CN111698036A - Multi-microwave signal frequency estimation method based on microwave photons - Google Patents

Abstract

The invention proposes a multi-microwave signal frequency estimation method based on microwave photons, which aims to realize the estimation of multiple microwave signal frequencies at the same time and improve the estimation accuracy. The implementation steps are: constructing a microwave photonic system S; the receiving antenna unit receives a plurality of microwave signals of known frequencies; the first Mach-Zehnder modulator M1 performs intensity modulation on the microwave signal and the optical carrier signal; The band signal is filtered multiple times; the second Mach-Zehnder modulator M2 performs intensity modulation on the received time-delayed microwave signal and the signal filtered by B; the carrier frequency signal measurement unit C measures the optical power of the carrier frequency signal; The system S obtains the optical power of the carrier frequency signal of the microwave signal to be measured at the intensity modulation frequency, and obtains the frequency of the microwave signal to be measured. The invention adopts the microwave photon-based system to estimate the frequency of multiple microwave signals, and uses the formula of the convex optimization problem to process the calculation data. Object detection and passive localization.

Description

Frequency estimation method of multi-microwave signal based on microwave photons

technical field

The invention belongs to the technical field of photoelectric communication, and relates to a multi-microwave signal frequency estimation method, which can be used for target detection and passive positioning.

Background technique

Microwave signals refer to electromagnetic wave signals with wavelengths between 0.1 mm and 1 m. Since the 1970s, with the vigorous development of photonics and microwave technologies such as semiconductor lasers, high-speed optoelectronic modulators, fiber optics, integrated photonics, microwave antennas, microwave monolithic integrated circuits, etc. Microwave photonics is an interdisciplinary field combining the two disciplines of microwave and optics. Microwave photonics is an emerging discipline that studies the use of photonic methods to process microwave signals. The unique advantages of microwave photonic technology, such as large bandwidth, small integration volume and strong anti-electromagnetic interference, provide a potential solution for processing large bandwidth and high frequency millimeter microwave signals.

Due to the continuous increase of the frequency band of the radar radiation source in modern society, the analysis and identification tasks of the reconnaissance system have become more difficult. The traditional electronic method for frequency estimation is limited by the electronic bottleneck of electronic devices. Therefore, the received microwave signal is introduced into Microwave photonic systems for processing are promising for solving the above problems. Compared with the frequency estimation scheme in the electronic field, the microwave signal frequency measurement scheme based on microwave photons has the advantages of large instantaneous bandwidth, low loss, and anti-electromagnetic interference.

At present, there are two methods to realize the frequency estimation of microwave signals by using microwave photonics technology. The estimated rate is related to the amplitude comparison function, so as to obtain the estimated rate of the frequency to be measured; another method is to use the frequency space compression method of asynchronous optical sampling to asynchronously sample the high-frequency microwave signal, and analyze the data to obtain the frequency of the signal to be measured. Based on the Nyquist theorem, when the sampling rate is more than twice the highest frequency of the signal to be measured, the frequency measured in the sampled data is the frequency of the signal to be measured. However, when the frequency of the signal is very high, the frequency measurement cannot be realized due to the limitation of the slew rate of the device, and the method of asynchronous light sampling effectively solves this problem. The so-called asynchronous optical sampling is to use a lower frequency signal to sample a high frequency signal, which reduces the requirements for the sampling rate. Generally, the sampling rate of this method can reach several tenths of the highest rate of the signal to be measured. one.

The frequency measurement of microwave signals based on microwave photons is now in the transition stage from experiment to practical application in engineering, and has broad application prospects in the next few years. With the in-depth application of signal processing and the rapid development of electronic technology, parameter estimation for space electromagnetic waves is an important research field in signal processing. The important application background has received extensive attention.

In recent years, the research on frequency measurement technology based on microwave photonics has the following characteristics:

(1) Most of the current frequency estimation schemes focus on principle implementation and simulation verification. The frequency estimation range is not large, and the frequency estimation error mostly stays at about 0.2GHz. There are few schemes with high indicators, high performance and strong stability;

(2) Most of the schemes focus on single-frequency measurement. In some specific electromagnetic environments, the receiving end often receives multiple frequencies at the same time, but for the current mainstream frequency estimation scheme, it mostly stays in single-frequency measurement, and its scheme is not suitable for multi-frequency measurement conditions.

In actual measurement, in addition to loss, interference and other factors that are difficult to control, the settings of some device parameters and the size of microwave signals will affect the measurement accuracy and range, such as:

(1) To input the frequency of the microwave signal, it is necessary to select the appropriate measurement range and measurement accuracy to more accurately measure the frequency carried by the microwave signal;

(2) Bias drift caused by Mach-Zehnder modulator. When Mach-Zehnder modulator is used, it is necessary to control its bias point with a complex circuit. When bias drift occurs, measurement error will be introduced.

