Method for measuring angles of multiple targets of digital phased array radar

Abstract

The invention discloses a method for measuring multiple target angles of a digital phased array radar, which comprises a receiving system of a radio frequency direct sampling digital phased array radar or an intermediate frequency sampling digital phased array radar or a baseband sampling digital phased array radar, in the receiving system, each antenna unit corresponds to a downlink, and each antenna unit corresponds to an antenna unit. Each downlink comprises an antenna unit, a duplexer, an amplitude limiter, a low-noise amplifier and an analog radio-frequency signal converter which are connected in sequence, and each analog radio-frequency signal converter converts an analog radio-frequency signal output by the low-noise amplifier into a digital baseband complex signal; and calculating a receiving amplitude directional diagram of the phased array by using the digital baseband complex signals corresponding to the plurality of antenna units, and determining a target angle by using the maximum value direction of the receiving amplitude directional diagram. Compared with an existing target angle measurement method, the method can measure multiple target angles at the same time, and has the advantages of being high in angle measurement precision, high in angle measurement speed, high in anti-interference capacity and the like.

Description

Technical Field

[0001] The invention relates to the technical field of target angle measurement of digital phased array radar, and in particular to a method for measuring multiple target angles of a digital phased array radar. Background Art

[0002] Phased array radar can measure information such as target distance, target speed and target angle. The existing target angle measurement methods mainly include phase comparison angle measurement method and amplitude comparison angle measurement method.

[0003] The phase comparison angle measurement method usually uses the phase difference between the received signals of three antenna units to measure the target angle. When the spacing between two antenna units is small, a larger unambiguous angle measurement range can be obtained by using phase detector 1, but the angle measurement accuracy of phase detector 1 is low; when the spacing between two antenna units is large, a higher angle measurement accuracy can be obtained by using phase detector 2 relative to phase detector 1, but the unambiguous angle measurement range of phase detector 2 is small. In engineering, a combination of phase detector 1 and phase detector 2 is usually used to measure the target angle, where phase detector 1 is used to obtain a larger unambiguous angle measurement range, and phase detector 2 is used to obtain a higher angle measurement accuracy than phase detector 1. Nevertheless, the phase comparison angle measurement method usually only uses the phase difference between the received signals of a few antenna units to measure the target angle, so it is impossible to measure multiple target angles at the same time. In addition, the phased array contains a large number of antenna units, and the phase comparison angle measurement method does not make full use of the received signals of many antenna units to measure the target angle. Therefore, the angle measurement accuracy of the phase comparison angle measurement method is low and the anti-interference ability is poor.

[0004] The amplitude comparison angle measurement method requires the phased array antenna to continuously transmit narrow beams to scan the detection space, and measure the target angle by comparing the amplitude values ​​of the received signals of the array antenna. Although the amplitude comparison angle measurement method can measure multiple target angles, its angle measurement speed is slow. Summary of the invention

[0005] The present invention provides a method for measuring multiple target angles of a digital phased array radar, which uses digital baseband complex signals corresponding to multiple antenna units to calculate the receiving amplitude pattern of the phased array, and uses the maximum pointing direction of the receiving amplitude pattern to simultaneously determine multiple target angles, and has the advantages of high angle measurement accuracy, fast angle measurement speed, strong anti-interference ability, etc.

[0006] A method for measuring multiple target angles of a digital phased array radar, the technical solution of which is that the antenna array of the phased array adopts a one-dimensional linear array or a one-dimensional conformal array, in the receiving system of the digital phased array radar, the analog radio frequency signal received by each antenna unit is converted into a corresponding digital baseband complex signal after downlink processing, the digital baseband complex signals corresponding to the multiple antenna units are used to calculate the receiving amplitude pattern of the phased array, and the maximum value direction of the receiving amplitude pattern is used to determine the multiple target angles, which is specifically as follows:

[0007] If the phased array antenna array adopts a one-dimensional linear array, the one-dimensional linear array receiving amplitude pattern |P at the mth moment m The algorithm for (θ) is as follows:

[0008]

[0009] where || represents the modulus of the complex number, represents the digital baseband complex signal corresponding to the nth antenna unit of the one-dimensional linear array, m represents the discrete time independent variable, Obtained by the downlink signal processing corresponding to the nth antenna element of the one-dimensional linear array, Δψ n Represents the phase deviation value of the downlink corresponding to the nth antenna element of the one-dimensional linear array, Δa n represents the amplitude deviation percentage of the downlink corresponding to the nth antenna unit of the one-dimensional linear array, θ represents the angle between the incident direction of the electromagnetic wave and the normal of the one-dimensional linear array, and the value range of θ is -90°≤θ≤90°, N represents the number of antenna units in the one-dimensional linear array, and d represents the spacing between adjacent antenna units in the one-dimensional linear array. The value of d must satisfy In engineering, d is usually selected Nearby values, c represents the speed of light, f 0 represents the carrier frequency of the analog radio frequency signal, e represents the natural exponential symbol, and j represents the imaginary unit;

[0010] Set the threshold value |V|, the value of |V| must satisfy 0.212max(P m (θ))≤|V|<max(P m (θ)), max(P m (θ)) represents |P m (θ) maximum value; use θ i (m) means |P m (θ)-|V|The value of θ corresponding to the i-th maximum value, then θ i (m) is the angle between the ith target and the normal of the one-dimensional linear array at the mth moment;

[0011] Based on formula (1), the angle θ between the i-th target and the normal of the one-dimensional linear array is calculated M times continuously: i(m), m = 1, 2 ... M, M is at least 1, then the angle θ between the i-th target and the normal of the one-dimensional linear array is i The algorithm is as follows:

[0012]

[0013] If the phased array antenna array adopts a one-dimensional conformal array, a virtual one-dimensional linear array is constructed based on the one-dimensional conformal array. At the mth moment, the virtual one-dimensional linear array receives an amplitude pattern |P m The algorithm for (θ) is as follows:

[0014] in represents the digital baseband complex signal corresponding to the nth antenna element of the one-dimensional conformal array, Obtained by the downlink signal processing corresponding to the nth antenna element of the one-dimensional conformal array, Δψ n Represents the phase deviation value of the downlink corresponding to the nth antenna element of the one-dimensional conformal array, Δa n represents the amplitude deviation percentage of the downlink corresponding to the nth antenna unit of the one-dimensional conformal array, θ represents the angle between the incident direction of the electromagnetic wave and the normal of the virtual one-dimensional linear array, and the value range of θ is -90°≤θ≤90°, N represents the number of antenna units of the virtual one-dimensional linear array, and d represents the spacing between adjacent antenna units of the virtual one-dimensional linear array. The value of d must satisfy In engineering, d is usually selected Nearby values, L n represents the distance difference between the nth antenna element of the one-dimensional conformal array and the nth antenna element of the virtual one-dimensional linear array in the θ direction;

[0015] Set the threshold value |V|, the value of |V| must satisfy 0.212max(P m (θ))≤|V|<max(P m (θ)), max(P m (θ)) represents |P m (θ) maximum value; use θ i (m) means |P m (θ)-|V|The value of θ corresponding to the i-th maximum value, then θ i (m) is the angle between the ith target and the normal of the virtual one-dimensional linear array at the mth moment;

[0016] Based on formula (3), the angle θ between the i-th target and the normal line of the virtual one-dimensional linear array is calculated continuously M times: i (m), m = 1, 2 ... M, M is at least 1, then the angle θ between the i-th target and the normal of the virtual one-dimensional linear array is i The algorithm is as follows:

[0017]

[0018] If the antenna array of the phased array adopts a two-dimensional planar array, the two-dimensional planar array is composed of multiple horizontal one-dimensional linear arrays when viewed horizontally, and is composed of multiple vertical one-dimensional linear arrays when viewed vertically; select one of the horizontal one-dimensional linear arrays, and use formula (2) to calculate the angle between the i-th target and the normal of the horizontal one-dimensional linear array; select one of the vertical one-dimensional linear arrays, and use formula (2) to calculate the angle between the i-th target and the normal of the vertical one-dimensional linear array; calculate the spatial angle of the i-th target through the angle between the i-th target and the normal of the horizontal one-dimensional linear array and the angle between the i-th target and the normal of the vertical one-dimensional linear array.

