Abstract: A mobile station apparatus is provided which is capable of obtaining a diversity effect and preventing an increase in noise even if an antenna phase difference containing an error is detected. The mobile station apparatus includes a closed-loop transmit diversity control section for exerting, when the quality of the component from the second antenna is lower than a predetermined quality value based on the quality measured by the common pilot channel quality measurement section, control to cause the feedback information generation section not to use the detection result at the antenna phase difference detection section, and to continue to use the immediately preceding feedback information, control to cause the antenna verification section not to operate, and control to cause the first channel inference section to operate and the second channel inference section not to operate.

Abstract: A radio transmitting apparatus that has a plurality of antennas and changes the number of modulated signals transmitted simultaneously according to the propagation environment and so forth. A transmission power changing section 12 of a radio transmitting apparatus of the present invention adjusts the pilot symbol signal level so as to match the data symbol composite signal level according to the number of transmit modulated signals set by a modulated signal number setting section 11. By this means, the operating range of received pilot, symbols and the operating range of received data symbols become approximately the same on the receiving side, enabling pilot symbol quantization error to be reduced. As a result, the precision of radio wave propagation environment estimation, time synchronization, and frequency offset estimation using pilot symbols improves, and consequently data reception quality improves.

Abstract: Provided are apparatus and method for receiving signals in a wireless communication system.

Abstract: A switched current resistor (SCR) PGA for constant-bandwidth gain control includes an inverting amplifier, a feedback resistor forming a feedback loop between an output side and an input side of the inverting amplifier, and a switched current resistor (SCR) array connected in parallel to the feedback resistor, and configured to tune a gain range between a maximum and a minimum. The SCR array includes a plurality of switched resistors, each comprising a switch in series with a resistor. When the plurality of switched resistors are switched by a gain-control logic, a plurality of switched current sources and a plurality of grounded resistors are switched correspondingly to deliver a transient current, an equivalent of which flows through the plurality of grounded resistors out from the input side of the inverting amplifier, leading to a feedback factor of the PGA being constant.

Abstract: A radio receiver adapted to alternatively receive data over a communication channel in a first mode and a second mode. The second mode facilitates reception of data at higher data rates than the first mode. The radio receiver comprises a signal-processing unit and a control unit. The signal processing unit is adapted to determine a quality condition of the communication channel. The control unit is adapted to determine, based on the quality condition, whether the communication channel facilitates operation in the second mode and assess at least one configuration condition, one of the at least one configuration condition being that the communication channel is determined to facilitate operation in the second mode. The control unit is further adapted to configure the radio receiver to operate in the second mode when all of at least one configuration condition are fulfilled or to operate in the first mode otherwise. A method for controlling the radio receiver is also disclosed.

Abstract: A method and apparatus for controlling transmissions of data via an enhanced dedicated channel (E-DCH) are disclosed. A list of available transport format combinations (TFCs) is generated based on a plurality of dedicated channel medium access control (MAC-d) flows. An enhanced uplink medium access control (MAC-e) protocol data unit (PDU) is generated using a TFC which is selected from the list of available TFCs. The MAC-e PDU is forwarded to a hybrid-automatic repeat request (H-ARQ) process unit for transmission. The list of available TFCs is continuously updated by eliminating and recovering TFCs based on remaining E-DCH power, an E-DCH transport format combination set (TFCS), a power offset of a highest priority MAC-d flow that has E-DCH data to transmit, and a gain factor for each TFC.

Abstract: A technique for providing stable tracking performance to an AGC loop circuit comprises amplifying a wideband radio frequency signal; detecting signals and blockers adjacent to the radio frequency signal; lowering a gain of the radio frequency signal; mixing a local oscillator signal with the radio frequency signal; shifting a frequency of the radio frequency signal from a radio frequency to an intermediate frequency; continuously varying a gain of the intermediate frequency signal; converting the intermediate frequency signal into a digital output signal; comparing the digital output signal with predefined thresholds comprising an upper threshold and a lower threshold; switching a post mixer amplifier (PMA) to a high gain state when an input of a variable gain amplifier (VGA) is greater than the upper threshold, and switching the PMA to a low gain state when an input of the VGA is lower than the lower threshold.

