CN102819016A - Passive detection system and method for detecting low-altitude target by using navigation radar signals - Google Patents

Abstract

The invention discloses a passive detection system for detecting low-altitude targets by using navigation radar signals, which relates to the field of passive radar and includes a non-cooperative navigation radar, a passive receiving system, a signal information processing module and a geographic information module for displaying positioning results. The invention also discloses a method for passively locating low-altitude targets by using navigation radar, which includes steps: 1. The passive receiving system measures the angle of arrival of the direct signal and the target reflection signal; The azimuth angle of the path scanning to the target reflection path; 3. Use the signal information processing module to obtain the time delay of the target reflection signal relative to the direct signal; 4. Obtain the above measurement, solve the triangle formed by the navigation radar, the target and the passive receiving system, and get The three-dimensional coordinates of the target; 5. The target position is given on the electronic map. The invention has the ability to detect low-altitude targets that maintain electromagnetic silence, and can realize situation monitoring and early warning.

Description

Passive detection system and method for detecting low-altitude targets using navigation radar signals

1. Technical field

The invention belongs to the technical field of passive radar, and in particular relates to the passive detection technology of a low-altitude target by using navigation radar signals on a sea movement platform.

2. Background technology

In modern warfare, due to the development of electronic offensive technology, active radar radar systems are facing increasingly serious threats from advanced weapons such as anti-radiation missiles and stealth aircraft, as well as combat methods such as integrated electronic interference and low-altitude penetration. Therefore, in order to improve the survivability of the radar and give full play to the effectiveness of the radar, various countermeasures must be adopted comprehensively.

In the field of traditional active radar, many measures against the four major threats have been proposed, including the use of specially designed signal waveforms to achieve low interception, improving the mobility of radars to prevent attacks from anti-radiation missiles, etc. However, due to the limitation of the curvature of the earth, the effective detection range of active radar for ultra-low-flying cruise missiles is reduced, which shortens the early warning time. When the low-altitude antenna beam configuration is used to detect low-altitude targets, the weak signal reflected by the low-altitude target is hidden in the ground clutter noise, which is difficult to distinguish. The passive radar that uses the signals emitted by the target's own radiation source intercepted by multiple receiving stations to locate the target is an effective measure against anti-radiation missiles. It determines the position of the radiation source and its carrier platform (target) by measuring the time delay and arrival angle parameters of the target signal to each station. But this passive radar fails when the target is radio silent and does not emit a signal.

The most promising countermeasure is not to emit electromagnetic signals itself, but to use the reflected signals on the target of electromagnetic signals emitted for other purposes in the environment to obtain the Doppler frequency shift, time difference of arrival and angle of arrival of the target echo. , so as to realize the passive radar system for target detection and positioning. The radar of this system can detect and track the target when the target remains "quiet", and the passive receiving station can still detect and track the target. The research on ground-based passive detection system based on TV DTV or FM radio DAB, Wimax and Wifi LAN signals, GSM mobile phone and other signals has achieved remarkable results and attracted widespread attention. Its typical representative is the "Silent Sentinel" developed by the United States, which made its debut at the Washington Exhibition on October 12, 1998. So far, there have been many land-based passive detection systems that focus on signals such as radio and television. However, in contrast, in the open sea area, due to the limitations of the available signals on the mobile platform, there have been no reports on the passive detection system of the ship-borne, submarine-borne and other maritime mobile platforms. It is almost impossible to receive civilian signals such as radio and television in the sea area of 10,000 kilometers.

With the development of the global maritime shipping industry, the International Maritime Organization (IMO) stipulates that in order to avoid collisions with other ships and fixed water targets, most ships must be equipped with navigation radar. At present, navigation radar has been popularized on private small ships. On large cargo ships, navigation radars with multiple different bands must be equipped. In the busy waterways and ports on the sea, for the safety of shipping, there are also navigation radars for monitoring sea traffic. The navigation radar radiation sources on all these platforms provide the possibility for passive detection and positioning of ship-borne, submarine-borne and other maritime mobile platforms.