[0019] If the antenna array of the phased array adopts a two-dimensional conformal array, the two-dimensional conformal array is composed of multiple one-dimensional conformal arrays in the horizontal direction and multiple one-dimensional conformal arrays in the vertical direction; one of the one-dimensional conformal arrays is selected to construct a virtual one-dimensional linear array in the horizontal direction, and the angle between the i-th target and the normal of the virtual one-dimensional linear array in the horizontal direction is calculated by formula (4); one of the one-dimensional conformal arrays in the vertical direction is selected to construct a virtual one-dimensional linear array in the vertical direction, and the angle between the i-th target and the normal of the virtual one-dimensional linear array in the vertical direction is calculated by formula (4); the spatial angle of the i-th target is calculated by the angle between the i-th target and the normal of the virtual one-dimensional linear array in the horizontal direction and the angle between the i-th target and the normal of the virtual one-dimensional linear array in the vertical direction.

[0020] If the digital phased array radar adopts a radio frequency direct sampling digital phased array radar, in the receiving system of the radio frequency direct sampling digital phased array radar, each antenna unit corresponds to a downlink, and each downlink includes an antenna unit, a duplexer, a limiter, a low noise amplifier, and an analog radio frequency signal converter connected in sequence. The signal processing method of each downlink is as follows:

[0021] use represents the analog RF signal corresponding to the nth antenna unit, t represents the continuous time independent variable, and cos(2πf 0 t) represents the carrier of the analog radio frequency signal, express The transmitted analog baseband modulated signal is Where R n (t) is The amplitude signal, for The analog-to-digital converter uses the same sampling time interval T in all analog RF signal converters. S , T S The value of must satisfy where f M represents the highest cutoff frequency of the analog radio frequency signal; The digital RF signal obtained by the analog-to-digital converter is n (k) indicates that where k represents the discrete time independent variable; H n (k) and O c (k) The output signal obtained after multiplication by the first digital multiplier is A n (k) indicates that A n (k) The output signal obtained by filtering out the high-frequency signal through the first finite impulse response low-pass filter is expressed as B n (k) indicates that H n (k) and O s (k) The output signal obtained after multiplication by the second digital multiplier is C n (k) indicates that C n (k) The output signal obtained by filtering out the high-frequency signal through the second finite impulse response low-pass filter is D n (k) indicates that Among them, c (k) = 2cos(2πf 0 T S k),

[0022] O s (k) = -2sin(2πf 0 T S k), O c (k) and O s (k) are two mutually orthogonal digital sinusoidal signals generated by a digital sinusoidal signal generator, and the same digital sinusoidal signal generator is used in all analog radio frequency signal converters; the first extractor and the second extractor in all analog radio frequency signal converters use the same extraction interval; B n (k) The digital baseband real signal obtained by the first extractor is used Indicates that D n (k) The digital baseband real signal obtained by the second extractor is used Indicates that Where s is an integer representing the sampling interval of the extractor, and the value of s must satisfy The integer part of f b represents the highest cutoff frequency of the analog baseband modulation signal; and Obtained by digital baseband complex signal synthesizer but The digital baseband complex signal synthesizer synthesizes two digital baseband real signals into one digital baseband complex signal.

[0023] If the digital phased array radar adopts an intermediate frequency sampling digital phased array radar, in the receiving system of the intermediate frequency sampling digital phased array radar, each antenna unit corresponds to a downlink, and each downlink includes an antenna unit, a duplexer, a limiter, a low noise amplifier, and an analog RF signal converter connected in sequence. The signal processing method of each downlink is as follows:

[0024] use represents the analog RF signal corresponding to the nth antenna unit, t represents the continuous time independent variable, and cos(2πf 0 t) represents the carrier of the analog radio frequency signal, express The transmitted analog baseband modulated signal is Where R n (t) is The amplitude signal, for The same analog sine wave generator is used in all analog RF signal converters. The analog sine wave generated by the analog sine wave generator is used Indicates that f 1 represents the frequency of the simulated sine wave; and The output signal obtained after multiplication by the analog multiplier is used express, The analog intermediate frequency signal is obtained by filtering out the high frequency signal through the analog bandpass filter. Indicates that

[0025] where f i =f 0 -f 1 represents the carrier frequency of the analog intermediate frequency signal; the analog-to-digital converters in all analog radio frequency signal converters use the same sampling time interval T s , T s The value of must satisfy where f m represents the highest cutoff frequency of the analog intermediate frequency signal; The digital intermediate frequency signal obtained by the analog-to-digital converter is n (l) indicates that Where l represents the discrete time independent variable; I n (l) and O c (1) The output signal obtained after multiplication by the first digital multiplier is A n (l) means,

[0026] A n (l) The output signal obtained by filtering out the high-frequency signal through the first finite impulse response low-pass filter is expressed as B n (l) indicates that I n (l) and O s (1) The output signal obtained after multiplication by the second digital multiplier is C n (l) indicates that C n (l) The output signal obtained by filtering out the high-frequency signal through the second finite impulse response low-pass filter is D n (l) indicates that Among them, c (l) = 2cos(2πf i T s l),

[0027] O s (l) = -2sin(2πf i T s l), O c (l) and O s (l) two mutually orthogonal digital sinusoidal signals generated by a digital sinusoidal signal generator, and the same digital sinusoidal signal generator is used in all analog radio frequency signal converters; the first extractor and the second extractor in all analog radio frequency signal converters use the same extraction interval; B n (l) The digital baseband real signal obtained by the first extractor is used Indicates that

[0028] D n (l) The digital baseband real signal obtained by the second extractor is used Indicates that Where S is an integer representing the sampling interval of the extractor, and the value of S must satisfy The integer part of f b represents the highest cutoff frequency of the analog baseband modulation signal; and Obtained by digital baseband complex signal synthesizer but

[0029] If the digital phased array radar adopts a baseband sampling digital phased array radar, in the receiving system of the baseband sampling digital phased array radar, each antenna unit corresponds to a downlink, and each downlink includes an antenna unit, a duplexer, a limiter, a low noise amplifier, and an analog RF signal converter connected in sequence. The signal processing method of each downlink is as follows:

[0030] use represents the analog RF signal corresponding to the nth antenna unit, t represents the continuous time independent variable, and cos(2πf 0 t) represents the carrier of the analog radio frequency signal, express The transmitted analog baseband modulated signal is Where R n (t) is The amplitude signal, for phase signal; the same first analog sine wave generator is used in all analog RF signal converters, and the analog sine wave generated by the analog sine wave generator is used Indicates that f 1 represents the frequency of the simulated sine wave; and The output signal obtained after multiplication by the third analog multiplier is used express, The analog intermediate frequency signal is obtained by filtering out the high frequency signal through the analog bandpass filter. Indicates that where f i =f 0 -f 1 A carrier frequency representing the analog intermediate frequency signal; With O c (t) The output signal obtained after multiplication by the first analog multiplier is A n (t) indicates that A n (t) The analog baseband signal obtained by filtering out the high-frequency signal through the first analog low-pass filter is n (t) represents, then With O s (t) The output signal obtained after multiplication by the second analog multiplier is C n (t) indicates that C n (t) The analog baseband signal obtained by filtering out the high-frequency signal through the second analog low-pass filter is D n (t) represents, then Among them, c (t) = 2cos(2πf i t), O s (t) = -2sin(2πf i t), O c (t) and O s(t) are two mutually orthogonal analog sine wave signals generated by the second analog sine wave generator, and the same second analog sine wave generator is used in all analog RF signal converters; the first analog-to-digital converter and the second analog-to-digital converter in all analog RF signal converters use the same sampling time interval T s , T s The value of must satisfy f m represents the highest cutoff frequency of the analog baseband modulation signal; B n (t) The digital baseband real signal obtained by the first analog-to-digital converter is used Indicates that D n (t) The digital baseband real signal obtained by the second analog-to-digital converter is used Indicates that and Obtained by digital baseband complex signal synthesizer but

[0031] Beneficial effects of the method for measuring multiple target angles of the digital phased array radar:

[0032] 1. Compared with the phase comparison angle measurement method, the method effectively utilizes the digital baseband complex signals corresponding to all antenna units of a one-dimensional linear array or a one-dimensional conformal array, can calculate multiple target angles at the same time, and has the advantages of high angle measurement accuracy and strong anti-interference ability.

[0033] 2. Compared with the amplitude ratio angle measurement method, the method does not require the phased array antenna to perform beam scanning on the detection space, and has the advantage of fast angle measurement speed.

[0034] 3. In practical applications, due to the consistency differences in signal processing of each downlink, all digital phased array radars must be calibrated and measured for the downlink before leaving the factory to obtain the phase deviation value and amplitude deviation percentage of the downlink corresponding to each antenna unit. The algorithms of formula (1) and formula (3) effectively utilize the phase deviation value and amplitude deviation percentage of the downlink corresponding to each antenna unit, eliminating the influence of the above consistency differences on the received amplitude pattern. Therefore, the multiple target angles calculated based on formula (1) and formula (3) are more accurate.

[0035] 4. The method is not only applicable to radars transmitting single-frequency RF signals to detect multiple target angles, but is also applicable to radars transmitting various modulated signals (such as spread spectrum signals, frequency hopping signals, etc.) to detect multiple target angles. Note: Radars transmitting spread spectrum signals can greatly reduce the possibility of their own radar signals being detected by the enemy, and radars transmitting frequency hopping signals can greatly reduce the possibility of their own radar signals being locked by the enemy.

[0036] 5. The method is not only applicable to detecting the target angle by actively transmitting a signal from a radar, but can also detect the target angle by utilizing the transmitting signal from a target radar (such as a radar on a target aircraft), and by utilizing other reflected waves from the target (such as when the target is irradiated by other electromagnetic waves).

[0037] An analog radio frequency signal converter for a radio frequency direct sampling digital phased array comprises an analog-to-digital converter, a digital sinusoidal signal generator, a first digital multiplier, a first finite impulse response low-pass filter, a first extractor, a second digital multiplier, a second finite impulse response low-pass filter, a second extractor, and a digital baseband complex signal synthesizer. The same digital sinusoidal signal generator is used in all analog radio frequency signal converters. The input end of the analog-to-digital converter is connected to the analog radio frequency signal, and the output end of the analog-to-digital converter is connected to an input end of the first digital multiplier and an input end of the second digital multiplier. The digital sinusoidal signal generator generates two mutually orthogonal digital sinusoidal signals, one of which is connected to the other input end of the first digital multiplier, and the other is connected to the other input end of the second digital multiplier. The output end of the first digital multiplier is sequentially connected to the first finite impulse response low-pass filter and the first extractor, and the output end of the second digital multiplier is sequentially connected to the second finite impulse response low-pass filter and the second extractor. The output signal of the first extractor and the output signal of the second extractor are used to obtain a digital baseband complex signal through the digital baseband complex signal synthesizer.

[0038] The beneficial effects of the analog RF signal converter of the RF direct sampling digital phased array are as follows: the analog RF signal converter directly samples the analog RF signal, and the entire system adopts fully digital signal processing technology, which is conducive to improving the integration, stability and reliability of the RF direct sampling digital phased array.

[0039] An analog radio frequency signal converter for an intermediate frequency sampling digital phased array comprises an analog multiplier, an analog sine wave generator, an analog bandpass filter, an analog-to-digital converter, a digital sine signal generator, a first digital multiplier, a first finite impulse response low-pass filter, a first extractor, a second digital multiplier, a second finite impulse response low-pass filter, a second extractor, and a digital baseband complex signal synthesizer. The same analog sine wave generator and the same digital sine signal generator are used in all analog radio frequency signal converters. One input end of the analog multiplier is connected to the analog radio frequency signal, and the other input end is connected to the output end of the analog sine wave generator. The output end of the analog multiplier is connected to the analog band signal generator in sequence. A digital baseband complex signal generator is provided for generating two orthogonal digital sinusoidal signals, one of which is connected to the other input end of the first digital multiplier and the other is connected to the other input end of the second digital multiplier. The output end of the first digital multiplier is connected to the first finite impulse response low-pass filter and the first extractor in sequence, and the output end of the second digital multiplier is connected to the second finite impulse response low-pass filter and the second extractor in sequence. The output signal of the first extractor and the output signal of the second extractor are connected to obtain a digital baseband complex signal through a digital baseband complex signal synthesizer.

[0040] The beneficial effects of the analog RF signal converter of the intermediate frequency sampling digital phased array are as follows: the analog RF signal converter converts the analog RF signal into an analog intermediate frequency signal, which is easy to implement in the analog intermediate frequency signal sampling engineering, and the data transmission rate of the digital intermediate frequency signal is low, and the subsequent digital signal processing is easy to implement.

