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 call apparatus, a call method and a call system, are disclosed, in which the problem otherwise caused by fixed setting of the sound volume level of the BGM or the effect sound with respect to the call voice may be overcome. A decoded output of a decoder 17 (PCM data) is multiplied in a gain adjustment unit 18 with a gain coefficient k2, as the SE sound volume level as set by a user. A multiplication output of the gain adjustment unit 18 is sent to an adder 13. The decoded output of a decoder 20 is multiplied in a gain adjustment unit 21 with a gain coefficient k3, as the BGM sound volume level, as set by the user. A multiplication output of the gain adjustment unit 21 is sent to an adder 13. The adder 13 sums the multiplication outputs of the gain adjustment units 12, 18 and 21 and sends a sum output to an encoder 22.

Abstract: An AGC circuit controls LNA and VGA amplifiers such that a received signal is converted at a high speed with tracking errors prevented according to each modulation scheme. The AGC circuit generates LNA and VGA control signals controlling the LNA and VGA amplifiers, respectively. A digital signal, converted from the received signal, is calculated for a power value, on which scaling is performed by a scaling section to then be provided through an adder and a register to a control signal generator for generating the LNA and VGA control signals. The scaling section compares the power value with a target value to perform scaling with a scaling coefficient according to the sign of the comparison value so that an increase of the tracking error is avoided, thus preventing phenomena where the AGC control oscillates without convergence, thereby making it possible to attain the optimum automatic gain control.

Abstract: An input signal detecting apparatus and method in a digital receiver is provided. The input signal detecting apparatus includes an outer AGC for receiving an input signal and thereby controlling gains of RF and IF AGC amplifiers and generating an IF AGC gain value; an inner AGC for receiving the input signal and thereby generating an inner AGC gain value; and an input signal detector for receiving the input signal, a predetermined input signal power reference value, the IF AGC gain value and the inner AGC gain value and thereby generating a signal for representing a condition of stability of an input signal and a signal for representing a condition of existence of an input signal, thereby making it possible to reduce the channel information scanning time and determine a time at which an after-edge recoverer should be activated, by using the condition of existence of an input signal and the condition of stability of an input signal.

Abstract: When switching over from a portable telephone system of 800 MHz band to a UWB communication system of 9 GHz band, depending upon a signal for changing over a high pass filter and a low pass filter, a reactance element, which is determined to be matching with a load Z of the high pass filter, is connected to an output terminal of a transmitting power amplifier. With this, it is possible to achieve a multi-band or multi-mode wireless receiver of using a frequency band from 800 MHz to 10 GHz, without an enlargement of a circuit scale and an increase of costs.

Abstract: When a radio communication terminal including an AGC receiver starts, a set gain of the AGC receiver is switched in a short updating period. At this time, the terminal switches among antennas, and calculates and stores a received power of a received radio signal through each antennal. This calculation is performed a predetermined number of times for each antenna. After that, the terminal compares the calculated received powers of the radio signal through each antenna, and fixedly uses, as a receiving antenna, one of the antennas which receives a signal with the largest power.

Abstract: A device for measuring voltage levels includes a root mean square (RMS) detector. The RMS detector includes a linear multiplier, a log converter, a low-pass filter and a temperature compensator. The linear multiplier multiplies a voltage of an input signal by the voltage of the input signal. The low-pass filter couples to an output of the linear multiplier. The log converter generates a logarithmic signal having a voltage that is logarithmically related to a voltage of an output of the low-pass filter. The temperature compensator adjusts the logarithmic signal based on a temperature of the RMS detector. The RMS detector is capable of determine an RMS voltage level of the input signal.

Abstract: The method is applicable to a receiver (1) of signals corresponding to packets of digital data transmitted in bursts, which comprises an analogue pickup subassembly (3) connected to a digital processing subassembly (8) by means for converting analogue signals into digital signals (7). Gain adjustment means (5) act on the amplification means (5) in order to alter the power of signals supplied to the conversion means. The method provides a preadjustment of the gain, in the absence of a burst, for detecting the arrival of signals even if they are weak, and an adjustment of the gain as a function of a power value of the signal determined from burst start symbols, as obtained after conversion. This adjustment is dependent on the recognition of symbols scheduled at the start of a burst, it is carried out during a time scheduled for a symbol otherwise left unexploited by the method.

