with inductors in a series leg of the low-pass filter facilitates changing input and output resistance of the filter with little or no change in the reactance of the inductors. Furthermore, the reactance of the capacitors in the shunt legs of the filter will be substantially unaffected. This assists the designer in matching the impedance of the filter in the pass-band while still providing substantial impedance mismatching in the stop-band without substantially affecting the characteristics of the filter. Facilitating impedance matching in the pass-band and impedance mismatching in the stop-band is accomplished without the need for more complex active components. POTS splitters making use of such filters can facilitate impedance matching of line and load termination in a telecommunications system in response to signals within the frequencies of typical analog telephony service while providing impedance mismatching in response to signals within the frequencies of typical xDSL service.

An image processing apparatus is provided which offers higher versatility than conventional image processing apparatuses. When an input signal to a spatial filtering block is a monochrome signal that contains Y component only, a selector selects its input terminal and a selector selects its input terminal. Then, a low-pass filter output signal of a programmable spatial filter is inputted to a spatial filter, and a low-pass filter output signal of the spatial filer is inputted to a spatial filter. That is, the programmable spatial filter and the spatial filters are connected in series (in cascade), and the cascade-connected three spatial filters perform filtering operation. In this example, low-pass filters with 5×5 taps are connected in cascade in three stages, which enables low-pass filtering with 13×13 taps.

A frequency-warped processing system using either sample-by-sample or block processing is provided. Such a system can be used, for example, in a hearing aid to increase the dynamic-range contrast in the speech spectrum, thus improving ease of listening and possibly speech intelligibility. The processing system is comprised of a cascade of all-pass filters that provide the frequency warping. The power spectrum is computed from the warped sequence and then compression gains are computed from the warped power spectrum for the auditory analysis bands. Spectral enhancement gains are also computed in the warped sequence allowing a net compression-plus-enhancement gain function to be produced. The speech segment is convolved with the enhancement filter in the warped time-domain to give the processed output signal. Processing artifacts are reduced since the frequency-warped system has no temporal aliasing.

The invention discloses a method of detecting fruit surface defects based on low pass filter. Binary mask image B' is constructed based on B component of fruit colorful image. R component f(x, y) of removed background is obtained by the dot product of B' and R component. Central transformation of f(x, y) is performed to obtain f'(x, y) and discrete Fourier transformation of f'(x, y) is performed to obtain F(u, v). Low frequency component G(u, v) is obtained by the multiplication of F(u, v) and low pass filter H(u, v). g(x, y) is obtained by negative discrete Fourier transformation of G(u, v). i'(x, y), which is the surface brightness image of f(x, y), is obtained by the multiplication of g(x, y) and the function of (-1)x + y. Homogenization brightness image f''(x, y) is obtained by the division of f(x, y) and i'(x, y). Fruit surface defects are detected by single threshold method of f''(x, y). Fruit surface defects are easily detected in the invention by single threshold method, wherein homogenization correction of fruit surface brightness is carried out. The method of the invention overcomes the complexity of conventional defect inspection algorithm and is free of considering the sizes and shapes of fruits to be detected, thus is better adjusted than standard ball brightness adjustment method. The images are acquired by a single camera, thereby avoiding the problem of low processing speed due to the information fusion of images from a plurality of cameras.

A wireless communications mobile station (10) includes at least one antenna (240) and a RF transceiver (210,220) containing a direct conversion receiver (1) coupled to the antenna. The direct conversion receiver contains a low noise amplifier (3) for amplifying a received RF signal and for outputting the amplified RF signal to a current switching down-conversion mixer (4). The down-conversion mixer has a first input node for receiving the amplified RF signal, a second input node for receiving a local oscillator (LO) signal for mixing with the amplified RF signal and an output node coupled to an input of an operational amplifier forming a low pass filter (5A). In accordance with an aspect of this invention the low pass filter has a low pass pole generated by a resistor R and a capacitor C coupled in parallel in a feedback path of the operational amplifier, where a low pass comer frequency of the low pass filter is inversely proportional to the product of R and C. In a preferred embodiment at least the down-conversion mixer and the low pass filter are implemented as part of an integrated circuit, and the resistor and the capacitor are fabricated within the integrated circuit.

