Method for defending satellite from electronic reconnaissance by electromagnetic signal of frequency equipment

Abstract

The application discloses a method for defending satellite electronic reconnaissance by using frequency equipment electromagnetic signals, which comprises the following steps: S1, establishing a satellite electronic reconnaissance model; S2, establishing an electronic reconnaissance threat degree evaluation model; and S3, electronic noise interference. By adopting the evasion and active interference mode in the four dimensions of time, frequency, space and energy, the application reduces the probability of the frequency equipment electromagnetic signals being reconnoitered by the enemy electronic reconnaissance satellite, and ensures the safety of the frequency equipment electromagnetic signals.

Description

Technical Field

[0001] This invention belongs to the field of anti-satellite reconnaissance technology, and in particular relates to a method for preventing satellite electronic reconnaissance of electromagnetic signals of frequency-using equipment. Background Technology

[0002] With the continuous development of global technology, modern military activities and defense in various countries rely heavily on reconnaissance satellites to acquire space-based or ground-based military intelligence, making it a crucial intelligence gathering technology in modern warfare. Modern satellite electronic reconnaissance utilizes the positioning capabilities of distant-space satellites, aided by radar and other devices, and enhanced by communication and electronic systems, to transmit and receive various electromagnetic signals, thereby determining the signal radiation location and controllable radius of various strategic targets. Modern satellite electronic reconnaissance methods are becoming increasingly diversified, deeply integrating laser, infrared imaging, and other equipment, and combining multiple satellite networks to achieve outstanding reconnaissance work. Therefore, anti-satellite technology, as a tactical means, can destroy enemy communication chains on the battlefield, inflicting significant damage on the enemy's psychology and overall combat capabilities.

[0003] For reconnaissance satellites, existing countermeasures mainly involve evading reconnaissance. Since reconnaissance satellites operate on specific orbits, tracking and measurement can not only calculate when a satellite will pass overhead on a specific day, at a specific time, but also roughly determine the type, level, and purpose of the onboard reconnaissance equipment, issuing early warnings and taking advantage of gaps and "blank spots" in satellite reconnaissance operations. However, this method is limited in its application and lacks variety, and there are still situations where it is impossible to avoid satellite overflight reconnaissance. Currently, there is a lack of effective counter-reconnaissance jamming techniques. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a method for preventing satellite electronic reconnaissance of electromagnetic signals used by frequency-based devices.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] A method for preventing satellite electronic reconnaissance of electromagnetic signals used by frequency-based equipment, comprising the following steps:

[0007] S1. Establish a satellite electronic reconnaissance model

[0008] Assuming the main lobe beam center of the electronic reconnaissance satellite's antenna always points towards the Earth's center, and given the Earth's radius as Re, the satellite's orbital altitude as h, the electronic reconnaissance satellite's half-field of view as β, and the geocentric angle α of the ground covered by the electronic reconnaissance satellite as...

[0009]

[0010] The width of the electronic reconnaissance satellite coverage band is W.

[0011]

[0012] The area A1 of the instantaneous reconnaissance range is

[0013]

[0014] For non-geostationary orbit electronic reconnaissance satellites, the coverage area is related to the nadir trajectory. The nadir is the vertical projection of the satellite's position onto the Earth's surface; it is the intersection of the line connecting the satellite and the Earth's center with the Earth's surface, expressed in geocentric latitude. The longitude λ represents the satellite orbital elements a, e, Ω, i, ω, t. p Where a represents the semi-major axis of the elliptical orbit, e represents the eccentricity of the elliptical orbit, Ω represents the right ascension of the ascending node, i represents the inclination of the orbital plane, ω represents the argument of the pericenter, and t p The time of passing the pericenter is represented by λ; then the longitude λ and latitude of the sub-satellite point are... for

[0015]

[0016] in,

[0017]

[0018] In the formula, μ=ω+θ, λ B =Ω-α(t), where α(t) is the right ascension of the satellite at time t, and r = (α(t)(1-e)^2) / (1+ecosθ); θ is the angle between the line connecting the frequency-using equipment and the Earth's center, and between the line connecting the satellite and the Earth's center;

[0019] S2. Establish an electronic reconnaissance threat assessment model.

[0020] 2.1 Temporal Threat Level

[0021] Temporal threat refers to the temporal visibility of frequency-using equipment by electronic reconnaissance satellites, including the number of revisits within a specified time and the reconnaissance time.

