A transmit quadrature error calibration system, method utilizing a receive path

Abstract

The present application belongs to the field of signal calibration, and particularly relates to a system and method for calibrating transmitting quadrature error by using a receiving channel, aiming at solving the problem that the transmitting quadrature calibration module of the existing zero intermediate frequency architecture cannot track in real time and has poor calibration effect. The system comprises: a calibration tone generation module, configured to generate a single tone signal of one or more frequencies and transmit the signal through a transmitting channel; and further configured to compensate and calibrate the transmitting signal according to the transmitting channel quadrature error estimated by a QEC calibration module; the QEC calibration module, configured to estimate the quadrature error of the receiving channel and compensate and calibrate, and estimate the transmitting channel quadrature error; and a channel estimation module, configured to estimate the channel response between the transmitting channel and the receiving channel and compensate and calibrate based on the single tone signal generated by the calibration tone generation module and the signal compensated and calibrated by the QEC calibration module. The present application can track the transmitting quadrature error in real time, and effectively improve the quadrature of the radio frequency transmitting signal of the zero intermediate frequency architecture.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of signal calibration, and particularly relates to a system and method for calibrating transmit quadrature error by using a receiving channel. BACKGROUND

[0002] Zero intermediate frequency architecture refers to that a transmitter and a receiver can directly convert a baseband into a radio frequency signal without conversion of an intermediate frequency (IF), and can also be understood as that the IF is a zero frequency. The zero intermediate frequency architecture reduces the use of circuits such as intermediate frequency conversion and intermediate frequency filtering. Correspondingly, a quadrature mixing structure is required to be used to process data in the zero intermediate frequency architecture. Quadrature mixing refers to that a local oscillator with a phase difference of 90 degrees is used to perform frequency conversion on a radio frequency signal. Both the I path and the Q path should include matched analog-to-digital converters (ADCs) and digital-to-analog converters (DACs), filters, amplifiers, and the like. Quadrature error refers to that the I path and the Q path use separate analog processing paths, and the device characteristics thereof cannot be completely matched, resulting in mismatch of the phase and amplitude between the I path and the Q path signals.

[0003] The positions where the quadrature error of the I path and the Q path is generated are mainly in a mixer and a baseband processing link. The quadrature error generated at the mixer position is usually irrelevant to the frequency of the in-band signal, and the quadrature error generated at the baseband processing link position usually changes with the frequency of the in-band signal. The existing transmitter quadrature calibration algorithm can only estimate and compensate the average quadrature error in the band, and cannot achieve good quadrature calibration effect. Moreover, since the quadrature error changes with temperature and other environmental factors, there is an urgent need for a frequency-dependent quadrature calibration module with tracking function, which can estimate and compensate the transmit quadrature error in real time according to environmental changes. SUMMARY

[0004] In order to solve the above problems in the prior art, that is, to solve the problem of the existing zero intermediate frequency architecture transmit quadrature calibration module that cannot track in real time and has poor calibration effect, the present application provides, in a first aspect, a system for calibrating transmit quadrature error by using a receiving channel, which comprises:

[0005] a calibration tone generation module configured to generate a single tone signal of one or more frequencies and transmit the single tone signal through a transmitting channel, and further configured to compensate and calibrate the transmitted signal according to the transmit channel quadrature error parameters estimated by the QEC calibration module;

[0006] the QEC calibration module configured to estimate and compensate and calibrate the quadrature error parameters of the receiving channel and estimate the quadrature error parameters of the transmitting channel;

[0007] a channel estimation module configured to estimate a channel response between the transmitting channel and the receiving channel and compensate for the calibration based on the single-tone signal generated by the calibration tone generation module and the signal compensated for the quadrature error compensation calibration by the QEC calibration module.

[0008] In some preferred embodiments, the calibration tone generation module comprises an I-path data generator, a Q-path data generator, a transmitting quadrature error compensator;

[0009] The transmitting quadrature error compensator comprises a first complex multiplier, a second complex multiplier, a first adder, a first finite impulse response filter, a first digital delay, a first digital-to-analog converter, a second digital-to-analog converter;

[0010] The I-path data, after being processed by the first digital delay and the first digital-to-analog converter, is transmitted to the transmitting channel; the Q-path data processed by the first complex multiplier and the I-path data processed by the second complex multiplier are added by the first adder and then processed by the first finite impulse response filter and the second digital-to-analog converter before being transmitted to the transmitting channel;

[0011] The transmitting quadrature error compensator is configured to decompose the transmitting quadrature error parameter obtained by the QEC calibration module into two parts, which are respectively used as the input of the complex multiplier and the coefficient of the finite impulse response filter, so as to compensate for the transmitting signal, i.e., inputting to the first complex multiplier when processing and inputting to the second complex multiplier when processing. T (t) as the coefficient of the first finite impulse response filter, wherein h T (t) represents the transmitting quadrature error calibration function at time t.

[0012] In some preferred embodiments, the channel estimation module comprises a complex multiplier, a division operator, and an arctan operator connected in sequence.

[0013] In some preferred embodiments, the QEC calibration module comprises a quadrature error estimator, a channel response compensator, and a receiving quadrature error compensator.

[0014] The quadrature error estimator comprises a summation operator, a first squaring operator, a second squaring operator, a multiplier, a first division operator, a second division operator, a first square root operator, a second square root operator, and an inverse sine operator.

