Abstract: A hardware control loop (19) derives an AGC setting for a communication receiver based on signal strength information (16), without incurring program execution delay of a baseband processor.

Abstract: A communications receiver includes an analog input for receiving an analog signal having a time-varying DC voltage drift. A variable gain amplifier is coupled to the analog input and is adapted to amplify the analog signal based on a gain set by a gain control input to the amplifier. An analog-to-digital (A/D) converter is coupled to an output of the amplifier and is adapted to convert the amplified analog signal to a series of digital values. A drift estimator is coupled to the A/D converter, which generates an estimate of the time-varying DC voltage drift based on the series of digital values. A gain adjuster is coupled between the drift estimator and the amplifier, which adjusts the gain control input based on the drift estimate.

Abstract: Method of obtaining a transmission gain function for an array of antennae communicating to a telecommunication terminal. The method includes determining a first weighting vector {overscore (b)}u maximizing on reception by the array a ratio (C/(Iu+Nu))u of a received signal coming from the telecommunication terminal to a noise plus interference disturbing an uplink channel, and calculating from the first weighting vector {overscore (b)}u a second weighting vector {overscore (b)}d maximizing on reception by the telecommunication terminal a ratio (C/(Id+Nd))d of a received signal coming from the array to a noise plus interference disturbing the downlink channel. The second weighting vector is in the form of a matrix product including a first noise matrix Du which is a function of a power of the first isotropic noise and/or a power of the first directional noise and a second noise matrix Dd which is a function of a power of the second isotropic noise and/or a power of the second directional noise.

Abstract: A digital automatic gain control linearizer for controlling a variable gain control element for automatically controlling gain, using an analog signal obtained by converting input digital data includes a memory an average calculation unit. The memory outputs upper and lower limit data corresponding respectively to the upper and lower limits of a binary data range which can be expressed by a plurality of upper bits forming the digital data. The average calculation unit calculates the average of one and other data of the upper and lower limit data, and repeats average calculation a predetermined number of times using the calculated average at least one of the upper limit data and the lower limit data. Average calculation is repeated a number of times corresponding to the lower-bit value of the digital data except for the plurality of upper bits, and the variable gain control element is controlled in accordance with the average calculated by the average calculation unit.

Abstract: A video signal processing apparatus capable of improving signal level while reducing noise component no matter a video signal of what illuminance is input is provided, which apparatus includes a video signal amplifying circuit amplifying an input video signal and outputting a video signal of a predetermined image size in accordance with a gain control coefficient, a frame addition circuit connected to the video signal amplifying circuit for adding outputs of the video signal amplifying circuit by a predetermined number of frames, a first signal level detecting circuit connected to the video signal amplifying circuit and calculating the gain control coefficient and a multiplication coefficient in accordance with an output of the video signal amplifying circuit, and a first multiplier connected to the frame addition circuit and the first signal level detecting circuit and receiving as inputs an output of the frame addition circuit and the multiplication coefficient.

Abstract: A method of controlling the power in a wireless communication system. In one embodiment of the invention, a base station determines the information rate of a signal to be transmitted to a mobile station, and obtains the variable power control scaling factor based on this information rate. The base station then transmits the variable power control scaling factor to the mobile station. The mobile station determines a target signal quality measurement for a received signal from the base station, such as a target Eb/N0, and scales the target Eb/N0 by the variable power control scaling factor. The mobile station also obtains an information rate scaling factor based on the information rate of the received signal, and further scales the target Eb/N0 by this information rate scaling factor. The mobile station then compares the target Eb/N0 to a measured Eb/N0 of the received signal.

Abstract: A receiver is adaptively calibrated by using a coherent reference signal. The reference signal is selected to be offset from a center frequency of the calibration signal such that the resultant product is offset from baseband by some small amount. The resultant product is used to determine a next value of the calibration parameters.

Abstract: An antenna tuning apparatus for VHF/UHF antenna comprises an automatic gain control (AGC) arrangement, including an amplifier, the gain of which is controlled by the AGC arrangement, and a plurality of impedance matching networks which are coupled between an antenna input of the tuning apparatus and the AGC-controlled amplifier. A remote controller is provided to select both channels of a television apparatus, for which the tuning apparatus provides VHF/UHF signals, and proper matching networks suitable for respective ones of selected channels simultaneously. Each one of the plurality of matching networks exclusively provides the AGC arrangement with a respective group of RF signals which includes a plurality of receivable broadcast channels. The gain of the amplifier is controlled in response to the level of the group of RF signals.

