Calculation Method for Noise Level of Multi-Station Phased Array Incoherent Scatter Radar

Abstract

The present invention belongs to the field of radar detection and relates to a method for calculating the noise level of a multi-station phased array incoherent scatter radar, aiming to solve the problem that there is a lack of an effective method for calculating the noise level of a multi-station incoherent scatter radar in the prior art. The present invention includes: obtaining the beam cross-covariance between the transmitting beam and each receiving beam; determining the distance distribution covariance between the transmitting beam and each receiving beam; determining the scattering volume covariance of the intersection of the transmitting beam and each receiving beam; obtaining a three-dimensional scattering volume integral, and further determining the received power and noise power of the multi-station incoherent scatter radar; determining the noise parameters; and calculating the noise level of the multi-station incoherent scatter radar. Starting from the perspective of beam width, the present invention solves the scattering volume through the method of covariance matrix, and then determines the noise level, filling the blank of the method for calculating the noise level of a multi-station phased array incoherent scatter radar.

Description

Background Art

[0002] The ionosphere is a partially ionized plasma region in the altitude range of 50 - 60 km to 1000 - 2000 km above the Earth's surface. It is closely related to human activities in the solar-terrestrial space environment and has a significant impact on radio communication, satellite navigation and positioning, manned spaceflight, etc. Incoherent scatter radar ( Incoherent Scatter Radar , ISR) is currently the most powerful ionospheric sounding means, with advantages such as strong detection function, multiple parameters, high accuracy, good resolution, and large altitude range coverage. Since 1958, many scholars have studied incoherent scatter radar and confirmed that it can measure ionospheric parameters by using electron thermal fluctuation scattering signals (for references: Dougherty , J . P ., and D . T . Farley (1960), “ A theory of incoherent scattering of radio waves by a plasma ,” Proc. Royal Soc. Lond , vol .259, pp .79–99, Feb 1960. DOI :10.1098 / rspa .1960.0212; Fejer , J . A ., “ Radio - waves scattering by an ionized gas in the male equilibrium ,” Journal of Geophysical Research , vol . 65, no . 9, pp . 2635–2636, Sep 1960. DOI : 10.1029 / jz 065 i 009 p 02635; Salpeter E . E ., “ Electron Density Fluctuations in a Plasma ,” Phys Rev, vol .120, no .5, pp .1528-1535. Dec 1960. DOI : 10.1103 / PhysRev .120.1528; Rosenbluth M N , Rostoker N , “ Scattering of Electromagnetic Waves by a Nonequilibrium Plasma ,” Physics of Fluids , vol.5, no .7, pp .776 - 788, Jul 1962, DOI : 10.1063 / 1.1724446; Hagfors , T .,“ Density fluctuations in a plasma in a magnetic field , with applications to the ionosphere ,” Journal of Geophysical Research , vol .66, no .6, Jun 1961. DOI : 10.1029 / JZ 066 i 006 p 01699).

[0003] Incoherent scatter radars obtain ionospheric information by transmitting high - power electromagnetic waves and receiving Thomson scattering echoes of electrons (for references: Evans , J . V . (1969), Theory and practice of ionosphere study by Thomson scatter radar , Proceedings of the IEEE , 57(4), 4 96–530. https: / / doi.org / 10.1109 / proc.1969.7005;Mathews , J . D . (1984), The incoherent scatter radar as a tool for studying the ionospheric D region - Atmos , J . Sol . Terr . Phys . https: / / ., 46(11), 975–986. doi.org / 10.1016 / 0021-9169(84)90004-7) EISCAT . The European Schlegel K Association operates three ISR radars, and the UHF radar is a multi - station parabolic incoherent scatter radar (for references: Moorcroft , EISC , D . R . (1989), AT as a tristatic auroral radar Journal of Geophysical Research Space Physics . https , 94( A 2):1430 - 1438. doi : / / org . ja / 10.1029 / ia 094 Wannberg 02 p 01430; Wolf , G .,etal , I ., The EISCAT Svalbard radar .(1997). A case study in modern incoherent scatter radar system : design ​ . RadioScience , 32(6), 2283–2307. https: / / doi.org / 10.1029 / 97rs01803) 。Its transmitting station is located in Tromsø, and the receiving stations are located in Tromsø, Kiruna, and Sodankyla. This radar is the world's first multi-station incoherent scatter radar with a parabolic antenna system. This multi-station incoherent scatter radar uses a parabolic antenna and scans by mechanical rotation. It usually takes dozens of minutes to switch the beam direction. Therefore, it can only detect fixed points, cannot achieve scanning detection, and cannot ensure that the measured ionospheric parameters remain unchanged during the measurement, which has defects in observation; at the same time, using a parabolic antenna, the antenna gain does not change with mechanical rotation. Therefore, the change of its gain with azimuth and elevation angles can be ignored, so it is relatively simple in data processing, but its existing formula cannot be directly applied to the phased array incoherent scatter radar system.