[0015] The input of the quadrature error estimator in the receiving quadrature error estimation mode is the I data and Q data received by the receiving channel, and the output is a receiving quadrature error parameter; the input of the quadrature error estimator in the transmitting quadrature error estimation mode is the I data and Q data output by the channel response compensator, and the output is a transmitting quadrature error parameter;

[0016] The I data and Q data received by the receiving channel are processed by the first squaring operator, the second squaring operator and the multiplier, and the outputs of the first squaring operator, the second squaring operator and the multiplier are accumulated and averaged by the summation operator to obtain accumulated average result one, accumulated average result two and accumulated average result three respectively; the accumulated average result one and the accumulated average result two are input into the first square root operator through the first division operator to obtain a quadrature amplitude error; the accumulated average result one and the accumulated average result two are multiplied by the multiplier, and then input into the second division operator with the accumulated average result three after being processed by the second square root operator, and the output of the second division operator is input into the inverse sine operator to obtain a quadrature phase error;

[0017] The receiving quadrature error compensator comprises a first analog-to-digital converter, a second analog-to-digital converter, a third complex multiplier, a fourth complex multiplier, a second finite impulse response filter, a second digital delay device and a second adder;

[0018] The I data processed by the first analog-to-digital converter is sequentially processed by the second digital delay device and the third complex multiplier, and then sent to the channel response compensator;

[0019] The Q data sequentially processed by the second analog-to-digital converter and the second finite impulse response filter is added to the I data processed by the second digital delay device and the fourth complex multiplier by the second adder, and then sent to the channel response compensator;

[0020] The receiving quadrature error parameter obtained by the QEC calibration module is divided into two parts, which are respectively input into the complex multiplier and the coefficient of the finite impulse response filter; that is, the input of the third complex multiplier is The input of the fourth complex multiplier is h R (t) is taken as the coefficient of the second finite impulse response filter; h R (t) represents a receiving quadrature error calibration function at time t, represents a receiving quadrature amplitude error;

[0021] The channel response compensator comprises a phase shifter and a complex multiplication operator.

[0022] The input of the channel response compensator is the I and Q data output by the quadrature error compensator and the channel response parameter output by the channel estimation module, and the output is the I and Q data after channel response compensation; the channel response parameter estimated by the channel estimation module is used as the input of the complex multiplication operator.

[0023] The I and Q data output by the quadrature error compensator are sent to the quadrature error estimator after passing through the phase shifter and the complex multiplication operator.

[0024] In the second aspect of the present application, a method for calibrating the transmission quadrature error of a receiving channel is provided, which is based on the above-mentioned system for calibrating the transmission quadrature error of a receiving channel. The method comprises the following steps:

[0025] S10: controlling the calibration tone generation module to generate single-tone signals of multiple frequencies, transmitting the single-tone signals through the transmission channel, receiving the single-tone signals by the receiving channel, and estimating the quadrature error parameters of the receiving channel by using the QEC calibration module; the quadrature error parameters comprise quadrature phase error and quadrature amplitude error.

[0026] S20: controlling the calibration tone generation module to generate a single-tone signal of a single frequency, transmitting the single-tone signal through the transmission channel, receiving the single-tone signal by the receiving channel, compensating the quadrature error of the receiving channel by using the QEC calibration module, and transmitting the signal after quadrature error compensation to the channel estimation module to estimate the channel response parameter.

[0027] S30: controlling the calibration tone generation module to generate single-tone signals of multiple frequencies, transmitting the single-tone signals through the transmission channel, receiving the single-tone signals by the receiving channel, compensating the quadrature error of the receiving channel by using the QEC calibration module, compensating the channel response between the transmission channel and the receiving channel by using the channel estimation module, and then estimating the quadrature error parameters of the transmission channel by using the QEC calibration module.

[0028] S40: compensating the radio signal generated by the calibration tone generation module by using the quadrature error parameters of the transmission channel estimated by the QEC calibration module; the radio signal comprises a radar signal and a communication signal.

[0029] In some preferred embodiments, the method for generating the single-tone signal in S10, S20 and S30 is as follows:

[0030] In S10, the single-tone signals of multiple frequencies are generated by modifying the transmission local oscillator frequency and adding a digital signal with a fixed direct current in the baseband.

[0031] In S20, by fixing the transmitting local oscillator frequency to be the same as the receiving local oscillator frequency, a digital signal of a fixed frequency single tone is added in the baseband to generate a single frequency single tone signal;

[0032] In S30, by fixing the transmitting local oscillator frequency to be the same as the receiving local oscillator frequency, a digital signal of multiple frequency single tones is added in the baseband to generate multiple frequency single tone signals.

[0033] In some preferred embodiments, the quadrature error of the receiving channel is compensated by using the QEC calibration module, and the method is as follows:

[0034] The quadrature phase error and the quadrature amplitude error corresponding to each frequency point are estimated by frequency sweeping;

[0035]

[0036] wherein α, respectively represent the quadrature phase error and the quadrature amplitude error, y I (t), y Q (t) represent the baseband signals of the I channel and the Q channel data respectively, E represents the average statistical quantity of the input I channel or Q channel data, n represents the current statistical data index, and N represents the total length of the statistical data;

[0037] Based on the quadrature phase error and the quadrature amplitude error, the local oscillator quadrature phase error is solved; combined with the local oscillator quadrature phase error, the frequency response is transformed into a time domain sequence by using IFFT operation to obtain a receiving baseband channel calibration function;

[0038] Combined with the local oscillator quadrature phase error and the receiving baseband channel calibration function, the quadrature error of the receiving channel is compensated by using the receiving quadrature error compensator.

[0039] In some preferred embodiments, the channel response parameter is calculated as follows:

[0040]

[0041]

[0042] s(t) = cosωt + j * sinωt

[0043] wherein Φ represents the channel response parameter, imag represents the imaginary part, real represents the real part, s(t) represents the signal generated by the calibration tone generation module in the channel calibration stage, and ω represents a certain frequency in the baseband bandwidth, represents the conjugate multiplication of s(t) and y(t), and y(t) represents the signal received after the quadrature error of the receiving channel is compensated.