Abstract: A radio frequency tuner is provided for selecting channels from a cable distribution network or other reception system. The tuner has one or more stages whose performance, such as signal to noise plus intermodulation, and gain are functions of the stage power consumption. A comparator compares the tuner performance, such as bit error rate, with a predetermined performance. When the tuner performance exceeds the predetermined performance, a power consumption control circuit reduces the power consumption of one or more of the stages so as to reduce the tuner power consumption while maintaining acceptable tuner performance. As an alternative, the control circuit may have an input which allows the power consumption to be preset in accordance with the tuner application. The control circuit also controls a variable gain arrangement to compensate for changes in gain resulting from changes in power consumption.

Abstract: A time signal carrying encoded time information transmitted at a transmission frequency from any one of plural time signal transmitters is received, amplified, and evaluated to acquire the time information. The transmission frequency of the received time signal is determined (provided is the time information signal's just emitted frequency f), and an amplification factor of the amplification of the signal is adjusted depending on the transmission frequency. A receiver circuit for a radio-controlled clock in this regard includes at least one amplifier having a variable amplification factor that is adjustable dependent on the frequency of the received time signal.

Abstract: Disclosed is an AGC (automatic gain control) device and method of an OFDM system with a DC offset compensation function, and a recording medium storing a program including the method. The AGC device calculates an energy of input signals with DC offsets as the summation of the square of the input signals, and calculates an energy of the DC offsets in the input signals as the summation of the square of the DC offsets. Pure signal energy without DC offsets is produced by subtracting the energy of the DC offsets from the energy of the calculated input signal. The energy and an AGC reference value are then compared, and feedback of a comparison result is performed.

Abstract: An apparatus, system, and method improve the dynamic range of a receiver in the presence of a narrowband interfering signal. An error rate of a received signal is computed, and the input intercept point of a low noise amplifier in the receiver is adjusted based on the error rate. The transmit power level is detected, and the input intercept point is adjusted based also on the transmit power level. The received signal strength is also detected, and the gain of the low noise amplifier is adjusted based on the received signal strength. In this manner, the effect of crossmodulation on the received signal is reduced.

Abstract: A dual-mode analog baseband circuit is implementable on a single IC with reduced chip area. The baseband portion of the IC includes a single dual-mode complex filter that is reconfigurable to be a filter for Bluetooth signals or for wireless local area network (wireless LAN) format signals, such as 802.11b, and includes a single dual-mode amplifier that is reconfigurable to amplify Bluetooth signals or wireless LAN format signals.

Abstract: Channel fluctuation values on propagation paths of modulated signals transmitted from a plurality of antennas are estimated, an eigenvalue of a channel fluctuation matrix created with the above-mentioned channel fluctuation values as elements is found in order to relate antenna received signals to modulated signals, and using that eigenvalue, receiving antenna selection, combining of modulated signals, and weighting processing on soft decision decoded values, are performed, and modulated signals are demodulated. By this means, it is possible to perform demodulation processing based on the effective reception power of a modulated signal (that is to say, the essential reception power, of the reception power obtained by a receiving apparatus, that can be effectively used when demodulating a modulated signal), enabling the precision of demodulation of modulated signals to be improved.

Abstract: An adaptation process for automatic gain control is adapted to obtains the statistical characteristics of the received signal to estimate the input signal power level. The estimated input signal power level is used to adjust the gain of a variable gain amplifier for the automatic gain control.

Abstract: An automatic gain control circuit for a receive apparatus for a mobile object which automatically controls the gain of a variable gain amplifier amplifying a received signal from an antenna installed in the mobile object and outputting the amplified signal to the receive apparatus. The circuit comprises an intensity detector that detects an intensity of the received signal; a comparator that compares the detected intensity with first and second threshold voltages; and a controller that outputs a control signal for adjusting the gain to the variable gain amplifier based on the comparing results of the comparator so that the gain of the variable gain amplifier has a hysteresis with respect to the intensity of the received signal.

Abstract: The invention improves the control behavior of a control circuit for digital signals which is used in AGCs (automatic gain control), using a simple supplementary circuit. In a first example of an embodiment, the output signal of an integrator member is looped back to the input of said integrator member in the loop-back branch of the control circuit. In a second example, a counter is provided. Said counter monitors the overflow of the integrator member and weights the input signal accordingly.