Abstract: In TDD mobile networks, an incoming signal is received during a time period where no uplink communication takes place. The incoming signal is measured and analyzed to determine a noise level. Based on the noise level and on an uplink signal level from expected in a future uplink time slot, a gain for the automatic gain controller is set for use in future uplink communications. The gain is set to optimize the operation of an analog-to-digital converter.

Abstract: To calibrate a bandpass filter, a received signal strength corresponding to a received communication channel is determined. A variable element of the bandpass filter is adjusted based on the received signal strength of the received communication channel to calibrate the bandpass filter.

Abstract: Aspects of a method and system for channel estimation in a MIMO communication system with multiple RF chains for WCDMA/HSDPA may comprise receiving a plurality of communication signals from a plurality of transmit antennas. A plurality of vectors of baseband combined channel estimates may be generated based on phase rotation of the received plurality of communication signals. A matrix of processed baseband combined channel estimates may be generated based on the generated plurality of vectors of baseband combined channel estimates. A plurality of amplitude and phase correction signals may be generated based on the generated plurality of vectors of baseband combined channel estimates. An amplitude and a phase of at least a portion of the received plurality of communication signals may be adjusted based on the generated plurality of amplitude and phase correction signals, respectively.

Abstract: An analog/digital gain control device avoid some of the requirements associated with the nature of a closed-loop AGC circuits and which meets the remaining requirements without much difficulty uses an analog to digital conversion method that increases the number of effective ADC bits by compressing the baseband input analog signal using a logarithmic circuit. After the compressed analog signal is converted into a digital signal, a digital anti-log process or look-up table (LUT) is used to expand the digital signal back to the original linear scale. The word size of the output of the anti-log process is larger than the input word size due to the nature of the anti-log function. To reduce the word size of the digital signal an open loop normalization technique can be applied.

Abstract: An adaptive equalizer may include one or more equalizing gain stages coupled to an input signal. An automatic gain control circuit may be used to control the gain of the one or more equalizing gain stages, the automatic gain control circuit having an AGC reference input. A dual-output DC restoration circuit may be coupled to the output of the one or more equalizing gain stages for generating a first output signal using a first hysteresis slicer that DC restores the input signal and for generating a second output signal using a second hysteresis slicer that is coupled to the AGC reference input of the automatic gain control circuit, wherein the second hysteresis slicer introducing less hysteresis than the first hysteresis slicer.

Abstract: A Wireless Access Point (WAP) of a Wireless Local Area Network (WLAN) infrastructure includes a processor, a radio and a directional antenna. The radio supports communications with a plurality of wireless terminals to gather participatory data, and listens to, but does not participate in transmissions of at least some of the plurality of wireless terminals to collect non-participatory WAP data. Based upon the participatory WAP data and non-participatory WAP data, the processor creates WAP operational reports and provides the WAP operational reports to the WLAN. The WLAN creates directions based thereon and directs the WAP to alter the gain pattern of the directional antenna.

Abstract: A single chip wireless transceiver operable to perform voice, data and radio frequency (RF) processing is provided. This processing may be divided between various processing modules. This single chip includes a processing module having an ARM microprocessor and a digital signal processor (DSP), an RF section, and an interface module. The processing module converts an outbound voice signal into an outbound voice symbol stream, converts an inbound voice symbol stream into an inbound voice signal, converts outbound data into an outbound data symbol stream, and converts an inbound data symbol stream into inbound data. These functions may be divided between the ARM microprocessor and DSP, where the DSP supports physically layer type applications and the ARM microprocessor supports higher layer applications. Further bifurcation may be based on voice applications, data applications, and/or RF control.

