3080 results about "Automatic gain control" patented technology

A current-mode switching regulator uses adaptive current sensing to reliably monitor an inductor current in a cost-efficient and power-efficient manner. A semiconductor switch periodically turns on to conduct the inductor current. A voltage drop across the semiconductor switch is monitored when the semiconductor switch is on. A variable gain amplifier with an automatic gain control loop generates a feedback signal from the voltage drop of the semiconductor switch when conducting to provide an indication of the inductor current to a controller. The automatic gain control loop compensates for any variations in the on-resistance of the semiconductor switch.

A transceiver employing a steerable phased-array antenna includes a modem architecture in which signals from each antenna element in the array are independently processed down to the individual baseband channel level, and digital beamforming is performed at baseband. The data rate reduction from IF to baseband permits parallel signal data from multiple antenna elements to be time multiplexed and serially processed at acceptable data rates at baseband with minimal modem hardware requirements. Both for transmit signal modulation and received signal demodulation, the computation of carrier tracking, automatic gain control (AGC)/power-control, and beamforming are shared by the same processing circuitry for all channels when performed at baseband. The resulting baseband circuitry is only incrementally larger than that required for carrier tracking and AGC alone, yet accomplishes independent beamforming for each antenna element on each user channel.

A hearing compensation system comprises a plurality of bandpass filters having an input connected to an input transducer and each bandpass filter having an output connected to the input of one of a plurality of multiplicative automatic gain control (MAGC) circuits whose outputs are summed together and connected to the input of an output transducer. The MAGC circuits attenuate acoustic signals having a constant background level without the loss of speech intelligibility. The identification of the background noise portion of the acoustic signal is made by the constancy of the envelope of the input signal in each of the several frequency bands. The background noise that will be suppressed includes multi-talker speech babble, fan noise, feedback whistle, florescent light hum, and white noise. For use in the consumer electronics field background acoustic noise may be sensed and used to adjust gain in the various MAGC circuits so as to improve a user's listening experience, whether the user is hearing impaired or not.

A system and method for controlling amplification of a signal received by a ZIF radio having a power level within a full power range relative to a minimum noise floor. The ZIF radio includes a ZIF receiver front end, an overload detector, an ADC, a saturation detector, a DC and power estimator, and control logic. The control logic utilized full visibility of the ADC to limit gain of the baseband amplifier to a maximum gain setting sufficient to view the minimum noise floor and to view a received signal having a power level within any of several segments of the power spectrum. The segmentation of the power spectrum is based on an overload condition of the ZIF receiver front end and a saturation condition of the ADC. The control logic further employs limited gain stepping of the baseband amplifier to avoid exceeding a DC budget of the ADC.

In accordance with the teachings described herein, systems and methods are provided for a precision adaptive equalizer. A variable gain equalizer may be used to apply a variable gain to an input signal to generate an equalized output signal. A phase and pattern detector circuit may be coupled in a feedback loop with the variable gain equalizer. The phase and pattern detector circuit may be used to identify a high frequency data pattern in the equalized output signal and compare the high frequency data pattern with a clock signal to detect a high frequency phase error. The phase and pattern detector circuit may be further operable to generate an automatic gain control signal as a function of the high frequency phase error, the automatic gain control signal being fed back to the variable gain equalizer to control the variable gain applied to the input signal.

Methods and apparatuses for reducing DC offsets in a communication system are described. In a first aspect, a feedback loop circuit reduces DC offset in a wireless local area network (WLAN) receiver channel. The frequency response of the feedback loop circuit can be variable. In a second aspect, a circuit provides gain control in a WLAN receiver channel. The stored DC offset is subtracted from the receiver channel. First and second automatic gain control (AGC) amplifiers are coupled in respective portions of the receiver channel. In a third aspect, a feedback loop circuit reduces DC offset in a WLAN receiver channel. The feedback loop circuit includes a storage element that samples and stores receiver channel DC offset. The loop is opened, and the DC offset stored in the storage element is subtracted from the receiver channel. Circuits for monitoring DC offset, and for providing control signals for controlling the frequency response of the DC offset reducing circuits are also provided.

Audio signal processing relating to the measurement and control of the perceived sound loudness and/or the perceived spectral balance of an audio signal is useful, for example, in one or more of: loudness-compensating volume control, automatic gain control, dynamic range control (including, for example, limiters, compressors, expanders, etc.), dynamic equalization, and compensating for background noise interference in an audio playback environment. In various embodiments, modification parameters are derived for modifying the audio signal in order to reduce the difference between its specific loudness and a target specific loudness.