Abstract: Systems and methods are provided for reducing the peak to average ratio of signals, so that the signals can be amplified more efficiently. An error signal that corresponds to crests of the input signal is generated, and subtracted from the input signal. When a crest is so long that it corresponds to more than one sample, only the maximum sample contained in the crest is used to form the error signal. Optionally, multiple stages of decresting may be implemented sequentially.

Abstract: The present invention is directed to a system and method which statistically determines when regularly occurring interference events of a predictable duration will occur, for example radar pulses and dynamically adjusts an automatic gain control (AGC) for RF data transmissions accordingly. The repetition rate and width of radar pulses are regular. By averaging and watching for correlations, the present AGC identifies the pulse rate and pulse widths and over a fairly short period of time predicts when the next pulse is coming. When the next pulse occurs, the AGC is adjusted to react accordingly. The AGC can raise or lower gain levels for the duration of the pulse; or ignore the pulse, if it is of a very short duration, so that the AGC level will coast through the event.

Abstract: A transceiver according to some embodiments of the present invention receives data from a plurality of frequency separated transmission channels from a complementary transmitter of another transceiver and adjusts the power output of certain channels in a transmitter of the receiver. Upon start-up, the power output levels of signals in individual channels in the transmitter can be preset. A power balance can determine new power output levels of the transmitter from parameters in the receiver while receiving data transmitted by a similarly situated complementary transmitter in a second transceiver coupled to the transceiver. In some embodiments, a complementary receiver of the other transceiver determines the power outputs of the transmitter and the power levels are transmitted to the transmitter by the other transceiver.

Abstract: The invention provides a communication semiconductor integrated circuit device (RF IC) capable of pulling in the frequency of a PLL circuit to a desired set frequency at high speed even in the case where a frequency settable range of the PLL circuit is wide without providing a current source other than a current source for charging and discharging in an normal operation. An oscillator as a component of a PLL circuit is constructed so as to be operative in a plurality of bands. In a state where a control voltage of the oscillator is fixed to a predetermined value, an oscillation frequency of the oscillator is measured in each of bands and stored in a storing circuit. A set value for designating a band supplied at the time of PLL operation is compared with the stored measured frequency value. From a result of comparison, a band to be actually used in the oscillator is determined, and a frequency difference between the maximum frequency of the selected band and the set frequency is obtained.

Abstract: A gain processor circuit calculates a first AGC signal for a first one of a number of receive chains, each including a gain-controlled front-end circuit, and derives one or more additional AGC signals from the calculation of that first AGC signal for any remaining chains. The first AGC signal may be calculated by tracking received power for one or more of the receive chains. An AGC signal may be derived for each additional receive chain by assuming that its received power is the same, i.e., the same AGC command is used. Alternatively, an additional AGC command is derived based on a scaling value determined from a ratio of received powers for the first and additional receive chains. Such powers may be expressed as channel tap powers, which may be available from other circuit elements associated with signal demodulation. Alternatively, the scaling value further incorporates received interference and/or noise powers.

Abstract: An automatic gain control (AGC) method and circuit (10) within a receiver uses a digital state machine (26) to implement the AGC function. independent from interaction with a host processor (36) and for multiple modulation protocols without duplicating circuitry. Modulation protocol and parameters for any of various gain responses are stored in a register (29). Multiple states, each corresponding to a predetermined range of RF input signal strength, are stored in the register. Each state contains parameters that determine a gain control signal for controlling a variable gain amplifier (16). The states are independent and may be selectively disabled to create asymmetric responses. Within any state, an adaptable number of iterations may be set to implement a different update rate or step size after a predetermined number of closed loop gain change iterations has not resulted in a transition to a state that represents a desired output gain.

Abstract: In a direct conversion receiver with zero-frequency intermediate frequency (IF) signal, the DC offset and 1/f noise of the IF signal is compensated by means of double-sampling. The first period of the doubling-sampling is a calibration phase, which stores the DC offset and the 1/f noise. The second period is a signal flow phase during which the stored DC offset and 1/f noise is connected in opposition with the IF signal to cancel the DC offset and 1/f noise.

Abstract: A communication system is provided of selecting the most approximate line from two or more connectable lines and connecting with a provider through the selected line in the mobile communication environment. The mobile device and the public phone of each phone company provide a standard wireless data communication facility, respectively. The public line pre-stores information about dial-up numbers of access points and a transmission speed of an internet provider. When the user starts the communication, the mobile device operates to obtain the most approximate access point information from each of the public phones and then dial up the most approximate access point through the public phone/line well-specified to the user.