3. Contents of the invention

1. Technical problems to be solved

The technical problem to be solved by the present invention is to provide a system for passive detection of low-altitude aircraft such as cruise missiles and ultra-low-altitude aircraft by using navigation radar signals, which can be used for low-altitude or ultra-low-altitude targets by ship-borne, submarine-borne and other marine motion platforms. monitoring and early warning.

The further technical problem to be solved by the present invention is to provide a positioning method for low-altitude or ultra-low-altitude targets using navigation radar signals for ship-borne, submarine-borne and other maritime motion platforms, which can obtain the three-dimensional coordinates of the target.

2. Technical solution

In order to solve the problems of the technologies described above, the present invention adopts the following technical measures:

Provide a passive detection system for detecting low-altitude or ultra-low-altitude targets using navigation radar signals, including non-cooperative navigation radar, passive receiving system, signal information processing module and geographic information module for displaying target positioning results, wherein the passive receiving system includes The direct wave channel is used to extract synchronization and reference information, and the reconnaissance channel is used to receive scattered signals of targets in the surveillance airspace.

A method for locating low-altitude or ultra-low-altitude targets using navigation radar signals is provided, including steps:

1. The passive receiving system measures the angle of arrival of the direct signal of the navigation radar and the reflected signal of the target;

2. Using the fluctuation characteristics of the direct wave pulse signal to estimate the azimuth angle of the navigation radar antenna scanning from the direct path to the target scattering path;

3. The signal information processing module uses the navigation radar signal intercepted by the direct wave channel as a reference signal to coherently process the target reflection signal received by the reconnaissance channel, and obtains the time delay of the target reflection signal relative to the direct wave signal;

4. Obtain the above measurement results, solve the bistatic triangle formed by the navigation radar, the target and the passive receiving system, and then obtain the three-dimensional coordinates of the low-altitude or ultra-low-altitude target;

5. Give the target location on the electronic map.

3. Beneficial effect

The beneficial effects of the present invention are: the passive detection system of the present invention has the advantages of wide detection area, high positioning accuracy, strong environmental adaptability, etc., and can provide long-distance passive detection cruise missiles, The capabilities of low-altitude and ultra-low-altitude aircraft such as ultra-low-altitude aircraft can provide situational surveillance and long-range early warning for maritime mobile combat platforms, which is of great military application value.

4. Description of drawings

Fig. 1 is a schematic diagram of the passive detection system of the present invention.

Fig. 2 is a three-dimensional geometric relationship diagram of the system space of the present invention.

Fig. 3 is a step diagram of the method of the present invention.

Fig. 4 is a flow chart of time delay and Doppler frequency shift parameter estimation of the target echo signal according to the present invention.

Fig. 5 is a schematic diagram of the specific application results of the present invention.

Fig. 6 is the positioning result of the target detected by the specific application of the present invention on the electronic map.

5. Specific implementation

The present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the present invention provides a passive detection system that uses navigation radar signals to detect low-altitude targets, including a non-cooperative navigation radar radiation source, a dual-channel passive receiving system, a signal information processing module, and a geographic display for displaying target positioning results. information module;

Among them, when the working frequency of the passive receiving system is tuned to the transmitting frequency of the non-cooperative navigation radar, the direct wave channel of the passive receiving system will detect the non-cooperative navigation radar signal propagating along the baseline, and its target reconnaissance channel will intercept the target in the surveillance area The reflected coherent coherent signal, and then the signal intercepted by the dual-channel passive receiving system is transmitted to the signal information processing module, which sorts the received direct wave signal and suppresses the direct wave interference in the target echo signal, and uses the signal information The processing module measures the relative delay and Doppler frequency shift of the echo signal of the target to be measured, and at the same time uses the fluctuation characteristics of the sorted direct wave signal to scan the azimuth angle θt of the transmitting antenna from the direct path to the target scattering path Estimate; then use the acquired target echo signal angle of arrival, relative time delay, Doppler frequency shift, angle of arrival of the direct wave signal, transmitting antenna azimuth angle θ _t information to perform target positioning, and form the target track; Finally, the geographic information module is used to display the target positioning results and track information on the electronic map to form a comprehensive situation map of the target.