[0004] With the development of radar technology, phased array antennas have come into people's view with their advantages such as large-range rapid scanning, fine scanning, flexible controllability, and long-time continuous observation. Phased array antennas can achieve beam switching at the millimeter level. Therefore, incoherent scatter radars have begun to use phased array antennas to replace traditional parabolic antennas. The United States has proposed AMISR ( Advance dModularIncoherentScatterRadar ,Advanced Modular Incoherent Scatter Radar)active phased array radar project. By controlling the beam through software, the beam direction can be switched rapidly at the microsecond level, improving the time ambiguity problem of traditional parabolic radars (for reference, see ValenticT ., BuonocoreJ ., CousinsM ., HeinselmanC ., JorgensenJ .& KellyJ . etal ,“ AMISR the advanced modular incoherent scatter radar , ” IEEE Internation al Symposium on Phased Array Systems & Technology , Waltham , MA , USA , pp . 659-663, 2013, DOI : 10.1109 / ARRAY .2013.6731908). After completion, the array surface is placed at the Fairbanks near Poker observation and research site for test operation, and other array surfaces are installed in ResoluteBays, all of which are located in high-latitude regions (for references: Heinselman , C . J ., andM . J . Nicolls (2008), A Bayesian approach to electric field and E - region neutral wind estimation with the Poker Flat Advanced Modul ar Incoherent Scatter Ra dar, Radio Sci., 43, RS5013, https: / / doi.org / 10.1029 / 2007RS003805; Semeter , J ., T . W . Butler , M . Zettergren , C . J . Heinselman , andM . J . Nicolls (2010), Composite imaging of auroral forms and convective flows during a substorm cycle , J . Geophys . Res ., 115, A 08308, doi :10.1029 / 2009 JA 014931). Both of its existing radars are single-station phased-array incoherent scatter radars. The single-transmission and single-reception mode cannot accurately measure the horizontal-region ionospheric vector information, and the obtained ionospheric information is incomplete, making it difficult to conduct multi-dimensional detection and analysis.

[0005] To achieve multi-dimensional detection, the Institute of Geology and Geophysics of the Chinese Academy of Sciences has built a 1-transmission and 3-reception incoherent scatter detection system in Hainan Island. It is transmitted from the Sanya Station in Hainan and received by Sanya, Fuke in Danzhou, and Wenchang. It is the world's first low-latitude ionospheric multi-station phased-array incoherent radar detection system (for references: Yue , X ., Wan , W ., Ning , B ., Jin , L ., Ding , F ., Zhao , B ., etal . (2022). Development of the Sanya incoherent scatter radar and p reliminary results . Journal of Geophysical Research: Space Physics, 127, e2022JA030451. https: / / doi.org / 10.1029 / 2022JA0;Yue, X., Ning, B., Jin, L.,Ding, F., Ke, C., Wang, J., et al. (2024). The Sanya incoherent scatter radar tristatic system and initial experiments. Space Weather , 22, e 2024 SW 003963. https : / / doi . org / 10.1029 / 2024 SW 003963). Compared with a single - station radar, it can improve the detection ability, measure the ionospheric drift velocity vector, and provide multi - level, multi - parameter, and high - precision ionospheric parameters. The three - station incoherent scatter radar in China can not only measure the ionospheric drift velocity vector, but also has the advantages of phased - array scanning. It can achieve fast scanning within the microsecond level, ensuring the timeliness of measurement data. At the same time, it can also perform fast large - range scanning to achieve full - sky detection. However, the phased - array system brings many technical difficulties. For example, the phase, gain, and beam width of the radar's electronic scanning change in real time. At the same time, co - body detection needs to be achieved within a wide area. Therefore, the scattered signals to be detected in multi - station incoherent scatter radar detection are very weak, increasing the calculation difficulty of the signal - to - noise ratio. Although there are existing achievements related to the signal - to - noise ratio of multi - station incoherent scatter radar in the prior art, the calculation of the signal - to - noise ratio is rough. Therefore, not only a more in - depth analysis of the noise level is required, but also in order to obtain effective scattered signals, a certain time accumulation of the received signals is needed. In summary, there is currently a lack of an effective method for calculating the noise level of multi - station incoherent scatter radar, which cannot provide a reference for actual detection experiments. Summary of the Invention