Abstract: The invention provides a signal amplifying stage, used in a signal receiver. The signal amplifying stage has: a fixed-gain low noise amplifier (LNA), amplifying an input signal; a variable-gain LNA (VG-LNA) array, amplifying the input signal, including a plurality of parallel VG-LNAs, the VG-LNA array being parallel with the fixed-gain LNA; a variable-gain amplifier (VGA), being in series with the fixed-gain LNA and the VG-LNA array, for amplifying output signals from the fixed-gain LNA and the VG-LNA array to generate an output signal; an attenuator, being in parallel with a combination of the fixed-gain LNA, the VG-LNA array and the VGA, for attenuating the input signal to generate the output signal; and a control loop, coupled to the VGA and the attenuator, for detecting power levels of the output signal to enable and control the fixed-gain LNA, the VG-LNA array, the VGA and the attenuator.

Abstract: A mobile station apparatus is provided which is capable of obtaining a diversity effect and preventing an increase in noise even if an antenna phase difference containing an error is detected. The mobile station apparatus includes a closed-loop transmit diversity control section for exerting, when the quality of the component from the second antenna is lower than a predetermined quality value based on the quality measured by the common pilot channel quality measurement section, control to cause the feedback information generation section not to use the detection result at the antenna phase difference detection section, and to continue to use the immediately preceding feedback information, control to cause the antenna verification section not to operate, and control to cause the first channel inference section to operate and the second channel inference section not to operate.

Abstract: A complex signal in which one of two signals that are generated from one real signal and that have phases shifted from each other by 90° is a real part and the other signal is an imaginary part is applied as input to an input terminal. A filter unit generates an output signal that is a complex signal by means of a convolution operation of this input signal and filter coefficients that are real signals and supplies the result to an output terminal. A coefficient control unit composed of a common unit and separate units controls the envelope target value based on the input signal and updates the filter coefficients such that the value of the envelope derived from the output signal approaches the envelope target value.

Abstract: The audio signals associated with different co-located groups of talkers in a teleconference are detected (e.g., by comparing the voiceprint for the current talker group with stored voiceprints corresponding to all of the co-located teleconference participants) and processed using different and appropriate automatic gain control (AGC) levels, where each group has a corresponding stored AGC level. Depending on the embodiment, each group may have one or more participants.

Abstract: A wireless receiver with automatic gain control and a method for automatic gain control of a receiving circuit utilized in a wireless receiver are provided. The receiving circuit includes a programmable gain amplifier and a low noise amplifier, and the method includes: comparing a gain code of the programmable gain amplifier with a predetermined code range, wherein the gain code is determined by a frequency signal received through the low noise amplifier; and adjusting a gain of the low noise amplifier when the gain code is out of the predetermined code range.

Abstract: A power control system includes a reference path filter used to suppress high frequencies in an input signal and generate a filtered envelope signal, a reference path amplifier to scale the filtered input signal based on a gain signal and generate a reference signal, a signal path amplifier to amplify an RF modulated signal and generate a signal path output signal scaled by a gain of an actuator signal, and a power detector to detect a power associated with the signal path output signal. The system includes an ADC to receive, pre-filter and convert the detected envelope signal into a measurement signal, and a comparator block to receive the reference signal and the measurement signal, and generate an error signal based on the difference, and a controller to generate the actuator signal for controlling the gain of the signal path amplifier based on the error signal.

Abstract: A method, system and apparatus using hybrid automatic repeat-request (HARQ) to enhance a system throughput in a transmit diversity system.

Abstract: A Wireless Access Point (WAP) of a Wireless Local Area Network (WLAN) infrastructure includes a processor, a radio and a directional antenna. The radio supports communications with a first plurality of wireless terminals and listens to, but does not participate in transmissions of at least some of a second plurality of wireless terminals to collect non-participatory WAP data. Based upon the non-participatory WAP data, the processor creates WAP operational reports and provides the WAPs operational reports to the WLAN. The WLAN creates directions based thereon and directs the WAP to alter the gain pattern of the directional antenna.