As shown in Figure 2, the present invention also provides a method for passive positioning of low-altitude or ultra-low-altitude targets by using navigation radar signals. The specific implementation method is divided into the following steps:

1. The dual-channel passive receiving system measures the angle of arrival of the direct signal of the navigation radar and the reflected signal of the target;

2. Using the fluctuation characteristics of the direct wave pulse signal to estimate the azimuth angle of the navigation radar antenna scanning from the direct path to the target scattering path;

3. The signal information processing module uses the navigation radar signal intercepted by the direct wave channel as a reference signal to perform coherent processing with the target reflection signal received by the reconnaissance channel, and obtains the time delay of the target reflection signal relative to the direct wave signal;

4. Obtain the above measurement results, solve the bistatic triangle formed by the navigation radar, the target and the passive receiving system, and then obtain the three-dimensional coordinates of the low-altitude or ultra-low-altitude target;

5. Give the target location on the electronic map.

The analysis process of the passive positioning method for low-altitude or ultra-low-altitude targets using navigation radar signals is given below.

Taking the position of the passive receiving system as the origin, the target position is calculated in the Cartesian coordinate system composed of non-cooperative navigation radar-target-passive receiving system, and its spatial three-dimensional geometric relationship is shown in Figure 3. In the figure, R _t and R _r are the distances from the navigation radar radiation source and the passive receiving system to the target respectively, and the target height is represented by H. θ _t , φ _t represent the azimuth and pitch angles of the target relative to the navigation radar; θ _r , φ _r represent the azimuth and pitch angles of the target relative to the passive receiving system; θ _T , θ _R represent the relative Viewpoints of navigation radar emitters and passive receiving systems. Generally, for the system of the present invention, the azimuth angle θ _r and elevation angle φ _r of the target relative to the passive receiving system, and the bistatic time delay τ of the target echo relative to the direct wave pulse can be obtained relatively accurately. Assuming c is the speed of light, then

R _t +R _r -L=cτ (1)

Therefore, the prerequisite for the target to be localized is that both θ _t and L must have a parameter that is measurable. As for this system, the position information of the non-cooperative navigation radar is unknown a priori, so L is an unknown parameter. By comparing the signals emitted by different lobes of the navigation radar antenna, the azimuth angle θ _t can be estimated by using the fluctuation characteristics of the direct pulse sequence.

From the spatial geometric relationship shown in Figure 3, using the sine law, we can get

$\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; \&perp;</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; \&perp;</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, the subscript _⊥ represents the projection of the corresponding component on the vertical plane, and from Figure 3, we can know

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; \&perp;</span>}}{\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

H＝R _r⊥ tanφ _r ＝R _r cosφ _r tanφ _r ＝R _r sinφ _r (4)

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; \&perp;</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="HSA00000519351000041.png"\; state="\{\{state\}\}">h</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

cosθ _R = cosφ _r cosθ _r (6)

$\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

but

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; \&perp;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; c\&tau;</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

H＝R _r sinφ _r (10)

Substituting equations (8), (9), and (10) into equation (5), we get

${<span\; class="notranslate">\; [</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; c\&tau;</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

Solving equation (11), the slant distance of the target is

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; c\&tau;</span>}\frac{<span\; class="notranslate">\; \{</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span>\sqrt{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="sin"\; filenames="HSA00000519351000041.png"\; state="\{\{state\}\}">sin</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \}</span>}{{<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="sin"\; filenames="HSA00000519351000041.png"\; state="\{\{state\}\}">sin</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; )</span>$