[0006] In order to solve the above problems in the prior art, that is, the problem of the lack of a method for calculating the noise level in multi - station incoherent scatter radar detection, the first aspect of the present invention proposes a method for calculating the noise level of a multi - station phased - array incoherent scatter radar, which is applied to the observation of ionospheric parameters of an incoherent scatter radar, and realizes the calculation of the noise level of important parameters and the spatial distribution analysis in radar signal and data processing. The method includes the following steps:

[0007] S1. Based on the beam equivalent method, determine the transmit beam covariance and receive beam covariance of the multi - station incoherent scatter radar, and then obtain the beam cross - covariance between the transmit beam and each receive beam;

[0008] S2. Determine the distance parameter of the beam, and then obtain the distance distribution covariance between the transmit beam and each receive beam;

[0009] S3. Based on the beam cross - covariance and the distance distribution covariance, determine the scattering volume covariance of the intersection between the transmit beam and each receive beam;

[0010] S4. According to the properties of the Gaussian distribution, obtain the three - dimensional scattering volume integral based on the scattering volume covariance;

[0011] S5. Determine the received power and noise power of the multi-station incoherent scatter radar based on the three-dimensional scattering volume integral;

[0012] S6. Determine the noise parameters, where the noise parameters include the delay length and the corresponding number of delays, and the number of incoherent integrations;

[0013] S7. Calculate the noise level of the multi-station incoherent scatter radar based on the noise parameters, in combination with the received power and the noise power.

[0014] In some preferred embodiments, the transmit beam covariance and the receive beam covariance of the incoherent scatter radar are determined based on the beam equivalence method. The method is as follows:

[0015] When the beam is pointed in the zenith direction, the beam shape is an axisymmetric Gaussian shape. According to the beam parameters of the beam equivalence method, the standard deviation of the corresponding transmit beam and the standard deviation of the corresponding receive beam are obtained, and then the transmit beam covariance and the receive beam covariance are obtained.

[0016] In some preferred embodiments, the three-dimensional scattering volume integral is obtained. The method is as follows:

[0017] According to the properties of the Gaussian distribution, the three-dimensional scattering volume integral is obtained from the integral of the scattering volume covariance of the N-dimensional Gaussian distribution :

[0018] ;

[0019] where represents the scattering volume covariance matrix.

[0020] In some preferred embodiments, the received power of the multi-station incoherent scatter radar is determined. The method is as follows:

[0021] Based on the three-dimensional scattering volume integral, determine the received power of the multi-station phased array incoherent scatter radar as:

[0022] ;

[0023] where P t is the peak power of the radar transmission, N e is the electron density, is the single electron scattering cross section, β is the angle between the transmit beam and the scattered wave vector, is the wavelength, I T represents the integral of the transmit beam, I R represents the integral of the receive beam.

[0024] In some preferred embodiments, the noise power of the multi-station incoherent scatter radar is determined as follows:

[0025] ;

[0026] wherein, is the Boltzmann constant, is the system noise temperature, B is the signal bandwidth, is the signal sampling interval.

[0027] In some preferred embodiments, the number of time delays, the calculation method thereof is:

[0028] In multi-station incoherent scatter calculation, the signal is a random signal. Therefore, the time delay length is determined according to the transmitted pulse, and combined with the interval, the number of time delays is obtained :

[0029] ;

[0030] wherein, is the time of a sampling period, i.e., the time delay length, is the signal sampling interval.