The technology of direct signal processing using traditional electronic devices has some unavoidable shortcomings, such as too large loss, high dispersion, inaccurate high-frequency measurement and so on. And the traditional signal processing system is bulky, lacks flexibility, and is not suitable for use in a high-speed changing environment. For ultra-wideband signals, the traditional microwave signal processing based on electronic devices can only use the segmentation processing method. For the parts that cannot be directly processed in the middle and high frequency parts, it is necessary to use the intermediate frequency technology to convert them into low frequency signals, and then use digital sampling technology to become digital signal processing. The intermediate frequency technology specifically divides the medium and high frequency signal into GHz segments, and then uses the mixing method to convert the low frequency signal. . At the same time, this method requires multiple parallel systems to process each signal segment cut from the broadband signal. For example, if the microwave frequency range to be measured is 0 to 40 GHz, 40 IF systems with a bandwidth of 1 GHz need to be used. , which will bring disadvantages such as high cost and large volume. The latest microwave signal frequency estimation method is to use microwave photons to estimate the microwave signal frequency. This method aims to estimate the microwave signal frequency by using optoelectronic devices and optoelectronic methods. It has the advantages of strong interference ability and small system, which can overcome the electronic bottleneck and adapt to the complex electromagnetic environment. For example, the paper Pan S, Yao J.Photonics-Based Broadband Microwave Measurement[J].Journal of Lightwave Technology,2017,35(16):3498-3513. published a method for measuring microwave frequency based on microwave photonic technology, but due to This method can only measure the frequency of a single signal, and cannot be measured when multiple signals arrive at the same time, so the frequency estimation range is limited, and the estimation efficiency and estimation accuracy are low.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a method for estimating the frequency of multiple microwave signals based on microwave photons, aiming at realizing the estimation of the frequencies of multiple microwave signals at the same time and improving the accuracy of the estimation. To achieve the above object, the technical scheme adopted by the present invention comprises the following steps:

(1) Construct a microwave photonic system S:

Construct a microwave photonic system S, including a receiving antenna unit R, a first Mach-Zehnder modulator M1, a second Mach-Zehnder modulator M2, a laser signal source L, a first optical filter B1 and a second optical filter connected in parallel An optical filter group B composed of B2, a carrier frequency signal measurement unit C composed of a third optical filter B3 and an optical power meter W; one input end of the M1 is connected to the output end of R, and the other input end is connected to the laser signal The source L is cascaded, and the output end of the M1 is cascaded with the optical filter bank B; one input end of the M2 is connected with the output end of the R through the microwave time delay line T, and the other input end is connected with the optical filter bank B. The output ends are cascaded, and the output end of the M2 is cascaded in turn with the third optical filter B3 and the optical power meter W; wherein: the frequency of the optical carrier signal of the laser signal source L is f;

(2) The receiving antenna unit receives a plurality of microwave signals of known frequencies:

相邻微波信号的频率间隔为△f，其中，

表示t₁时刻R接收到的频率为

的第n个微波信号，N≥1，△f≥500MHz；The receiving antenna unit R receives N microwave signals with known frequencies and the frequencies increase sequentially

The frequency interval of adjacent microwave signals is Δf, where,

It means that the frequency received by R at time _t1 is

The nth microwave signal of , N≥1, △f≥500MHz;

(3) The first Mach-Zehnder modulator M1 performs intensity modulation on the microwave signal and the optical carrier signal:

和激光信号源L输出的光载波信号v_f(t₁)进行强度调制，输出端得到N组一阶边带信号

其中

和

分别表示频率为

和

的一阶边带信号；The microwave signal of each known frequency received by the first Mach-Zehnder modulator M1 for R

Intensity modulation is performed with the optical carrier signal v _f (t ₁ ) output by the laser signal source L, and N groups of first-order sideband signals are obtained at the output end.

in

and

Respectively, the frequency is

and

The first-order sideband signal of ;

(4) The optical filter bank B performs multiple filtering on the first-order sideband signal:

分组依次进行N次滤波，具体为：当n＝1时，B1对第一组一阶边带信号中的

进行滤波，B2对

进行滤波，当n＝2…N时，B1对第n组及之前所有组的一阶边带信号中的

及频率大于

的一阶边带信号进行滤波，B2对

及频率小于

的一阶边带信号进行滤波，得到滤波后的N组一阶边带信号

Optical filter set B to N sets of first-order sideband signals

The grouping is sequentially filtered N times, specifically: when n=1, B1 filters the first-order sideband signals in the first group.