[0022] (1) Number of revisits within the specified time

[0023] The specified number of revisits refers to the total number of times the frequency-using equipment appears within the reconnaissance area of ​​an electronic reconnaissance satellite within a specified time period;

[0024] The criteria for determining whether a frequency-using device is within the reconnaissance area are: assuming the current time is t, and the latitude and longitude of the frequency-using device on the ground are... The latitude and longitude of the electronic reconnaissance satellite's nadir point are: At this point, the geocentric angle between the frequency-using device and the nadir point of the electronic reconnaissance satellite is obtained as follows:

[0025]

[0026] If α m If (t) < α, the frequency-using equipment is located within the reconnaissance area of ​​the electronic reconnaissance satellite; otherwise, it is not within the reconnaissance area of ​​the electronic reconnaissance satellite.

[0027] (2) Reconnaissance time

[0028] Reconnaissance time refers to the time during which an electronic reconnaissance satellite conducts reconnaissance of a frequency-using device. The half-field-of-view angle of the electronic reconnaissance satellite's reconnaissance beam is β. When the frequency-using device is located at a position where the trajectory deviation angle of the electronic reconnaissance satellite's nadir point is ε, the arc segment of the trajectory that can be detected on the nadir point trajectory is...

[0029]

[0030] The effective reconnaissance time for this frequency-using device is then...

[0031] t1=T0P1 (8)

[0032] When ε = 0°, the reconnaissance target is on the nadir trajectory, and t1 is the maximum reconnaissance time:

[0033]

[0034] Let the maximum reconnaissance time threshold be T. v When t 1max >T v And α m When (t) < α, time-domain concealment cannot function properly, generating a time-domain threat warning;

[0035] 2.2 Frequency Domain Threat Level

[0036] Frequency domain threat level is measured by the detectable frequency occupancy. Detectable frequency occupancy is defined as the degree to which electronic reconnaissance satellites can detect frequency-using equipment in the frequency domain, that is, the degree of overlap between the operating frequency and the reconnaissance frequency band of the electronic reconnaissance satellites. Detectable frequency occupancy is the ratio of the frequency range that electronic reconnaissance satellites can detect to the frequency-using equipment to the frequency range that the frequency-using equipment can operate.

[0037]

[0038] In the formula, m represents the number of frequencies that the electronic reconnaissance satellite can access for reconnaissance; f i2 f i1 The upper and lower limits of frequencies that electronic reconnaissance satellites can detect for frequency-using equipment; n is the number of frequency bands that the frequency-using equipment can operate on; f j2 f j1 These are the upper and lower limits of the frequency used by the frequency-consuming device when it operates in the j-th frequency band.

[0039] Let Thr be the maximum detectable frequency occupancy threshold. v When Thr f >Thr v At this time, frequency domain concealment cannot function properly, generating a frequency domain threat warning;

[0040] 2.3 Airspace Threat Level

[0041] The airspace threat level is the ratio of the spatial angular range of the electronic reconnaissance satellite relative to the frequency-using equipment to the spatial angular range of the frequency-using equipment's antenna main lobe beam when the main lobe beam of the electronic reconnaissance satellite antenna covers the frequency-using equipment; it includes azimuth coverage and elevation coverage.

[0042] (1) Azimuth coverage

[0043] When the main lobe beam of an electronic reconnaissance satellite's reconnaissance antenna covers the frequency-using equipment, the probability that the electronic reconnaissance satellite will appear within the azimuth range of the frequency-using equipment's antenna.

[0044]

[0045] In the formula, Δθ represents the azimuth range of the electronic reconnaissance satellite located at the frequency-using equipment when the main lobe beam of the electronic reconnaissance satellite antenna covers the frequency-using equipment; α 0.5 θ1 is the azimuth beamwidth of the frequency-using equipment antenna; θ2 and θ1 are the upper and lower limits of the azimuth effective range of the frequency-using equipment antenna.

[0046] (2) Coverage at elevation angle

[0047] When the main lobe beam of an electronic reconnaissance satellite's antenna covers the frequency-using equipment, the probability that the electronic reconnaissance satellite will appear within the elevation range of the frequency-using equipment's antenna is as follows:

[0048]

[0049] In the formula, When the main lobe beam of an electronic reconnaissance satellite antenna covers the frequency-using equipment, the electronic reconnaissance satellite is located within the elevation angle range of the frequency-using equipment; β 0.5 The azimuth beamwidth of the frequency-using equipment antenna; These are the upper and lower limits of the azimuth range of the frequency-using equipment's antenna;

[0050] Let the azimuth coverage threshold be S. θv The elevation angle coverage threshold is S. ψv When S θ >S θv And S ψ >S ψv At that time, the airspace concealment function cannot work properly, generating an airspace threat warning;