[0031] In some preferred embodiments, the method for calculating the noise level of the multi-station incoherent scatter radar is:

[0032] In multi-station incoherent scatter calculation, the noise level is related to the measurement variance, and the noise level is:

[0033] ;

[0034] wherein A is the maximum value of the zero-delay autocorrelation function, is the measurement variance;

[0035] When the time delay length is fixed, the measurement variance is half of the zero-delay estimation variance of the autocorrelation function :

[0036] ;

[0037] In multi-station incoherent scatter calculation, the zero-delay estimation variance of the autocorrelation function is:

[0038] ;

[0039] wherein, is the number of non-coherent accumulation times, represents the signal-to-noise ratio:

[0040] ;

[0041] Combining the above formulas, we can get the noise level of the incoherent scattering radar: for:

[0042] .

[0043] A second aspect of the present invention provides a multi-station phased array incoherent scattering radar noise level calculation system, the system comprising:

[0044] The scattering volume calculation module is configured to determine the transmit beam covariance and receive beam covariance of the multi-station incoherent scattering radar based on the beam equivalence method, thereby obtaining the beam cross covariance between the transmit beam and each receive beam; determine the beam range parameter, thereby obtaining the range distribution covariance between the transmit beam and each receive beam; and determine the scattering volume covariance of the intersection of the transmit beam and each receive beam based on the beam cross covariance and the range distribution covariance;

[0045] a power calculation module configured to obtain a three-dimensional scattering volume integral based on the scattering volume covariance according to Gaussian distribution properties, and further determine the received power and noise power of the multi-station incoherent scattering radar;

[0046] The noise level calculation module is configured to determine noise parameters, wherein the noise parameters include a delay length and a corresponding delay number, and a number of incoherent accumulations; and calculate the noise level of the multi-station incoherent scatter radar based on the noise parameters in combination with the received power and the noise power.

[0047] A third aspect of the present invention provides a device for calculating noise levels of a multi-station phased array incoherent scattering radar, comprising:

[0048] at least one processor; and

[0049] a memory communicatively connected to at least one of the processors; wherein,

[0050] The memory stores instructions that can be executed by the processor, and the instructions are used to be executed by the processor to implement the above-mentioned method for calculating the noise level of a multi-station phased array incoherent scattering radar.

[0051] A fourth aspect of the present invention provides a computer-readable storage medium storing computer instructions, which are used to be executed by the computer to implement the above-mentioned method for calculating the noise level of a multi-station phased array incoherent scattering radar.

[0052] Beneficial effects of the present invention:

[0053] The noise level calculation method of the present invention can quantitatively calculate the noise level of a multi-station phased array incoherent scatter radar; through a unique method of beam equivalence, it effectively overcomes the key difficulty that the gain of a phased array antenna changes in real time with the azimuth angle and elevation angle and is difficult to be expressed by a detailed formula; and it uses the covariance form to accurately represent the scattering volume expression obtained by beam intersection, and depicts the change of the beam antenna gain in the simplest form to the greatest extent;

[0054] In the process of calculating the noise level, all aspects of data processing are comprehensively considered, including the number of accumulations, the number of time delays, etc., which significantly improves the accuracy and reliability of the noise level calculation, and realizes the accurate calculation and spatial distribution analysis of the important parameter noise level in radar signal and data processing;

[0055] By adopting the phased array scanning technology and combining with the multi-station technology, multi-beam synchronous detection can be realized, and full-space coverage can be provided instantaneously, and three-dimensional imaging of the ion drift velocity vector in the full sky can be carried out in a short time, which greatly expands the detection space range and time efficiency; it helps to optimize the radar detection scheme and improve the radar detection performance, and has important application value and academic significance. Brief Description of the Drawings

[0056] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, other features, objects and advantages of the present application will become more obvious:

[0057] Figure 1 is a flow chart of a method for calculating the noise level of a multi-station phased array incoherent scatter radar according to the present invention;

[0058] Figure 2 is the noise level at different heights of the transmitting station Sanya and the receiving station Funke in the embodiment of the present invention. Detailed Embodiments

[0059] The following further describes the present application in detail with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention and are not intended to limit the invention. In addition, it should be noted that only the parts related to the invention are shown in the drawings for the convenience of description.

[0060] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and embodiments.

