436 results about "Signal envelope" patented technology

A frequency translating repeater (200) for use in a WLAN environment includes an in-band management link. A signal received on an antenna (300) is split to provide signal detection in a detection and control unit (385) wherein detection is performed by detectors (370, 371) filters (375, 376), converters (380, 381) and a processor (385). Delay is added using delay lines (360, 361). The in-band signal envelope may be modulated with variable gain amplifier (330) and demodulated with detectors (370, 371) to establish the management link with higher protocol layer capability. Alternatively, a modern function at least partially compliant to 802.11 modulation may be used in parallel with the frequency translating repeater.

Linearity of an RF/microwave power amplifier is enhanced by an amplitude and phase distortion correction mechanism based upon signal envelope feedback, that operates directly on the RF signal passing through the power amplifier. A phase-amplitude controller responds to changes in gain and phase through the RF/microwave power amplifier signal path caused by changes in RF input power, DC power supply voltages, time, temperature and other variables, and controls the operation of a gain and phase adjustment circuit, so as to maintain constant gain and transmission phase through the RF/microwave power amplifier.

The present invention is directed to a method and apparatus for performing seek operations in a disk drive having a disk surface with spiral servo information written thereon. In one embodiment, a disk surface is provided with a read head associated therewith. The disk surface has spiral servo information written thereon. The read head generates a read signal envelope when reading the spiral servo information. A plurality of integration windows is provided. The plurality of integration windows have a standard interval therebetween. A position error signal is generated based upon a location of a read signal envelope within an integration window. The interval between adjacent integration windows is adjusted from the standard interval to generate a position error signal. The read head is moved in a radial direction based upon the position error signal. This process may be repeated to seek across the disk surface.

A transceiver comprises an amplifying circuit for amplifying an input signal to produce an output signal. A power supply is operable for varying the level of power supplied to the amplifying circuit in response to variation of an input signal envelope directed to the power supply. A processing circuit is operable for digitally detecting the input signal envelope to provide variation of the power supply level. The processing circuit is further operable for digitally delaying the digital input signal envelope to time align the power supply level with the input signal.

The present invention is directed to a method and apparatus for dynamic placement of an integration window in a disk drive having a disk surface with spiral servo information written thereon. A read head is provided for reading the spiral servo information and generating a read signal envelope. A repetitive spiral position error, associated with one spiral of the spiral servo information, is measured. Placement of an integration window is dynamically adjusted based upon the measured repetitive spiral position error, so that a read signal envelope read by the read head appears more towards the center of the integration window than if the placement of the integration window was not dynamically adjusted. By adjusting the placement of the integration window, dynamic range is increased without increasing the size of the integration window.

A transmitter comprises an amplifier operable for receiving an input signal and amplifying the input signal to produce an output signal. A power supply is coupled to the amplifier for supplying power to the amplifier, the power supply operable for tracking the input signal and varying the level of power supplied to the amplifier in response to variation of the input signal. A predistortion circuit is coupled to the power supply, the predistortion circuit operable for receiving the input signal and predistorting the input signal to the power supply for addressing input signal tracking capabilities of the power supply.

An implantable stimulation arrangement is described for generating electrode stimulation signals for an implanted electrode array having stimulation electrodes. A filter bank pre-processor processes an input acoustic audio signal to generate band pass signals each corresponding to an associated band of audio frequencies. A signal envelope module computes a corresponding signal envelope for each band pass signal. A stimulation pulse generator extracts stimulation signal information from the rate of change of the signal envelopes such as a time-based derivative to generate stimulation event signals defining electrode stimulation timings and amplitudes for some or all of the stimulation electrodes.

The present invention relates to methods and devices to control and operate the functionality of a power amplifier system (100) capable of operating in at least three differential amplification modes. The drive signal's amplitude envelope controls an integrated switch network (104; 105, 106) that routes both the signal envelope and signal phase to different modulation blocks (111, 112: 109, 110: 115). Depending on the envelope strength, the operational mode of the amplifier system is possible to alter to best serve the signal statistics to provide the highest overall power efficiency.

A data encryption and decryption system securely geoencrypts data using location-dependent navigation signals. To increase the entropy of the cryptographic key to guard against a brute-force attack, geoencryption is made to depend on largely time-independent characteristics of the navigation signals that are not easily spoofed, including the time difference of arrival, the envelope-to-cycle difference, the differential signal-to-noise, the signal envelope shape, and the directions of arrival of the navigation signal set.

A method for eliminating interference to blood oxygen saturation monitoring includes steps of digitally filtering acquired red light and infrared light PPG (photoplethysmography) signals, removing low-frequency interference signals in direct current components, computing accurate direct-current component value, computing PPG signal envelope curves to extract alternating-current components, separating signals relevant with interference and serving the same as reference signals to be subjected to self-adaptive filtering, eliminating movement interference generated from aliasing of frequency and target signals in the alternating-current components, computing to obtain the accurate PPG alternating-current component value, and finally computing the blood oxygen saturation after the interference is eliminated according to the Lambert-Beer's law. The method is capable of suppressing movement interference well and computing to obtain the accurate blood oxygen saturation value. By extracting the reference signals directly from the red light and infrared light PPG signals to realize self-adaptive filtering, the method is simple in construction, simple in algorithm and small in computing number, has no need of an extra device for providing reference signals, is free of multiple self-adaptive filtering, and facilitates miniaturization and portability of monitoring equipment.