filter, B2 pairs

For filtering, when n=2...N, B1 will filter the first-order sideband signals of the nth group and all previous groups

and frequency greater than

Filter the first-order sideband signal of , B2 pairs

and frequency less than

Filter the first-order sideband signals of , to obtain N groups of first-order sideband signals after filtering

(5) The second Mach-Zehnder modulator M2 performs intensity modulation on the received time-delayed microwave signal and the B-filtered signal:

与经过B滤波后的的一阶边带信号

进行强度调制，输出端得到强度调制后的N组输出信号，其中τ表示T所产生的时延；The microwave signal formed by the second Mach-Zehnder modulator M2 for the N microwave signals received by R after passing through the microwave time delay line T

and the B-filtered first-order sideband signal

Perform intensity modulation, and the output terminal obtains N groups of output signals after intensity modulation, where τ represents the time delay generated by T;

(6) The carrier frequency signal measuring unit C measures the optical power of the carrier frequency signal:

The third optical filter B3 in the carrier frequency signal measurement unit C filters each group of modulated output signals, filters out N groups of first output signals with frequency f, and measures each group of filtering results through an optical power meter W. The optical power of the carrier frequency signal is obtained to obtain the optical power of the N groups of carrier frequency signals

(7) Obtain the optical power of the carrier frequency signal of the microwave signal to be measured at the intensity modulation frequency through the microwave photonic system S:

(7a) The receiving antenna unit R receives N microwave signals with frequencies to be measured v ₁ (t ₂ ), v ₂ (t ₂ ),...,v _n (t ₂ ),...,v _N (t ₂ ), where v _n (t ₂ ) represents the n-th microwave signal with frequency f _n received by R at time t ₂ ,;

(7b) M1 performs intensity modulation on the microwave signal v _n (t ₂ ) to be measured at each frequency received by R and the optical carrier signal v _f (t ₂ ) output by the laser signal source L, and the output terminal obtains N groups of first-order edges With signals v _f-1 (t ₂ ), v _f+1 (t ₂ ); v _f-2 (t ₂ ), v _f+2 (t ₂ ); ...; v _fn (t ₂ ), v _{f+ n} (t ₂ );...;v _fN (t ₂ ),v _f+N (t ₂ ), where v _fn (t ₂ ) and v _f+n (t ₂ ) denote frequencies ff _n and f+f, respectively the first-order sideband signal of _n ;

(7c) Optical filter group B pairs N groups of first-order sideband signals v _f-1 (t ₂ ), v _f+1 (t ₂ ); v _f-2 (t ₂ ), v _f+2 (t ₂ );...;v _fn (t ₂ ),v _f+n (t ₂ );...;v _fN (t ₂ ),v _f+N (t ₂ ) are grouped for N filtering in turn, specifically: when n= When 1, B1 filters v _f-1 (t ₂ ) in the first group of first-order sideband signals, and B2 filters v _f+1 (t ₂ ). When n=2...N, B1 filters the first V _fn (t ₂ ) in the first-order sideband signals of the n groups and all the previous groups and the first-order sideband signals with frequencies greater than ff _n are filtered, and B2 filters v _f+1 (t ₂ ) and frequencies less than f+f Filter the first-order sideband signals of _n to obtain N groups of first-order sideband signals after filtering v' _f-1 (t ₂ ), v' _f+1 (t ₂ ); v' _f-2 (t ₂ ) ,v' _f+2 (t ₂ );...;v' _fn (t ₂ ),v' _f+n (t ₂ );...;v' _fN (t ₂ ),v' _f+N (t ₂ ) ;

(7d) Let τ=τ ₁ , τ ₂ ,...,τ _l ,...,τ _M , then the microwave signal received by M2 after T delay is expressed as:

A ₁ (t ₂ ),A ₂ (t ₂ ),…,A _l (t ₂ ),…,A _M (t ₂ )

A _l (t ₂ )=v ₁ (t ₂ +τ _l ),v ₂ (t ₂ +τ _l ),…,v _n (t ₂ +τ _l ),…,v _N (t ₂ +τ _l )

where τ _l represents the l-th modification to τ, M represents the number of modifications, and M≥3;

(7e) The microwave signals A ₁ (t ₂ ), A ₂ (t ₂ ),…,A _l (t ₂ ),…,A _M (t ₂ ) output by M2 to T are respectively combined with the filtered N groups of first-order signals Sideband signals v' _f-1 (t ₁ ), v' _f+1 (t ₁ ); v' _f-2 (t ₁ ), v' _f+2 (t ₁ ); ...; v' _fn (t ₁ ), v' _f+n (t ₁ ); ...; v' _fN (t ₁ ), v' _f+N (t ₁ ) perform intensity modulation, and the output terminal obtains M N groups of output signals after intensity modulation;