[0061] Aiming at the difficulty that in the prior art, the gain of a phased array antenna changes in real time with the azimuth angle and elevation angle, and it is impossible to use a detailed formula to represent the noise level of a multi-station phased array incoherent scatter radar. The first embodiment of the present invention establishes a calculation method for the noise level of a multi-station phased array incoherent scatter, starting from the beam width angle, solving important parameters such as the scattering volume and noise level through the method of covariance matrix. At the same time, this method considers the corresponding non-coherent accumulation times when calculating the autocorrelation function in the incoherent scatter radar, and can set the scattering volume range according to the actual situation, and can quantitatively calculate the noise level of the multi-station phased array incoherent scatter radar. As Figure 1 shown, the specific steps are as follows:

[0062] S1. Determine the covariance of the transmitting beam and the covariance of the receiving beam of the multi-station incoherent scatter radar based on the beam equivalence method and the covariance of the receiving beam , and then obtain the beam cross-covariance between the transmitting beam and each receiving beam ; the method is:

[0063] ;

[0064] Among them, is the covariance of the transmitting beam, is the covariance of the receiving beam, is the beam cross-covariance.

[0065] This application calculates the noise level from the perspective of covariance:

[0066] When the beam points to the zenith direction, according to antenna theory, the beam shape is an axisymmetric Gaussian shape. There is a proportional conversion relationship between the beam width and the standard deviation of the Gaussian distribution. According to the beam parameters of the beam equivalence method, the standard deviation of the corresponding transmitting beam and the standard deviation of the corresponding receiving beam are obtained, and then the covariance of the transmitting beam and the covariance of the receiving beam are obtained. Through the transmitting beam and receiving beam represented by covariance, the covariance result of the intersection of the transmitting beam and the receiving beam can be obtained.

[0067] S2. Determine the distance parameter of the beam, and then obtain the distance distribution covariance between the transmitting beam and each receiving beam .

[0068] S3. Based on the beam cross-covariance and the distance distribution covariance determine the covariance of the scattering volume of the intersection of the transmitting beam and each receiving beam , the method is:

[0069] .

[0070] Since when calculating the scattering volume, not only the angular parameters of the beam but also the distance parameters of the beam are required, the covariance of the scattering volume at the intersection of two beams can be obtained through the covariance of the distance distribution and the covariance of the beam intersection.

[0071] Furthermore, in order to obtain the received power of the phased array multi-station, it is necessary to solve the antenna gain integration.

[0072] S4. According to the properties of the Gaussian distribution, a three-dimensional scattering volume integral is obtained based on the covariance of the scattering volume, and the method is as follows:

[0073] According to the properties of the Gaussian distribution, from the covariance of the scattering volume of the three-dimensional Gaussian distribution , the three-dimensional scattering volume integral is obtained:

[0074] ;

[0075] By establishing a calculation formula for the scattering volume at the intersection of the multi-station phased array beams, quantitative calculation of the scattered echo signal is further realized.

[0076] S5. Based on the three-dimensional scattering volume integral, the received power and noise power of the multi-station incoherent scatter radar are determined, and the method is as follows:

[0077] According to the three-dimensional scattering volume integral , the received power of the multi-station phased array incoherent scatter radar is:

[0078] ;

[0079] Among them, P t is the peak power of radar transmission, N e is the electron density, is the single electron scattering cross section, β is the angle between the transmitting beam and the scattered wave vector, is the wavelength, I T represents the integral of the transmitting beam, I R represents the integral of the receiving beam;

[0080] Determine the noise power of the incoherent scatter radar is:

[0081] ;

[0082] Among them, is the Boltzmann constant, is the system noise temperature, is the signal bandwidth, is the signal sampling interval.

[0083] In multi-station incoherent scatter calculations, due to the complexity of its processing method, it is not enough to simply calculate the ratio of the received power to the noise power to evaluate the noise level. It is necessary to further consider parameters such as the number of accumulations and the number of time delays.

[0084] S6. Determine the noise parameters, where the noise parameters include the time delay length and the corresponding number of time delays, and the number of incoherent accumulations.

[0085] In incoherent scatter calculations, the signal is a random signal. Mainly, the signal is analyzed through different time delays. Different time delays are uncorrelated, and at the same time, different time delays have the same variance. During the analysis process, it is necessary to determine the time delay length, which can be determined according to the transmitted pulse. is the corresponding number of time delays; Different time delays, such as the first time delay, the second time delay, etc., are usually considered in the calculation of the autocorrelation function.