Abstract: A low-noise current reference circuitry includes a voltage source, a current source, and a controller. The voltage source generates a reference voltage. The current source provides a low-noise output current in response to a control signal. The controller provides the control signal based at least in part on the relative magnitudes of the reference voltage and a voltage derived from the output current. A low-noise voltage reference circuitry includes a reference voltage source, a voltage source, and a controller. The reference voltage source generates a reference voltage. The voltage source provides a low-noise output voltage in response to a control signal. The controller provides the control signal based at least in part on the relative magnitudes of the output voltage and the reference voltage.

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 high frequency amplifier for amplifying inputted television signals; a mixer for subjecting the television signals which have been amplified to frequency conversion into intermediate frequency signals; a SAW filter for selecting, out of the intermediate frequency signals, intra-range intermediate frequency signals emerging in a range within a prescribed intermediate frequency band; and an intermediate frequency amplifier for amplifying the intra-range intermediate frequency signals are provided, and wide band detecting means for detecting the intermediate frequency signals inputted to the SAW filter and generating a first AGC voltage is provided to control a gain of the high frequency amplifier with the first AGC voltage.

Abstract: A signal pre-processing device particularly in wireless LAN devices is provided that comprises an AGC (Automatic Gain Control) unit, an ADC (Analog-to-Digital Converting) unit and a normalization unit. The AGC unit amplifies a received analog input signal and outputs an amplified analog signal. Further, it automatically controls an amplification gain when amplifying the analog input signal. The ADC unit receives the amplified analog signal, converts it into a digital signal and outputs the digital signal. The normalization unit is receives the digital signal, applies a normalization function to the digital signal and outputs the normalized digital signal. Thus, less precise AGC units can be used, thereby reducing production costs as well as the size and complexity of the AGC unit. Further, shorter circuit development times are obtainable.

Abstract: The invention provides a communication semiconductor integrated circuit device (RF IC) capable of pulling in the frequency of a PLL circuit to a desired set frequency at high speed even in the case where a frequency settable range of the PLL circuit is wide without providing a current source other than a current source for charging and discharging in an normal operation. An oscillator as a component of a PLL circuit is constructed so as to be operative in a plurality of bands. In a state where a control voltage of the oscillator is fixed to a predetermined value, an oscillation frequency of the oscillator is measured in each of bands and stored in a storing circuit. A set value for designating a band supplied at the time of PLL operation is compared with the stored measured frequency value. From a result of comparison, a band to be actually used in the oscillator is determined, and a frequency difference between the maximum frequency of the selected band and the set frequency is obtained.

Abstract: In a radio system, the transmission power is controlled by a receiver (1; 2) evaluating the signal from a transmitter (2; 1) and a determining power adjustment information (TPC) as a function of this, and sending this information to the transmitter (2; 1) during successive timeslots (4), in order to control the transmission power. In what is referred to as the slotted mode, the same power adjustment information (TPC) is transmitted to the transmitter (2; 1) in a number of successive timeslots (4) following a section (9) which is not filled with information.

Abstract: Disclosed is a novel and improved dynamically programmable linear receiver which provides the required level of system performance with reduced power consumption. In one embodiment, disclosed is a programmable receiver coupled to a jammer detector for detecting the presence of jamming in an RF signal, the jammer detector coupled to a state machine, and the state machine having means for controlling the receiver based on the results of the jammer detector detecting the presence of jamming in the RF signal. The disclosed receiver is capable of detecting the presence of jammers, with a means to adjust the bias current downward if no jammers are present, which improves the receiver's standby time and prolongs battery life.

Abstract: A Radio Frequency (RF) receiver includes a low noise amplifier (LNA) and a mixer coupled to the output of the LNA. The gain of the LNA is adjusted to maximize signal-to-noise ratio of the mixer and to force the mixer to operate well within its linear region when an intermodulation interference component is present. The RF receiver includes a first received signal strength indicator (RSSI_A) coupled to the output of the mixer that measures the strength of the wideband signal at that point. A second received signal strength indicator (RSSI_B) couples after the BPF and measures the strength of the narrowband signal. The LNA gain is set based upon these signal strengths. By altering the gain of the LNA by one step and measuring the difference between a prior RSSI_B reading and a subsequent RSSI_B? reading will indicate whether intermodulation interference is present.