[0051] 2.4 Energy Domain Threat Level

[0052] The energy domain threat level is determined by the maximum reconnaissance range, and the sensitivity of the electronic reconnaissance satellite receiver is P. rmin The antenna gain of the electronic reconnaissance equipment is G. r The transmitting power of the frequency-using equipment is P t The gain of the frequency-using equipment antenna in the direction of the reconnaissance receiver is G. t Given (θ), the signal wavelength of the frequency-using equipment is λ, and the total losses due to atmosphere, polarization, and the equipment are L; then the maximum reconnaissance range of the electronic reconnaissance satellite for the frequency-using equipment is given by the reconnaissance equation, specifically:

[0053]

[0054] Let the transmit power threshold of the frequency-using equipment be P. v When P t >P v When the energy domain concealment fails to function properly, an energy domain threat warning is generated;

[0055] S3, Electronic noise interference

[0056] Noise interference is employed by setting up a noise interference source and emitting a noise signal with a certain bandwidth. The bandwidth of the noise signal is greater than the signal bandwidth or operating bandwidth of the frequency-using equipment, and the noise signal strength is greater than the signal strength.

[0057] When providing cover for ground-based frequency-using equipment, jammers are deployed around the equipment station. The jammers' interference frequency is aligned with the operating frequency of the equipment, and the maximum value direction of the jammer's antenna is pointed towards the electronic reconnaissance satellite. It is deduced that the minimum equivalent radiated power of the jammer is...

[0058] P j G j =2·P t G t (θ) (14)

[0059] In the formula, P t G t (θ) represents the equivalent radiated power of the frequency-using equipment at an angle θ, where θ is the solid angle of the electronic reconnaissance satellite relative to the ground-based frequency-using equipment;

[0060] The reconnaissance capability of an electronic reconnaissance system is analyzed using reconnaissance equations.

[0061]

[0062] In the formula, P t G represents the emission power of the radiation source. t G represents the gain of the radiating source antenna in the direction of the electronic reconnaissance equipment. r Antenna gain of electronic reconnaissance equipment; λ is the wavelength of the radiation source signal; P rminSensitivity of the receiver in electronic reconnaissance equipment;

[0063] The reconnaissance range R of electronic reconnaissance equipment under noise interference conditions is derived from the reconnaissance equation. r max j The variation with external noise is as follows

[0064] R r max j =R r max (N r0 / (N r0 +ηN j )) 1 / 2 (16)

[0065] Where, N r0 For internal noise of the receiver in electronic reconnaissance equipment; N j The noise power is the external noise interference; η is the matching factor between the receiver filter bandwidth and the noise spectrum bandwidth, 0 < η < 1; when the noise interference signal entering the receiver of the electronic reconnaissance equipment is compared with the target signal power... At that time, the signal-to-noise ratio in the receiver of the electronic reconnaissance equipment deteriorated sharply, making it impossible to detect and intercept the radiation source signal.

[0066] Furthermore, the maximum effective range of the aforementioned electronic reconnaissance equipment is less than the altitude of the satellite above the ground.

[0067] Due to the adoption of the technical solution described above, the present invention has the following advantages:

[0068] This method for preventing electromagnetic signals of frequency-using equipment from being detected by enemy electronic reconnaissance satellites reduces the probability of these signals being detected by enemy electronic reconnaissance satellites by employing avoidance and active interference methods in four dimensions: time, frequency, space, and energy, thus ensuring the security of the electromagnetic signals of the frequency-using equipment. It can also avoid interference with our own electronic reconnaissance satellites, ensuring their normal operation. Attached Figure Description

[0069] Figure 1 This is a schematic diagram of the reconnaissance model of an electronic reconnaissance satellite;

[0070] Figure 2 This is a schematic diagram of the structure of the reconnaissance coverage area of ​​an electronic reconnaissance satellite;

[0071] Figure 3 This is a structural block diagram of the threat assessment indicators for frequency-using equipment posed by electronic reconnaissance satellites;

[0072] Figure 4 This is a flowchart of the method for using frequency-controlled equipment to prevent satellite electronic reconnaissance. Detailed Implementation

[0073] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0074] A method for preventing satellite electronic reconnaissance of electromagnetic signals used by frequency-based equipment, comprising the following steps:

[0075] S1. Establish a satellite electronic reconnaissance model

[0076] If we consider the Earth as a perfect sphere, the coverage area of ​​an electronic reconnaissance satellite is defined as the region on the Earth's surface covered by the main lobe beam of the satellite's antenna. For example... Figure 1 As shown, assuming the main lobe beam center of the electronic reconnaissance satellite's antenna always points to the Earth's center position O, and the Earth's radius is Re, the satellite's orbital altitude is h, the electronic reconnaissance satellite's half-field of view is β (half of the main lobe beam of the reconnaissance antenna), and the geocentric angle α of the ground covered by the electronic reconnaissance satellite is...