[0044] In some preferred embodiments, the QEC calibration module estimates the quadrature error parameters of the transmitting channel by:

[0045] The transmitting quadrature phase error and the transmitting quadrature amplitude error corresponding to each frequency point are estimated by sweeping frequency;

[0046] The transmitting local oscillator phase error and the transmitting baseband error function are separated by combining the transmitting quadrature phase error and the transmitting quadrature amplitude error, and the actual transmitting local oscillator phase error and the transmitting quadrature error calibration function are solved, and then the transmitting quadrature compensation matrix is constructed;

[0047]

[0048] wherein θ represents the transmitting local oscillator phase error, h T represents the transmitting quadrature error calibration function.

[0049] The present application has the following advantages:

[0050] The present application can track the transmitting quadrature error in real time, effectively improve the quadrature of the zero intermediate frequency architecture radio frequency transmitting signal, significantly improve the image rejection of the radio frequency transmitting signal, greatly improve the transmitting signal frequency band utilization and power utilization of communication and other applications, and improve the calibration effect. The influence of temperature and other time-varying factors on the transmitting quadrature error can be overcome.

[0051] The present application can be applied to any platform without any additional calibration link, and is a general transmitter quadrature error calibration method. After the transmitting quadrature calibration, the IRR can reach 60 dB. BRIEF DESCRIPTION OF DRAWINGS

[0052] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the accompanying drawings.

[0053] Figure 1 is a structural schematic diagram of a transmitting quadrature error calibration system using a receiving channel according to an embodiment of the present application;

[0054] Figure 2 is a detailed structural schematic diagram of a transmitting quadrature error calibration system using a receiving channel according to an embodiment of the present application;

[0055] Figure 3 is a structural schematic diagram of a receiving channel according to an embodiment of the present application;

[0056] Figure 4 is a schematic diagram of the variation of the quadrature phase error parameter with frequency according to an embodiment of the present application;

[0057] Figure 5is a schematic diagram of frequency variation of quadrature amplitude error parameters of an embodiment of the present application;

[0058] Figure 6 is a structural schematic diagram of a receiving quadrature error compensator of an embodiment of the present application;

[0059] Figure 7 is a structural schematic diagram of a transmitting quadrature error compensator of an embodiment of the present application;

[0060] Figure 8 is a structural schematic diagram of a QEC calibration module of an embodiment of the present application;

[0061] Figure 9 is a schematic diagram of a channel estimation module of an embodiment of the present application;

[0062] Figure 10 is a flow schematic diagram of a transmitting quadrature error calibration method using a receiving channel of an embodiment of the present application;

[0063] Figure 11 is a spectrum diagram of a transmitting wideband signal before implementation of quadrature calibration of an embodiment of the present application;

[0064] Figure 12 is a spectrum diagram of a transmitting wideband signal after implementation of quadrature calibration of an embodiment of the present application. DETAILED DESCRIPTION

[0065] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0066] The present application will be further described below in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, but not to limit the application. In addition, it should be noted that, for the convenience of description, only the parts related to the application are shown in the drawings.

[0067] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0068] The first embodiment of the present application proposes a transmitting quadrature error calibration system using a receiving channel, as shown in the figure, the system comprises: Figure 1

[0069] ​The calibration tone generation module is configured to generate one or more single-tone signals of various frequencies and transmit them through the transmission channel; it is also configured to compensate and calibrate the transmitted signal based on the orthogonal error parameters of the transmission channel estimated by the QEC calibration module.

[0070] The QEC calibration module is configured to estimate the orthogonal error parameters of the receiving channel and perform compensation calibration, and to estimate the orthogonal error parameters of the transmitting channel.

[0071] The channel estimation module is configured to estimate the channel response between the transmit channel and the receive channel and perform compensation calibration based on the single-tone signal generated by the calibration tone generation module and the signal after orthogonal error compensation calibration by the QEC calibration module.

[0072] To more clearly illustrate the transmit orthogonal error calibration structure utilizing the receiving channel of the present invention, the modules of one embodiment of the system of the present invention will be described in detail below with reference to the accompanying drawings.

[0073] This invention uses the RX receiver transmit channel to receive data, employs a channel estimation module to estimate the channel response between the transmit and receive channels, and utilizes a QEC calibration module to estimate and compensate for frequency-dependent transmit orthogonality errors in real time, thereby overcoming the influence of temperature and other environmental factors on orthogonality errors. Specifically:

[0074] This invention discloses a transmit orthogonal error calibration system utilizing a receiving channel, such as... Figure 2 As shown, ( Figure 2 The hardware marked 103 is a finite impulse response filter, the hardware marked 102 is a transmit quadrature mixer, the hardware marked 104 is a transmit local oscillator, the hardware marked 105 refers to the transmit baseband signal, the hardware marked 106 refers to the transmit RF signal after quadrature mixing, the hardware marked 115 refers to the receive baseband signal, the hardware marked 116 refers to the receive RF signal, the hardware marked 107 is a transmit power amplifier, and the hardware marked 117 is a receive low noise amplifier. The system includes: 100 transmit channels, 110 receive channels, 120 calibration tone generation module, 130 channel estimation module, and 140 QEC calibration module.

[0075] The calibration tone generation module 120 is configured to generate one or more single-tone signals of different frequencies (i.e., a series of single-tone signals of different frequencies) and transmit them through the transmission channel 100; it is also configured to compensate and calibrate the transmitted signal according to the orthogonality error of the transmission channel.

[0076] In this embodiment, the calibration tone generation module includes an I-channel data generator, a Q-channel data generator, and a transmission quadrature error compensator;

[0077] Launch an orthogonal error compensator, such as Figure 7As shown, it includes a first complex multiplier, a second complex multiplier, a first adder, a first finite impulse response filter, a first digital delay unit, a first digital-to-analog converter, and a second digital-to-analog converter;

[0078] The I-channel data is processed by the first digital delay unit and the first digital-to-analog converter (DAC) and then sent to the transmission channel; the Q-channel data processed by the first complex multiplier and the I-channel data processed by the second complex multiplier are added by the first adder and then processed by the first finite impulse response filter and the second DAC before being sent to the transmission channel.

