36results about How to "Compensation for non-linearity" patented technology

A linear motor system includes a discontinuous linear motor and motor control device. The discontinuous linear motor includes a mover and a plurality of individual motors spaced from each other along a movement path of the mover. Each of the individual motors functions as an armature on a primary side of one independent linear motor. A sensor, arranged to act as a linear scale, is disposed for each individual motor and detects a position of the mover. The motor control device includes a plurality of individual motor control units and a multiple unit controller to comprehensively control the individual motor control units. The individual motor control units control the individual motors disposed in curved path sections, and each of the individual motor control units includes a curved-line correspondence corrector to correct a detection value obtained from the sensor according to a relationship between a curved line of the path and a position of the sensor.

The invention discloses a GaAs HBT high-gain broadband linear transconductance unit circuit comprising an input stage subcircuit, a basic transconductance subcircuit, a linear subcircuit, a negative resistance subcircuit and a mirror current source subcircuit, wherein the input stage subcircuit is used for level shift of input differential voltages IN_P and IN_N and conducts shifted signals into the basic transconductance subcircuit; the basic transconductance subcircuit is used for converting the input differential voltage signals into differential current signals; the linear subcircuit is used for improving the linearity of the basic transconductance subcircuit; the negative resistance subcircuit is used for improving the gain of the transconductance circuit; and the mirror current source subcircuit is used for providing bias current for the rest circuits. The circuit is designed and manufactured by a GaAs HBT technology and has wide operation bandwidth; the adopted linear subcircuit can effectively complement the nonlinearity of the circuit and provides excellent linearity; and the negative resistance subcircuit is adopted to effectively solve the conflict between the high-gainrequirement of circuits and transistor saturation and improves high-gain performance.

The invention provides a method and a device for compensating nonlinearity of an electro-absorption modulator. A system comprises a laser, an electro-absorption modulator, a spectral filter, a preprocessing module, and an optical receiver, wherein the laser is used for generating an optical signal, the electro-absorption modulator connected with the laser is used for modulating the optical signal to obtain multi-sideband spectrum of the optical signal, the spectral filter connected with the electro-absorption modulator is used for controlling the amplitude of 0-order spectral sideband of the optical signal according to the multi-sideband spectrum so as to obtain the compensated optical signal, the processing module connected with the spectral filter is used for preprocessing the compensated optical signal, and the optical receiver connected with the preprocessing module is used for converting the preprocessed optical signal into an electrical signal and outputting the electrical signal. The method and the device have the advantages that the 0-order spectral sideband of the optical signal is processed, thus the nonlinearity of the modulator is compensated only by spectral band-stop filtering and limitation of the microwave photonic system is avoided.

A method and system for automatic gain control is provided. The automatic gain control may be used, for example, with a microphone and voice codec of a speakerphone telephone. In an exemplary embodiment, an amplification gain lookup table stores the gain values. The power of the input signal is estimated and the appropriate gain value is selected as a function of the estimated power of the input signal. The gain value is applied to the input signal to provide an automatic gain controlled output signal. In another embodiment, the gain lookup table may be adapted to compensate for the non-linearity of the microphone and voice codec of the speakerphone. In this alternate embodiment, the output power of the automatic gain controlled signal is estimated and compared to a reference signal to generate an error signal. The error signal may be scaled and used to update and dynamically adapt the gain values in the gain lookup table.

A voltage controlled oscillator and a method of operating a voltage-controlled oscillator are disclosed. The oscillator comprises a current controlled oscillator having a variable frequency current output, a first control path for generating a first control current having a first adjustable gain, and a second control path for generating a second control current having a second adjustable gain. A summer is provided for adding the first and second control currents to obtain a summed control current, and for applying the summed control current as an input current to the current controlled oscillator. A control sub-circuit is used for controlling the gain of the first control current as a function of a defined voltage on the second control path to maintain constant the gain of the current output of the current controlled oscillator over a given operating range of the current controlled oscillator.

The invention discloses a sweep frequency linearization and coherent enhancement method based on a composite optical phase-locked fiber laser. The method comprises the following steps of: in an open-loop state of a sweep frequency laser light source system, obtaining a group of control voltage signals through calculation, and preliminarily correcting the response linearity of the sweep frequency fiber laser under the driving of the control voltage signals; and on the basis of the open-loop state of the frequency sweep laser light source system, adding a piezoelectric ceramic driving loop and an acousto-optic frequency shifter loop to form a closed-loop state, making frequency sweep light signals pass through a Mach-Zehnder interference structure and a photoelectric detector to generate beat frequency signals with frequency sweep information, and frequency sweep driving signals, outputting error signals through a digital phase discriminator, loading the error signals to the control voltage signals to form new feedback control signals, and making the piezoelectric ceramic driving loop and the acousto-optic frequency shifter loop enter a closed-loop feedback control state under the driving of the new feedback control signals. By adopting the composite optical phase locking technology, the sweep frequency linearization and coherence of the optical fiber laser are enhanced at the same time.

The invention disclose a measurement system for sea water temperature, which comprises a nonequilibrium bridge circuit unit, a constant current source generation circuit unit, a voltage follower circuit unit and a filter amplifier circuit unit, wherein the input end of the nonequilibrium bridge circuit unit is connected with an anode of direct voltage through a resistor R8; the output end of the nonequilibrium bridge circuit unit is connected with the voltage follower circuit unit; the output end of the constant current source generation circuit unit is connected with the nonequilibrium bridge circuit unit; the voltage follower circuit unit is connected with the filter amplifier circuit unit through a resistor R9 and a resistor R10; and the input end of the constant current source generation circuit unit is connected with a plus 5V power supply. The measurement system has the characteristics of high sensitivity, good stability, long service life and the like; the measurement precisionof the measurement system is much higher than that of the traditional thermocouple or the pressure type thermodetector; and the measurement system has obvious technical advantages in the conventionaltemperature measurement range (minus 2 DEG C - 30 DEG C) of the sea water.