Abstract: A radio broadcasting receiver having auto tuning process a digital signal processor includes a process for detecting a maximum value of a received signal output for each of a plurality of broadcasting stations selected during station selection, storage means for storing a detected maximum value of received signal output of each of the broadcasting stations, process for calculating a mean value of a plurality of stored maximum values of received signal outputs, and a process for calculating an output gain on the basis of a maximum value of a received signal output of a broadcasting station to be received and the mean value, and there is provided a process for conducting a gain control upon station selection according to an output of the digital signal processor so as to instantaneously bring the received signal output closer to the mean value, and which conducts automatically a sound volume adjustment at the time of station selection.

Abstract: A digital automatic gain control (AGC) system comprising an AGC amplifier configured to scale an input signal by a scale factor, and configured to generate an analog scaled input signal. An analog-to-digital (A/D) converter is configured to sample and convert the analog scaled input signal into a digital scaled input signal. The frequency down converted digital scaled input signal is processed by a power level detector circuit to detect its power level. The logarithmic comparison circuit (LCC) is configured to compare the detected power level of the digital scaled input signal to a predetermined reference signal and configured to generate a digital error signal. Finally, an error processing circuit is configured to process the digital error signal and configured to determine the scale factor of the AGC circuit.

Abstract: A system adjusts a receiving device in response to sensing symbols. An automatic gain control is adjusted in response receiving a first symbol of a data unit from a first antenna. After adjusting the automatic gain control at least a second and a third symbol of the data unit are received, and in response thereto (1) a first energy of at least one of the second and third symbols is calculated, (2) a first frequency offset of at least one of the second and third symbols is calculated, and (3) a first temporal offset of at least one of the second and third symbols is calculated. The automatic gain control in response receiving a fourth symbol of the data unit from a second antenna is received.

Abstract: The invention relates to a method for transmitting OFDM signals which arc conditioned in an OFDM modulator on the transmitter side for each symbol of the data stream to be transmitted and sent as a multicarrier signal. For each OFDM signal, the maximum amplitude of a block is determined for at least one block and then normalized to a system-related transmitter-specific maximum value.

Abstract: A programmable linear receiver which provides the requisite level of system performance at reduced power consumption. The receiver minimizes power consumption based on measurement of the non-linearity in the output signal from the receiver. The amount of non-linearity can be measured by the RSSI slope or energy-per-chip-to-noise-ratio (Ec/Io) measurement. The RSSI slope is the ratio of the change in the output signal plus intermodulation to the change in the input signal. The input signal level is periodically increased by a predetermined level and the output signal from the receiver is measured. The output signal comprises the desired signal and intermodulation products from non-linearity within the receiver. When the receiver is operating linearly, the output signal level increases dB per dB with the input signal level. However, as the receiver transitions into non-linear region, intermodulation products due to non-linearity increase faster than the desired signal.

Abstract: A circuit for compensating temperature of an automatic gain control (AGC) circuit includes a low noise amplifier (LNA) for amplifying a received radio frequency A) signal, an attenuation control unit for generating an attenuation control signal by sensing the amplified RF signal, and a PIN diode attenuator for attenuating the RF signal inputted to the LNA by driving the PIN diode with an attenuation control signal. A temperature compensation unit for compensating an attenuation change amount of the PIN diode caused by the change of temperature compensates the voltage change between the PIN diodes by using an additional PIN diode having identical characteristic of temperature as the PIN diode of the PIN diode attenuator.

Abstract: A wireless telecommunications system is described in which mobile station power control is affected by a functional combination of signal-to-interference sampling, bit error rate sampling, and frame error rate sample. The signal-to-interference sampling provides rapid power control adjustment, while the bit error rate and frame error rate factors provide less speedy but better power control adjustment. The power control function has applicability in single link and multiple link power control adjustments.