A complex filter such as the channel select filter in a radio transceiver is implemented using a transconductance / C topology to benefit from the ability to tune such filters and thereby stabilize the output transfer function of the filter over variations in temperature, power supply voltage and process. The topology is based on an active R / C biquadratic topology to achieve the additional benefit of independently controlled stages. The problem created by the R in the output impedance is can be overcome by separately tuning the R value along with the transconductance / C ratio, by implementing the R as a transconductance amplifier having common mode feedback, or by implementing the transconductance amplifiers of the topology using Nauta transconductors, and unbalancing the common mode circuit of the Nauta transconductor to achieve a differential resistance that can be used to implement the R in the output impedance.

The invention discloses a stable photoelectric oscillator. The stable photoelectric oscillator comprises a laser device, an electro-optical modulator, a long optical fiber, a photoelectric detector, an amplifier, an electric band-pass filter, an electrically-controlled microwave phase shifter, a high-stability microwave source, a 2*1 wave combiner or directional coupler, a first 1*2 power divider or directional coupler, a second 1*2 power divider or directional coupler, a third 1*2 power divider or directional coupler and a phase locking control module, wherein the phase locking control module comprises a frequency mixer, an electric low pass filter and a servo control module, the output end of the frequency mixer is connected to the input end of the electric low pass filter, and the output end of the electric low pass filter is connected to the input end of the servo control module. According to the stable photoelectric oscillator, an electric injection of the external high-stability microwave source and a phase locking control mechanism are added based on a traditional single-loop OEO structure. Compared with the prior art, the stable photoelectric oscillator has the advantages that insertion loss of an optical link in a resonant cavity is not increased, the high signal to noise ratio of the photoelectric resonant cavity is maintained, and the structural complexity of the stable photoelectric oscillator is lower than that of an existing scheme. The stable photoelectric oscillator is easy to obtain.

A method and apparatus for obtaining power computation parameters is presented. Accurate computation of power requires multiplying voltage and current at the same instant of time and integrating the results over time. The present invention provides a method of using a single Analog to Digital Converter to convert both voltage and current for all the phases of any electrical system and then digitally compensating for the phase error caused by the non-simultaneous sampling of the current and voltage signals. The compensating filter could be implemented as a simple interpolator, an all-pass filter, or a combination of both. A single multiplexer is used to select which signal is processed by the Analog to Digital Converter. By scheduling and converting the voltage and analog signals one at a time, potential for crosstalk is significantly reduced, power requirement is reduced, and die size requirement is reduced.

A cardiac signal processing apparatus includes: a unit for acquiring, from a heartbeat sensor, cardiac signals relating to heartbeats of a subject; a low-pass filter for allowing passage of those cardiac signals having a first predetermined frequency or lower, among the cardiac signals; higher harmonic noise acquisition unit for acquiring harmonic signals of low-frequency noise by performing high frequency extrapolation on the signals output from the low-pass filter; a high-pass filter for allowing passage of those cardiac signals having a second predetermined frequency or higher, among the cardiac signals; and higher harmonic noise removal unit for removing the harmonic signals of low-frequency noise from the signals output from the high-pass filter. It is thus made possible to remove noise from the cardiac signals and to obtain desirable heartbeat detection characteristics.

A hearing aid includes an input transducer for provision of an input signal, a high pass filter configured for providing a high pass filtered part of the input signal, a low pass filter configured for providing a low pass filtered part of the input signal, a synthesizing unit configured for generating a synthetic signal from the high pass filtered part using a model based on a periodic function, wherein a phase of the synthetic signal is at least in part randomized, a combiner configured for combining the low pass filtered part with the synthetic signal for provision of a combined signal, a hearing loss processor configured for processing the combined signal for provision of a processed signal, and a receiver coupled to the hearing loss processor, wherein the receiver is configured for converting an audio output signal into an output sound signal.