Abstract: A satellite navigation device including a flexible radio frequency (RF) receiver is described. The receiver receives a signal that includes at least a first spread-spectrum signal from a first satellite. The receiver has a first channel that includes an analog-to-digital (A/D) converter to sample and quantize the signal and an automatic gain control (AGC) to adjust an amplification of the signal. The A/D converter has a first non-zero quantization threshold magnitude and a second non-zero quantization threshold magnitude. The AGC may adjust a gain in accordance with the first non-zero quantization threshold magnitude. The gain may correspond to a first pre-determined probability of a non-zero sample and the second non-zero quantization threshold magnitude may correspond to a second pre-determined probability of a non-zero sample.

Abstract: A control of an amplifier in an automatic gain control (AGC) loop, e.g. in the RF front end circuitry of an OFDM receiver, provides phase adjustment control data to an associated automatic frequency control (AFC), to compensate for a phase jump that would otherwise be caused by switching of the AGC gain between discrete gain states. In the disclosed example, for each gain state, comparators detect a signal energy estimate crossing either a high threshold or a low threshold. Upon threshold crossing, multiplexers select compensation data corresponding to the necessary transition from the prior state to the new state determined by the comparators, based on identification of the prior state and on the particular threshold that has been crossed (high or low). The phase compensation data supplied to the AFC, for one interval corresponding to the timing of the gain switching, adjusts phase rotation implemented in the AFC.

Abstract: A fast settling AGC system includes a “fast settle” comparator that facilitates fast settling of strong radio receiver output signals from a maximum to an intermediate voltage level at the start of each transmission burst, and a “normal” AGC comparator that further settles the output signal from the intermediate voltage level to a desired target output voltage level at a slower “normal” rate. The gain control signal components generated by both the “fast settle” comparator and the “normal” AGC comparator are summed and applied to the gain control terminal of a variable gain amplifier. The gain control signal component generated by the “fast settle” comparator has a higher current level than the gain control signal component generated by the “normal” comparator, but is terminated when receiver output signal drops to the intermediate voltage level.

Abstract: The demodulator in the receiving module of the invention supplies a signal produced based on a signal level detected by a first detector to a second amplifier as an amplification degree adjustment signal. With this arrangement, when a second receiver works, an AGC voltage supplied to the second receiver is already close to an ultimately converging certain value. The AGC voltage supplied to the second receiver is thus stabilized in its value, from the value close to the ultimately converging certain value to the certain value. Accordingly, a time period required from the second receiver starts working until the AGC voltage supplied to second amplifier ultimately converges into the certain value is shortened.

Abstract: An integrated circuit (IC) includes an RF receiver having an AGC module that generates an automatic gain control (AGC) signal based on a strength of a received signal, and a low noise amplifier that amplifies the received signal based on the AGC signal. A processing module generates a power mode signal based on the AGC signal, the power mode signal for adjusting a power consumption parameter of the IC based on the power mode signal.

Abstract: Whether the reception electric field level of the antenna #1 is higher than the predetermined level is judged. If the reception electric field level of the antenna #1 is not higher than the predetermined level, the communication mode is to be set to the multi-slot mode, and then whether the reception electric field level of the antenna #1 is higher is judged by comparison of the reception electric field level of the antenna #1 and the reception electric field level of the antenna #2. If the reception electric field level of the antenna #1 is higher, the call mode is to be set to the antenna #1 for executing transmission and reception, or if the reception electric field level of the antenna #1 is not higher, the communication mode is to be set to the antenna #2 for executing transmission and reception.