[0079] The transmit quadrature error compensator is configured to decompose the transmit quadrature error parameters obtained by the QEC calibration module into two parts, which are respectively used as the input of the complex multiplier and the coefficients of the finite impulse response filter, thereby compensating for the transmitted signal. That is, the input is used when the first complex multiplier processes the signal. The second complex multiplier processes the input. h T (t) is used as the coefficient of the first finite impulse response filter. h represents the transmission quadrature amplitude error. T (t) represents the emission orthogonal error calibration function at time t.

[0080] QEC calibration module 140 is configured to estimate the receive channel (receive channel such as...) Figure 3 The orthogonality error (as shown) is calculated and compensated for, and the orthogonality error of the transmission channel is estimated.

[0081] In this embodiment, the QEC calibration module, such as Figure 8 As shown, it includes an orthogonal error estimator, a channel response compensator, and a receiver orthogonal error compensator;

[0082] The orthogonal error estimator includes a summation operator, a first square operator, a second square operator, a multiplier, a first division operator, a second division operator, a first square root operator, a second square root operator, and an arcsine operator;

[0083] In the receive quadrature error estimation mode, the input of the quadrature error estimator is the I-channel data and Q-channel data received by the receive channel, and the output is the receive quadrature error parameter; in the transmit quadrature error estimation mode, the input of the quadrature error estimator is the I-channel data and Q-channel data output by the channel response compensator, and the output is the transmit quadrature error parameter.

[0084] The I-channel and Q-channel data received through the receiving channel are processed by the first square operator and the second square operator, respectively, and then simultaneously processed by the multiplier (i.e., the I-channel data is processed by the first square operator, the Q-channel data by the second square operator, and the processing results of the two square operators are input into the multiplier for further processing). The outputs of the first square operator, the second square operator, and the multiplier are all summed and averaged by the summator, and these summations are respectively used as three cumulative average results: cumulative average result one, cumulative average result two, and cumulative average result three (specifically, the summation results of the first square operator, the second square operator, and the multiplier are summed and averaged). The outputs of the multiplier and the multiplier are collected at 8192 points over time. The output data of the 8192 points are then summed and averaged independently in three separate streams. The first accumulated average result and the second accumulated average result are passed through the first division unit and output to the first square root unit to obtain the quadrature amplitude error. The first accumulated average result and the second accumulated average result are multiplied by the multiplier, then passed through the second square root unit and input to the second division unit along with the third accumulated average result. The output of the second division unit is input to the arcsine unit to obtain the quadrature phase error.

[0085] The receiving orthogonal error compensator, such as Figure 6 As shown, it includes a first analog-to-digital converter, a second analog-to-digital converter, a third complex multiplier, a fourth complex multiplier, a second finite impulse response filter, a second digital delay unit, and a second adder;

[0086] The I-channel data processed by the first analog-to-digital converter is sequentially processed by the second digital delay unit and the third complex multiplier before being sent to the channel response compensator.

[0087] It will sequentially pass through the second analog-to-digital converter (the analog-to-digital converter is...) Figure 2 The Q-channel data processed by the ADC and the second finite impulse response filter, and the I-channel data processed by the second digital delay unit and the fourth complex multiplier are added by the second adder and then sent to the channel response compensator.

[0088] The received quadrature error parameters obtained by the QEC calibration module are decomposed into two parts, which are used as the input of the complex multiplier and the coefficients of the finite impulse response filter, respectively; that is, the input of the third complex multiplier during processing. The fourth complex multiplier processes the input... h R (t) serves as the coefficient of the second finite impulse response filter; h R (t) represents the receiver orthogonal error calibration function at time t. Indicates the received quadrature amplitude error;

[0089] The channel response compensator comprises a phase shifter and a complex multiplication operator.

[0090] The input of the channel response compensator is the I and Q data output by the quadrature error compensator and the channel response parameter output by the channel estimation module, and the output is the I and Q data after channel response compensation; the channel response parameter estimated by the channel estimation module is used as the input of the complex multiplication operator.

[0091] The I and Q data output by the quadrature error compensator are sent to the quadrature error estimator after passing through the phase shifter and the complex multiplication operator (i.e. the I data is sent to the quadrature error estimator after passing through the phase shifter and the complex multiplication operator, and the Q data is sent to the quadrature error estimator after passing through the phase shifter and the complex multiplication operator).

[0092] The channel estimation module 130 is configured to estimate and compensate the channel response between the transmission channel and the receiving channel based on the single-tone signal generated by the calibration tone generation module and the signal compensated by the QEC calibration module.

[0093] In the embodiment, the channel estimation module comprises a complex multiplier, a division operator and an arctan operator connected in sequence. Figure 9

[0094] It should be noted that the above embodiment provides a transmission quadrature error calibration system using a receiving channel, which is only used as an example for the division of the above functional modules. In actual application, the above functions can be completed by different functional modules according to needs, that is, the modules or steps in the embodiment of the present application are further decomposed or combined, for example, the modules in the above embodiment can be combined into one module, or further split into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiment of the present application are only used to distinguish the modules and steps, and are not considered as improper limitation of the present application.

[0095] The second embodiment of the present application is based on the above-mentioned transmission quadrature error calibration system using a receiving channel, and proposes a transmission quadrature error calibration method using a receiving channel. The following will be described in detail with reference to the accompanying drawings. Figure 10 The modules in one embodiment of the method of the present application are described in detail.