Abstract: A receiver portion of a radio includes an analog circuit for determining a peak amplitude in a way that eliminates or reduces the effects of frequency errors that are introduced by crystals within filters and other devices. A voltage follower and a current mirror in which a MOSFET coupled to an output node produces a voltage across its gate to source terminals whose value is a function of a sum of the gate to source voltages of two MOSFET devices that receive a logarithm of an I modulated channel and a logarithm of a Q modulated channel, respectively.

Abstract: Audio equipment and a method of controlling audio equipment include a switching power amplifier circuit and a controller controlling a switching frequency of the power amplifier circuit. The controller varies the switching frequency of the power amplifier circuit in accordance with a receiving frequency in a case of receiving at least a medium-wave broadcast wave.

Abstract: A transmitter for a portable radio communication apparatus comprising a modulator having first port for inputting a baseband signal and a second port for inputting a local oscillator signal, and including means for rectifying the input local oscillator signal to provide a conductance waveform at a multiple of the local oscillator signal, and means for mixing the baseband signal with the conductance waveform at said multiple of the local oscillator signal frequency for up-converting the baseband signal to a radio frequency modulated carrier, the transmitter including means for controlling the gain of the modulator thereby to control the output level of the modulator.

Abstract: The AGC threshold of electric intensity level is set by the signal processor portion 107 in response to the measured result of the error rate measuring circuit 109 that measures the error rate of the received signal, and the gain control operation of the gain control circuit 106 is caused to start when the electric field intensity detected by the field intensity detector 105 reaches the threshold of electric intensity level. Accordingly, the optimum AGC threshold of electric intensity level can be set to meet the radio wave situation in which the radio receiver, i.e., the receiving situation of the received signal and also the gain control of the gain controlling means can be achieved to optimize the signal quality of the received signal in the situation of either the IM characteristic or the electric field variation characteristic, e.g., under the environment of the strong electric field IM or the environment in which the electric field is changed strongly.

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: Variable gain amplifier and a LSI including the variable gain amplifier that expands an output voltage range or control voltage range without increasing power consumption. The variable gain amplifier includes a voltage-current conversion circuit; a variable gain unit; and a voltage output unit. The voltage-current conversion circuit outputs a first positive current and a first negative current in proportion to an input voltage. The variable gain unit inputting the first positive current and the first negative current controlled by a control signal and outputs four output currents including a second positive current, a third positive current, a second negative current and a third negative current. The voltage output unit inputs either the second positive current and the second negative current or the third positive current and the third negative current Iop3, and outputs a positive output voltage and a negative output voltage.

Abstract: The present embodiments provide apparatuses and methods for use in receiving radio frequency signals. In some embodiments, a method receives an input signal comprising data and jamming signals, amplifies the input signal according to a first adjustable bias level and producing a first internal signal. The first internal signal is mixed with an intermediate frequency signal to produce a second internal signal. The method detects a level of a signal that is proportional to a level of the input signal prior to baseband limiting filtering and as such is proportional to a level of the data and jamming signals. A bias control signal is generated that is dependent on the detected level of the detected signal, and the first bias level is adjusted according to the bias control signal. The bias control signal can increase as the level of the detected signal increases and can compensate for the jamming signals.

Abstract: In a gain control device for packet signal receiver, a variable gain amplifier amplifies an input signal with a gain corresponding to a control voltage applied thereto, and a power detector detects output power of the variable gain amplifier. A packet detection circuit detects a packet signal based on the detected output power. A control circuit outputs the control voltage variable with the detected output power, and the control voltage is provided for the amplifier. Thus high-speed gain control is performed immediately after the start of detection of the packet signal. When the elapsed time after the start of detection of the packet signal exceeds a predetermined time, a sample-hold circuit sample-and-holds the control voltage. This control voltage is provided for the amplifier up to the end of reception of the packet signal thereafter. Thus low-speed gain control is performed to provide stable power without distorting the signal wave.

Abstract: A DS-CDMA (Direct Sequence-Code Division Multiple Access) multi-user interference canceller cancels interference waves of a plurality of users. The DS-CDMA includes a variable gain controller for comparing reception characteristics of reception signals received from the plurality of users prior to interference cancellation processing with reception characteristics upon the interference cancellation processing and evaluating a comparison result, and controlling gains prior to baseband decoding of the reception signals so as to maximize improvements of the reception characteristics of the reception signals on the basis of an evaluation result. A CDMA multi-user system using the above canceller is also disclosed.