The invention, which belongs to the field of the wireless communication technology, particularly relates to a high-sensitivity receiver front-end circuit with an impedance mapping function. The high-sensitivity receiver front-end circuit comprises a linearity compensation circuit, a low-noise trans-conductance amplifier circuit, an active negative feedback circuit, a divider circuit, a passive mixer circuit, an in-phase trans-impedance amplifier and a quadrature trans-impedance amplifier. With the impedance mapping function of the passive mixer circuit, the impedance with a low-pass characteristic at a low-frequency site is mapped to a radio-frequency side by using a local frequency as a center; and the output terminal of the low-noise trans-conductance amplifier forms abandpass filter with a high-frequency high-quality factor equivalently. The low-noise trans-conductance amplifier provides gains at a first level of a receiver, so that noises of the post-stage circuit can be suppressed effectively and the sensitivity of the whole link can be improved. Moreover, with the active negative feedback of the low-noise trans-conductance amplifier, the impedance is mapped to the input terminal and the out-of-band blocking signal is suppressed by using impedance matching of the input terminal, so that the anti-interference capability of the receiver can be enhanced and the dynamic range of the front end can be extended.

The invention discloses a simulation rotary table control system based on PID control. The system includes a measurement and control unit, an execution unit and a feedback unit. The measurement and control unit is connected to a simulation rotary table through the execution unit. The measurement and control unit includes a DSP motion control card. The DSP motion control card and the execution unitare connected. The execution unit includes an analog-to-digital converter, a driver, a servo motor and a decelerator which are successively connected. The decelerator and the simulation rotary tableare connected. The simulation rotary table is connected to the controller through the feedback unit. The feedback unit includes a speed feedback apparatus and a position feedback apparatus. The speedfeedback apparatus includes a speed ring and a speed ring controller. The speed ring controller uses a PI controller. The position feedback apparatus includes a position ring and a position ring controller. The position ring controller uses a PID controller. According to the invention, the system herein has a simple structure, and can control the operation of the simulation rotary table through the measurement and control unit, the execution unit and the feedback unit. The system can also increase the stability of the operation of the simulation rotary table, and ensures the stable operation of the simulation rotary table.

The invention provides a global pixel nonlinear compensation structure. A global pixel includes a pixel circuit module and an analog-to-digital conversion module; the analog-to-digital conversion module comprises a comparator which is provided with a positive input end Vin1 connected with the pixel circuit module and a negative input end Vin2 receiving reference voltage Vramp; the nonlinear compensation structure comprises a compensation circuit module; and the compensation circuit module is connected between reference voltage Vramp signals and the negative input end Vin2 of the comparator and is used for compensating nonlinearity led by the inner circuit of the pixel circuit module. With the global pixel nonlinear compensation structure of the invention adopted, the nonlinearity of the global pixel can be compensated, and the dynamic range of the global pixel can be improved; and a time sequence can be optimized when the nonlinearity is compensated; and power consumption which is as low as possible is just brought.

A method may include determining a power level of a signal and a temperature level of a transmitter originating the signal. At least one of the power and temperature levels may be compared to a lookup table containing predistortion coefficients. The method is capable of predistorting a signal based on the comparison. An apparatus is disclosed in relation to the method.

An acoustic reflectometry instrument and method for ascertaining fluid presence in an ear. Drive side normalization involves normalizing the speaker to adjust its output to compensate for non-linearity over a frequency range used for acoustic reflectometry measurement of the ear. The microphone is normalized to compensate for system non-linearity. Measurement involves repetition a selected number of times until the spectral gradient angle is within a specified range for each repetition to provide validation of the measurement. For enhanced reliability, various sources of error are tested.

A high-linearity amplifier including a main operational amplifier, a feedback circuit, and a compensation circuit is shown. The feedback circuit couples an output signal of the main operational amplifier to an input port of the main operational amplifier. The compensation circuit is coupled to the input port of the main operational amplifier to compensate for the non-linearity of the feedback circuit. A signal coupled to the input port of the main operational amplifier through the compensation circuit has an inverse phase compared to the output signal of the main operational amplifier.

A power linearizer of a CDMA system preferably includes a linearization input unit for compensating a level of an input signal to remove a non-linearity of a power amplifier; an amplification controller for controlling an amplification of the power amplifier; and the power amplifier operated under the control of the amplification controller, for amplifying the power of the level-compensated input signal. By adjusting the voltage inputted to the input terminal of the voltage controlled power amplifier (VCA), the non-linearity of the VCA can be accurately compensated and the power compensation can be easily performed. In addition, the capacity of the CDMA system can be increased.

The invention relates to a driving voltage optimization method for a tunable Fabry-Perot filter, which converts the rising part of the traditional AC driving voltage into a plurality of gradually increasing DC voltage segments, and searches for the optimal split voltage through the particle swarm algorithm. The duration of the segment DC voltage is used to obtain the optimized DC voltage; the center position of the reflection peak obtained by scanning the traditional AC voltage drive is converted into the center position of the response of the adjustable filter under the optimized DC voltage to obtain the final AC-DC drive Voltage. To effectively compensate the voltage-wavelength nonlinearity of the tunable Fabry-Perot filter, without adding any hardware equipment, only digital compensation is used to correct the AC drive voltage, thereby compensating for the nonlinearity of the filter. The method of the invention has low cost, strong transplantability and high reliability.