Abstract: The number of times of referring to of a storing unit in a distortion compensating apparatus is averaged and temporary degradation of the distortion property is avoided. The distortion compensating apparatus include a pre-distorting unit that applies a distortion compensating process to a transmission signal using a distortion compensation coefficient, a distortion compensation calculating unit that calculates a distortion compensation coefficient based on the transmission signal before the distortion compensation and a feedback fed back from an output of a distortion device, an address generating circuit that produces an address corresponding to the transmission signal, and a storing unit that updates the calculated distortion compensation coefficient to the produced address and that stores the produced address.

Abstract: The apparatus includes: distortion amount detector which detects the amount of distortion of an output signal of an amplifier; parameter holder which holds a parameter having been set therein, the parameter holder being capable of varying the difference according to the parameter set therein; parameter corrector which corrects the parameter held in the parameter holder in such a manner that the distortion amount detected by the distortion amount detector is improved; noise component detector which detects a noise component that can be caused in the output signal resulting from a quadrature modulation; and noise component remover which performs processing for removing the noise component detected by the noise component detector. This arrangement makes it possible to suppress image frequency component generation in an output signal of the amplifier accompanying quadrature modulation and to optimize parameters in distortion compensation.

Abstract: The present apparatus includes: distortion amount detector which detects the amount of distortion of an output signal of the amplifier; parameter holder; parameter corrector which corrects a parameter held in the parameter holder in such a manner that the distortion amount detected by the distortion amount detector is improved; controller which controls frequency components to be subjected to distortion amount detection that is performed by the distortion amount detector, based on the distortion amounts of a plurality of different frequency components of the output signal of the amplifier and on specification values relating to the distortion amounts. This arrangement makes it possible to set (control) appropriate distortion data measurement point (frequency component to be detected) according to multiple specification values (for example, ACLR specification values) relating to the distortion amount.

Abstract: The distortion compensating apparatus which adaptively updates a distortion compensation coefficient for an amplifier based on a difference between input and output signals of the amplifier, comprises: a distortion amount detector which detects the amount of distort of an output signal of the amplifier; a parameter holder which holds a parameter having been set therein; a parameter corrector which corrects the parameter in such a manner that the distortion amount detected by the detector is improved; and a distortion amount corrector which corrects the distortion amount detected by the detector in such a manner that the distortion amount is reduced by an offset amount according to an detection error. This arrangement makes it possible to accurately set the parameter relating to difference detection which is a factor of updating of distortion compensation coefficients of the distortion compensating apparatus.

Abstract: The distortion compensating apparatus, which adaptively updates a distortion compensation coefficient for an amplifier based on a difference between input and output signals of the amplifier, comprises: a distortion amount detector which detects the amount of distortion of an output signal of the amplifier; a parameter holder which holds a parameter having been set therein; a parameter corrector which corrects the parameter in such a manner that the distortion amount detected by the detector is improved; a power monitor which monitors output power of the amplifier or a factor of variation in the power; and a controller which halts, if a monitoring result by the power monitor is smaller than a specified threshold value, the correction of the parameter. This arrangement makes it possible to accurately set the parameter relating to difference detection which is a factor of updating of distortion compensation coefficients of the distortion compensating apparatus.

Abstract: It is an object of the present invention to provide a DC offset correction means capable of correctly performing DC offset correction even when transmitting a non-modulation signal in radio communication equipment for performing orthogonal modulation by a direct RF modulation method. The DC offset correction device comprises a fixed value setting unit for setting a value for outputting a non-modulation signal with a specific phase from a modulator, a non-modulation signal switch unit for switching between a main signal and the value set by the fixed value setting unit and a DC offset correction control unit for sequentially changing the specific phase of the non-modulation signal outputted from the modulator by sequentially changing the value set by the fixed value setting unit and operating a DC offset correction value to be added to an input signal by a DC offset correction unit, based on feedback signal data generated from the non-modulation signal whose phase is sequentially changed.