Abstract: Described herein is a method of automatic gain control and simultaneous digital correction of three types of variations in I/Q receivers: gain imbalance, phase imbalance, and DC offset. Three adaptation loops can operate simultaneously and use the output of an analog to digital converter (ADC) as their input, with the output driving digitally controllable analog components. With appropriate knowledge of signal statistics, the algorithm automatically optimally fills the ADC's full input signal range, providing an automatic gain control function and thus maximizing the signal-to-quantization-noise ratio. In so doing, it corrects gain imbalances between I and Q paths, while additional circuitry corrects DC offsets and phase imbalances.

Abstract: An antenna (8), mounted to a roof (3) of a building (1), receives digital broadcast transmissions and feeds a signal through a cable (9) to a desk stand (2). The desk stand has an amplifier and a loop antenna. A mobile telephone handset (6) capable of receiving digital broadcast transmissions also includes a loop antenna. Using inductive coupling, the signal is transmitted from the desk stand to the mobile telephone handset.

Abstract: Techniques are disclosed for detecting a packet. One technique includes sampling a received signal to produce a sequence of samples wherein the sequence of samples includes a plurality of subsequences of samples; cross correlating the subsequences of samples with a known form of the subsequence to produce cross correlations; self correlating the cross correlations to produce a plurality of self correlations; summing the self correlations; and processing the sum of the self correlations.

Abstract: A radio communication system for conducting the radio communication with a terminal device includes a first radio communication apparatus for processing a first signal; a second radio communication apparatus for processing a second signal, and to combine the first signal and the second signal; a common amplifier for amplifying the first and second signals from the second radio communication apparatus, transmitting the amplified signals to the terminal device, amplifying first and second signals received from the terminal device, and outputting the amplified signals to the second radio communication apparatus, the second radio communication apparatus separating the amplified first and second signals; and a switching apparatus coupled to the first radio communication apparatus, the second radio communication apparatuses and the common amplifier to disconnect the first or second radio communication apparatus when a fault occurs in the first or second radio communication apparatus, respectively.

Abstract: Methods and apparatuses, including computer program products, for spatial processing in a radio receiver. One embodiment is a radio receiver for operation in a wireless communication system. The radio receiver may include a receive processing unit to process signals received by an antenna array by applying a selected spatial processing mode of a plurality of spatial processing modes. The modes include one or more modes of one or more spatial processing methods. The receiver also includes a selector to select the spatial processing mode from the plurality of spatial processing modes. The selecting includes selecting the spatial processing method in the case that the set of spatial processing modes are of more than one spatial processing method.

Abstract: An automatic gain control (AGC) method according to the present invention applies an initial gain by a digital AGC circuit in a timeslot is determined using a final calculated gain from the same timeslot in the previous frame together with an offset factor. An erase function is activated for a given data sample block when the number of saturated data samples that are detected within the block exceeds a threshold value. The power measurement made by the AGC circuit and used to update the gain is adjusted based on the number of measured data samples that are saturated. These elements provide a gain limiting function and allows limiting of the dynamic range for further signal processing.

Abstract: A tuner down-converts a Radio Frequency (RF) wireless signal and outputs the converted signal. The tuner compensates for a TOP depending on a temperature and: detects a received signal strength depending on a RF output of the tuner and transmitting the detected strength to a gain control unit; measures an operating temperature of the tuner and transmits the measured temperature value; receives the measured temperature value to compare the received temperature value with a reference TOP value, compensating compensates for the TOP value depending on variation in temperature and outputting outputs the compensated value; and receives the compensated value to control the RF output based on the TOP value and the received signal strength.

Abstract: A plurality of music apparatus 10 to 30 such as an electronic musical instrument and a microphone apparatus are connected by wireless to a mixer apparatus 40. A Bluetooth module is adopted as wireless communication means to construct a piconet with mixer apparatus 40 functioning as a master and music apparatus 10 to 30 functioning as slaves. Audio signals and MIDI data from music apparatus 10 to 30 are transmitted by wireless to mixer apparatus 40 through isosynchronous communication procedure using Bluetooth modules 11, 21, 31, 41. In mixer apparatus 40, with regard to the MIDI data, music tone signals based on the MIDI data are produced, whereafter the produced music tone signals and the aforesaid audio signals transmitted by wireless are mixed. Wiring by means of cables between a plurality of music apparatus and a mixer apparatus is abolished, thereby eliminating the cumbersomeness of wiring and the restrictions accompanying the wiring.