[0041] An analog radio frequency signal converter for a baseband sampling digital phased array comprises a third analog multiplier, a first analog sine wave generator, an analog bandpass filter, a second analog sine wave generator, a first analog multiplier, a first analog low-pass filter, a first analog-to-digital converter, a second analog multiplier, a second analog low-pass filter, a second analog-to-digital converter, and a digital baseband complex signal synthesizer. The same first analog sine wave generator and the same second analog sine wave generator are used in all analog radio frequency signal converters. One input end of the third analog multiplier is connected to an analog radio frequency signal, and the other input end is connected to an output end of the first analog sine wave generator. The output end of the third analog multiplier is connected to the analog band The analog bandpass filter is connected to the input end of the analog bandpass filter, the output end of the analog bandpass filter is connected to an input end of the first analog multiplier and an input end of the second analog multiplier, the second analog sine wave generator generates two mutually orthogonal sine waves, one of which is connected to the other input end of the first analog multiplier, and the other is connected to the other input end of the second analog multiplier, the output end of the first analog multiplier is connected to the first analog low-pass filter and the first analog-to-digital converter in sequence, the output end of the second analog multiplier is connected to the second analog low-pass filter and the second analog-to-digital converter in sequence, and the output signal of the first analog-to-digital converter and the output signal of the second analog-to-digital converter are connected to obtain a digital baseband complex signal through a digital baseband complex signal synthesizer.

[0042] The beneficial effects of the analog RF signal converter of the baseband sampling digital phased array are as follows: the analog RF signal converter converts the analog RF signal into an analog intermediate frequency signal, and then converts the analog intermediate frequency signal into an analog baseband signal, which makes it easier to implement the analog baseband signal sampling engineering, and the data transmission rate of the digital baseband signal is lower, and the subsequent digital signal processing is easier to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 Analog RF signal converter of RF direct sampling digital phased array radar and its signal processing flow chart;

[0045] Figure 2 Analog RF signal converter of intermediate frequency sampling digital phased array radar and its signal processing flow chart;

[0046] Figure 3 Analog RF signal converter of baseband sampling digital phased array radar and its signal processing flow chart;

[0047] Figure 4 Schematic diagram of the structure of a one-dimensional linear array. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings in the present invention. The following description is only a partial embodiment of the present invention, not all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present invention.

[0049] A method for measuring multiple target angles of a digital phased array radar, the technical solution of which is that the antenna array of the phased array adopts a one-dimensional linear array or a one-dimensional conformal array, referring to Figure 1-3 In the receiving system of the digital phased array radar, the analog RF signal received by each antenna unit is converted into a corresponding digital baseband complex signal after downlink processing. The digital baseband complex signals corresponding to multiple antenna units are used to calculate the receiving amplitude pattern of the phased array, and the maximum value pointing of the receiving amplitude pattern is used to determine multiple target angles, which are as follows:

[0050] If the phased array antenna array adopts a one-dimensional linear array, refer to Figure 4 , the algorithm for the one-dimensional linear array receiving amplitude pattern at the mth moment is as follows:

[0051]

[0052] Where |P m (θ)| represents the one-dimensional linear array receiving amplitude pattern at the mth moment, || represents the modulus of the complex number, represents the digital baseband complex signal corresponding to the nth antenna unit of the one-dimensional linear array, m is an integer representing the discrete time independent variable, It is obtained by processing the downlink signal corresponding to the nth antenna unit of the one-dimensional linear array. θ represents the angle between the incident direction of the electromagnetic wave and the normal of the one-dimensional linear array. The value range of θ is -90°≤θ≤90°. N represents the number of antenna units in the one-dimensional linear array. d represents the spacing between adjacent antenna units in the one-dimensional linear array. c represents the speed of light. f 0 represents the carrier frequency of the analog RF signal, e represents the natural exponential symbol, j represents the imaginary unit, Δψ n Represents the phase deviation value of the downlink corresponding to the nth antenna element of the one-dimensional linear array, Δa n Represents the amplitude deviation percentage of the downlink corresponding to the nth antenna element of the one-dimensional linear array, Δψ n , Δa nThe value of is obtained during the downlink calibration of the digital phased array radar; (Note: All digital phased array radars must be calibrated and measured for the phase deviation and amplitude deviation percentage of each downlink before leaving the factory)

[0053] In order to prevent grating lobes from appearing in the one-dimensional linear array receiving pattern, the value of d must satisfy In engineering, d is usually selected Nearby values, in this case, |P m (θ)-|V| is a function with a maximum value, where |V| represents the threshold value, and the value of |V| must satisfy 0.212max(P m (θ))≤|V|<max(P m (θ)), max(P m (θ)) represents |P m (θ) maximum value; use θ i (m) means |P m (θ)-|V|The value of θ corresponding to the i-th maximum value, then θ i (m) is the angle between the ith target and the normal of the one-dimensional linear array at the mth moment;

[0054] Formula (1) can be used to calculate the angle θ between the i-th target and the normal of the one-dimensional linear array at any time: i (m), m = 1, 2…M, where M represents the number of calculations, and the value of M is at least 1; since the target's moving angle is very small in a short time, M times θ is calculated continuously in a short time i (m), m = 1, 2…M, then the angle between the i-th target and the normal of the one-dimensional linear array is calculated as follows:

[0055]

[0056] where θ i Represents the angle between the ith target and the normal of the one-dimensional linear array.

[0057] If the antenna array of the phased array adopts a one-dimensional conformal array, a virtual one-dimensional linear array is constructed based on the one-dimensional conformal array, and the algorithm for receiving the amplitude pattern of the virtual one-dimensional linear array at the mth moment is as follows:

[0058]

[0059] Where |P m (θ) represents the amplitude pattern of the virtual one-dimensional linear array received at the mth moment, represents the digital baseband complex signal corresponding to the nth antenna element of the one-dimensional conformal array, Obtained by the downlink signal processing corresponding to the nth antenna element of the one-dimensional conformal array, Δψ nRepresents the phase deviation value of the downlink corresponding to the nth antenna element of the one-dimensional conformal array, Δa n represents the amplitude deviation percentage of the downlink corresponding to the nth antenna element of the one-dimensional conformal array, Δψ n , Δa n The value of is obtained during the downlink calibration of the digital phased array radar, θ represents the angle between the incident direction of the electromagnetic wave and the normal of the virtual one-dimensional linear array, the value range of θ is -90°≤θ≤90°, N represents the number of antenna units of the virtual one-dimensional linear array, d represents the spacing between adjacent antenna units of the virtual one-dimensional linear array, and L n represents the distance difference between the nth antenna element of the one-dimensional conformal array and the nth antenna element of the virtual one-dimensional linear array in the θ direction;

[0060] In order to prevent the appearance of grating lobes in the receiving pattern of the virtual one-dimensional linear array, the value of d must satisfy In engineering, d is usually selected Nearby values, in this case, |P m (θ)-|V| is a function with a maximum value, where |V represents the threshold value, and the value of |V| must satisfy 0.212max(P m (θ))≤|V|<max(P m (θ)), max(P m (θ)) represents |P m (θ) maximum value; use θ i (m) means |P m (θ)-|V|The value of θ corresponding to the i-th maximum value, then θ i (m) is the angle between the ith target and the normal of the virtual one-dimensional linear array at the mth moment;

[0061] Formula (3) can be used to calculate the angle θ between the i-th target and the normal line of the virtual one-dimensional linear array at any time: i (m), m = 1, 2…M, where M represents the number of calculations, and the value of M is at least 1; since the target's moving angle is very small in a short time, M times θ is calculated continuously in a short time i (m), m = 1, 2…M, then the angle between the i-th target and the normal of the virtual one-dimensional linear array is calculated as follows:

[0062]

[0063] where θ i Represents the angle between the ith target and the normal of the virtual one-dimensional linear array.