Adaptive piezoelectric actuator control system, including:

• • a power supply,
  • a piezoelectric actuator,
  • a driver driving the actuator,
  • a signal generator providing a frequency signal to the driver,
  • a user interface allowing user input of operating conditions,
  • memory storing parameters of the actuator, and
  • system control means controlling the power supply, driver generator and memory so operating frequency of the actuator is monitored and regulated,
  • wherein the driver comprises
    • test means providing a test signal to the actuator,
    • voltage measurement means measuring voltage applied to the actuator caused by the test signal and voltage applied to the actuator caused by the frequency signal,
  • the system control means receiving a response signal in response to the test, and receiving voltages measured by the voltage measurement means, and comprising signal analysis means creating a response signal envelope and controlling the generator to generate a frequency signal corresponding to the envelope maximum.

A system and a method for providing a secure wireless ad-hoc network in a wireless communication system having at least two transceivers coupled by a wireless transmission link are disclosed. The method includes receiving a data transmission at a first transceiver from a second transceiver, wherein the data transmission identifies a source of a signal in the data transmission and the signal is identified by a signal envelope; detecting a deep fade in the data transmission, wherein the first and second transceivers are configured to sample the source of the signal in the data transmission; determining whether the received signal exceeds a predetermined threshold for deep fades, wherein the predetermined threshold is preset by the first and second transceivers; generating a bit-string corresponding to each of the transceivers based on channel fading information relating to the wireless transmission link; and, using the bit-string, generating a key.

The invention discloses a dispersion compensation method for a broadband light source. A polarization-preserving fiber polarization coupling testing system based on a Michelson interferometer is formed by the broadband light source, and the Michelson interferometer compensates the optical path difference between an excitation mode and a coupling mode in the polarization-preserving fiber, and a detector acquires an interference signal; specifically, the method comprises the following steps of: intercepting the initial data acquired by the detector through a window function, and taking out the interference data Imain between the excitation modes and the interference data Icoupling between the excitation mode and the coupling mode; respectively executing Hilbert transformation and Gaussian fitting on the Imain and the Icoupling, obtaining envelopes (I)main and (I)coupling of the interference signal, getting a birefringence dispersion coefficient Delta D according to a ratio Eta of the width of the (I)main to the width of the (I)coupling at a 1/e part, obtaining a phase factor needed for the dispersion compensation, and then multiplying the phase factor by a nonlinear frequency spectrum function with dispersion information to eliminate nonlinear phase items causing the widening of the interference signal envelopes; and finally, obtaining the dispersion compensated interference signal Icomp by executing Fourier inversion on the obtained linear frequency spectrum function.

The invention discloses a low-altitude target detection method based on multi-frequency point echo amplitude reversed order statistics. The low-altitude target detection method based on the multi-frequency point echo amplitude reversed order statistics mainly solves the problem that low-altitude target detection performance in the prior art is poor in multi-path environment. The low-altitude target detection method includes: 1) performing matched filtering and linear detection on multi-frequency point echo signals received by a radar, and outputting signal envelope; 2) selecting detection units and reference units from the signal envelope; 3) performing reversed order arrangement on the detection units to obtain a group of reversed order data; 4) evaluating reflection coefficient, and calculating an optimal K value; 5) utilizing the optimal K value and the reversed order data to calculate detection amount of the echo signals; 6) utilizing reference unit data to evaluate clutter amplitude through a unit average method; 7) calculating a detection threshold coefficient; 8) utilizing the clutter amplitude and the threshold coefficient to obtain a detection threshold of the echo signals; and 9) comparing the detection value to the detection threshold, and judging whether a target exist. The low-altitude target detection method based on the multi-frequency point echo amplitude reversed order statistics is high in detection performance at low signal-to-clutter ratio and improves radar detection capacity of the low-altitude target.

An error adjustment method of equalizing transmission characteristics of a signal processing circuitry is disclosed. In a first step, an original complex IQ signal is generated, on which error adjustment is performed. Then, the adjusted complex IQ signal is processed in the signal processing circuitry, thereby obtaining a processed real signal. The envelope of the real signal is detected and this real signal envelope and the original complex IQ signal are synchronized. The envelope of the original complex IQ signal is derived and the synchronized real signal envelope is compared with the synchronized original IQ signal envelope at two consecutive time instances. Finally, a processed complex IQ signal is obtained from the real signal envelope on the basis of the comparison result, which processed complex IQ signal is used in performing error adjustment.

The present invention provides an Offset Modulation Orthogonal Frequency Division Multiplexing (OFDM) and multi-access transmission method with a Cyclic Prefix (CP), including a generating method of the sent signal in the sending terminal and a processing method of the received signal in the receiving terminal, the method includes: in the sending terminal, performing generalized discrete Fourier Transform on real-value digital baseband modulated symbols and obtaining the frequency-domain signal; performing conjugate symmetric extension, frequency-domain filtering, sub-carrier mapping on the frequency-domain signal; performing Inverse Fast Fourier Transform on the frequency-domain signal after sub-carrier mapping; inserting a CP and obtaining the time-domain sent signal; in the receiving terminal, including: removing the CP, performing Fast Fourier Transform on CP removed symbols and obtaining the frequency-domain received signal; and based on multiple user joint frequency-domain equalization performing iterative detection decoding on the frequency-domain received signal. The present invention can obtain the low-signal envelope volatility in the condition of remaining spectrum efficiency, and adopting iterative received signal processing method based on multiple user joint frequency-domain equalization ensures the transmission reliability with low-complexity.