Abstract: A distortion compensating technique applied to a transmitter for transmitting a quadrature modulated signal in a wireless digital communication system is provided. A phase adjustment value is determined for a quadrature demodulated feedback signal based on comparison between the feedback signal and a reference signal to be transmitted from the transmitter. This phase adjustment value is compared with the previous phase adjustment value. If the comparison result between the current and previous phase adjustment values satisfies a prescribed condition, correction for quadrature modulation, such as DC offset correction, orthogonality correction, or IQ amplitude correction, is performed.

Abstract: An address frequency operation unit counts frequencies of occurrences of addresses output by an address conversion unit 14, and a CPU 16 rewrites an address conversion table in the address conversion unit 14 based on a comparison between the counted result and a threshold value. When the frequency of the address is lower than the threshold value, the frequency of occurrence of an output address is increased by increasing the number of input addresses corresponding to one output address. Also, distortion in an output signal which is fed back is detected and the address conversion table is rewritten so that the distortion is decreased.

Abstract: A step size parameter ? is adaptively varied when a distortion compensation coefficient is calculated in a distortion compensation apparatus, relation between transmission signal level and step size parameter ? is considered. The distortion compensation apparatus includes a memory storing distortion compensation coefficient in a designated write address, and outputting distortion compensation coefficient being stored in a designated readout address; a predistortion section performing distortion compensation processing onto a transmission signal, using the distortion compensation coefficient being output from memory; and a distortion compensation section calculating an update value of distortion compensation coefficient, based on error component existent between transmission signal before distortion compensation processing and transmission signal after being amplified by an amplifier.

Abstract: Provided is a distortion compensation apparatus to prevent divergence of distortion compensation coefficients caused by an abnormal distortion compensation coefficient value. The distortion compensation apparatus includes a storage for storing a distortion compensation coefficient in a specified write address, and outputting a distortion compensation coefficient stored in a specified readout address; a predistortion portion for performing distortion compensation processing onto a transmission signal, using the distortion compensation coefficient being output from the storage; and a distortion compensator for calculating a distortion compensation coefficient based on the transmission signal before the distortion compensation processing and the transmission signal after being amplified by an amplifier.

Abstract: A distortion compensation apparatus is provided to restrain an increased calculation time caused by a large amount of calculation required for obtaining a phase variation amount for compensation from the correlation.

Abstract: To shorten the time required for writing of the distortion compensation coefficient and to reduce amount of data of the distortion compensation coefficient stored as the initial value of the distortion compensation apparatus. The distortion compensation apparatus for amplifying the transmitting signal after implementing the distortion compensation process comprises a coefficient memory for storing corresponding to each address the coefficient used for the distortion compensation process, an initial value memory for storing the initial value of the coefficient, and a controller for write control corresponding to n (n: natural number equal to 2 or larger) addresses of the coefficient read from the initial value memory corresponding to one address.

Abstract: A distortion compensation apparatus shortens the time until start of the transmission. The distortion compensating apparatus for amplifying the transmitted signal after implementation of the distortion compensation process thereto comprises a coefficient memory operable to store coefficients used for the distortion compensation process, an initial value memory operable to store the initial values of the coefficients, and a controller which controls the coefficient memory to store, with limitation, only the coefficients corresponding to the first portion among those stored in the initial value memory for the initial write to the coefficient memory and to store thereafter the coefficients corresponding to the second portion.

Abstract: Disclosed is a distortion compensating amplifier having a distortion compensator for compensating for distortion of an amplifier by updating distortion compensation coefficients so as to null a difference between a transmit signal and a feedback signal, and subjecting the transmit signal to distortion compensation processing using the distortion compensation coefficients, an amplifier for amplifying the transmit signal, which has undergone distortion compensation, in order to transmit the signal from an antenna, and a feedback unit for inputting an output signal from the amplifier to a distortion compensation coefficient updater in the distortion compensator as the feedback signal. Whether the level of an unwanted-wave signal that penetrates the amplifier from space via an antenna is greater than a set level is monitored. If the level of the unwanted-wave signal is above the set level, processing for updating distortion compensation coefficients is suspended.