(7f) The third optical filter B3 in the carrier frequency signal measuring unit C filters each N group of output signals in the M N groups of output signals after intensity modulation, and filters out N groups of second outputs with frequency f signal, and measure the optical power of the carrier frequency signal of each group of filtering results by the optical power meter W, and obtain the optical power of M N groups of carrier frequency signals:

P ₁ , P ₂ , ..., P _l , ..., P _M

P _l =p _l1 ,p _l2 ,...,p _ln ,...,p _lN ;

(8) Obtain the frequency of the microwave signal to be measured:

计算光功率经验公式中常数的经验值O_n，则N组载频信号光功率

对应的光功率经验公式中常数的经验值为O₁,O₂,…,O_n,…,O_N，并将步骤(7f)中的p_ln和O_n的商作为比值数据Q_ln，再通过所有的比值数据Q_1n,Q_2n,…,Q_ln,…,Q_Mn计算实际观测向量Y_n：(8a) Through the optical power of the carrier frequency signal obtained in step (6)

Calculate the empirical value O _n of the constant in the empirical formula of optical power, then the optical power of N groups of carrier frequency signals

The empirical values of the constants in the corresponding empirical _formula of optical power are O ₁ , O ₂ ,…,On ,…, _ON , and the quotient of _{p ln} and On in step (7f) is taken as the ratio data Q _ln , and then Calculate the actual observation vector Y _n from all the ratio data Q _1n , Q _2n ,…,Q _ln ,…,Q _Mn :

Y _n =[Q _1n ,Q _2n ,...,Q _ln ,...,Q _Mn ] ^T

Among them, [ ] ^T represents transpose;

和

对实际观测向量Y_n进行重塑，得到消除噪声后的实际观测向量Y_n'：(8b) via Z

and

Reshape the actual observation vector Y _n to obtain the actual observation vector Y _n ' after noise removal:

是(1-ρ)的稀疏表示系数矢量,

表示维度为M×N的矩阵，in

is the sparse representation coefficient vector of (1-ρ),

represents a matrix of dimension M×N,

(8c) The formula of the convex optimization problem is adopted, and the frequency f _n of the microwave signal to be measured v _n (t ₂ ) is calculated by Y _n '.

Compared with the prior art, the present invention has the following advantages:

1. The present invention obtains the empirical values of the constants in the N optical power empirical formulas corresponding to the optical powers of the N groups of carrier frequency signals through N microwave signals of known frequencies received by a receiving antenna unit, and compares N by the N empirical values. The frequency of the microwave signal of unknown frequency is estimated, which avoids the defect that only one signal frequency can be estimated at a time in the prior art, and effectively improves the estimation efficiency.

2. The present invention processes the data by using the formula of the convex optimization problem, and calculates the frequency of the microwave signal to be measured, which reduces the calculation error, and effectively improves the estimation accuracy compared with the prior art.

Description of drawings

Fig. 1 is the realization flow chart of the present invention;

Fig. 2 is the structure schematic diagram of microwave photonic system S constructed in the present invention;

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

1, the present invention includes the following steps:

Step 1) Construct the microwave photonic system S shown in Figure 2:

Construct a microwave photonic system S, including a receiving antenna unit R, a first Mach-Zehnder modulator M1, a second Mach-Zehnder modulator M2, a laser signal source L, a first optical filter B1 and a second optical filter connected in parallel An optical filter group B composed of B2, a carrier frequency signal measurement unit C composed of a third optical filter B3 and an optical power meter W; here the first Mach-Zehnder modulator M1 is in the carrier suppression state, and the first optical filter B1 The parallel structure formed with the second optical filter B2 is to filter out the first-order sideband signal generated after the microwave signal is modulated by the first Mach-Zehnder modulator M1, and the second Mach-Zehnder modulator M2 is in the carrier suppression state, The third optical filter B3 is to filter out the carrier frequency signal generated after the microwave signal is modulated by the second Mach-Zehnder modulator M2, and the optical power meter W is to obtain the optical power value of the microwave signal; an input of the M1 One end is connected to the output end of R, the other input end is cascaded with the laser signal source L, the output end of the M1 is cascaded with the optical filter bank B; one input end of the M2 is connected by the microwave time delay line T and R. The output end is connected, the other input end is cascaded with the output end of the optical filter bank B, the output end of the M2 is cascaded with the third optical filter B3 and the optical power meter W in turn; wherein: the optical carrier signal of the laser signal source L frequency is f;

Step 2) The receiving antenna unit receives the microwave signal of the known frequency:

的微波信号

相邻微波信号的频率间隔为△f＝2GHz；The receiving antenna unit R receives 2 frequencies as

microwave signal

The frequency interval of adjacent microwave signals is Δf=2GHz;

Step 3) The first Mach-Zehnder modulator M1 performs intensity modulation on the microwave signal and the optical carrier signal:

和激光信号源L输出的光载波信号v_f(t₁)进行强度调制，可以借此将电信号用光信号的形式表示出来，同时由于第一马赫增德尔调制器M1处于载波抑制状态，因此产生2组关于载频信号对称的一阶边带信号

The microwave signal for each known direction of arrival angle received by the first Mach-Zehnder modulator M1 for R

The intensity modulation is performed with the optical carrier signal v _f (t ₁ ) output by the laser signal source L, so that the electrical signal can be expressed in the form of an optical signal. At the same time, since the first Mach-Zehnder modulator M1 Generate 2 sets of first-order sideband signals symmetrical about the carrier frequency signal

Step 4) The optical filter bank B performs multiple filtering on the first-order sideband signal:

分组依次进行2次滤波，具体为：当n＝1时，B1对第一组一阶边带信号中的

进行滤波，B2对

进行滤波，当n＝2时，B1对第2组和第1组的一阶边带信号中的

进行滤波，B2对

进行滤波，得到滤波后的2组一阶边带信号

其中，在第一次进行滤波的时候，就可以测量出

和

的频率，在第二次进行滤波的时候，

和

的频率信息与

和

的频率信息是结合在一起被测量出来的，但是由于

和

的频率已经被测得了，因此就可以得到

和

的频率；Because frequency estimation of microwave signals needs to be performed on multiple groups of signals at the same time, multiple filtering needs to be performed in this step. Optical filter bank B pairs 2 sets of first-order sideband signals

The groups are filtered twice in turn, specifically: when n=1, B1 filters the first-order sideband signals in the first group.

filter, B2 pairs

For filtering, when n=2, B1 will filter the first-order sideband signals in the second and first groups

filter, B2 pairs

Perform filtering to obtain two groups of first-order sideband signals after filtering

Among them, when filtering is performed for the first time, it can be measured

and

frequency, when filtering for the second time,

and

frequency information with

and

The frequency information of , is measured together, but due to

and

frequency has been measured, so it is possible to obtain

and

Frequency of;

Step 5) The second Mach-Zehnder modulator M2 performs intensity modulation on the received time-delayed microwave signal and the B-filtered signal:

与经过B滤波后的的一阶边带信号

进行强度调制，由于第二马赫曾德尔调制器M2处于载波抑制状态，因此输出端会得到强度调制后的关于载频信号对称的2组输出信号，其中τ表示T所产生的时延；Because the first-order sideband signal obtained at the output of the first Mach-Zehnder modulator M1 is limited, it is not enough to meet the quantitative requirements of the final microwave signal frequency estimation, so by introducing the microwave time delay line T, one can obtain the signal received by one antenna. A new group of microwave signals with a delay added to a group of microwave signals is used for intensity modulation by the second Mach-Zehnder modulator M2. The microwave signal formed by the second Mach-Zehnder modulator M2 and the two microwave signals received by R after passing through the microwave time delay line T

and the B-filtered first-order sideband signal

Intensity modulation is performed. Since the second Mach-Zehnder modulator M2 is in the carrier suppression state, the output terminal will obtain two sets of output signals symmetrical about the carrier frequency signal after intensity modulation, where τ represents the time delay generated by T;

Step 6) The carrier frequency signal measuring unit C measures the optical power of the carrier frequency signal:

Because frequency estimation of microwave signals needs to be performed on multiple groups of signals at the same time, multiple filtering needs to be performed in this step. The third optical filter B3 in the carrier frequency signal measurement unit C filters each group of modulated output signals to obtain 2 groups of first output signals with a frequency of f, and measures each group of filtering results through an optical power meter W. The optical power of the carrier frequency signal is obtained, and the optical power of the 2 groups of carrier frequency signals is obtained.