Abstract: An adaptive equalizer with a large data rate range is provided. The equalizer comprises an equalizer core, a slicer and an automatic gain control (AGC) loop. The equalizer core is coupled to an input signal from a transmission medium and applies a transfer function to the input signal to compensate for losses incurred in the transmission medium in order to generate a core output signal. The equalizer core is also coupled to a bandwidth control signal that controls a bandwidth of the transfer function. The slicer is coupled to the core output signal and converts the core output signal to a digital output signal having a fixed digital output swing that approximates a transmission swing of the input signal prior to transmission over the transmission medium. The AGC loop is coupled to the core output signal and the digital output signal and compares the core output signal with the digital output signal in order to generate the bandwidth control signal.

Abstract: A wireless communication apparatus includes an antenna receiving a radio signal, a variable gain amplifier amplifying the received signal using a variable gain, an analog-to-digital converter converting the amplified signal into a digital signal, a gain setting unit periodically updating the gain of the variable gain amplifier in accordance with an output from the analog-to-digital converter, and an operating mode selection unit selecting one of a plurality of operating modes characterized by different gain updating periods in accordance with the output from the analog-to-digital converter, the selected operating mode being set in the gain setting unit. With this construction, the precision in conversion by the analog-to-digital converter is maintained at a proper level when an environment for signal reception varies.

Abstract: Automatic gain control (AGC) methods and apparatus suitable for use in orthogonal frequency division multiplexing (OFDM) receivers are described. One AGC method includes the steps of repeatedly performing a first AGC process which adjusts amplifier gain based on determining that a signal level of multiple time sample values is outside a limit set by a first predefined threshold; and repeatedly performing a second AGC process which adjusts the amplifier gain based on determining that a signal level of multiple frequency sample values associated with a plurality of pilot tones is outside a limit set by a second predefined threshold. Preferably, the first AGC process is performed repeatedly at a first rate and the second AGC process is performed repeatedly at a second rate that is less than the first rate.

Abstract: The invention concerns a method (200) and a system (100) for ensuring audio safety in an audio device (110). The system includes a processor (112), a sensor (116), an analog safety circuit (114) and a first feedback loop (117). The processor is programmed to output an acoustic output signal (310, 410), the sensor monitors the acoustic output signal and the analog safety circuit is coupled to an output of the processor. The first feedback loop feeds the monitored acoustic signal from the sensor to the analog safety circuit. The analog safety circuit adjusts from a first level (312, 412) to a second level (316, 414) the acoustic output signal when the acoustic output signal exceeds a predetermined safety threshold (314, 420) such that the audio device has an output capacity that is capable of driving a sound pressure level of the acoustic output signal above the predetermined safety threshold.

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: The invention aims to minimize the analogue/digital converter over-dimensioning within the framework of reception of signals originating from a satellite and exhibiting power levels which can vary over time. The invention proposes a technique of automatic gain control which handles the setting of the noise level associated with the amplified signal. The automatic gain control is achieved by neutralizing the signal received by the antenna, and by adjusting the gain during the neutralization of the signal received until a predetermined noise level is obtained at the end of the reception facility. The invention also pertains to a device comprising the means for implementing the method.

Abstract: An automatic gain control (AGC) system (100) for a controlled gain receiver (1101) includes a magnitude generator (160) and a gain corrector (170). The magnitude generator (160) generates a binary voltage squared signal (165) having a binary value that is directly proportional to a recovered signal power of an intercepted signal (113). The gain corrector (170) determines an adjustment of a gain control value (195) as a multiple of increments that are approximately 3 decibel (dB), by shifting (475, 445) a reference threshold by one or more bits and comparing (485, 455) the shifted reference threshold to the binary voltage squared signal. An initial setting of a state of a step attenuator (114) during a track mode (172) is determined during a warm up mode (171) by comparing the binary voltage squared signal (165) to two different thresholds (245, 255). A filter (162) accommodates a variety of bandwidths and symbol rates by settings of an accumulator (505) and scaler (510) that are included in the filter (162).

Abstract: An amplifier (125) includes a gain stage (210) for amplifying a signal received by the amplifier (125). The amplifier (125) also includes an AGC circuit (400) that adjusts the amplification of the gain stage (210) and that includes a comparator (440) for determining whether the input signal is one of a digital pilot signal and one of an analog pilot signal. The AGC circuit (400) processes both digital and analog pilot signals and automatically adjusts the processing method depending upon the type of pilot signal.