[0077]

[0078] The width W of the electronic reconnaissance satellite coverage area is

[0079]

[0080] The area A1 of the instantaneous reconnaissance range is

[0081]

[0082] For non-geostationary orbit electronic reconnaissance satellites, their spatial position changes over time, causing their coverage area on the Earth's surface to change as well, thus forming the electronic reconnaissance satellite coverage area, such as... Figure 2 No.

[0083] The coverage area of ​​an electronic reconnaissance satellite is related to its nadir point trajectory. The nadir point is the vertical projection of the satellite's position onto the Earth's surface; it is the intersection of the line connecting the satellite and the Earth's center with the Earth's surface, measured in geocentric latitude. The longitude λ represents the satellite orbital elements a, e, Ω, i, ω, t. p Where a represents the semi-major axis of the elliptical orbit, e represents the eccentricity of the elliptical orbit, Ω represents the right ascension of the ascending node, i represents the inclination of the orbital plane, ω represents the argument of the pericenter, and t p The time of passing the pericenter is represented by λ; then the longitude λ and latitude of the sub-satellite point are... for

[0084]

[0085] in,

[0086]

[0087] In the formula, μ=ω+θ, λ B =Ω-α(t), where α(t) is the right ascension of the satellite at time t, and r = (α(t)(1-e)^2) / (1+ecosθ); θ is the angle between the line connecting the frequency-using equipment and the Earth's center, and between the line connecting the satellite and the Earth's center;

[0088] S2. Establish an electronic reconnaissance threat assessment model.

[0089] Due to differences in orbit, reconnaissance payload, and other factors, electronic reconnaissance satellites pose varying threats to ground-based frequency-using equipment from different angles. These threats can differ significantly and are generally described in the time domain, frequency domain, spatial domain, and energy domain. Figure 3 As shown.

[0090] 2.1 Temporal Threat Level

[0091] Temporal threat refers to the temporal visibility of frequency-using equipment by electronic reconnaissance satellites, including the number of revisits within a specified time and the reconnaissance time.

[0092] (1) Number of revisits within the specified time

[0093] The specified number of revisits refers to the total number of times the frequency-using equipment appears within the reconnaissance area of ​​an electronic reconnaissance satellite within a specified time period;

[0094] The criteria for determining whether a frequency-using device is within the reconnaissance area are: assuming the current time is t, and the latitude and longitude of the frequency-using device on the ground are... The latitude and longitude of the electronic reconnaissance satellite's nadir point are: At this point, the geocentric angle between the frequency-using device and the nadir point of the electronic reconnaissance satellite is obtained as follows:

[0095] If α m If (t) < α, the frequency-using equipment is located within the reconnaissance area of ​​the electronic reconnaissance satellite; otherwise, it is not within the reconnaissance area of ​​the electronic reconnaissance satellite.

[0096] (2) Reconnaissance time

[0097] Reconnaissance time refers to the time during which an electronic reconnaissance satellite conducts reconnaissance of a frequency-using device. The half-field-of-view angle of the electronic reconnaissance satellite's reconnaissance beam is β. When the frequency-using device is located at a position where the trajectory deviation angle of the electronic reconnaissance satellite's nadir point is ε, the arc segment of the trajectory that can be detected on the nadir point trajectory is...

[0098]

[0099] The effective reconnaissance time for this frequency-using device is then...

[0100] t1=T0P1 (8)

[0101] When ε = 0°, the reconnaissance target is on the nadir trajectory, and t1 is the maximum reconnaissance time:

[0102]

[0103] Let the maximum reconnaissance time threshold be T. v When t 1max >T v And α m When (t) < α, time-domain concealment cannot function properly, generating a time-domain threat warning;

[0104] 2.2 Frequency Domain Threat Level

[0105] Frequency domain threat level is measured by the detectable frequency occupancy. Detectable frequency occupancy is defined as the degree to which electronic reconnaissance satellites can detect frequency-using equipment in the frequency domain, that is, the degree of overlap between the operating frequency and the reconnaissance frequency band of the electronic reconnaissance satellites. Detectable frequency occupancy is the ratio of the frequency range that electronic reconnaissance satellites can detect to the frequency-using equipment to the frequency range that the frequency-using equipment can operate.

[0106]

[0107] In the formula, m represents the number of frequencies that the electronic reconnaissance satellite can access for reconnaissance; f i2 f i1 The upper and lower limits of frequencies that electronic reconnaissance satellites can detect for frequency-using equipment; n is the number of frequency bands that the frequency-using equipment can operate on; f j2 f j1 These are the upper and lower limits of the frequency used by the frequency-consuming device when it operates in the j-th frequency band.