Abstract: Digital autonomous AGC for a DVB-H receiver comprises detecting a plurality of RF signals entering a LNA in the DVB-H receiver; detecting a RF transmitter blocker signal occurring at the LNA; and differentiating between a desired RF signal and an undesired RF transmitter blocker signal by varying a differential gain of current through the LNA. A RF servo loop is used for detecting the RF transmitter blocker signal. Logic circuitry of the RF servo loop is integrated with a baseband AGC loop to step control the differential gain of current through the LNA. A RF wideband detector is used for detecting the plurality of RF signals entering the LNA; and sending a voltage output corresponding to voltage levels of the RF signals to a plurality of comparators, wherein each of the plurality of comparators are set at a different programmable voltage threshold level compared with one another.

Abstract: The invention provides a radio frequency signal receiver with adequate gain control path to control the gain of a mixer and/or a channel selection filter, comprising a low noise amplifier for receiving and amplifying a radio frequency signal, a local oscillator (LO) for providing a LO signal, a mixer for down converting the radio frequency signal by the LO signal to an intermediate signal, a channel selection filter for receiving and filtering the intermediate signal to develop an output signal, and an automatic gain control unit for feedback adjusting the gain of the low noise amplifier and forward controlling the gain of the mixer and channel selection filter in accordance with the output signal of the low noise amplifier.

Abstract: When power to be transmitted varies, a control section instructs an AGC control section to control a gain of an IQ modulation processing section 6 in accordance with the power. A switch selects a power source voltage, corresponding to the power to be transmitted, from power source voltages V1 to V3 of a wireless module, in accordance with an instruction of the control section, so as to supply thus selected power source voltage to a power amplifier. Thus, it is possible to realize a wireless communication circuit which occupies a less area and consumes smaller amounts of power without narrowing a communication range.

Abstract: An embodiment of the present invention provides a method of closed loop MIMO calibration in a wireless communication system, comprising detecting that station calibration is obsolete and requires calibration, determining a range of automatic gain control which the station wants to calibrate and determining a list of transmission power for an Access Point (AP) in communication with the station, initiating by the station the calibration by sending the power list and N channel sounding preambles, where N is the number of transmit antennas at the station; and sending back by the AP a channel matrix and L sets of channel sounding preambles with a different transmission power level for each set, where L is the number of entries in the power list.

Abstract: In a clock noise canceling circuit, a coupler extracts a signal from a clock signal. A filter selects a harmonic component of a preset frequency in the extraction signal from the coupler. A phase shifter phase inverts the harmonic component of the preset frequency from the filter. An AGC amplifier amplifies the phase-inverted harmonic component from the phase shifter. Also, a combiner combines the amplified component from the phase shifter with the clock signal to eliminate the harmonic component of the preset frequency from the clock signal. A power detector detects a power level of the harmonic component of the preset frequency in an output signal of the combiner. Additionally, a controller controls gain of the automatic gain control amplifier based on the power level of the harmonic component detected by the power detector, thereby canceling noises.

Abstract: An apparatus and method for controlling a digital AGC in a communication system in which power changes significantly from frame to frame. In the digital AGC controlling apparatus, an SNR estimator estimates an uplink SNR of a next frame. A power measurer measures uplink received power of every frame. A gain calculator estimates uplink power of an nth frame using an SNR estimate of an (n?1)th frame received from the SNR estimator and a received power measurement of the (n?1)th frame received from the power measurer, and calculates a gain to be applied to the nth frame in the digital AGC using the uplink power estimate of the nth frame.

