There is provided a calibration device including: a calibration signal supply unit configured to supply, as a calibration input signal, a multitone signal having tones at a plurality of frequency bands to a converter configured to multiply an input signal by each of a plurality of signal patterns and limit a band to obtain each of a plurality of bandpass signals, and reconstruct an output signal in accordance with the input signal from the plurality of bandpass signals; a calibration bandpass signal acquisition unit configured to acquire a plurality of calibration bandpass signals obtained by the converter in response to the multitone signal; and a calibration processing unit configured to calibrate a parameter for the reconstruction in the converter based on the plurality of calibration bandpass signals.

Certain aspects of the present disclosure provide techniques and apparatus for calibrating radio frequency (RF) circuits using machine learning. One example method generally includes calibrating a first subset of RF circuit calibration parameters. Values are predicted for a second subset of RF circuit calibration parameters based on a machine learning model and the first subset of RF circuit calibration parameters. The second subset of RF circuit calibration parameters may be distinct from the first subset of RF circuit calibration parameters. At least the first subset of RF circuit calibration parameters is verified, and after the verifying, at least the first subset of RF circuit calibration parameters are written to a memory associated with the RF circuit.

There is provided a calibration device including: a calibration signal supply unit configured to supply, as a calibration input signal, a multitone signal having tones at a plurality of frequency bands to a converter configured to multiply an input signal by each of a plurality of signal patterns and limit a band to obtain each of a plurality of bandpass signals, and reconstruct an output signal in accordance with the input signal from the plurality of bandpass signals; a calibration bandpass signal acquisition unit configured to acquire a plurality of calibration bandpass signals obtained by the converter in response to the multitone signal; and a calibration processing unit configured to calibrate a parameter for the reconstruction in the converter based on the plurality of calibration bandpass signals.

A reception device includes: a first A/D converter to convert the input analog information signal into a first digital information signal by A/D conversion to output it,; an analog amplifier to amplify the input analog information signal to output it; a second A/D converter to convert the analog information amplification signal output from the analog amplifier into a second digital information signal by A/D conversion to output it; a frequency characteristic corrector to output a second digital information correction signal obtained by correcting the second digital information signal output from the second A/D converter based on a frequency-dependent input/output characteristic of the analog amplifier; and an information signal selector and outputter to select and output, as a digital information signal, either the first digital information signal output from the first A/D converter or the second digital information correction signal output from the frequency characteristic corrector.

A communication system includes one or more transmitters, each transmitter to: transmit communication signals using a defined signaling protocol with multiple antenna elements to a target receiver, the communication signals containing known specific transmit sequences spread across a frequency spectrum of the communication signals to be detectable only by receivers having the known specific transmit sequences, and receive feedback from the target receiver indicating any errors in reception of the communication signals based upon the known specific transmit sequences, and a machine learning system to use configuration of the multiple antenna elements when the communication signal was sent and the feedback to predict preconfigured settings for transmitters. A test and measurement system located at a base station, a signal generator to generate one or more signals having a predetermined modulation format, a receiver to receive the one or more signals, and a machine learning system to develop a calibration matrix.

Methods and apparatus for calibration of a second-order input intercept point (IIP2) of a mixer, such as a mixer in a wireless receive chain. One example circuit for mixer IIP2 calibration generally includes a first receive chain comprising a first mixer and a single tone generator having an output coupled to an input of the first mixer and configured to generate a calibration signal having a single baseband tone. One example method of mixer IIP2 calibration generally includes generating a calibration signal comprising a single baseband tone, applying the calibration signal to an input of a mixer, such that the mixer generates a differential tone at an output of the mixer, and adjusting the mixer to minimize a power of the differential tone at the output of the mixer.

For a radio frequency (RF) receiver system (1) for use in a magnetic resonance (MR) imaging system, a solution for compensating residual coupling of RF receive coil elements (2) in the radio frequency (RF) receiver (1) system shall be created. This is achieved by a radio frequency (RF) receiver system for use in a magnetic resonance (MR) imaging system, the RF receiver system (1) comprising at least two simultaneously used RF receive coil elements (2), wherein the RF receive coil element (2) comprises a signal generator (3) for providing a compensation signal and an excitation path (4), wherein the excitation path (4) is configured to couple the compensation signal into the RF receive coil element (2), for reducing residual coupling in the RF receiver system (1) by means of the compensation signal coupled into the RF receive coil element (2). The present invention also refers to a magnetic resonance (MR) imaging system, a method for active decoupling of a radio frequency (RF) receiver system (1) of a magnetic resonance (MR) imaging system, a software package for a magnetic resonance (MR) imaging system, a software package for upgrading a magnetic resonance (MR) imaging system and a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method as described in the claims.

A calibration apparatus for a communication system. The calibration apparatus is configured to: a) set a variable termination-resistance at a receiver to a predetermined value; b) cause a transmitter to send a calibration pattern to the receiver by: setting the differential voltage on the line to a non-zero value during a non-zero-phase; and setting the differential voltage on the line to zero during a subsequent zero-phase; c) compare the differential voltage on the line during the zero-phase with a reduced-bit-value-threshold, wherein the reduced-bit-value-threshold is less than a bit-value-threshold that is used during active communication. If the differential voltage on the line during the zero-phase exceeds the reduced-bit-value-threshold, then the calibration apparatus adjusts the value of the variable termination-resistance and returns to step b). If the differential voltage on the line during the zero-phase does not exceed the reduced-bit-value-threshold, then the calibration apparatus stores the current value of the variable termination-resistance for subsequent use during active communication.

A signal processing apparatus according to the present disclose includes: a regulation unit configured to regulate one or both of an input signal and a calibration signal for performing calibration of transmission systems so that a difference between signal power of the input signal and signal power of the calibration signal is reduced; a compensation unit configured to perform distortion compensation for the input signal and the calibration signal; an amplifier configured to amplify the input signal and the calibration signal; and an output unit configured to output the input signal and the calibration signal that have been regulated by the regulation unit to the amplifier. Thus, there are provided the signal processing apparatus, a radio communication apparatus, a signal processing method, and a program that reduce non-linear distortion of an amplifier and distortion caused by a memory effect of the amplifier in the calibration signal.

A first wireless device and a second device may negotiate a configuration of an RF chain calibration process with each other. The configuration of the RF chain calibration process may include a number of calibration rounds. The second wireless device may exchange, in each calibration round in the number of calibration rounds, at least one RS and at least one feedback message with the first wireless device. The second wireless device may identify one or more calibration adjustment parameters for the second wireless device based on the RF chain calibration process. The second wireless device may communicate with another wireless device based on the one or more calibration adjustment parameters.