[0108] Let Thr be the maximum detectable frequency occupancy threshold. v When Thr f >Thr v At this time, frequency domain concealment cannot function properly, generating a frequency domain threat warning;

[0109] 2.3 Airspace Threat Level

[0110] Without considering the reconnaissance of frequency-using equipment by the sidelobes of the electronic reconnaissance satellite antenna, the airspace threat level is the ratio of the spatial angular range of the electronic reconnaissance satellite relative to the frequency-using equipment to the spatial angular range of the main lobe of the frequency-using equipment antenna when the main lobe beam of the electronic reconnaissance satellite antenna covers the frequency-using equipment; it includes azimuth coverage and elevation coverage.

[0111] (1) Azimuth coverage

[0112] When the main lobe beam of an electronic reconnaissance satellite's reconnaissance antenna covers the frequency-using equipment, the probability that the electronic reconnaissance satellite will appear within the azimuth range of the frequency-using equipment's antenna.

[0113]

[0114] In the formula, Δθ represents the azimuth angle range of the electronic reconnaissance satellite located on the frequency-using equipment when the main lobe beam of the electronic reconnaissance satellite antenna covers the frequency-using equipment, in degrees; α 0.5 θ1 is the azimuth beamwidth of the frequency-using equipment antenna, in degrees; θ2 and θ1 are the upper and lower limits of the azimuth range of the frequency-using equipment antenna. Generally, θ2-θ1=360°.

[0115] (2) Coverage at elevation angle

[0116] When the main lobe beam of an electronic reconnaissance satellite's reconnaissance antenna covers the frequency-using equipment, the probability of the electronic reconnaissance satellite appearing within the elevation range of the frequency-using equipment's antenna is as follows.

[0117]

[0118] In the formula, When the main lobe beam of an electronic reconnaissance satellite antenna covers the frequency-using equipment, the elevation angle range of the electronic reconnaissance satellite relative to the frequency-using equipment is measured in degrees; β 0.5 The azimuth beamwidth of the frequency-using equipment antenna is expressed in degrees (°). This represents the upper and lower limits of the azimuth range of the frequency-using equipment's antenna. Generally,

[0119] For geostationary orbit (GEO), since the electronic reconnaissance satellite is stationary relative to the Earth, its azimuth and elevation angles at the frequency-using equipment are fixed. Threats in the airspace primarily depend on the main lobe beamwidth of the frequency-using equipment's antenna;

[0120] Let the azimuth coverage threshold be S. θv The elevation angle coverage threshold is S. ψv When S θ >S θv And S ψ >S ψv At that time, the airspace concealment function cannot work properly, generating an airspace threat warning;

[0121] 2.4 Energy Domain Threat Level

[0122] The energy domain threat level is expressed by the maximum reconnaissance range, which is related not only to the sensitivity of the electronic reconnaissance satellite's reconnaissance receiver, but also to the transmission power of the frequency-using equipment and the antenna.

[0123] The sensitivity of the electronic reconnaissance satellite receiver is P. rmin The antenna gain of the electronic reconnaissance equipment is G. r The transmitting power of the frequency-using equipment is P tThe gain of the frequency-using equipment antenna in the direction of the reconnaissance receiver is G. t Given (θ), the signal wavelength of the frequency-using equipment is λ, and the total losses due to atmosphere, polarization, and the equipment are L; then the maximum reconnaissance range of the electronic reconnaissance satellite for the frequency-using equipment is given by the reconnaissance equation, specifically:

[0124]

[0125] Let the transmit power threshold of the frequency-using equipment be P. v When P t >P v When the energy domain concealment fails to function properly, an energy domain threat warning is generated;

[0126] S3, Electronic noise interference

[0127] Electronic jamming is achieved by using active interference to submerge the electromagnetic signals radiated by frequency-using equipment at the antenna receiver of an electronic reconnaissance satellite in noise or dense false target signals, thus preventing the electronic reconnaissance satellite from effectively detecting the radiated signals of the frequency-using equipment.

[0128] In this invention, the active interference method uses noise interference. By setting a noise interference source, a noise signal with a certain bandwidth is emitted. The bandwidth of the noise signal is greater than the signal bandwidth or operating bandwidth of the frequency-using equipment, and the noise signal strength is greater than the signal strength.

[0129] Assuming the need is to protect ground-based frequency-using equipment, to achieve good protection, the noise power reaching the electronic reconnaissance satellite needs to be 3dB greater than the signal power of the frequency-using equipment. Generally, jammers are deployed around the frequency-using equipment station, at a distance much smaller than the altitude of the reconnaissance satellite. To enhance the jamming effect, the jammer's jamming frequency is aligned with the operating frequency of the frequency-using equipment, and the maximum value direction of the jammer's antenna is aligned with the electronic reconnaissance satellite. It can be deduced that the minimum equivalent radiated power of the jammer is...