Abstract: An analog/digital gain control device avoid some of the requirements associated with the nature of a closed-loop AGC circuits and which meets the remaining requirements without much difficulty uses an analog to digital conversion method that increases the number of effective ADC bits by compressing the baseband input analog signal using a logarithmic circuit. After the compressed analog signal is converted into a digital signal, a digital anti-log process or look-up table (LUT) is used to expand the digital signal back to the original linear scale. The word size of the output of the anti-log process is larger than the input word size due to the nature of the anti-log function. To reduce the word size of the digital signal an open loop normalization technique can be applied.

Abstract: A conventional method of controlling the passband of a filter involves an increase in cost for a chip due to a large area of a detection circuit for determining the level of an interference wave. The present invention utilizes a result obtained by detecting the amplitude level of a signal with an automatic gain control circuit to appropriately control the passband of a filter. The amplitude level of all the signals including a desired wave and an interference wave is detected by utilizing the automatic gain control circuit to thereby control the passband of a filter on the basis of the result.

Abstract: In a wireless transmitting device which performs transmission by an OFDM using a plurality of subcarriers orthogonal to each other, a plurality of preambles to which a plurality of different subcarrier groups selected from a plurality of subcarriers within an OFDM signal band are allocated are transmitted by using a plurality of transmit antennas, and data is transmitted by using the antennas after the preambles are transmitted.

Abstract: A variable attenuator and method of attenuating a signal is presented. The variable attenuator contains an input that receives an input signal to be attenuated. A voltage divider between a resistor and parallel MOSFETs provides the attenuated input signal. The MOSFETs have different sizes and have gates that are connected to a control signal through different resistances such that the larger the MOSFET, the larger the resistance. The control signal is dependent on the output of the attenuator. The arrangement extends the linearity of the attenuation over a wide voltage range of the control signal and decreases the intermodulation distortion of the attenuator.

Abstract: In a communication receiver having a variable gain amplifier and an automatic gain controller, the automatic gain controller is operable to measure values of a system performance parameter indicative of the performance of the communication system, determine a statistical value of the system performance parameter, and adjust the variable gain of the amplifier in response to the statistical value to maintain the statistical value in a control range.

Abstract: The demodulator in the receiving module of the invention supplies a signal produced based on a signal level detected by a first detector to a second amplifier as an amplification degree adjustment signal. With this arrangement, when a second receiver works, an AGC voltage supplied to the second receiver is already close to an ultimately converging certain value. The AGC voltage supplied to the second receiver is thus stabilized in its value, from the value close to the ultimately converging certain value to the certain value. Accordingly, a time period required from the second receiver starts working until the AGC voltage supplied to second amplifier ultimately converges into the certain value is shortened.

Abstract: An Automatic Gain Control (AGC) circuit as used in a digital receiver that utilizes a main loop filter that is of a relatively wide bandwidth. A pre-filter, wideband variance is determined from the input digital signal, and a post-filter, narrowband variance is also determined. The wideband and narrowband variances are then compared to determine if the wideband signal power indicates a variance level that is too great to permit normal loop operation. By reapplying this difference in the power levels to the filter output as needed, such as by a scaling operation, the loss in dynamic range is effectively recovered. In a preferred embodiment, an adjustable gain input amplifier feeds an intermediate frequency (IF) signal to an analog-to-digital converter (ADC). The digitized IF signal is then down-converted to a baseband frequency and subjected to digital filtering. A narrowband sample variance (PN) of the digitally filtered (narrowband) data is then determined.

Abstract: Reception levels are measured in respective branches to compare the results of the measurements with one another to select the result of the measurement of a maximum reception level which is the highest reception level. The gains of variable gain amplifiers (6. 7) of all the branches including variable gain amplifiers (6, 7) included in a branch corresponding to the maximum reception level are adjusted to the same value such that output levels of the variable gain amplifiers (6, 7) are set to a preset target level.