Thus, the easy target height is

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; c\&tau;</span>}\frac{<span\; class="notranslate">\; \{</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span>\sqrt{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="sin"\; filenames="HSA00000519351000041.png"\; state="\{\{state\}\}">sin</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \}</span>}{{<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="sin"\; filenames="HSA00000519351000041.png"\; state="\{\{state\}\}">sin</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 13</span>}<span\; class="notranslate">\; )</span>$

As shown in Figure 4, the process of estimating time delay and Doppler frequency shift parameters in the signal information processing module includes the following steps:

(1) The direct wave signal is delayed and conjugated and multiplied with the target echo signal;

(2) Utilize the CIC filter to extract the result of step (1), thereby reducing the data sampling rate, narrowing the frequency analysis range, and filtering the result of extraction through a low-pass filter;

(3) Fast Fourier transform FFT is done to the filtered data, thereby obtaining the Doppler frequency shift estimation at this time delay unit;

(4) Repeat the process of (1), (2) and (3), and then perform peak detection on the mutual ambiguity function plane to obtain the maximum likelihood estimation of the target time delay and Doppler frequency shift.

As shown in Fig. 5, be an application example of the present invention, utilize the frequency that the navigation radar on a commercial passenger ship transmits is the signal of 9.41GHz, to the bistatic distance of the relative direct wave signal of the target echo intercepted in the monitoring area Difference and Doppler shift estimation results.

As shown in Figure 6, for the specific application of the present invention, using the target angle of arrival information obtained by the passive detection system and the bistatic distance difference and Doppler frequency shift of the target, the calculated position of the target relative to the passive detection system in the electronic map Finally, targets were found at distances of 31.5km, 19.7km and 70km from the passive detection system.

Claims (6)

1. utilize the passive detection system of navar acquisition of signal low target, it is characterized in that: comprise non-cooperation navar, passive receiving system, signal message processing module and geography information module;

When wherein the frequency of operation of passive receiving system is tuned at the transmission frequency of non-cooperation navar radiation source; Highly sensitive passive receiving system will detect along baseline and propagate direct wave signal and the target echo after the scattering of monitor area internal object that arrives; The signal of then passive receiving system being intercepted and captured is transferred to the signal message processing module; Obtain navar direct signal and time delay and Doppler shift through between the same source signal of target reflection; And utilize the signal message processing module, and resolve three-dimensional coordinate, speed, the flight path that obtains low latitude or treetop level target with the target time delay that receives and Doppler shift information and direct wave and the target echo angle of arrival, the parameter pairing of emission visual angle; Utilize the geography information module to preserve the signal message processing module at last and resolve the target position information that obtains at every turn, and on electronic chart, show the positioning result and the flight path of corresponding target.

2. passive detection system as claimed in claim 1 is characterized in that: described navar signal is S, the signal of C or many kinds of frequency ranges of X.

3. passive detection system as claimed in claim 1 is characterized in that: described navar is that navar, bank base harbour surveillance radar, commercial boat-carrying navar are kept watch in maritime traffic.

4. passive detection system as claimed in claim 1 is characterized in that: can be according to the adjustment of the monitor area of the system non-cooperation navar that utilizes of Dynamic Selection adaptively.

5. localization method that utilizes navar acquisition of signal low target, comprise step: 1. passive receiving system is measured the direct signal of navar and the angle of arrival of target echo; 2. utilize the fluctuation characteristic of direct wave pulse signal to estimate that the navar antenna scans the position angle in target scattering path from direct path; The signal message processing module utilize navar signal that the direct wave passage intercepts and captures as a reference signal with scout relevant processing of target echo that passage receives, obtain the time delay of the relative direct wave signal of target echo; 4. obtain above-mentioned measurement result, the bistatic triangle that Xie Youfei cooperation navar, target and passive receiving system constitute just can obtain the three-dimensional coordinate of low latitude or treetop level target; 5. on electronic chart, provide the target location.

6. method as claimed in claim 5 is characterized in that: it can survey aerial and sea-surface target equally, can position aircraft, guided missile, surface ship at a distance.

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