[0064] If the antenna array of the phased array adopts a two-dimensional planar array, the two-dimensional planar array is composed of multiple horizontal one-dimensional linear arrays when viewed horizontally, and is composed of multiple vertical one-dimensional linear arrays when viewed vertically; select one of the horizontal one-dimensional linear arrays, and use formula (2) to calculate the angle between the i-th target and the normal of the horizontal one-dimensional linear array; select one of the vertical one-dimensional linear arrays, and use formula (2) to calculate the angle between the i-th target and the normal of the vertical one-dimensional linear array; calculate the spatial angle of the i-th target through the angle between the i-th target and the normal of the horizontal one-dimensional linear array and the angle between the i-th target and the normal of the vertical one-dimensional linear array.

[0065] If the antenna array of the phased array adopts a two-dimensional conformal array, the two-dimensional conformal array is composed of multiple one-dimensional conformal arrays in the horizontal direction and multiple one-dimensional conformal arrays in the vertical direction; one of the one-dimensional conformal arrays is selected to construct a virtual one-dimensional linear array in the horizontal direction, and the angle between the i-th target and the normal of the virtual one-dimensional linear array in the horizontal direction is calculated by formula (4); one of the one-dimensional conformal arrays in the vertical direction is selected to construct a virtual one-dimensional linear array in the vertical direction, and the angle between the i-th target and the normal of the virtual one-dimensional linear array in the vertical direction is calculated by formula (4); the spatial angle of the i-th target is calculated by the angle between the i-th target and the normal of the virtual one-dimensional linear array in the horizontal direction and the angle between the i-th target and the normal of the virtual one-dimensional linear array in the vertical direction.

[0066] If the digital phased array radar adopts a radio frequency direct sampling digital phased array radar, refer to Figure 1 In the receiving system of the RF direct sampling digital phased array radar, each antenna unit corresponds to a downlink, and each downlink includes an antenna unit, a duplexer, a limiter, a low noise amplifier, and an analog RF signal converter connected in sequence. The signal processing method of each downlink is as follows:

[0067] n represents the serial number of antenna elements in the one-dimensional linear array or the one-dimensional conformal array, and represents the analog RF signal corresponding to the nth antenna unit, t represents the continuous time independent variable, without loss of generality, cos(2πf 0 t) represents the carrier of the analog radio frequency signal, express The transmitted analog baseband modulated signal is Where R n (t) is The amplitude signal, for The analog-to-digital converter uses the same sampling time interval T in all analog RF signal converters. S , T S The value of must satisfy where f M represents the highest cutoff frequency of the analog radio frequency signal; The digital RF signal obtained by the analog-to-digital converter is n (k) indicates that Where k is an integer representing a discrete time independent variable; H n (k) and O c (k) The output signal obtained after multiplication by the first digital multiplier is A n (k) indicates that A n (k) The high-frequency signal is filtered out by the first finite impulse response (FIR) low-pass filter (LPF)

[0068] The output signal is obtained by B n (k) indicates that

[0069] H n (k) and O s (k) The output signal obtained after multiplication by the second digital multiplier is C n (k) indicates that C n (k) The high-frequency signal is filtered out by the second FIR LPF The output signal obtained is D n (k) indicates that Among them, c (k) and O s (k) are two mutually orthogonal digital sinusoidal signals generated by a digital sinusoidal signal generator, and the same digital sinusoidal signal generator is used in all analog RF signal converters, without loss of generality, c (k) = 2cos(2πf 0 T S k), O s (k) = -2sin(2πf 0 T S k); the first decimator and the second decimator use the same decimation interval in all analog RF signal converters; B n (k) The digital baseband real signal obtained by the first extractor is used Indicates that D n (k) The digital baseband real signal obtained by the second extractor is used Indicates that

[0070] Where s is an integer representing the sampling interval of the extractor, and the value of s must satisfy The integer part of f brepresents the highest cutoff frequency of the analog baseband modulation signal; and Obtained by digital baseband complex signal synthesizer but

[0071] The digital baseband complex signal synthesizer synthesizes two digital baseband real signals into one digital baseband complex signal. is the digital baseband complex signal corresponding to the nth antenna element, The amplitude signal yes The sampling signal of the amplitude signal Rn(t), The phase signal yes The phase signal The sampling signal.

[0072] If the digital phased array radar adopts an intermediate frequency sampling digital phased array radar, refer to Figure 2 In the receiving system of the intermediate frequency sampling digital phased array radar, each antenna unit corresponds to a downlink, and each downlink includes an antenna unit, a duplexer, a limiter, a low noise amplifier, and an analog RF signal converter connected in sequence. The signal processing method of each downlink is as follows:

[0073] n represents the serial number of antenna elements in the one-dimensional linear array or the one-dimensional conformal array, and represents the analog RF signal corresponding to the nth antenna unit, t represents the continuous time independent variable, without loss of generality, cos(2πf 0 t) represents the carrier of the analog radio frequency signal, express The transmitted analog baseband modulated signal is Where R n (t) is The amplitude signal, for phase signal; the same analog sine wave generator is used in all analog RF signal converters. Without loss of generality, the analog sine wave generated by the analog sine wave generator is used Indicates that f 1 represents the frequency of the simulated sine wave; and The output signal obtained after multiplication by the analog multiplier is used Indicates that The high frequency signal is filtered out by an analog bandpass filter (BPF) The obtained analog intermediate frequency signal is used Indicates that where f i =f 0 -f 1 represents the carrier frequency of the analog intermediate frequency signal; the analog-to-digital converters in all analog radio frequency signal converters use the same sampling time interval T s , T s The value of must satisfy where f m represents the highest cutoff frequency of the analog intermediate frequency signal; The digital intermediate frequency signal obtained by the analog-to-digital converter is n (l) indicates that Where l is an integer representing a discrete time independent variable; I n (l) and O c (1) The output signal obtained after multiplication by the first digital multiplier is A n (l) indicates that A n (l) The high-frequency signal is filtered out by the first finite impulse response (FIR) low-pass filter (LPF) The output signal is obtained by B n (l) indicates that I n (l) and O s (1) The output signal obtained after multiplication by the second digital multiplier is C n (l) indicates that C n (l) The high-frequency signal is filtered out by the second FIR LPF The output signal obtained is D n (l) indicates that Among them, c (l) and O s (l) are two mutually orthogonal digital sinusoidal signals generated by a digital sinusoidal signal generator, and the same digital sinusoidal signal generator is used in all analog RF signal converters, without loss of generality, c (l) = 2cos(2πf i T s l), O s (l) = -2sin(2πf i T s l); the first decimator and the second decimator use the same decimation interval in all analog RF signal converters; B n (l) The digital baseband real signal obtained by the first extractor is used Indicates that D n (l) The digital baseband real signal obtained by the second extractor is used Indicates that Where S is an integer representing the sampling interval of the extractor, and the value of S must satisfy The integer part of f b represents the highest cutoff frequency of the analog baseband modulation signal; and Obtained by digital baseband complex signal synthesizer but in is the digital baseband complex signal corresponding to the nth antenna element, The amplitude signal yes The amplitude signal R n (t) is the sampling signal, The phase signal yes The phase signal The sampling signal.