Abstract: The combined TV receiver can receive and process an analog broadcasting signal as well as a digital broadcasting signal, and includes a controller determining whether a channel selected by a user is a digital broadcast or an analog broadcast. The controller generates station selection data on the selected channel and a control signal pertinent to the determination. A tuner receives the station selection data and tunes to a broadcasting signal associated with the selected channel, out of signals received through an antenna. A switch unit forwards the broadcasting signal tuned at the tuner, in response to the control signal, to either an analog broadcasting processor or a digital broadcasting processor. An AGC (auto-gain controller) receives a gain signal either from the analog broadcasting processor or from the digital broadcasting processor, and adjusts a signal gain of the broadcasting signal tuned at the tuner, thereby allowing reception of both analog and digital signals.

Abstract: Radio receivers which switches the received voice signal according to a supervisory signal used for supervising the condition of the propagation path through which the voice signal is transmitted are known. However, if the reception level of the radio wave received by a conventional radio receiver is low, the level of the supervisory signal becomes lower while the level of the noise accompanying the supervisory signal becomes higher, whereby the noise acts like the supervisory signal so as to provide a voice signal containing a lot of noise to the user of the radio receiver. To solve this problem, the radio receiver according to the present invention compares the level of the supervisory signal and the level of the noise accompanying the supervisory signal, so as to control the outputting of the voice signal according to the comparison result.

Abstract: A convergence coefficient determination section 104 compares an average value calculated by an average value calculator 103 with a preset threshold value, and determines a convergence coefficient. A gain coefficient determination section 106 determines a control gain based on the aforementioned convergence coefficient and the aforementioned average value. A gain/voltage converter 107 converts the gain coefficient to a voltage to obtain a voltage control value. A GCA 101 amplifies a received signal in accordance with the voltage control value after it has undergone digital conversion.

Abstract: A direct downconversion receiver architecture having a DC loop to remove DC offset from the signal components, a digital variable gain amplifier (DVGA) to provide a range of gains, an automatic gain control (AGC) loop to provide gain control for the DVGA and RF/analog circuitry, and a serial bus interface (SBI) unit to provide controls for the RF/analog circuitry via a serial bus. The DVGA may be advantageously designed and located as described herein. The operating mode of the VGA loop may be selected based on the operating mode of the DC loop, since these two loops interact with one another. The duration of time the DC loop is operated in an acquisition mode may be selected to be inversely proportional to the DC loop bandwidth in the acquisition mode. The controls for some or all of the RF/analog circuitry may be provided via the serial bus.

Abstract: A method for controlling the power transmission levels in a spread spectrum or CDMA cellular system is disclosed, in which the decision to increase or decrease the transmission power level of a mobile station or base station, and the amount of any such increase or decrease made, is based on the weighted combination of a plurality of factors that indicate existing channel conditions. For example, the weight can be set according to the reliability of each channel condition factor involved.

Abstract: A wireless or wired communication system and method is provided including a transmitter and a receiver. A RF communication system in accordance with the present invention includes an apparatus and gain control method between RF receiver and baseband modem in case of a plurality of gain stages inside a receiver. The gain of each stage can be controlled by an integrated gain controller. The gain controller monitors the signal level of each gain stage to place its gain to optimal value. The gain control apparatus and method can be implemented in a digital AGC system. The gain controller accepts a signal implementing gain control and thus there is no stability issue. When distributed gain stages are present inside a related art receiver and separate gain control loops are used, stability issues can arise. In a preferred embodiment of an apparatus and method, the baseband modem decides the amount of gain control and adjusts the gain of certain gain stages by the proper amount.

Abstract: According to a disclosed embodiment, a receiver comprising a digital rotator in combination with a frequency error discriminator in a digital automatic frequency control loop is used to arrive at accurate digital values used to calibrate a local oscillation frequency. A frequency error in the oscillation frequency of a local frequency generation loop causes a change in the baseband input signal frequency. The change in the baseband input signal frequency related to the frequency error in the local frequency generation loop can be detected as a phase rotation by the frequency error discriminator. By using the digital automatic frequency control loop, the frequency error introduced by the local frequency generation is determined with accuracy. The frequency error and corresponding control bits are entered into a calibration table. The calibration table may be used to adjust the local oscillation frequency for temperature changes, pilot frequency searching, and quick paging.

Abstract: A servo channel digitally processes the data read from a magnetic media. The channel uses both edges of a system clock to detect peaks and generates position error systems by an area-based automatic gain control loop. By altering the sample delay, the channel digitally, up-samples at higher rates without requiring a higher system clock.