[0096] S10, control the calibration tone generation module to generate single-tone signals of multiple frequencies, transmit the single-tone signals through the transmission channel, receive the single-tone signals by the receiving channel, and estimate the quadrature error parameters of the receiving channel by the QEC calibration module; the quadrature error parameters include quadrature phase error and quadrature amplitude error.​

[0097] In this embodiment, for convenience of formula derivation, it is assumed that the transmitter in the communication system is an ideal transmitter, and no transmission quadrature error exists, so that the received signal 116 at the front end of the receiver can be expressed as:

[0098] r(t) = z I (t) cos(ω c t) + z Q (t) sin(ω c t)

[0099] where ω c represents the carrier frequency (the local oscillator frequency of the transmitter); z I , z Q (t) represents an ideal transmission signal without quadrature error.

[0100] The received local oscillator 114 with non-ideal quadrature error can be expressed as:

[0101]

[0102] where ω LO represents the local oscillator frequency of the receiver, and the frequency is equal to ω c ; α, represents the quadrature error parameters of amplitude and phase.

[0103] After the quadrature mixing and low-pass filtering of r(t), the actual obtained complex baseband signal 115 is expressed as:

[0104]

[0105] Using matrix representation, it is:

[0106] The quadrature error matrix of the receiver can be expressed as:

[0107] Considering that the quadrature error characteristics of the digital baseband channel can be equivalent to the transfer functions h I and h Q , the above formula can be further expressed as:

[0108]

[0109] Since the quadrature error exists between the I channel and the Q channel, and the I channel is regarded as an ideal reference signal, the influence of the quadrature error can be equivalent to being applied to the Q channel, and h I and h Q can be combined to be expressed as h D , and the following formula is obtained:

[0110]

[0111] where the frequency domain characteristic of the transfer function is H D (f) = A(f)e jωf At this time, the orthogonal error parameter matrix can be expressed as:

[0112] where α(f) and is the h D The orthogonal error amplitude and the orthogonal error phase corresponding to a certain frequency obtained by the orthogonal error function.

[0113] Considering that the equivalent ideal baseband signal z(t) to be calibrated should have cyclic symmetry, then:

[0114]

[0115] According to the above receiving orthogonal error matrix properties and cyclic symmetry characteristics, it can be obtained that:

[0116]

[0117] The above formula is transformed to obtain:

[0118]

[0119] Through the above formula, the receiving orthogonal phase and amplitude error corresponding to a certain frequency can be obtained.

[0120] Then, using the sweep sequence, n α and orthogonal error values within the baseband transmission bandwidth can be obtained, and these orthogonal error amplitude and phase values can be regarded as the phase frequency and amplitude frequency response of the complete receiver orthogonal error function H R '(f). Using IFFT operation, the sequence value of the complete receiver orthogonal error function h R '(t) can be obtained.

[0121] According to the example analysis, the orthogonal error calibration function h R can be modeled as an all-real sequence, and its frequency response satisfies the characteristics of even symmetry of the amplitude frequency response and odd symmetry of the phase frequency response. The total orthogonal phase error is expressed as , where represents the local oscillator orthogonal phase error, and φ(f) is the baseband orthogonal phase error, and φ(f) is odd symmetric with frequency. Considering that the total orthogonal amplitude error α(f) can be expressed as δ+β(f), δ is the local oscillator orthogonal amplitude error, and β(f) is the baseband orthogonal amplitude error, and β(f) is even symmetric with frequency, then δ+β(f) is also even symmetric with frequency. Therefore, according to the n α and orthogonal error values obtained by the sweep sequence, the local oscillator orthogonal phase error Let φ(f) be the phase response of the quadrature error function and α(f) be the amplitude response of the quadrature error function, then the sequence value of h R can be obtained.

[0122] According to the derivation of the quadrature error function above, the matrix expression of the receiver quadrature error calibration can be obtained, and the actual received signal of the receiver can be expressed as:

[0123]

[0124] Considering that h R (t) and h D (t) are inverse functions of each other and the following formula is true: h R (t)×h D (t) = 1

[0125] The Q channel of the received data is filtered by h R , which is a filter with tap coefficients, then:

[0126]

[0127] The above formula is filtered by the local oscillator quadrature compensation matrix, then:

[0128]

[0129] Finally, the obtained I and Q channel data are compensated by cosθ, and the quadrature error of the receiver can be completely calibrated.

[0130] Considering that the derivation above is based on the ideal transmission and the absence of transmission quadrature error, in practice, the transmitter baseband data can be defined as a constant, and the difference between the transmission local oscillator frequency and the reception local oscillator frequency is adjusted by δ, at this time:

[0131] z I (t) = C, z Q (t) = C

[0132] r(t) = C*(cos((ω LO + δ)t) + sin((ω LO + δ)t))

[0133] After the r(t) is quadrature mixed and low-pass filtered, the actual obtained complex baseband signal is expressed as:

[0134]

[0135] At this time, the influence of the transmission quadrature error can be completely eliminated, and the independent estimation and compensation of the reception quadrature error can be completed.

[0136] S20, the calibration tone generation module generates a single frequency tone signal, and transmits the signal through the transmitting channel, receives the signal by the receiving channel, compensates the quadrature error of the receiving channel by the QEC calibration module, and transmits the signal compensated by the quadrature error to the channel estimation module to estimate the channel response parameter;

[0137] In the embodiment, the expression of the transmitter output signal with quadrature error is:

[0138] a(t) = z I (t) * cos(ω c t) + [-sinθz I (t) + cosθz Q (t) * h p (t)] * sin(ω c t)

[0139] where ω c represents the carrier frequency (transmitter local oscillator frequency), θ represents the quadrature phase error of the transmitting local oscillator, h p (t) represents the transmitting baseband quadrature error, z I , z Q (t) represents the ideal transmission signal without quadrature error.

[0140] For formula derivation, it is assumed that the receiver has completed the calibration of the quadrature error, and the receiving local oscillator can be represented as:

[0141] x LO (t) = cos(ω LO t + Φ) + jsin(ω LO t + Φ)

[0142] where ω LO represents the receiver local oscillator frequency, which is equal to ω c ; Φ represents the phase value corresponding to the delay between the transmitting and receiving.