The invention discloses a radio frequency electrically adjusted band-pass filter with a constant absolute bandwidth. The band-pass filter consists of an upper-layer micro-band structure, a middle medium basal plate and lower-layer grounding meta, wherein the upper-layer micro-band structure comprises a first half wavelength resonator, a second half wavelength resonator, an input feed network, an output feed network, an input port and an output port, wherein a fifth micro-band line of the first half wavelength resonator and a seventh micro-band line of the second half wavelength resonator are arranged in parallel to form an interstage coupling structure; the first half wavelength resonator consists of a first micro-band line, a second micro-band line, a third micro-band line, a fourth micro-band line, a fifth micro-band line, a sixth micro-band line and a variable capacitance diode; and the second half wavelength resonator and the first half wavelength resonator have the same structure, and are symmetrically arranged based on the central axis of the interstage coupling structure. The radio frequency electrically adjusted band-pass filter has the characteristics of keeping the absolute constant bandwidth while resonating the center frequency and inhibiting second harmonic wave, and can be applied to the reconfigurable radio frequency front-end in wireless communication.

The invention relates to a waveform signal generator with optionally adjustable output signal offset, which comprises a frequency control word, a phase accumulator, an address accumulator, a waveform lookup table, a divider, an adder, a data negator, a D / A converter, and a low pass filter. On the basis of the prior art, the storage mode of the waveform lookup table is changed according to the characteristics of a waveform signal, and the storage space is saved; the size of the output waveform signal data is changed by adjusting a dividing coefficient of the divider; and the adder is arranged between the divider and the data negator, the offset in the vertical direction of the waveform signal is adjusted by changing the adding coefficient of the adder, and the waveform signal is transmitted to the data negator, passes through the D / A converter and the low pass filter and is output finally. Due to the adoption of the waveform signal generator with the optionally adjustable output signal offset, the frequency, amplitude and offset of the output waveform signal can be flexibly adjusted so as to meet the requirement of a user on the waveform signal.

The invention discloses an LCL-type single-phase grid-connected inverter power control and active damping optimization method. An equivalent synchronous coordinate PI controller is adopted, a two-phase virtual orthogonal system is constructed by adopting an all-pass filter, the problem that data used in previous construction methods have asynchrony or noise interference is introduced is solved, regulation of grid-connected currents at fundamental frequency in a zero steady state error is achieved, and the stability of the system is improved. According to the LCL-type single-phase grid-connected inverter power control and active damping optimization method, the primary differential and the high-frequency components of the grid-connected currents are fed back in real time, the damping of the system is increased, the resonance peak of the LCL filter is restrained, an optimized parameter selection method is given, single-current feedback factors are reduced to a variable, the defect that parameters are difficult to select in single current high-frequency component feedback is overcome, and the reliability and the dynamic nature of the system are improved.

A low dropout voltage regulator is described having a pass device, differential amplifiers, and a feedback loop including a low pass filter. Two differential amplifiers arranged in parallel coupled to the low pass filter in the feedback loop provide a specified and stable DC voltage whose input-to-output voltage difference is low. Improved stability, reduced die area, improved power supply rejection ratio, increased bandwidth, decreased power consumption, and better electrostatic discharge (ESD) protection may result.

A system and method of generating electrode stimulation signals for an implanted multi-channel electrode array of a cochlear implant includes processing an acoustic audio signal with a bank of filters. Each filter in the bank of filters is associated with at least one channel having an electrode. The bank of filters includes a first band pass filter that produces a broadband signal b(t) with frequencies that substantially cover at least one of a pitch frequency range of 100 Hz to 400 Hz and a first format range of 400 Hz-1000 Hz. At least one electrode associated with the first band pass filter is activated with electrode stimulation signals based, at least in part, on the broadband signal b(t). The filter bank may include at least one electrode associated with one or more filters other than the first band pass filter, the one or more filters producing signals having only higher frequencies than broadband signal b(t).