[0074] If the digital phased array radar adopts a baseband sampling digital phased array radar, refer to Figure 3 In the receiving system of the baseband sampling digital phased array radar, each antenna unit corresponds to a downlink, and each downlink includes an antenna unit, a duplexer, a limiter, a low noise amplifier, and an analog RF signal converter connected in sequence. The signal processing method of each downlink is as follows:

[0075] n represents the serial number of antenna elements in the one-dimensional linear array or the one-dimensional conformal array, and represents the analog RF signal corresponding to the nth antenna unit, t represents the continuous time independent variable, without loss of generality, cos(2πf 0 t) represents the carrier of the analog radio frequency signal, express The transmitted analog baseband modulated signal is Where R n (t) is The amplitude signal, for phase signal; in all analog RF signal converters, the same first analog sine wave generator is used, without loss of generality, the analog sine wave generated by the analog sine wave generator is used Indicates that f 1 represents the frequency of the simulated sine wave; and The output signal obtained after multiplication by the third analog multiplier is used Indicates that The high frequency signal is filtered out by an analog bandpass filter (BPF) The obtained analog intermediate frequency signal is used Indicates that where f i =f 0 -f 1 A carrier frequency representing the analog intermediate frequency signal; With O c (t) The output signal obtained after multiplication by the first analog multiplier is A n (t) represents, then A n (t) The high-frequency signal is filtered out by the first analog low-pass filter (LPF) The analog baseband signal obtained is expressed as B n (t) represents, then With O s (t) The output signal obtained after multiplication by the second analog multiplier is C n (t) represents, then C n (t) The high-frequency signal is filtered out by the second analog LPF The analog baseband signal obtained is D n (t) represents, then

[0076] Among them, c (t) and O s (t) are two mutually orthogonal analog sine wave signals generated by the second analog sine wave generator, and the same second analog sine wave generator is used in all analog RF signal converters, without loss of generality, c (t) = 2cos(2πf i t), O s (t) = -2sin(2πf i t); the first analog-to-digital converter and the second analog-to-digital converter in all analog RF signal converters use the same sampling time interval T s , T s The value of must satisfy f m represents the highest cutoff frequency of the analog baseband modulation signal; B n (t) The digital baseband real signal obtained by the first analog-to-digital converter is used Indicates that Dn(t) is the digital baseband real signal obtained by the second analog-to-digital converter. Indicates that and Obtained by digital baseband complex signal synthesizer but in is the digital baseband complex signal corresponding to the nth antenna element, The amplitude signal yes The sampling signal of the amplitude signal Rn(t), The phase signal yes The phase signal The sampling signal.

[0077] An analog RF signal converter for RF direct sampling digital phased array, referring to Figure 1 , including an analog-to-digital converter, a digital sinusoidal signal generator, a first digital multiplier, a first FIR LPF, a first extractor, a second digital multiplier, a second FIR LPF, a second extractor, and a digital baseband complex signal synthesizer. The same digital sinusoidal signal generator is used in all analog-to-radio frequency signal converters. The input end of the analog-to-digital converter is connected to the analog radio frequency signal, and the output end of the analog-to-digital converter is connected to an input end of the first digital multiplier and an input end of the second digital multiplier. The digital sinusoidal signal generator generates two mutually orthogonal digital sinusoidal signals, one of which is connected to the other input end of the first digital multiplier, and the other is connected to the other input end of the second digital multiplier. The output end of the first digital multiplier is connected to the first FIR LPF and the first extractor in sequence, and the output end of the second digital multiplier is connected to the second FIR LPF and the second extractor in sequence. The output signal of the first extractor and the output signal of the second extractor are passed through the digital baseband complex signal synthesizer to obtain a digital baseband complex signal.

[0078] An analog RF signal converter for an intermediate frequency sampling digital phased array, referring to Figure 2, including an analog multiplier, an analog sine wave generator, an analog BPF, an analog-to-digital converter, a digital sine signal generator, a first digital multiplier, a first FIRLPF, a first extractor, a second digital multiplier, a second FIR LPF, a second extractor, and a digital baseband complex signal synthesizer. The same analog sine wave generator and the same digital sine signal generator are used in all analog RF signal converters. One input end of the analog multiplier is connected to the analog RF signal, and the other input end is connected to the output end of the analog sine wave generator. The output end of the analog multiplier is connected to the analog BPF and the analog-to-digital converter in sequence. The output end of the analog-to-digital converter is connected to an input end of the first digital multiplier and an input end of the second digital multiplier. The digital sine signal generator generates two mutually orthogonal digital sine signals, one of which is connected to the other input end of the first digital multiplier, and the other is connected to the other input end of the second digital multiplier. The output end of the first digital multiplier is connected to the first FIRLPF and the first extractor in sequence, and the output end of the second digital multiplier is connected to the second FIR LPF, the second extractor, the output signal of the first extractor and the output signal of the second extractor are synthesized by a digital baseband complex signal to obtain a digital baseband complex signal.

[0079] A baseband sampling digital phased array analog RF signal converter, referring to Figure 3 , including a third analog multiplier, a first analog sine wave generator, an analog BPF, a second analog sine wave generator, a first analog multiplier, a first analog LPF, a first analog-to-digital converter, a second analog multiplier, a second analog LPF, a second analog-to-digital converter, and a digital baseband complex signal synthesizer, wherein the same first analog sine wave generator and the same second analog sine wave generator are used in all analog RF signal converters, one input end of the third analog multiplier is connected to the analog RF signal, and the other input end is connected to the output end of the first analog sine wave generator, and the output end of the third analog multiplier is connected to the input end of the analog BPF, The output end of the analog BPF is connected to an input end of the first analog multiplier and an input end of the second analog multiplier. The second analog sine wave generator generates two mutually orthogonal sine waves, one of which is connected to the other input end of the first analog multiplier, and the other is connected to the other input end of the second analog multiplier. The output end of the first analog multiplier is connected to the first analog LPF and the first analog-to-digital converter in sequence, and the output end of the second analog multiplier is connected to the second analog LPF and the second analog-to-digital converter in sequence. The output signal of the first analog-to-digital converter and the output signal of the second analog-to-digital converter are used to obtain a digital baseband complex signal through a digital baseband complex signal synthesizer.