Abstract: An apparatus (150), system (100) and method (400-440) are illustrated for power amplification of an input signal to produce a substantially linear amplified output signal, for broadband wireless applications such as 3G cellular and broadband CDMA systems, without causing significant intermodulation distortion or spectral growth. The preferred system (100) embodiment includes an envelope detector (110) to determine an envelope detector voltage from the input signal; a tracking power supply (120) to determine a supply voltage, preferably as a substantially quantized replica of the envelope detector voltage; an input signal conditioner (150) to determine, in response to the supply voltage, a corresponding phase adjustment and a corresponding gain adjustment, and to modify the input signal using the corresponding phase adjustment and the corresponding gain adjustment to produce a conditioned input signal for power amplification.

Abstract: An automatic gain control circuit for amplifying an input signal of varying strength and having a fast attack mode of operation and a tracking mode of operation includes a gain controlled amplifier for receiving the input signal and producing an amplified analog output signal, a receive signal strength indicator (RSSI) circuit for receiving the amplified analog signal and producing an output voltage indicative of strength of the signal, and decision logic circuitry responsive to the output voltage from the RSSI circuit for controlling gain to the gain controlled amplifier. A plurality of comparators is provided for comparing the output voltage from the RSSI circuit to threshold voltages in generating output signals indicative of the voltage comparisons which can indicate the RSSI output voltage being very low, low, high, or very high as inputs to the decision logic circuit.

Abstract: A fast attack Automatic Gain Control (AGC) loop (100) having the capability to selectably shape one or more decaying current sources (242, 260) contained within an off-channel feedback loop and an on-channel feedback loop of the AGC loop by sequentially and selectively switching out weighted transistors (Tr0, Tr1, Tr2, . . . , Tr10) of a plurality of weighted current mirrors (313, 379, 453, 519) at predetermined intervals (t0, t1, t2, . . . , t10).

Abstract: An automatic gain control (AGC) amplifier including a high gain transimpedance amplifier, a resistive feedback network and multiple transconductance stages coupled in the feedback path of the AGC amplifier. The feedback network receives an input signal and is coupled to the output of the high gain amplifier and has multiple intermediate nodes. Each transconductance stage has an input coupled to an intermediate node of the feedback network and an output coupled to the input of the high gain amplifier. Each transconductance stage is independently controllable to position a virtual ground within the feedback network to control closed loop gain. Each transconductance stage may have a bias current input coupled to a bias current control circuit. The control circuit controls each bias current to vary the gain of the AGC amplifier. The bias currents may be linearly controlled employing a ramp function to achieve a linear in dB gain response.

Abstract: A soft limiter for a signal processor includes a variable-gain amplifier, and a threshold detector. The variable-gain amplifier includes a signal input for receiving an input signal, a signal output for providing an output signal representative of the input signal, and a gain control input for controlling a gain of the amplifier. The threshold detector is coupled to the gain control input, and includes a control input for receiving a control variable thereon. The threshold detector is configured to set the gain of the amplifier to a first gain value when the control variable exceeds a threshold value, and to set the gain to a second gain value different from the first gain value when the control variable is less than the threshold value.

Abstract: An intelligent gain controller operates to control the gain in each one of wideband uplink and downlink signal paths. Weak desired signals, within each wideband signal path, are detected using a narrowband down converter and detector, and these desired signals monitored by the micro controller. Based on the monitored signals, the micro controller operates, under control of suitable software implementing an Adaptive Control Algorithm, to adjust the gain in each of the uplink and downlink paths in order to dynamically optimize performance.

Abstract: In order to rapidly converge a gain control operation of an AGC amplifier which is provided for amplifying burst signals, a level of an incoming bust signal is detected. Following this, a signal indicative of the level of the burst signal is latched in response to a first latch control signal. On the other hand, an output of said AGC amplifier is derived and a level deviation thereof from a reference level is detected. Subsequently, a signal indicative of the level deviation is latched in response to a second latch control signal. The above-mentioned gain control signal is generated using the two kinds of signals held in the latches.