[0143] After the quadrature mixing and low-pass filtering of a(t), the actual I and Q baseband signals are represented as:

[0144]

[0145] By matrix representation, it can be:

[0146]

[0147] Due to the phase value Φ corresponding to the delay between the transmitting and receiving, the quadrature error parameter obtained when the quadrature error is estimated this time is rotated by Φ from the actual transmitter quadrature error parameter, which causes the failure of the transmitting quadrature calibration, so the channel phase response Φ needs to be compensated first.

[0148] The channel phase response Φ can be estimated by maximum likelihood estimation method. In the channel calibration stage, the signal generated by the calibration tone generation module is:

[0149] s(t) = cosωt + j*sinωt

[0150] where ω is a frequency within the baseband bandwidth.

[0151] The received signal y(t) can be represented as:

[0152]

[0153] Conjugate multiplication of s(t) and y(t) is performed. Considering that the transmission quadrature error is small, it can be ignored when maximum likelihood estimation is performed. Therefore:

[0154]

[0155]

[0156] The numerical compensation of Φ is solved.

[0157] S30, control the calibration tone generation module to generate a plurality of frequency single tone signals, transmit through the transmission channel, receive by the receiving channel, compensate the quadrature error of the receiving channel by the QEC calibration module, and compensate the channel response between the transmission channel and the receiving channel by the channel estimation module. After compensation, the quadrature error parameter of the transmission channel is estimated by the QEC calibration module again.

[0158] In this embodiment, the receiving quadrature error estimation, compensation and channel response estimation, compensation have been completed according to the above S10, S20. On this basis, the transmission quadrature error is estimated and compensated. Under the condition that the transmission quadrature calibration compensation is not performed, the transmission end baseband data can be represented as:

[0159]

[0160] The data after the transmission baseband transmission path is represented as:

[0161]

[0162] The quadrature phase error matrix of the transmission mixer is represented as:

[0163] The mixed transmission data is:

[0164]

[0165] The data obtained by the receiver from the above transmitting signal is:

[0166]

[0167] The receiver compensates the channel response and the receiving quadrature error function in sequence to obtain:

[0168]

[0169] At this time, the quadrature error of the received data is introduced by the transmitting quadrature error. The transmitting quadrature phase and amplitude error of a plurality of frequency points corresponding to the sweep sequence are estimated by using the QEC calibration module, and the transmitting quadrature error calibration function h T is used to separate the transmitting local oscillator phase error and the transmitting baseband error function, and then the actual transmitting local oscillator phase error θ and the transmitting quadrature error calibration function h T are solved. T The transmitting quadrature compensation matrix is constructed by using the transmitting local oscillator phase error θ and the transmitting quadrature error calibration function h

[0170]

[0171] The transmitting baseband signal is obtained after the transmitting baseband signal is compensated by the transmitting quadrature compensation matrix:

[0172]

[0173] The transmitting data is obtained after the above baseband data compensated by the transmitting quadrature error is transmitted through the transmitting baseband transmission channel:

[0174]

[0175] Considering that h R (t) and h D (t) are inverse functions of each other and the following formula is established: h T (t)×h p (t)=1;

[0176] Then:

[0177]

[0178] The above data is obtained after the transmitting mixer:

[0179]

[0180] It can be known from the above derivation that the quadrature error of the transmitter is completely calibrated.

[0181] S40, the orthogonal error parameters of the transmission channel are estimated by the QEC calibration module to compensate for the radio signal generated by the calibration tone generation module; the radio signal includes radar signal and communication signal.

[0182] In this embodiment, after the above three steps, the transmission quadrature error has been calibrated. Considering the influence of temperature and other characteristics under the working state, the transmission quadrature error changes ineffectively over time. At this time, the output under the working state is fed back to the receiving path at the same time. The transmission quadrature phase error θ and transmission quadrature amplitude error β are solved in real time using the QEC calibration module, so that the transmission quadrature error can be tracked.

[0183] To facilitate a clearer understanding of the present invention, the calibration process is illustrated below:

[0184] 1) The control calibration tone generation module generates local oscillator signals from 984MHz to 1015MHz sequentially with a frequency jump interval of 1MHz. Each local oscillator signal lasts for 200ms. The receiving local oscillator is fixed at 1GHz. The receiver's QEC calibration module receives the current transmit local oscillator frequency and other related information generated by the calibration tone generation module, as well as the received transmission signal from the receiving channel. At this time, the received data does not contain transmit quadrature error, but only transmit quadrature error, and the quadrature phase error α and quadrature amplitude error corresponding to each frequency point estimated by frequency sweep. The result is as follows Figure 4 , Figure 5 As shown, the orthogonal error parameters are decomposed using the formula derived above, and the receiving local oscillator phase error is obtained. The frequency response is then transformed into a time-domain sequence using IFFT operations to obtain the receiving baseband channel calibration function h. R .

[0185]

[0186]

[0187] The above results and h R Substitute Figure 6 It is used to receive orthogonal calibration.

[0188] 2) The calibration tone generation module is controlled, with a fixed transmit local oscillator of 1GHz and a baseband signal of 1MHz. The receive local oscillator is also fixed at 1GHz. The received 1MHz single-tone signal is processed by the receive quadrature compensation module to compensate for the receive quadrature error. This ADC signal, along with the 1MHz single-tone signal from the calibration tone generation module to the DAC, is then transmitted to... Figure 9 The signal estimation module uses the maximum likelihood estimation method described in the above formula to solve for the channel phase response Φ. Φ = 0.0751 rad.

[0189] 3) Control calibration sound generation module, fixed transmit local oscillator is 1GHz, with frequency hopping interval is 1MHz, -16MHz~15MHz baseband signal is generated in turn, receive local oscillator is fixed as 1GHz, at this time, the received sweep signal contains multiple influencing factors such as transmit quadrature error, channel response error, receive quadrature error, according to Figure 10 Operation estimation process, the received sweep sequence is compensated for receive quadrature error and channel response respectively, then the sweep sequence is imported into QEC calibration module to estimate transmit quadrature error and store transmit local oscillator phase error θ and transmit quadrature error calibration function h T .