[0086] Preferably, the time delay length, and its calculation method is:

[0087] In multi-station incoherent scatter calculations, the signal is a random signal. Therefore, the time delay length is determined according to the transmitted pulse and combined with the interval to obtain the number of time delays :

[0088] ;

[0089] where is the time of one sampling period, that is, the time delay length, is the signal sampling interval.

[0090] S7. Based on the noise parameters, combined with the received power and the noise power, calculate the noise level of the multi-station incoherent scatter radar.

[0091] In multi-station incoherent scatter calculations, the maximum value of the autocorrelation function at zero time delay is proportional to the total scattering power of the plasma. Therefore, the noise level γ (the square root of the average relative variance per unit time delay) is:

[0092] ;

[0093] where A is the maximum value of the autocorrelation function at zero time delay, is the actually measured variance.

[0094] In order to obtain the same variance matrix at different time delays, the variance matrix can be expressed as the sum of n terms. According to continuity, these terms are approximately equal. Therefore, the sum is N times that of a single term. Therefore, one term can be replaced by the sum of multiple terms and its average value can be taken.

[0095] Therefore, in a specific experiment (i.e., when the delay length is fixed), this constant (the actually measured variance) can be regarded as half of the variance of the zero-delay estimation of the autocorrelation function :

[0096] ;

[0097] For the variance of the zero-delay estimation of the autocorrelation function, it can be expressed using the signal-to-noise ratio:

[0098] ;

[0099] where is the number of non-coherent integration times, represents the signal-to-noise ratio:

[0100] ;

[0101] Combining the above equations, the noise level of a radar at a receiving station under multi-station non-coherent scattering is calculated as:

[0102] .

[0103] When calculating the noise level of a multi-station non-coherent scattering radar, the corresponding non-coherent integration times are considered during the calculation of the autocorrelation function, and the scattering volume range can be set according to the actual situation; through the noise level calculation method of the multi-station non-coherent scattering radar, the calculation and spatial distribution analysis of the important parameter noise level in radar signal and data processing are realized, providing a theoretical basis for radar experimental mode detection.

[0104] According to the above method, regardless of the situation of three-receiving, four-receiving or other multi-receiving non-coherent scattering radars, the noise level of any station can be solved.

[0105] Preferably, in this embodiment, according to the above noise level calculation method of the multi-station non-coherent scattering radar, a certain data during the operation of the Hainan three-station high-power phased array non-coherent scattering radar is calculated, and based on the calculation results, the noise levels of a single station and a double station are plotted.

[0106] Among them, the receiving station of the single station is Sanya Station, and the receiving station of the double station is represented by Fuk Station. The results of plotting the noise levels of the single station and the double station are as Figure 2As shown in the figure, it can be seen that the noise level of Sanya Station's self-transmission and self-reception shows a concentric circle distribution. When Sanya Station transmits and Fuke Station receives, an oval structure appears at 100 km. As the height increases, it gradually changes to a concentric circle distribution. It can be seen from the figure that for the bistatic noise level within the ranges of 100 km, 300 km, and 500 km, it is higher than that of the monostatic. The main reason is that the number of antenna elements on the receiving station's array surface is small, so the receiving gain is low. In order to achieve data quality similar to that of the transmitting station, the receiving station needs to accumulate more times to reduce the noise level.

[0107] In the above embodiments, although each step is described in the above sequential order, those skilled in the art can understand that in order to achieve the effects of this embodiment, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in a reversed order, and these simple changes are all within the protection scope of the present invention.

[0108] The multi-station phased array incoherent scatter radar noise level calculation system according to the second embodiment of the present invention, the system includes:

[0109] A scattering volume calculation module, configured to determine the transmit beam covariance and receive beam covariance of a multi-station incoherent scatter radar based on the beam equivalence method, and then obtain the beam cross-covariance between the transmit beam and each receive beam; determine the distance parameter of the beam, and then obtain the distance distribution covariance between the transmit beam and each receive beam; determine the scattering volume covariance of the intersection between the transmit beam and each receive beam based on the beam cross-covariance and the distance distribution covariance;

[0110] A power calculation module, configured to obtain a three-dimensional scattering volume integral based on the scattering volume covariance according to the properties of the Gaussian distribution, and then determine the received power and noise power of the multi-station incoherent scatter radar;

[0111] A noise level calculation module, configured to determine noise parameters, where the noise parameters include the autocorrelation function noise level, the variance of the power profile estimate, the delay length and the corresponding number of delays, the number of non-coherent accumulations, and the number of range gates; calculate the noise level of the multi-station incoherent scatter radar based on the noise parameters, in combination with the received power and the noise power.