Abstract: An AGC amplifier circuit has a fixed-gain amplifier, of which the gain is not controlled by an AGC voltage, and a variable-gain amplifier, of which the gain is controlled by the AGC voltage, that are connected in parallel. When the AGC voltage is within a predetermined voltage range, the overall gain of the AGC amplifier circuit is varied by the variable-gain amplifier; however, when the AGC voltage is outside the predetermined voltage range, the overall gain is kept constant by the fixed-gain amplifier. The minimum gain of the AGC amplifier circuit is set to be equal to the gain of the fixed-gain amplifier.

Abstract: An apparatus and method for high speed detection, storing, and switching broadcast channels. The broadcast signal is discriminated to exist based an automatic gain control signal. This discrimination is done at a very high speed by the use of speed-up drive units. The invention also performs channel storing and switching operations at high speed by using speed-up drive units.

Abstract: In an automatic gain control amplifier AGCa, an RF automatic gain controller 2 controls the gain of a radio frequency signal Srf. A frequency converter 3, 4 frequency-converts the radio frequency signal Srfa into an intermediate frequency signal Sifa. An IF automatic gain controller 5 controls the gain of the intermediate frequency Sifa. A level detector LDa detects a signal level of the gain-controlled intermediate frequency signal Sifa, and generates a level signal SLa. An automatic gain control signal generator SGa, SGb separately controls, based the level signal SLa, SLb, the RF automatic gain controller 2 and the IF automatic gain controller 5.

Abstract: An automatic digital level control adjuster (310) processes an analog input signal (305) to adjust its signal level, based on input (311) from a digital module (330) that is clocked by a clock signal (325) derived from the analog signal (305). Preferably, the input (311) from the digital module (330) changes at a rate dependent on the clock signal (325), and such changes are made during crossovers of the analog signal across a predetermined zero reference threshold.

Abstract: A multimode fast attack automatic gain control (AGC) circuit (100) includes an analog feedback loop and a digital feedback loop. The analog feedback loop is switched into the amplifier stage (102) by a first switch (126) when dynamic control of the gain attenuation is desired. The digital feedback loop is switched into the amplifier stage when attenuation is to be adjusted periodically, such as between sequentially received time slots in a time division multiple access (TDMA) mode of communication.

Abstract: The present invention is a method and apparatus for tracking a frequency of a signal. The received signal is converted to an intermediate frequency (IF) signal using a frequency reference. An automatic gain control (AGC) is provided to the IF signal. The AGC generates a control value. The magnitude and phase parameters of the IF signal are estimated. A frequency error is estimated based on the phase parameter. A control quantity is generated based of the control value, the estimated magnitude parameter and the estimated frequency error. The control quantity adjusts the frequency reference.

Abstract: At the power-on, a determination section (9) outputs a switch control signal (m) to a selector switch (7) to select the output of a sweep signal generator (6) which generates a voltage sweep signal (h) that increases from the minimum value to the maximum value of the gain control voltage range (p) at the same time, then provides the voltage sweep signal (h) to the variable gain amplifier (1), and calculates the difference (f) between the level detection value of an output signal (c) and a convergence value (e) and detects a sweep voltage value (j) obtained when (f)=0 and stores the sweep voltage value (j) into memory. After the sweep operation, the sweep voltage value (j) stored in memory is provided as a gain control signal (b) to the variable gain amplifier (1). Then the primary automatic gain control via the closed loop control system is started.

Abstract: A method and system for intelligently controlling the linearity of an RF receiver by selectively increasing the effective third-order intercept point (IP3) value of a low noise amplifier (LNA)/mixer channel only when needed. A control signal is generated based on mode of operation (receive mode); received signal strength information (RSSI); transmit channel output power, as indicated by a Tx automatic gain control (AGC) signal; and the true received signal strength, as indicated by the pilot signal-to-noise ratio in a CDMA system. The control signal is then used to selectively increase the bias current—and thus linearity—of the LNA/mixer channel, or to select one of several LNAs having differing IP3 values to effectively increase the linearity of the LNA/mixer channel.

Abstract: A gain control circuit controls the gain of a variable-gain amplifier for amplifying a radio-frequency signal having at least one of a plurality of predetermined transmission rates is controlled. A received signal level is detected from a received signal amplified by the variable-gain amplifier and a transmission rate of the received signal is determined. Then, the gain of the variable-gain amplifier is controlled depending on a gain control adjusting signal produced based on the received signal level and the transmission rate of the received signal.