[0080] The above embodiments specifically illustrate the contents of the present invention, but the present invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the concept of the present invention, and these equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A method for measuring multiple target angles of a digital phased array radar, characterized in that: The antenna array of the phased array adopts a one-dimensional linear array or a one-dimensional conformal array. In the receiving system of the digital phased array radar, the analog RF signal received by each antenna unit is converted into a corresponding digital baseband complex signal after downlink processing. The digital baseband complex signals corresponding to multiple antenna units are used to calculate the receiving amplitude pattern of the phased array, and the maximum value pointing of the receiving amplitude pattern is used to determine multiple target angles. The details are as follows: When the phased array antenna array adopts a one-dimensional linear array, the one-dimensional linear array receiving amplitude pattern |P at the mth moment m The algorithm for (θ) is as follows: When the phased array antenna array adopts a one-dimensional conformal array, a virtual one-dimensional linear array is constructed based on the one-dimensional conformal array. The receiving amplitude pattern of the virtual one-dimensional linear array at the mth moment |P m The algorithm for (θ) is as follows: where || represents the modulus of the complex number, represents the digital baseband complex signal corresponding to the nth antenna element of a one-dimensional linear array or a one-dimensional conformal array, m represents the discrete time independent variable, Obtained by the downlink signal processing corresponding to the nth antenna element of a one-dimensional linear array or a one-dimensional conformal array, Δψ n Represents the phase deviation value of the downlink corresponding to the nth antenna element of a one-dimensional linear array or a one-dimensional conformal array, Δa n represents the amplitude deviation percentage of the downlink corresponding to the nth antenna unit of the one-dimensional linear array or one-dimensional conformal array, θ represents the angle between the incident direction of the electromagnetic wave and the normal of the one-dimensional linear array or the virtual one-dimensional linear array, and the value range of θ is -90°≤θ≤90°, N represents the number of antenna units of the one-dimensional linear array or the virtual one-dimensional linear array, d represents the spacing between adjacent antenna units of the one-dimensional linear array or the virtual one-dimensional linear array, and the value of d must satisfy c represents the speed of light, f0 represents the carrier frequency of the analog radio frequency signal, e represents the natural exponential symbol, j represents the imaginary unit, L n represents the distance difference between the nth antenna element of the one-dimensional conformal array and the nth antenna element of the virtual one-dimensional linear array in the θ direction; Set the threshold value |V|, the value of |V| must satisfy 0.212max(P m (θ))≤|V|<max(P m (θ)), max(P m (θ)) represents |P m (θ) maximum value; use θ i (m) means |P m (θ)-|V|The value of θ corresponding to the i-th maximum value, then θ i (m) is the angle between the ith target and the normal of the one-dimensional linear array or virtual one-dimensional linear array at the mth moment; Based on formula (1) or formula (3), the angle θ between the i-th target and the normal line of the one-dimensional linear array or virtual one-dimensional linear array is calculated continuously M times: i (m), m = 1, 2…M, then the angle θ between the i-th target and the normal of the one-dimensional linear array or virtual one-dimensional linear array is i The algorithm is as follows:

2. The method for measuring multiple target angles of a digital phased array radar according to claim 1, characterized in that: The antenna array of the phased array adopts a two-dimensional planar array, which is composed of multiple horizontal one-dimensional linear arrays when viewed horizontally and multiple vertical one-dimensional linear arrays when viewed vertically; one of the horizontal one-dimensional linear arrays is selected, and the angle between the i-th target and the normal of the horizontal one-dimensional linear array is calculated using formula (A); one of the vertical one-dimensional linear arrays is selected, and the angle between the i-th target and the normal of the vertical one-dimensional linear array is calculated using formula (A); the spatial angle of the i-th target is calculated by the angle between the i-th target and the normal of the horizontal one-dimensional linear array and the angle between the i-th target and the normal of the vertical one-dimensional linear array.

3. The method for measuring multiple target angles of a digital phased array radar according to claim 1, characterized in that: The antenna array of the phased array adopts a two-dimensional conformal array, which is composed of multiple one-dimensional conformal arrays in the horizontal direction and multiple one-dimensional conformal arrays in the vertical direction; one of the one-dimensional conformal arrays is selected to construct a virtual one-dimensional linear array, and the angle between the i-th target and the normal of the virtual one-dimensional linear array is calculated by using formula (A); Select one of the longitudinal one-dimensional conformal arrays to construct a longitudinal virtual one-dimensional linear array, and use formula (A) to calculate the angle between the ith target and the normal of the longitudinal virtual one-dimensional linear array; calculate the spatial angle of the ith target by the angle between the ith target and the normal of the transverse virtual one-dimensional linear array and the angle between the ith target and the normal of the longitudinal virtual one-dimensional linear array.