[0130] P j G j =2·P t Gt(θ) (14)

[0131] In the formula, P t G t (θ) represents the equivalent radiated power of the frequency-using equipment at an angle θ, where θ is the solid angle of the electronic reconnaissance satellite relative to the ground-based frequency-using equipment;

[0132] The reconnaissance capability of an electronic reconnaissance system is analyzed using reconnaissance equations.

[0133]

[0134] In the formula, P tG is the transmitted power of the radiation source; G is the gain of the radiation source antenna in the direction of the electronic reconnaissance equipment; G r Antenna gain of electronic reconnaissance equipment; λ is the wavelength of the radiation source signal; P rmin The sensitivity of the receiver in electronic reconnaissance equipment.

[0135] The reconnaissance range of electronic reconnaissance equipment under noise interference conditions is derived from the reconnaissance equation.

[0136] R rmaxj =R rmax (N r0 / (N r0 +ηN j )) 1 / 2 (16)

[0137] Where, N r0 For internal noise of the receiver in electronic reconnaissance equipment; N j Let η be the noise power of external noise interference; η is the matching factor between the receiver filter bandwidth and the noise spectrum bandwidth of the electronic reconnaissance equipment, 0 < η < 1; when the noise power ηN enters the receiver of the electronic reconnaissance equipment... j When it is large, its detection range R rmax j It will decrease significantly; when the power ratio of the noise interference signal entering the receiver of the electronic reconnaissance equipment to the target signal... At that time, the signal-to-noise ratio inside the receiver of the electronic reconnaissance equipment deteriorated sharply, making it impossible to detect and intercept the radiation source signal;

[0138] To ensure the jamming effect, the maximum effective range of the aforementioned electronic reconnaissance equipment is less than the altitude of the satellite above the ground.

[0139] The technical solution of the present invention will be described in detail below through a method of preventing reconnaissance by a single electronic reconnaissance satellite using a single frequency-using device.

[0140] exist Figure 4 In the middle, {f1, f2, ..., f n} represents the set of operating frequencies of the radiation sources of the frequency-using equipment, F S For electronic reconnaissance satellite reconnaissance frequency band, P t G t P represents the equivalent radiated power in the main lobe direction of the frequency-using equipment's radiation source. t G t ′ represents the equivalent radiated power in the sidelobe direction of the frequency-using equipment's radiation source. The equivalent received power at the radiation source location corresponds to the sensitivity of the electronic reconnaissance satellite receiver.

[0141] like Figure 4 As shown, a method for preventing satellite electronic reconnaissance using electromagnetic signals of frequency-based equipment includes the following specific steps:

[0142] Step 1: Analyze and determine whether the electronic reconnaissance satellite is in a geosynchronous orbit. If so, the satellite can conduct reconnaissance throughout the entire time domain and cannot be avoided in terms of time. In this case, avoidance can be achieved in the frequency domain, and proceed to Step 2. If it is not in a geosynchronous orbit, calculate the specific time period of the satellite's transit and use a time-avoidance method to determine the avoidance time interval to prevent the signal from being detected or to interfere with the satellite.

[0143] Step 2: Frequency domain avoidance requires our frequency-using equipment to avoid the frequencies used by satellite reconnaissance. If it is not possible to avoid them and there is an overlap in frequencies, then avoidance needs to be carried out in the airspace. Proceed to Step 3. If they can be avoided, calculate the safe frequencies that our frequency-using equipment can use and provide the set of usable frequencies.

[0144] Step 3, airspace avoidance, refers to airspace avoidance in terms of the orientation of our frequency-using equipment antenna. The main purpose is to ensure that the antenna's electromagnetic signal radiation range can avoid the satellite's reconnaissance antenna, so that the satellite's reconnaissance antenna is not within the radiation range of the ground frequency-using equipment antenna. If it can be effectively avoided, the usable airspace range of the antenna can be calculated. If airspace avoidance cannot be achieved due to usage requirements, then proceed to step 4.

[0145] Step 4, Energy Domain Avoidance, refers to the situation where the three domains in Steps 1 to 3 above cannot be avoided, but the equipment still needs to be powered on and used. In this case, the output power of the ground frequency equipment needs to be controlled so that the output signal power, after spatial attenuation, reaches the satellite reconnaissance antenna and is less than the antenna sensitivity. The maximum output power value of the ground frequency equipment is calculated through a calculation model. If power control still cannot effectively avoid the problem, then proceed to Step 5.