Step 7) Obtain the optical power of the carrier frequency signal of the microwave signal to be measured with the intensity modulation frequency through the microwave photonic system S:

(7a) The receiving antenna unit R receives two frequencies f ₁ , f ₂ assuming the microwave signals to be measured v ₁ (t ₂ ), v ₂ (t ₂ ), where the actual setting values of f ₁ and f ₂ are 3GHz, 5GHz;

(7b) M1 performs intensity modulation on the microwave signal v ₁ (t ₂ ), v ₂ (t ₂ ) received by R and the optical carrier signal v _f (t ₂ ) output by the laser signal source L, and the output terminal obtains 2 groups of first-order sideband signals v _f-1 (t ₂ ), v _f+1 (t ₂ ); v _f-2 (t ₂ ), v _f+2 (t ₂ );

(7c) Optical filter group B pairs two sets of first-order sideband signals v _f-1 (t ₂ ), v _f+1 (t ₂ ); v _f-2 (t ₂ ), v _f+2 (t ₂ ) grouping and filtering twice in turn, specifically: when n=1, B1 filters v _f-1 (t ₂ ) in the first group of first-order sideband signals, and B2 filters v _f+1 (t ₂ ) Filtering, when n=2, B1 filters v _f-2 (t ₂ ), v _f-1 (t ₂ ) in the first-order sideband signals of the second and first groups, and B2 filters v _{f +2} (t ₂ ), v _f+1 (t ₂ ) are filtered to obtain N groups of filtered first-order sideband signals v' _f-1 (t ₂ ), v' _f+1 (t ₂ ); v ' _f-2 (t ₂ ),v' _f+2 (t ₂ );

(7d) Let τ=τ ₁ , τ ₂ ,...,τ _l ,...,τ ₅ , then the microwave signal received by M2 after T delay is expressed as:

A ₁ (t ₂ ),A ₂ (t ₂ ),…,A _l (t ₂ ),…,A ₅ (t ₂ )

A ₁ (t ₂ )=v ₁ (t ₂ +τ ₁ ),v ₂ (t ₂ +τ ₁ )

A ₂ (t ₂ )=v ₁ (t ₂ +τ ₂ ),v ₂ (t ₂ +τ ₂ )

A _l (t ₂ )=v ₁ (t ₂ +τ _l ),v ₂ (t ₂ +τ _l )

A ₅ (t ₂ )=v ₁ (t ₂ +τ ₅ ),v ₂ (t ₂ +τ ₅ )

where τ _l represents the lth modification to τ, τ ₁ =0.005, τ ₂ =0.01, τ ₃ =0.015, τ ₄ =0.02, τ ₅ =0.025;

(7e) The microwave signals A ₁ (t ₂ ), A ₂ (t ₂ ),...,A _l (t ₂ ),...,A ₅ (t ₂ ) output by M2 to T are respectively combined with the filtered two groups of first-order Sideband signals v' _f-1 (t ₁ ), v' _f+1 (t ₁ ); v' _f-2 (t ₁ ), v' _f+2 (t ₁ ) perform intensity modulation, and the output terminal obtains the intensity 5 modulated 2-group output signals;

(7f) The third optical filter B3 in the carrier frequency signal measuring unit C filters each N group of output signals in the M N groups of output signals after intensity modulation, and filters out N groups of second outputs with frequency f signal, and measure the optical power of the carrier frequency signal of each group of filtering results by the optical power meter W, and obtain the optical power of M N groups of carrier frequency signals:

P ₁ , P ₂ , ..., P _l , ..., P ₅

P _l =p _l1 ,p _l2 ;

Step 8) Obtain the frequency of the microwave signal to be measured:

计算光功率经验公式中常数的经验值O_n，则2组载频信号光功率

对应的光功率经验公式中常数的经验值为O₁,O₂，并将步骤(7f)中的p_l1和O₁的商作为比值数据Q_l1，p_l2和O₂的商作为比值数据Q_l2，再通过所有的比值数据Q_1n,Q_2n,…,Q_ln,…,Q_5n计算实际观测向量Y_n：(8a) Through the optical power of the carrier frequency signal obtained in step (6)

Calculate the empirical value O _n of the constant in the empirical formula of optical power, then the optical power of 2 groups of carrier frequency signals

The empirical values of the constants in the corresponding empirical formula of optical power are O ₁ , O ₂ , and the quotient of p _l1 and O ₁ in step (7f) is taken as the ratio data Q _l1 , and the quotient of p _l2 and O ₂ is taken as the ratio data Q _l2 , and then calculate the actual observation vector Y _n through all the ratio data Q _1n , Q _2n ,…,Q _ln ,…,Q _5n :

Y ₁ =[Q ₁₁ ,Q ₂₁ ,…,Q _l1 ,…,Q ₅₁ ] ^T

Y ₂ =[Q ₁₂ ,Q ₂₂ ,…,Q _l2 ,…,Q ₅₂ ] ^T

Among them, [ ] ^T represents transpose;

The empirical values of the constants O ₁ , O ₂ ,…,On ,…, _ON in the optical power calculation _formula are as follows:

为微波信号

的角频率，

为微波信号

的角频率，

Among them, ∝ means proportional,

for microwave signals

angular frequency,

for microwave signals

angular frequency,

和

对实际观测向量Y₁和Y₂进行重塑，得到抑制噪声后的Y₁'和Y₂'：(8b) Pass

and

Reshape the actual observation vectors Y ₁ and Y ₂ to get Y ₁ ' and Y ₂ ' after noise suppression:

是(1-ρ)的稀疏表示系数矢量,

表示维度为5×2的矩阵，in

is the sparse representation coefficient vector of (1-ρ),

represents a matrix of dimension 5 × 2,

(8c) In order to improve the accuracy of the DOA estimation, the formula of the convex optimization problem is adopted, and the frequencies f of the microwave signals v ₁ (t ₂ ) and v ₂ (t ₂ ) to be measured are calculated by Y ₁ ' and Y ₂ ' ₁ = 3GHz, f ₁ = 5GHz, the simulation results show that the error between the obtained signal frequency and the actually set microwave signal frequency is 0, and the formula of the convex optimization problem is:

where ||·|| ₁ represents the 1-norm, ||·|| ₂ represents the 2-norm, and ε represents an arbitrarily small number.

Claims (3)

1. A multi-microwave signal frequency estimation method based on microwave photons is characterized by comprising the following steps:

(1) constructing a microwave photonic system S:

constructing a microwave photonic system S, which comprises a receiving antenna unit R, a first Mach-Zehnder modulator M1, a second Mach-Zehnder modulator M2, a laser signal source L, an optical filter bank B consisting of a first optical filter B1 and a second optical filter B2 which are connected in parallel, and a carrier frequency signal measurement unit C consisting of a third optical filter B3 and an optical power meter W; one input end of the M1 is connected with the output end of the R, the other input end of the M1 is cascaded with the laser signal source L, and the output end of the M1 is cascaded with the optical filter bank B; one input end of the M2 is connected with the output end of the R through a microwave time delay line T, the other input end of the M2 is cascaded with the output end of the optical filter group B, and the output end of the M2 is cascaded with the third optical filter B3 and the optical power meter W in sequence; wherein: the frequency of an optical carrier signal of the laser signal source L is f;

(2) the receiving antenna unit receives microwave signals of a plurality of known frequencies:

the receiving antenna unit R receives N microwave signals with known frequencies and sequentially increased frequencies

The adjacent microwave signals have a frequency separation of △ f, wherein,

represents t₁The frequency received at time R is

N is more than or equal to 1, and △ f is more than or equal to 500 MHz;

(3) the first mach-zehnder modulator M1 performs intensity modulation on the microwave signal and the optical carrier signal:

the first Mach-Zehnder modulator M1 receives a microwave signal of each known frequency for R

And an optical carrier signal v output by the laser signal source L_f(t₁) Intensity modulation is carried out, and N groups of first-order sideband signals are obtained at the output end

Wherein

And

respectively represent frequencies of

And

a first-order sideband signal;

(4) the optical filter bank B filters the first order sideband signals a plurality of times:

optical filter bank B pairs N sets of first order sideband signals

Grouping and sequentially carrying out N times of filtering, specifically: when n is 1, B1 pairs in the first set of first order sideband signals

Filtering is carried out, and B2 pairs

Filtering is carried out, when N is 2 … N, B1 pairs the nth and all previous groups of first-order sideband signals

And a frequency greater than

Is filtered, B2 is

And a frequency less than

Filtering the first-order sideband signals to obtain N groups of filtered first-order sideband signals

(5) The second mach-zehnder modulator M2 performs intensity modulation on the received time-delayed microwave signal and the signal after B filtering:

the second Mach-Zehnder modulator M2 receives N microwave signals from the R through the microwave delay line T to form microwave signals

With B-filtered first-order sideband signals

Intensity modulation is carried out, N groups of output signals after intensity modulation are obtained at an output end, wherein tau represents time delay generated by T;

(6) the carrier frequency signal measurement unit C measures the carrier frequency signal optical power:

a third optical filter B3 in the carrier frequency signal measurement unit C filters each modulated group of output signals to obtain N groups of first output signals with the frequency f, and measures the optical power of the carrier frequency signal of each group of filtering results by an optical power meter W to obtain N groups of optical powers of the carrier frequency signal

(7) Obtaining the carrier frequency signal light power of the microwave signal to be detected with the intensity modulation frequency through a microwave photon system S:

(7a) the receiving antenna unit R receives N microwave signals v with frequencies to be measured₁(t₂),v₂(t₂),…,v_n(t₂),…,v_N(t₂) Wherein v is_n(t₂) Represents t₂The received frequency received at time R is f_nThe nth microwave signal of (1);