Abstract: An intermediate-frequency signal is fed to a demodulated-signal processing circuit through a variable gain circuit, an active filter, and a limiter. An RSSI output signal responsive to a received signal level is obtained through a low-pass filter by detecting the output of each stage of the limiter at a detector and by summing the output of the detector at an adder. The linearity of the RSSI output signal responsive to the received signal level is improved by feeding, via a coefficient multiplier to the adder, the control signal of a level detector which detects the control signal of the variable gain circuit, which limits the signal input to the active filter.

Abstract: For use in a radiocommunication system using a frequency band close to a frequency band of a different radiocommunication system, a radiocommunication device, or a mobile, is controlled so that a maximum of transmission power is set according to an up-link frequency in use. The closer the up-link frequency in use is to the frequency band of the different radiocommunication system, the lower the maximum of transmission power is set.

Abstract: An RF signal received from an antenna is supplied to an RF portion. The RF portion mixes down the RF signal to an IF signal. An RSSI circuit of an automatic gain controlling circuit portion converts the received RF signal into a DC component and detects the electric field intensity of the received signal. A level determining unit has two threshold values of the input level. The level determining unit controls the variable amount of a gain varying unit corresponding to the input level. An averaging process circuit averages a digital signal in a predetermined time period T and controls the variable amount of the gain varying unit 3 so that the average value converges at a digital value with n bits that represent a predetermined amplitude level. A BB portion demodulates the digital signal that has been modulated on the transmitting side to original information.

Abstract: A system and method for providing automatic gain control (AGC) with high dynamic range. An AGC system comprises an open loop control system and a closed loop control system. The open control loop system senses the power level of an input signal and preprocesses the input signal based on its sensed power level. For instance, a strong input signal is attenuated by a fixed level via an analog attenuator, a weak input signal is amplified by a fixed factor via a low noise amplifier, and an intermediate level input signal is directly passed to the closed loop control system of the AGC without any attenuation or amplification. By preprocessing the input signal, the closed loop control system can operate in a range that is optimal for its performance. For instance, a gain variable amplifier of the closed loop control circuit can be prevented from operating in a high attenuation status where its noise figure is very high. A wide band receiver using the AGC system may have a dynamic range over 100 dB.

Abstract: A single chip superhetrodyne AM receiver is disclosed herein. To compensate for process variations in the implementation of the IC, bias currents setting the operating conditions for various amplifiers and other components in the system are adjusted based on frequency control signals in a PLL circuit in the local oscillator. Since the magnitude of the control signal reflects the process variations, the bias currents are adjusted based on the control signal to offset these variations in other portions of the receiver. To further improve the signal to noise ratio of the receiver, the IF filter is tuned within a range so as not to include any integer multiple or integer divisor of the timing reference frequency. Various techniques are described for enabling a complete superhetrodyne AM receiver to be implemented on a single chip which receives an antenna input signal and outputs a digital data signal.

Abstract: An AGC amplifier control circuit applying for both transmission and reception which the quantity of data memorizing in a memory is decreased and the address of the memory is simplified is provided. The AGC amplifier control circuit provides RF attenuators controlled in hysteresis and these RF attenuators are driven at the next gain renewing time of AGC amplifiers and provides attenuation controllers outputting the information whether the RF attenuators have a fixed attenuation quantity or not. In this construction of circuit, memories memorize the control voltage data of the gain of the AGC amplifiers with the relation of desired outputs, at the time when the RF attenuators are driven and have a fixed attenuation quantity, data conversion circuits convert the data to make the gain of the AGC amplifiers increase corresponding to these attenuation quantities.

Abstract: A method and apparatus is shown for controlling the input gain of a receiver wherein the input gain is controlled by sampling an amplified data signal during a time interval when a positive-going feedback transient from an output terminal of the receiver to an input terminal of the receiver is not present in the amplified data signal. An embodiment of a receiver circuit according to the present invention includes an input amplifier having variable gain determined by a gain control signal, a comparator which compares the amplified data signal from the input amplifier to a detection threshold voltage to produce a demodulated data signal and an analog delay circuit which delays the amplified data signal by a predetermined time interval to produce a delayed data signal. A switch is driven by the demodulated data signal to sample the delayed data signal for input to an automatic gain control circuit.