[0190] θ=0.0264 rad

[0191]

[0192] The above obtained θ and h T are brought into Figure 7 for transmit quadrature calibration.

[0193] Subsequently, under normal working conditions, the working signal is transmitted to the receiving channel in real time, the transmit quadrature error is estimated and compensated in real time by using the above steps, and the transmit quadrature tracking calibration can overcome the influence of temperature and other time-varying factors on the transmit quadrature error, the transmit signal spectrum before transmit quadrature calibration is as shown in Figure 11 , and the transmit signal spectrum after transmit quadrature calibration is as shown in Figure 12 .

[0194] The application can be applied to any platform, does not require any additional calibration link, and is a general transmitter quadrature error calibration method, and the IRR can reach 60dB after transmit quadrature calibration. The method can track the transmit quadrature error in real time, and can overcome the influence of temperature and other time-varying factors on the transmit quadrature error.

[0195] Those skilled in the art should clearly understand that the modules and method steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware, computer software or a combination of both. The programs corresponding to the software modules and method steps can be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In order to clearly illustrate the interchangeability of electronic hardware and software, the components and steps of each example have been described in the above description in general terms. Whether the functions are performed by electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0196] The terms "first", "second", and the like are used to distinguish similar objects, rather than to denote or imply a particular order or sequence. The term "comprise" or any other similar term is intended to encompass non-exclusive inclusion, so that a process, method, article or apparatus / device including a series of elements includes not only those elements, but also other elements not explicitly listed, or inherent to such process, method, article or apparatus / device.

[0197] So far, the technical solution of the present application has been described in combination with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after such changes or replacements will fall within the protection scope of the present application.

Claims

1. A transmission orthogonal error calibration system utilizing a receiving channel, characterized in that, The system includes: The calibration tone generation module is configured to generate one or more single-tone signals of various frequencies and transmit them through the transmission channel; it is also configured to compensate and calibrate the transmitted signal based on the orthogonal error parameters of the transmission channel estimated by the QEC calibration module. The QEC calibration module is configured as follows: In the receiving quadrature error estimation mode, the receiving channel quadrature error parameters are estimated and compensated based on the I and Q data received by the receiving channel; In the transmit quadrature error estimation mode, the transmit channel quadrature error parameters are estimated based on the I-channel and Q-channel data output by the channel response compensator. The input of the channel response compensator is the I-channel and Q-channel data output by the receive quadrature error compensator and the compensated channel response parameters output by the channel estimation module. The output is the I-channel and Q-channel data after channel response compensation. The channel estimation module is configured to estimate and compensate the channel response parameters between the transmit channel and the receive channel based on the single-tone signal generated by the calibration tone generation module and the signal after orthogonal error compensation calibration by the QEC calibration module.

2. The transmission orthogonal error calibration system utilizing a receiving channel according to claim 1, characterized in that, The calibration tone generation module includes an I-channel data generator, a Q-channel data generator, and a transmission quadrature error compensator; The transmit quadrature error compensator includes a first complex multiplier, a second complex multiplier, a first adder, a first finite impulse response filter, a first digital delay unit, a first digital-to-analog converter, and a second digital-to-analog converter; The I-channel data is processed by the first digital delay unit and the first digital-to-analog converter and then sent to the transmission channel; The Q-channel data processed by the first complex multiplier and the I-channel data processed by the second complex multiplier are added by the first adder, and then processed by the first finite impulse response filter and the second digital-to-analog converter before being sent to the transmission channel. The transmit quadrature error compensator is configured to decompose the transmit channel quadrature error parameters obtained by the QEC calibration module into two parts, which are respectively used as inputs to the first complex multiplier and the second complex multiplier, and as coefficients of the first finite impulse response filter, thereby compensating for the transmitted signal. Specifically, the input is used when the first complex multiplier processes the signal. The second complex multiplier processes the input... ;Will As coefficients of the first finite impulse response filter, Indicates the orthogonal amplitude error of the launch. This represents the emission orthogonal error calibration function at time t.

3. The transmission orthogonal error calibration system utilizing a receiving channel according to claim 2, characterized in that, The channel estimation module includes a complex multiplier, a divider, and an arctan arctangent operator connected in sequence.