[0146] Step 5: By adopting ground-based electronic jamming methods, mainly including noise jamming and deception jamming, the satellite reconnaissance range is compressed or the reconnaissance effectiveness against effective signals is reduced. The power value of active jamming is obtained through calculation models.

[0147] The above description is only a preferred embodiment of the present invention and not a limitation thereof. Any equivalent changes and modifications made in accordance with the scope of the present invention without departing from the spirit and scope of the present invention shall be within the scope of patent protection of the present invention.

Claims

1. A method for preventing satellite electronic reconnaissance of electromagnetic signals used by frequency-based equipment, characterized by: It includes the following steps: S1. Establish a satellite electronic reconnaissance model Assuming the main lobe beam center of the electronic reconnaissance satellite's antenna always points towards the Earth's center, and the Earth's radius is R. e The satellite's orbital altitude is h, the electronic reconnaissance satellite's half-field of view is β, and the geocentric angle of the ground covered by the electronic reconnaissance satellite is... for （1） The width W of the electronic reconnaissance satellite coverage area is （2） Area of ​​instantaneous reconnaissance range for （3）； For non-geostationary orbit electronic reconnaissance satellites, the coverage area is related to the nadir trajectory. The nadir is the vertical projection of the satellite's position onto the Earth's surface; it is the intersection of the line connecting the satellite and the Earth's center with the Earth's surface, expressed in geocentric latitude. and longitude It indicates that the satellite orbital elements are , , , , , ;in, Represents the semi-major axis of the elliptical orbit. The eccentricity of an elliptical orbit is represented by... The right ascension of the ascending node is indicated. Indicates the inclination angle of the orbital plane. Indicates the argument of the pericentric point. The time of passing the pericenter is indicated; then the longitude of the sub-satellite point is indicated. and latitude for （4） in, （5） In the formula, , , for The right ascension of the satellite at any given time, ; The angle between the frequency-using equipment and the line connecting the Earth's core, and between the satellite and the Earth's core; S2. Establish an electronic reconnaissance threat assessment model. 2.1 Temporal Threat Level Temporal threat refers to the temporal visibility of frequency-using equipment by electronic reconnaissance satellites, including the number of revisits within a specified time and the reconnaissance time. (1) Number of revisits within the specified time period The specified time revisit count refers to the total number of times the frequency-using equipment appears within the reconnaissance area of ​​an electronic reconnaissance satellite within a specified time period; The criteria for determining whether a frequency-using device is within the reconnaissance area are: assuming the current time is... The latitude and longitude of the frequency-using equipment on the ground are: The latitude and longitude of the electronic reconnaissance satellite's nadir point are: At this point, the geocentric angle between the frequency-using equipment and the nadir point of the electronic reconnaissance satellite is obtained as... （6） like If the frequency-using equipment is located within the reconnaissance area of ​​the electronic reconnaissance satellite, then it is located within the reconnaissance area of ​​the electronic reconnaissance satellite; otherwise, it is located outside the reconnaissance area of ​​the electronic reconnaissance satellite. (2) Reconnaissance time Reconnaissance time refers to the time during which an electronic reconnaissance satellite conducts reconnaissance of frequency-using equipment; the half-field-of-view angle of the electronic reconnaissance satellite's reconnaissance beam is... When the frequency-using equipment is located at the sub-satellite point of the electronic reconnaissance satellite, the trajectory deviation angle is... At a certain location, the trajectory arc of the frequency-using device can be detected on the sub-satellite point trajectory. （7） The effective reconnaissance time for this frequency-using device is then... （8） when The reconnaissance target is on the orbital path below the star. Maximum reconnaissance time: （9） Let the maximum reconnaissance time threshold be T. v When t 1max >T v And α m When (t) < α, time-domain concealment cannot function properly, generating a time-domain threat warning; 2.2 Frequency Domain Threat Level Frequency domain threat level is measured by the detectable frequency occupancy. Detectable frequency occupancy is defined as the degree to which electronic reconnaissance satellites can detect frequency-using equipment in the frequency domain, that is, the degree of overlap between the operating frequency and the reconnaissance frequency band of the electronic reconnaissance satellites. Detectable frequency occupancy is the ratio of the frequency range that electronic reconnaissance satellites can detect to the frequency-using equipment to the frequency range that the frequency-using equipment can operate. （10） In the formula, The number of frequencies that electronic reconnaissance satellites can access for reconnaissance purposes; The upper and lower limits of frequencies that electronic reconnaissance satellites can detect for frequency-using equipment; The number of frequency bands that the frequency-using equipment can operate on; For frequency-using equipment to operate in the first The upper and lower limits of the frequency band; Let