4. The method for measuring multiple target angles of a digital phased array radar according to any one of claims 1 to 3, characterized in that: The digital phased array radar adopts a radio frequency direct sampling digital phased array radar. In the receiving system of the radio frequency direct sampling digital phased array radar, each antenna unit corresponds to a downlink, and each downlink includes an antenna unit, a duplexer, a limiter, a low noise amplifier, and an analog radio frequency signal converter connected in sequence. The signal processing method of each downlink is as follows: represents the analog radio frequency signal corresponding to the nth antenna unit, t represents the continuous time independent variable, cos(2πf0t) represents the carrier of the analog radio frequency signal, and express The transmitted analog baseband modulated signal is The analog-to-digital converter uses the same sampling time interval T in all analog RF signal converters. S , T S The value of must satisfy where f M represents the highest cutoff frequency of the analog radio frequency signal; The digital RF signal obtained by the analog-to-digital converter is n (k) indicates that where k represents the discrete time independent variable; H n (k) and O c (k) The output signal obtained after multiplication by the first digital multiplier is A n (k) indicates that A n (k) The output signal obtained by filtering out the high-frequency signal through the first finite impulse response low-pass filter is expressed as B n (k) indicates that H n (k) and O s (k) The output signal obtained after multiplication by the second digital multiplier is C n (k) indicates that C n (k) The output signal obtained by filtering out the high-frequency signal through the second finite impulse response low-pass filter is D n (k) indicates that Among them, c (k) = 2cos(2πf0T S k), O s (k) = -2sin(2πf0T S k), O c (k) and O s (k) are two mutually orthogonal digital sinusoidal signals generated by a digital sinusoidal signal generator, and the same digital sinusoidal signal generator is used in all analog radio frequency signal converters; the first extractor and the second extractor in all analog radio frequency signal converters use the same extraction interval; B n (k) The digital baseband real signal obtained by the first extractor is used Indicates that D n (k) The digital baseband real signal obtained by the second extractor is used Indicates that Where s is an integer representing the sampling interval of the extractor, and the value of s must satisfy The integer part of f b represents the highest cutoff frequency of the analog baseband modulation signal; and Obtained by digital baseband complex signal synthesizer but 5. The method for measuring multiple target angles of a digital phased array radar according to any one of claims 1 to 3, characterized in that: The digital phased array radar adopts an intermediate frequency sampling digital phased array radar. In the receiving system of the intermediate frequency sampling digital phased array radar, each antenna unit corresponds to a downlink, and each downlink includes an antenna unit, a duplexer, a limiter, a low noise amplifier, and an analog RF signal converter connected in sequence. The signal processing method of each downlink is as follows: represents the analog radio frequency signal corresponding to the nth antenna unit, t represents the continuous time independent variable, cos(2πf0t) represents the carrier of the analog radio frequency signal, and express The transmitted analog baseband modulated signal is The same analog sine wave generator is used in all analog RF signal converters. The analog sine wave generated by the analog sine wave generator is used to Represents, wherein f1 represents the frequency of the simulated sine wave; and The output signal obtained after multiplication by the analog multiplier is used express, The analog intermediate frequency signal is obtained by filtering out the high frequency signal through the analog bandpass filter. Indicates that where f i =f0-f1 represents the carrier frequency of the analog intermediate frequency signal; the analog-to-digital converters in all analog radio frequency signal converters use the same sampling time interval T s , T s The value of must satisfy where f m represents the highest cutoff frequency of the analog intermediate frequency signal; The digital intermediate frequency signal obtained by the analog-to-digital converter is n (l) indicates that Where l represents the discrete time independent variable; I n (l) and O c (1) The output signal obtained after multiplication by the first digital multiplier is A n (l) indicates that A n (l) The output signal obtained by filtering out the high-frequency signal through the first finite impulse response low-pass filter is expressed as B n (l) indicates that I n (l) and O s (1) The output signal obtained after multiplication by the second digital multiplier is C n (l) indicates that C n (l) The output signal obtained by filtering out the high-frequency signal through the second finite impulse response low-pass filter is D n (l) indicates that Among them, c (l) = 2cos(2πf i T s l), O s (l) = -2sin(2πf i T s l), O c (l) and O s (l) two mutually orthogonal digital sinusoidal signals generated by a digital sinusoidal signal generator, and the same digital sinusoidal signal generator is used in all analog radio frequency signal converters; the first extractor and the second extractor in all analog radio frequency signal converters use the same extraction interval; B n (l) The digital baseband real signal obtained by the first extractor is used Indicates that D n (l) The digital baseband real signal obtained by the second extractor is used Indicates that Where S is an integer representing the sampling interval of the extractor, and the value of S must satisfy The integer part of f b represents the highest cutoff frequency of the analog baseband modulation signal; and Obtained by digital baseband complex signal synthesizer but 6. The method for measuring multiple target angles of a digital phased array radar according to any one of claims 1 to 3, characterized in that: The digital phased array radar adopts a baseband sampling digital phased array radar. In the receiving system of the baseband sampling digital phased array radar, each antenna unit corresponds to a downlink, and each downlink includes an antenna unit, a duplexer, a limiter, a low noise amplifier, and an analog RF signal converter connected in sequence. The signal processing method of each downlink is as follows: represents the analog radio frequency signal corresponding to the nth antenna unit, t represents the continuous time independent variable, cos(2πf0t) represents the carrier of the analog radio frequency signal, and express The transmitted analog baseband modulated signal is The same first analog sine wave generator is used in all analog RF signal converters. The analog sine wave generated by the analog sine wave generator is used to generate a Represents, wherein f1 represents the frequency of the simulated sine wave; and The output signal obtained after multiplication by the third analog multiplier is used express, The analog intermediate frequency signal is obtained by filtering out the high frequency signal through the analog bandpass filter. Indicates that where f i =f0-f1 represents the carrier frequency of the analog intermediate frequency signal; With O c (t) The output signal obtained after multiplication by the first analog multiplier is A n (t) indicates that A n (t) The analog baseband signal obtained by filtering out the high-frequency signal through the first analog low-pass filter is n (t) represents, then With O s (t) The output signal obtained after multiplication by the second analog multiplier is C n (t) indicates that C n (t) The analog baseband signal obtained by filtering out the high-frequency signal through the second analog low-pass filter is D n (t) represents, then Among them, c (t) = 2cos(2πf i t), O s (t) = -2sin(2πf i t), O c (t) and O s (t) are two mutually orthogonal analog sine wave signals generated by the second analog sine wave generator, and the same second analog sine wave generator is used in all analog RF signal converters; the first analog-to-digital converter and the second analog-to-digital converter in all analog RF signal converters use the same sampling time interval T s , T s The value of must satisfy f m represents the highest cutoff frequency of the analog baseband modulation signal; B n (t) The digital baseband real signal obtained by the first analog-to-digital converter is used Indicates that D n (t) The digital baseband real signal obtained by the second analog-to-digital converter is used Indicates that and Obtained by digital baseband complex signal synthesizer but 7. An analog RF signal converter of a RF direct sampling digital phased array for implementing the multiple target angle measurement method of claim 4, characterized in that: The invention comprises an analog-to-digital converter, a digital sinusoidal signal generator, a first digital multiplier, a first FIR LPF, a first extractor, a second digital multiplier, a second FIR LPF, a second extractor, and a digital baseband complex signal synthesizer. The same digital sinusoidal signal generator is used in all analog-to-radio frequency signal converters. The input end of the analog-to-digital converter is connected to the analog radio frequency signal, the output end of the analog-to-digital converter is connected to an input end of the first digital multiplier and an input end of the second digital multiplier. The digital sinusoidal signal generator generates two mutually orthogonal digital sinusoidal signals, one of which is connected to the other input end of the first digital multiplier and the other is connected to the other input end of the second digital multiplier. The output end of the first digital multiplier is connected to the first FIR LPF and the first extractor in sequence, the output end of the second digital multiplier is connected to the second FIR LPF and the second extractor in sequence, and the output signal of the first extractor and the output signal of the second extractor are connected to obtain a digital baseband complex signal through the digital baseband complex signal synthesizer.

8. An analog RF signal converter of an intermediate frequency sampling digital phased array for implementing the method for measuring multiple target angles as claimed in claim 5, characterized in that: The invention comprises an analog multiplier, an analog sine wave generator, an analog BPF, an analog-to-digital converter, a digital sine signal generator, a first digital multiplier, a first FIR LPF, a first extractor, a second digital multiplier, a second FIR LPF, a second extractor, and a digital baseband complex signal synthesizer. The same analog sine wave generator and the same digital sine signal generator are used in all analog RF signal converters. One input end of the analog multiplier is connected to the analog RF signal, and the other input end is connected to the output end of the analog sine wave generator. The output end of the analog multiplier is connected to the analog BPF and the analog-to-digital converter in sequence. The output end of the analog-to-digital converter is connected to an input end of the first digital multiplier and an input end of the second digital multiplier. The digital sine signal generator generates two mutually orthogonal digital sine signals, one of which is connected to the other input end of the first digital multiplier, and the other is connected to the other input end of the second digital multiplier. The output end of the first digital multiplier is connected to the first FIR LPF and the first extractor in sequence, and the output end of the second digital multiplier is connected to the second FIR LPF, the second extractor, the output signal of the first extractor and the output signal of the second extractor are synthesized by a digital baseband complex signal to obtain a digital baseband complex signal.

9. An analog RF signal converter of a baseband sampling digital phased array for implementing the method for measuring multiple target angles according to claim 6, characterized in that: The invention comprises a third analog multiplier, a first analog sine wave generator, an analog BPF, a second analog sine wave generator, a first analog multiplier, a first analog LPF, a first analog-to-digital converter, a second analog multiplier, a second analog LPF, a second analog-to-digital converter, and a digital baseband complex signal synthesizer. The same first analog sine wave generator and the same second analog sine wave generator are used in all analog RF signal converters. One input end of the third analog multiplier is connected to the analog RF signal, and the other input end is connected to the output end of the first analog sine wave generator. The output end of the third analog multiplier is connected to the input end of the analog BPF, and the output end of the analog BPF is connected to the first analog An input end of the quasi-multiplier is connected to an input end of the second analog multiplier, the second analog sine wave generator generates two mutually orthogonal sine waves, one of which is connected to the other input end of the first analog multiplier, and the other is connected to the other input end of the second analog multiplier, the output end of the first analog multiplier is connected to the first analog LPF and the first analog-to-digital converter in sequence, the output end of the second analog multiplier is connected to the second analog LPF and the second analog-to-digital converter in sequence, and the output signal of the first analog-to-digital converter and the output signal of the second analog-to-digital converter are connected through a digital baseband complex signal synthesizer to obtain a digital baseband complex signal.

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