[0112] It should be noted that for the multi-station phased array incoherent scatter radar noise level calculation system provided in the above embodiments, only the division of the above functional modules is used as an example for illustration. In practical applications, the above functions can be allocated to different functional modules according to needs, that is, the modules or steps in the embodiments of the present invention can be further decomposed or combined. For example, the modules in the above embodiments can be combined into one module, or further split into multiple sub-modules to complete all or part of the functions described above. For the names of the modules and steps involved in the embodiments of the present invention, they are only used to distinguish each module or step, and are not regarded as an improper limitation of the present invention.

[0113] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process and related descriptions of the above-described system can refer to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0114] A multi-station phased array incoherent scatter radar noise level calculation device according to the third embodiment of the present invention includes:

[0115] At least one processor; and

[0116] A memory communicatively connected to at least one of the processors; wherein,

[0117] The memory stores instructions executable by the processor, and the instructions are used to be executed by the processor to implement the above multi-station phased array incoherent scatter radar noise level calculation method.

[0118] A computer-readable storage medium according to the fourth embodiment of the present invention, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to be executed by a computer to implement the above multi-station phased array incoherent scatter radar noise level calculation method.

[0119] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process and related descriptions of the above-described electronic device and computer-readable storage medium can refer to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0120] Those skilled in the art should be able to realize that the modules and method steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. The programs corresponding to the software modules and method steps can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the technical field. To clearly illustrate the interchangeability of electronic hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in the form of electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0121] Computer program code for performing the operations of the present application can be written in one or more programming languages or combinations thereof. The above programming languages include object-oriented programming languages such as Java, Smalltalk, C++, and also include conventional procedural programming languages such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, executed as an independent software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (for example, by using an Internet service provider to connect through the Internet).

[0122] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagram may represent a module, a program segment, or a part of code that contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than marked in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or operations, or can be implemented by a combination of dedicated hardware and computer instructions.

[0123] The terms "first", "second", etc. are used to distinguish similar objects and are not used to describe or indicate a specific order or sequence.

[0124] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to those processes, methods, articles, or apparatus / devices.

[0125] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for calculating the noise level of a multi-station phased array incoherent scatter radar, characterized in that, The method includes the following steps: S1. Determine the transmit beam covariance and receive beam covariance of the multi-station incoherent scatter radar based on the beam equivalence method, and then obtain the beam cross-covariance between the transmit beam and each receive beam; S2. Determine the distance parameter of the beam, and then obtain the distance distribution covariance between the transmit beam and each receive beam; S3. Determine the scatter volume covariance of the intersection between the transmit beam and each receive beam based on the beam cross-covariance and the distance distribution covariance; S4. Based on the properties of the Gaussian distribution, obtain the three-dimensional scatter volume integral based on the scatter volume covariance; S5. Determine the received power and noise power of the multi-station incoherent scatter radar based on the three-dimensional scatter volume integral; S6. Determine the noise parameters, where the noise parameters include the delay length and the corresponding number of delays, and the number of non-coherent integrations; S7. Based on the noise parameters, and in combination with the received power and the noise power, calculate the noise level of the multi-station incoherent scatter radar; The method for calculating the noise level of the multi-station incoherent scatter radar is as follows: In multi-station incoherent scatter calculations, the noise level is related to the measurement variance and is given by: ； When the fixed delay length is considered, the measurement variance is half of the delay estimation variance when the autocorrelation function is zero: ​ ； In the multi-station incoherent scatter calculation, the variance of the zero-delay estimation of the autocorrelation function is: ； ； Obtain the noise level of the incoherent scatter radar : ； where A is the maximum value of the zero-delay autocorrelation function, is the measurement variance, is the number of non-coherent integrations, represents the signal-to-noise ratio; is the noise power of the multi-station incoherent scatter radar, P r is the received power of the multi-station phased array incoherent scatter radar; is the number of time delays, is the Boltzmann constant, is the system noise temperature, I T represents the integration of the transmit beam, I R represents the integration of the receive beam; B is the signal bandwidth, is the signal sampling interval; P t is the peak power of the radar transmission, N e is the electron density, is the single electron scattering cross section, β is the angle between the transmit beam and the scattered wave vector, is the wavelength, is the three-dimensional scattering volume integration, is the time of one sampling period.