4. The transmission orthogonal error calibration system utilizing a receiving channel according to claim 3, characterized in that, The QEC calibration module includes an orthogonal error estimator, a channel response compensator, and a receiver orthogonal error compensator. The orthogonal error estimator includes a summation operator, a first square operator, a second square operator, a multiplier, a first division operator, a second division operator, a first square root operator, a second square root operator, and an arcsine operator; In the quadrature error estimation mode, the input of the quadrature error estimator is the I-channel data and Q-channel data received by the receiving channel, and the output is the quadrature error parameter of the receiving channel; In the transmit quadrature error estimation mode, the input of the quadrature error estimator is the I-channel data and Q-channel data output by the channel response compensator, and the output is the transmit channel quadrature error parameter; The I-channel and Q-channel data received through the receiving channel are processed by the first square operator and the second square operator, respectively, and then simultaneously processed by the multiplier. The outputs of the first square operator, the second square operator, and the multiplier are all accumulated and averaged by the summator, resulting in three accumulated average results: accumulated average result one, accumulated average result two, and accumulated average result three. The accumulated average result one and the accumulated average result two are then processed by the first division operator and output to the first square root operator to obtain the quadrature amplitude error. The accumulated average result one and the accumulated average result two are multiplied by the multiplier, then processed by the second square root operator, and input together with the accumulated average result three into the second division operator. The output of the second division operator is then sent to the arcsine operator to obtain the quadrature phase error. The receiving quadrature error compensator includes a first analog-to-digital converter, a second analog-to-digital converter, a third complex multiplier, a fourth complex multiplier, a second finite impulse response filter, a second digital delay unit, and a second adder; The I-channel data processed by the first analog-to-digital converter is sequentially processed by the second digital delay unit and the third complex multiplier before being sent to the channel response compensator. The Q-channel data, which has been processed sequentially by the second analog-to-digital converter and the second finite impulse response filter, and the I-channel data, which has been processed by the second digital delay unit and the fourth complex multiplier, are added together by the second adder and then sent to the channel response compensator. The orthogonal error parameters of the receiving channel obtained by the QEC calibration module are decomposed into two parts, which are used as the inputs of the third complex multiplier and the fourth complex multiplier, and the coefficients of the second finite impulse response filter, respectively. That is, the input during processing by the third complex multiplier The fourth complex multiplier processes the input... ,Will As coefficients of the second finite impulse response filter; This represents the receiving orthogonal error calibration function at time t. Indicates the received quadrature amplitude error; The channel response compensator includes a phase shifter and a fifth complex multiplier; The inputs to the channel response compensator are the I-channel data and Q-channel data output by the receiving quadrature error compensator and the channel response parameters output by the channel estimation module, and the outputs are the I-channel data and Q-channel data after channel response compensation. The channel response parameters estimated by the channel estimation module are transmitted to the channel response compensator as input to the fifth complex multiplier to compensate for the channel response between the transmit channel and the receive channel. The I-channel data and Q-channel data output from the receiving quadrature error compensator are simultaneously transmitted to the quadrature error estimator after passing through the phase shifter and the fifth complex multiplier.

5. A method for calibrating transmission orthogonality error using a receiving channel, based on the transmission orthogonality error calibration system using a receiving channel as described in any one of claims 1-4, characterized in that, The method includes: S10, the calibration tone generation module is controlled to generate single-tone signals of multiple frequencies, which are transmitted through the transmission channel and received by the receiving channel. The QEC calibration module is then used to estimate the quadrature error parameters of the receiving channel. The quadrature error parameters of the receiving channel include quadrature phase error and quadrature amplitude error. S20, control the calibration tone generation module to generate a single-frequency single-tone signal, transmit it through the transmission channel, receive it through the receiving channel, use the QEC calibration module to compensate for the orthogonal error of the receiving channel, and transmit the orthogonal error compensated signal to the channel estimation module to estimate the channel response parameters; S30, control the calibration tone generation module to generate single-tone signals of multiple frequencies, transmit them through the transmission channel, receive them through the receiving channel, use the QEC calibration module to compensate for the orthogonal error of the receiving channel, and use the channel estimation module to compensate for the channel response parameters between the transmission channel and the receiving channel. After compensation, the QEC calibration module estimates the orthogonal error parameters of the transmission channel. S40, the radio signal generated by the calibration tone generation module is compensated by the orthogonal error parameters of the transmission channel estimated by the QEC calibration module; the radio signal includes radar signal and communication signal.

6. The method for calibrating transmission orthogonality error using a receiving channel according to claim 5, characterized in that, The methods for generating the single-tone signals in S10, S20, and S30 are as follows: In S10, by modifying the local oscillator frequency, a fixed DC digital signal is added to the baseband to generate single-tone signals of multiple frequencies; In S20, by fixing the transmit local oscillator frequency and the receive local oscillator frequency to be the same, a fixed frequency single-tone digital signal is added to the baseband to generate a single-tone signal of a single frequency. In S30, by fixing the transmit local oscillator frequency and the receive local oscillator frequency to be the same, multiple frequency single-tone digital signals are added to the baseband to generate multiple frequency single-tone signals.

7. The method for calibrating transmission orthogonality error using a receiving channel according to claim 6, characterized in that, The method for compensating for the orthogonality error of the receiving channel using the QEC calibration module is as follows: The quadrature phase error and quadrature amplitude error corresponding to each frequency point are estimated by frequency sweeping. ； in, , These represent the quadrature phase error and the quadrature amplitude error, respectively. , These represent the baseband signals for the I and Q channels, respectively. This represents the average statistic of the input I-channel or Q-channel data. Indicates the current statistical data label, Indicates the total length of statistical data; Based on the quadrature phase error and the quadrature amplitude error, the local oscillator quadrature phase error is calculated; combined with the local oscillator quadrature phase error, the frequency response is transformed into a time-domain sequence using IFFT operation to obtain the receiving baseband channel calibration function. The quadrature error of the receiving channel is compensated by the receiving quadrature error compensator, taking into account the local oscillator quadrature phase error and the receiving baseband channel calibration function.

8. The method for calibrating transmission orthogonality error using a receiving channel according to claim 7, characterized in that, The channel response parameters are calculated as follows: ； ； ； in, This represents the channel response parameters, where imag represents the imaginary part and real represents the real part. This indicates the signal generated by the calibration tone generation module during the channel calibration phase. This represents a specific frequency within the baseband bandwidth. express and Perform conjugate multiplication. This represents the signal received after compensating for the orthogonality error of the receiving channel.

9. A method for calibrating transmission orthogonality error using a receiving channel according to claim 8, characterized in that, The QEC calibration module estimates the orthogonal error parameters of the transmit channel using the following method: The transmit quadrature phase error and transmit quadrature amplitude error corresponding to each frequency point are estimated by frequency sweeping. Combining the transmitted quadrature phase error and the transmitted quadrature amplitude error, the transmitted local oscillator phase error and the transmitted baseband error function are separated, and the actual transmitted local oscillator phase error and the transmitted quadrature error calibration function are solved, thereby constructing the transmitted quadrature compensation matrix; ； in, This indicates the actual transmitted local oscillator phase error. This represents the launch orthogonal error calibration function.

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