阅读说明：本技术 一种计算并补偿i/q信号线性相位失衡的方法 (A method of it calculates and compensates i/q signal linear phase imbalance ) 是由 孟婕 叶芃 王厚军 郭连平 赵禹 曾浩 田雨 蒋俊 王猛 于 2019-08-01 设计创作，主要内容包括：本发明公开了一种计算并补偿I/Q信号线性相位失衡的方法,在不考虑噪声影响下,对解调后的I/Q两路基带信号进行ADC采样,以及N点傅里叶变换,再取单边谱计算互功率谱及互功率谱的相位谱,然后利用三点法进行相位解缠,最后根据解缠后的群延时差δ和相位偏置差<Image he="53" wi="48" file="DDA0002152130370000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>进行相位补偿,还原出时域信号。(The invention discloses a kind of methods for calculating and compensating i/q signal linear phase imbalance, in the case where not considering influence of noise, ADC sampling is carried out to the I/Q two-way baseband signal after demodulation, and N point Fourier transformation, unilateral spectrum is taken to calculate the phase spectrum of crosspower spectrum and crosspower spectrum again, then phase unwrapping is carried out using line-of-sight course, the group delay time difference δ and phase bias after finally twining according to solution are poor Phase compensation is carried out, time-domain signal is restored.)

1. a kind of calculating and the method for compensating i/q signal linear phase imbalance, which comprises the following steps:

(1), in the case where not considering influence of noise, ADC sampling is carried out to the I/Q two-way baseband signal after demodulation, after being used Two-way discrete signal, is denoted as: x_i[n] and x_q[n], n indicate the discrete instants of time；Again to x_i[n] and x_q[n] carries out N point respectively Fourier transformation obtains X_i[k] and X_q[k], wherein N is even number, and k meets: k=-N/2+1 ..., N/2；

(2), to X_q[k] carries out Hilbert transform, obtains

X is taken respectively_i[k] andPositive frequency side unilateral spectrum, obtain X '_i[k] and X '_q[k], k > 0 and satisfaction:

Wherein, δ andRespectively the channel Q is poor relative to the group delay time difference in the channel I and phase bias；

(3), the crosspower spectrum spectrum of transformed I/Q two paths of signals is calculated

Wherein,It is X_qThe conjugation of [k]；

(4), the phase spectrum for calculating crosspower spectrum, obtains phase difference θ [k]；

(5), phase unwrapping is carried out using line-of-sight course

(5.1), unwrapping is carried out plus the integral multiple of 2 π at Δ θ [k]；

Wherein,It is Δ θ [k_i] solution twine after phase value, m_iFor integer, M is the frequency points chosen；

(5.2), maximum three frequency points of the Signal to Noise Ratio (SNR) on phase spectrum and its phase value are taken, (k is denoted as₁,Δθ[k₁])、(k₂, Δθ[k₂])、(k₃,Δθ[k₃]), and the sample point twined as non-solution；

(5.3), the slope of Δ θ [k] is calculated using the first two sample point；

(5.4), group delay time difference δ and the phase bias for calculating two channel I/Q are poor

If first sample point does not need plus the integral multiple of 2 π, then m₁=0；

According toOn same straight line, it can obtain:

(4) formula is substituted into (6) formula, abbreviation can obtain:

(k₃-k₁)m₂=C+ (k₂-k₁)m₃ (7)

Wherein, variable

The deformation of (7) formula can be obtained: (k₃-k₁)m₂- C must be (k₂-k₁) integral multiple, therefore, by (7) formula rewrite are as follows:

(k₃-k₁)m₂=C (mod (k₂-k₁)) (8)

Wherein, mod () indicates complementation；

(8) formula is solved using linear modular equation, can be obtained:

(k₃-k₁)m₂=m_2,0+(L(k₂-k₁)/D) (9)

Wherein, D is (k₃-k₁) and (k₂-k₁) greatest common divisor, L=0,1 ..., D-1；m_2,0=A (C/D) (mod (k₂-k₁)), A is integer；

M is obtained according to (9) formula₂, then by m₂It is updated to (5) formula, obtains group delay time difference δ of the channel Q relative to the channel I；δ is substituted into To (3) formula, the phase bias for obtaining the channel Q relative to the channel II is poor