The invention discloses a configurable multi-mode multi-band satellite navigation receiving method and a radio frequency front end module constructed by the method. The front end module can receive signals of satellite navigation and positioning systems such as a global positioning system (GPS), the Big Dipper, a Galileo positioning system and a global navigation satellite system (Glonass), and comprises a configurable low-noise amplifier (LNA) with a buffer and an active balun, a folding passive mixer with a configurable frequency synthesizer, a configurable multi-mode filter, an automatic gain control (AGC) amplifier, a direct-current bias circuit, and a multi-mode multi-band program controlled and coded on-off control word from a receiving system. The radio frequency front end module can meet the requirement of multi-band multi-mode work through the control word programmed by the receiving system, has a simple and reliable structure, does not need complicated time division multiplexing control system and off-chip module, has low cost and high flexibility, and improves the noise performance of the radio frequency front end of the whole receiver and multi-mode multi-band signal processing capacity; and a one-channel signal is input into the module, and the module outputs a two-channel differential signal. The receiver can be used for receiving and processing multi-mode satellite navigation signals asynchronously, and receiving and processing satellite navigation signals with the required mode in different time intervals according to the requirement.

A method of amplification includes amplifying an input signal with a predetermined or user adjustable maximum gain to produce a second signal and compressing the dynamic range of the second signal with an automatic gain control to produce an output signal. The compression ratio of the automatic gain control is greater than one for output signals below a predetermined threshold output signal level and is essentially one for output signals above the predetermined threshold output signal level. The compression ratio may be predetermined or the method may include determining the compression ratio of the automatic gain control. The compression ratio may be determined according to the amplitude of the output signal or according to an input-output curve. The input-output curve my be predetermined and may be selected according to the auditory needs of a listener. Preferably the input-output curve is determined according to the predetermined or user adjustable maximum gain.

The invention provides a short distance transmission system for wireless electromagnetic wave signals of a downhole near bit and a short distance transmission method, and belongs to the field of geosteering systems and measurement while drilling instruments in industries such as petroleum, mines and geological prospecting. The automatic gain control technology is adopted in the short distance transmission system for realizing the automatic adjustment of enlargement factors of downhole weak signals. The short distance transmission system comprises a short section receiving assembly and a short section transmitting assembly, wherein the short section receiving assembly and the short section transmitting assembly are respectively provided with a receiving antenna and a transmitting antenna. Due to the fact that radial coupled antennas are adopted, the short distance transmission system is relatively simple in structure. Meanwhile, the short distance transmission system is high in arithmetic speed and can meet demands for real-time transmission of a large number of signals. Moreover, a front end processing module special for the downhole weak signals is utilized for carrying out the automatic gain adjustment to the collected signals, maintaining stable output of the signals and lowering processing difficulty of subsequent signals, and therefore the signal transmission quality is greatly improved.

A multi-channel remote keyless entry (RKE) transponder having dynamically re-configurable input channel selection, channel disable, settable sensitivity for each channel, wake-up filter timing parameters, automatic gain control hold, internal tuning capacitor selection for each channel's antenna, minimum modulation depth requirement for input signal and bi-directional talk-back. Programmable minimum modulation depth requirement reduces false wake-up of the RKE transponder. An antenna for each channel of the RKE transponder may be tuned with internal tuning capacitors for improved range and receiver sensitivity. The internal tuning capacitor parameters may be stored in a configuration register. Gain of the channel may be fixed while the antenna is tuned. The antennas may be de-queued for talk-back to a base station for low frequency bi-directional communications. An external control device may dynamically read from and write to the configuration registers via a serial communications interface.

The invention relates generally to the field of wireless communications and more particularly to a method of and device for detecting the presence of a received data packet in a digital receiver. The present invention proposes a simplified method of correlation by removing dependency on the amplitude fluctuations while at the same time maintaining phase relevancy. The key advancement involves mapping the complex quadrature amplitude modulation (QAM) preamble to a quantized phase shift keying (PSK) constellation before application to a matched complex correlator. The proposed process essentially “amplitude normalizes” the input signal without the use or complexity associated with a divider. This simplified normalization scheme makes the packet detection algorithm robust against amplitude variations in the input signal, while still allowing for good correlation output. In applications where interference is superimposed on the I/Q input signals, the invention improves the detection capability over automatic gain control (AGC) normalization methods.

Hands-free phones with voice activity detection using a comparison of frame power estimate with an adaptive frame noise power estimate, automatic gain control with fast adaptation and minimal speech distortion, echo cancellation updated in the frequency domain with stepsize optimization and smoothed spectral whitening, and echo suppression with adaptive talking-state transitions.