Thr be the maximum detectable frequency occupancy threshold. v When Thr f >Thr v At this time, frequency domain concealment cannot function properly, generating a frequency domain threat warning; 2.3 Airspace Threat Level The airspace threat level is the ratio of the spatial angular range of the electronic reconnaissance satellite relative to the frequency-using equipment to the spatial angular range of the frequency-using equipment's antenna main lobe beam when the main lobe beam of the electronic reconnaissance satellite antenna covers the frequency-using equipment; it includes azimuth coverage and elevation coverage. (1) Azimuth coverage When the main lobe beam of an electronic reconnaissance satellite's reconnaissance antenna covers the frequency-using equipment, the probability that the electronic reconnaissance satellite will appear within the azimuth range of the frequency-using equipment's antenna. （11） In the formula, When the main lobe beam of an electronic reconnaissance satellite antenna covers the frequency-using equipment, the electronic reconnaissance satellite is located within the azimuth range of the frequency-using equipment. The azimuth beamwidth of the frequency-using equipment antenna; These are the upper and lower limits of the azimuth range of the frequency-using equipment's antenna; (2) Coverage at elevation angle When the main lobe beam of an electronic reconnaissance satellite's reconnaissance antenna covers the frequency-using equipment, the probability that the electronic reconnaissance satellite will appear within the elevation range of the frequency-using equipment's antenna. （12） In the formula, When the main lobe beam of an electronic reconnaissance satellite antenna covers the frequency-using equipment, the electronic reconnaissance satellite is located within the elevation angle range of the frequency-using equipment; The azimuth beamwidth of the frequency-using equipment antenna; The upper and lower limits of the azimuth range of the frequency-using equipment antenna; Let the azimuth coverage threshold be S. θv The elevation angle coverage threshold is S. ψv When S θ >S θv And S ψ >S ψv At that time, the airspace concealment function cannot work properly, generating an airspace threat warning; 2.4 Energy Domain Threat Level The energy domain threat level is determined by the maximum reconnaissance range, and the sensitivity of the electronic reconnaissance satellite receiver is [value missing]. The antenna gain of the electronic reconnaissance equipment is The transmitting power of the frequency-using equipment is The gain of the frequency-using equipment antenna in the direction of the reconnaissance receiver is The signal wavelength of the frequency-using equipment is The total losses from the atmosphere, polarization, and equipment are: The maximum reconnaissance range of an electronic reconnaissance satellite over frequency-using equipment is given by the reconnaissance equation, specifically: （13） Let the transmit power threshold of the frequency-using equipment be P. v ,when >P v When the energy domain concealment fails to function properly, an energy domain threat warning is generated; S3, Electronic noise interference Noise interference is employed by setting up a noise interference source to emit a noise signal with a certain bandwidth. The bandwidth of the noise signal is greater than the signal bandwidth or operating bandwidth of the frequency-using equipment, and the noise signal strength is greater than the signal strength. When providing cover for ground-based frequency-using equipment, jammers are deployed around the equipment station. The jammers' interference frequency is aligned with the operating frequency of the equipment, and the maximum value direction of the jammer's antenna is pointed towards the electronic reconnaissance satellite. It is deduced that the minimum equivalent radiated power of the jammer is... （14） In the formula, For frequency-using equipment at angle The equivalent radiated power, The angle is the solid angle of the electronic reconnaissance satellite relative to the ground-based frequency-using equipment; The reconnaissance capability of an electronic reconnaissance system is analyzed using reconnaissance equations. （15） In the formula, 'This refers to the emission power of the radiation source; The gain of the radiating source antenna in the direction of the electronic reconnaissance equipment; Antenna gain of electronic reconnaissance equipment; 'Where the wavelength of the radiation source signal is located; Sensitivity of the receiver in electronic reconnaissance equipment; The reconnaissance range of electronic reconnaissance equipment under noise interference conditions is derived from the reconnaissance equation. The variation with external noise is as follows （16） in, This refers to the internal noise of the receiver in electronic reconnaissance equipment. The noise power is the noise power caused by external noise interference. The matching factor between the receiver filter bandwidth and the noise spectrum bandwidth, 0 < <1; When the power ratio of the noise interference signal entering the receiver of the electronic reconnaissance equipment to the target signal is... When the signal-to-noise ratio is greater than 1, the signal-to-noise ratio inside the receiver of the electronic reconnaissance equipment deteriorates sharply, making it impossible to detect and intercept the radiation source signal.

2. The method for preventing satellite electronic reconnaissance of frequency-using equipment using electromagnetic signals according to claim 1, characterized in that: In step S3, the maximum effective range of the electronic reconnaissance equipment is less than the altitude of the satellite above the ground.

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