(6), time delay module is poor according to group delay time difference δ and phase biasTo unilateral spectrum X '_q[k] is compensated, and is obtained compensated Unilateral spectrum X '_qc[k]；

X ' is obtained using image recovery module_qcThe conjugation of [k]Again by X '_qc[k] andIt is combined into bilateral spectrum X_qcd [k]；

By bilateral spectrum X_qcd[k] carries out Fourier inversion, obtains the compensated road Q time-domain signal x_qcd[n]。

2. a kind of calculating according to claim 1 and the method for compensating i/q signal linear phase imbalance, which is characterized in that The integer A and greatest common divisor D meet relationship are as follows:

D=A (k₃-k₁)+B(k₂-k₁)

Wherein, B is integer.

Technical field

The invention belongs to error correction techniques fields, more specifically, are related to a kind of calculating and to compensate i/q signal linear The method of phase imbalance.

Background technique

Front end structure is selected in the critical positions for influencing receiver integration and flexibility, and traditional superhet Framework has disadvantages that, in the past more than ten years, zero-if architecture is easy to that single-chip integration, structure be simple and cost function due to having Low advantage is consumed by favor, and unlike beat reception structure, it is equivalent that zero intermediate frequency receives the local frequency in structure In or close to input radio frequency signal frequency, to obtain direct current center or low intermediate frequency signal.However the structure is using same Particularly sensitive to radio frequency distortion mutually with orthogonal (I/Q) orthogonal mixing, wherein i/q signal orthogonal unbalance is that core therein influences Factor.Ideally, the road I and the road Q signal should have accurate 90 ° of phase differences and equal amplitude.However, in practical feelings In condition, difference, the difference of circuit design, the error of PCB layout of device used can all be such that the signal of the road I and the road Q signal generates The difference of phase and amplitude.In addition, the difference of the frequency response of the low-pass filter on the road I and the road Q, data converter and amplifier Also the overall magnitude and phase mismatch significantly influenced.Factors above all can cause I/Q unbalance, lead to incomplete mirror As signal decaying, and the bit error rate is improved in dpch signal.In addition to image frequency interference problem, I/Q is unbalance can serious shadow The performance of the power amplifier linearization technology based on predistortion of sound.With the more letters for using higher order modulation waveform or wider band Road signal, the influence that these are unbalance become readily apparent from.It must use at additional analog or digital signal in many systems Reason is to improve.

The phase imbalance that I/Q is unbalance is crucial problem therein, mainly by the undesirable and I/Q of analog demodulator local oscillator The group delay of two accesses of signal is inconsistent to be caused.Wherein different phase bias is generally caused by the undesirable of local oscillation signal, Its caused phase error is unrelated with frequency, is not influenced by base-band signal frequency, it will be appreciated that is constant, is that narrow band communication considers Main error, but for broadband connections, it is also contemplated that group delay deviation.Group delay deviation is introduced by I, Q two-way path Different delayed time cause, phase imbalance caused by this part is related with frequency, can change with the variation of base-band signal frequency, More difficult calculating and elimination, therefore the present invention provides one kind based on elimination two kinds of phases of i/q signal while calculating crosspower spectrum Imbalance error, i.e., the method for total linear phase imbalance.

Summary of the invention

It is an object of the invention to overcome the deficiencies of the prior art and provide calculate and compensate i/q signal linear phase imbalance Method, by line-of-sight course carry out phase unwrapping, and then compensate i/q signal linear phase imbalance.

For achieving the above object, a kind of method present invention calculating and compensate i/q signal linear phase imbalance, it is special Sign is, comprising the following steps:

(1), in the case where not considering influence of noise, ADC sampling is carried out to the I/Q two-way baseband signal after demodulation, is used Two-way discrete signal afterwards, is denoted as: x_i[n] and x_q[n], n indicate the discrete instants of time；Again to x_i[n] and x_q[n] respectively into Row N point Fourier transformation, obtains X_i[k] and X_q[k], wherein N is even number, and k meets: k=-N/2+1 ..., N/2；

(2), to X_q[k] carries out Hilbert transform, obtains

X is taken respectively_i[k] andPositive frequency side unilateral spectrum, obtain X_i' [k] and X'_q[k], k > 0 and satisfaction:

Wherein, δ andRespectively the channel Q is poor relative to the group delay time difference in the channel I and phase bias；

(3), the crosspower spectrum of transformed I/Q two paths of signals is calculated

Wherein,It is X_qThe conjugation of [k]；

(4), the phase spectrum for calculating crosspower spectrum, obtains phase difference θ [k]；

(5), phase unwrapping is carried out using line-of-sight course

(5.1), unwrapping is carried out plus the integral multiple of 2 π at Δ θ [k]；

Wherein,It is Δ θ [k_i] solution twine after phase value, m_iFor integer, M is the frequency points chosen；

(5.2), maximum three frequency points of the Signal to Noise Ratio (SNR) on phase spectrum and its phase value are taken, (k is denoted as₁,Δθ[k₁])、 (k₂,Δθ[k₂])、(k₃,Δθ[k₃]), and the sample point twined as non-solution；

(5.3), the slope of Δ θ [k] is calculated using the first two sample point；

(5.4), group delay time difference δ and the phase bias for calculating two channel I/Q are poor

If first sample point does not need plus the integral multiple of 2 π, then m₁=0；

According toOn same straight line, it can obtain:

(4) formula is substituted into (6) formula, abbreviation can obtain:

(k₃-k₁)m₂=C+ (k₂-k₁)m₃ (7)

Wherein, variable

The deformation of (7) formula can be obtained: (k₃-k₁)m₂- C must be (k₂-k₁) integral multiple, therefore, by (7) formula rewrite are as follows:

(k₃-k₁)m₂=C (mod (k₂-k₁)) (8)

Wherein, mod () indicates complementation；

(8) formula is solved using linear modular equation, can be obtained:

(k₃-k₁)m₂=m_2,0+(L(k₂-k₁)/D) (9)

Wherein, D is (k₃-k₁) and (k₂-k₁) greatest common divisor, L=0,1 ..., D-1；m_2,0=A (C/D) (mod (k₂- k₁)), A is integer；

M is obtained according to (9) formula₂, then by m₂It is updated to (5) formula, obtains group delay time difference δ of the channel Q relative to the channel I；By δ It is updated to (3) formula, the phase bias for obtaining the channel Q relative to the channel I is poor

(6), time delay module is poor according to group delay time difference δ and phase biasTo unilateral spectrum X'_q[k] is compensated, and is compensated Unilateral spectrum X' afterwards_qc[k]；

X' is obtained using image recovery module_qcThe conjugation of [k]Again by X'_qc[k] andIt is combined into bilateral Compose X_qcd[k]；

By bilateral spectrum X_qcd[k] carries out Fourier inversion, obtains the compensated road Q time-domain signal x_qcd[n]。

Goal of the invention of the invention is achieved in that

A kind of method present invention calculating and compensate i/q signal linear phase imbalance, in the case where not considering influence of noise, to solution I/Q two-way baseband signal after tune carries out ADC sampling and N point Fourier transformation, then unilateral spectrum is taken to calculate crosspower spectrum and mutually Then the phase spectrum of power spectrum carries out phase unwrapping, group delay time difference δ and phase bias after finally twining according to solution using line-of-sight course DifferencePhase compensation is carried out, time-domain signal is restored.

Meanwhile a kind of method for calculating and compensating i/q signal linear phase imbalance of the present invention also has the advantages that

(1), the present invention only need three frequency points of i/q signal that can realize estimation, do not need pilot signal and additionally Hardware.

(2), the present invention may be implemented to calculate and compensate while the group delay time difference and phase bias difference.

(3), there are in the case where I/Q amplitude imbalance, the present invention can also complete phase imbalance correction.

Detailed description of the invention

Fig. 1 is a kind of calculating of the present invention and the method flow diagram for compensating i/q signal linear phase imbalance；

Fig. 2 is quadrature receiver I/Q channel imbalance model framework chart；

Fig. 3 is the schematic diagram for calculating linear phase imbalance；

Fig. 4 is linear phase imbalance compensation block diagram.

Specific embodiment

A specific embodiment of the invention is described with reference to the accompanying drawing, preferably so as to those skilled in the art Understand the present invention.Requiring particular attention is that in the following description, when known function and the detailed description of design perhaps When can desalinate main contents of the invention, these descriptions will be ignored herein.