(7b) m1 pairs R received microwave signals v with each frequency to be measured_n(t₂) And an optical carrier signal v output by the laser signal source L_f(t₂) Intensity modulation is carried out, and N groups of first-order edges are obtained at the output endSignal v with signal_f-1(t₂),v_f+1(t₂)；v_f-2(t₂),v_f+2(t₂)；…；v_f-n(t₂),v_f+n(t₂)；…；v_f-N(t₂),v_f+N(t₂) Wherein v is_f-n(t₂) And v_f+n(t₂) Respectively representing frequencies f-f_nAnd f + f_nA first-order sideband signal;

(7c) optical filter bank B pairs N sets of first order sideband signals v_f-1(t₂),v_f+1(t₂)；v_f-2(t₂),v_f+2(t₂)；…；v_f-n(t₂),v_f+n(t₂)；…；v_f-N(t₂),v_f+N(t₂) Grouping and sequentially carrying out N times of filtering, specifically: when n is 1, B1 pairs v in the first set of first order sideband signals_f-1(t₂) Filtering, B2 for v_f+1(t₂) Filtering is carried out, when N is 2 … N, B1 pairs v in the first-order sideband signals of the nth group and all previous groups_f-n(t₂) And a frequency greater than f-f_nB2 filters v_f+n(t₂) And frequency less than f + f_nIs filtered to obtain N sets of filtered first-order sideband signals v'_f-1(t₂),v'_f+1(t₂)；v'_f-2(t₂),v'_f+2(t₂)；…；v'_f-n(t₂),v'_f+n(t₂)；…；v'_f-N(t₂),v'_f+N(t₂)；

(7d) Let τ be τ₁,τ₂,…,τ_l,…,τ_MThen the T-delayed microwave signal received by M2 is expressed as:

A₁(t₂),A₂(t₂),…,A_l(t₂),…,A_M(t₂)

A_l(t₂)＝v₁(t₂+τ_l),v₂(t₂+τ_l),…,v_n(t₂+τ_l),…,v_N(t₂+τ_l)

wherein tau is_lRepresents the l modification of tau, M represents the number of modifications, and M is more than or equal to 3;

(7e) microwave signal A output by M2 to T₁(t₂),A₂(t₂),…,A_l(t₂),…,A_M(t₂) Respectively with filtered N sets of first-order sideband signals v'_f-1(t₁),v'_f+1(t₁)；v'_f-2(t₁),v'_f+2(t₁)；…；v'_f-n(t₁),v'_f+n(t₁)；…；v'_f-N(t₁),v'_f+N(t₁) Carrying out intensity modulation, and obtaining M N groups of output signals after intensity modulation at an output end;

(7f) a third optical filter B3 in the carrier frequency signal measurement unit C filters each of N groups of output signals of M groups of output signals after intensity modulation, so as to obtain N groups of second output signals with frequency f, and measures the optical power of the carrier frequency signal of each group of filtering results by an optical power meter W, so as to obtain M groups of carrier frequency signal optical powers:

P₁，P₂，…，P_l，…，P_M

P_l＝p_l1,p_l2,…,p_ln,…,p_lN；

(8) acquiring the frequency of a microwave signal to be detected:

(8a) the optical power of the carrier frequency signal obtained in the step (6) is passed

Calculating an empirical value O of a constant in an empirical formula of optical power_nThen N sets of carrier frequency signal optical power

The empirical value of the constant in the corresponding empirical formula of the optical power is O₁,O₂,…,O_n,…,O_NAnd p in step (7f)_lnAnd O_nQuotient of (1)As ratio data Q_lnThen, the data Q is calculated by all the ratio data_1n,Q_2n,…,Q_ln,…,Q_MnCalculating the actual observation vector Y_n：

Y_n＝[Q_1n,Q_2n,…,Q_ln,…,Q_Mn]^T

Wherein [ ·]^TRepresenting a transpose;

(8b) by passing

And

for actual observation vector Y_nRemodeling to obtain an actual observation vector Y 'after noise elimination'_n：

Wherein

Is a sparse representation coefficient vector of (1-p),

a matrix of dimension M × N is represented,

(8c) adopting a formula of convex optimization problem and passing through Y'_nCalculating the microwave signal v to be measured_n(t₂) Frequency f of_n。

2. The method of claim 1, wherein the empirical value O of the constant in the optical power calculation formula in step (8a) is an empirical value O₁,O₂,…,O_n,…,O_NThe calculation formulas are respectively as follows:

wherein, oc represents a direct ratio,

as microwave signals

The angular frequency of (a) of (b),

3. the method for microwave photon-based frequency estimation of multiple microwave signals according to claim 1, wherein the convex optimization problem in step (8c) has the formula:

wherein | · | purple₁Represents 1-norm, | · | non-woven phosphor₂Representing a 2-norm, representing an arbitrarily small number.

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