2. The method for calculating the noise level of a multi-station phased array incoherent scatter radar according to claim 1, wherein The method for determining the transmit beam covariance and receive beam covariance of the incoherent scatter radar based on the beam equivalence method is as follows: When the beam points to the zenith direction, the beam shape is an axisymmetric Gaussian shape. According to the beam parameters of the beam equivalence method, obtain the standard deviation of the corresponding transmit beam and the standard deviation of the corresponding receive beam, and then obtain the transmit beam covariance and the receive beam covariance.

3. The method for calculating the noise level of a multi-station phased array incoherent scatter radar according to claim 2, characterized in that, The method for obtaining the three-dimensional scatter volume integral is as follows: According to the properties of the Gaussian distribution, the three-dimensional scattering volume integral is obtained from the covariance of the scattering volume of the three-dimensional Gaussian distribution : ； Among them, represents the scattering volume covariance matrix.

4. The method for calculating the noise level of a multi-station phased array incoherent scatter radar according to claim 3, wherein The method for determining the received power of the multi-station incoherent scatter radar is as follows: Determining the received power of a multi-station phased array incoherent scatter radar based on three-dimensional scattering volume integration P r as follows: ； Among them, P t is the peak power of radar emission, N e is the electron density, is the scattering cross section of a single electron, β is the angle between the emission beam and the scattering wave vector, is the wavelength, I T represents the integration of the emission beam, I R represents the integration of the receiving beam.

5. The method for calculating the noise level of a multi-station phased array incoherent scatter radar according to claim 4, wherein Determine the noise power of a multi-station incoherent scatter radar is: ； wherein, is the Boltzmann constant, is the system noise temperature, B is the signal bandwidth, is the signal sampling interval.

6. The method for calculating the noise level of a multi-station phased array incoherent scatter radar according to any one of claims 1-5, characterized in that The method for calculating the number of delays is as follows: In multi-station incoherent scattering calculations, the signal is a random signal. Therefore, the time delay length is determined based on the transmitted pulse, and combined with the interval, the number of time delays is obtained. : ； Among them, is the time of a sampling period, that is, the delay length, is the signal sampling interval.

7. A multi-station phased array incoherent scatter radar noise level calculation system, according to the multi-station phased array incoherent scatter radar noise level calculation method described in any one of claims 1-6, characterized in that, The system includes: A scatter volume calculation module configured to determine the transmit beam covariance and receive beam covariance of the multi-station incoherent scatter radar based on the beam equivalence method, and then obtain the beam cross-covariance between the transmit beam and each receive beam; determine the distance parameter of the beam, and then obtain the distance distribution covariance between the transmit beam and each receive beam; determine the scatter volume covariance of the intersection between the transmit beam and each receive beam based on the beam cross-covariance and the distance distribution covariance; A power calculation module configured to obtain the three-dimensional scatter volume integral based on the scatter volume covariance according to the properties of the Gaussian distribution, and then determine the received power and noise power of the multi-station incoherent scatter radar; A noise level calculation module configured to determine the noise parameters, where the noise parameters include the delay length and the corresponding number of delays, and the number of non-coherent integrations; based on the noise parameters, and in combination with the received power and the noise power, calculate the noise level of the multi-station incoherent scatter radar.

8. A multi-station phased array incoherent scatter radar noise level calculation device, characterized in that Includes: At least one processor; And A memory communicatively connected to at least one of the processors; wherein, The memory stores instructions executable by the processor, and the instructions are used to be executed by the processor to implement the method for calculating the noise level of the multi-station phased array incoherent scatter radar according to any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for being executed by the computer to implement the multi-station phased array incoherent scatter radar noise level calculation method according to any one of claims 1-6.

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