A radar P display afterglow simulation method based on double thresholds

Abstract

The present invention discloses a radar P display afterglow simulation method based on double thresholds, and the method comprises the following steps: a radar echo simulator generates an azimuth and corresponding radar video echo data; an attenuation factor is introduced, and the radar video echo data of the same azimuth in the previous circle is multiplied by the attenuation factor α, and the data is compared with the amplitude of each point of the current azimuth data, and the video echo data with a larger amplitude is retained; a double threshold judgment method is adopted to adjust the brightness of the radar video echo on the P display; and the radar echo data is displayed on the P display. The present invention attenuates the radar video echo amplitude by introducing an attenuation factor, and compares the amplitude of the video echo data of the current azimuth with the attenuated echo data of the same azimuth and distance in the previous circle, and the echo data with a larger amplitude is retained; a double threshold judgment method is adopted to display the processed radar echo data on the P display; after this method, the simulation effect and implementation efficiency of the P display afterglow are further improved.

Description

Technical Field

[0001] The invention relates to the technical field of radar display technology, and in particular to a radar P display afterglow simulation method based on double thresholds. Background Art

[0002] Radar uses the reflection of electromagnetic waves by the target to find the target's position. The radar display is used to display the target information and intelligence obtained by the radar. The displayed content includes the target's position and its movement trajectory, various characteristic parameters of the target, etc. For special types of radar, in addition to measuring the position of the target, it is also necessary to determine the nature of the target (such as model, track, number of aircraft, etc.) based on the characteristics and change rules of the radar video echo, which requires a variety of radar displays. Radar displays can be divided into distance displays, flat-panel displays, three-dimensional displays, etc. At present, flat-panel displays are the most widely used radar displays. They can display the distance and direction of radar targets and are two-dimensional displays; flat-panel displays provide all plane information in a 360° range, also known as PPI displays (Plan position indicator) or P displays.

[0003] The afterglow effect of radar P display is to judge the relevant parameters of the target (azimuth, distance, size and motion trajectory, etc.) by leaving a gradually fading afterglow on the radar P display. Traditional P display uses fluorescent materials inside the display to produce afterglow effect. Later, raster scanning radar display (also known as digital TV radar display) appeared, but raster scanning display cannot automatically produce the afterglow effect of fluorescent materials. At this time, artificial simulation is required to produce the afterglow effect. The line drawing method, fixed fan scanning method and point-by-point blanking method are the main simulation methods of afterglow of raster scanning display. These methods are also commonly used in computer simulation, but there is a problem that the simulation effect of afterglow effect is not obvious. Summary of the invention

[0004] In order to solve the above problems, an embodiment of the present invention provides a radar P display afterglow simulation method based on double thresholds, which specifically includes the following steps:

[0005] Step S1: The radar echo simulator generates the azimuth and corresponding radar video echo data;

[0006] Step S2: introducing the attenuation factor, when the antenna rotates to the sth circle (s≠1), multiplying the radar video echo data of the previous circle in the same direction by the attenuation factor α, and comparing it with the amplitude of each point of the current direction data, retaining the video echo data with a larger amplitude;

[0007] Step S3: using a double threshold decision method to adjust the brightness of the radar video echo on the P display;

[0008] Step S4: Display the radar echo data on the P display.

[0009] Preferably, step S1 comprises the following steps:

[0010] Step S11: The radar echo simulator generates azimuths at regular intervals; the radar antenna has a fixed rotation speed, and each rotation of the radar antenna is 360 degrees, which is divided into M azimuths on 360 degrees;

[0011] Step S12: Generate the radar transmission signal according to the following formula:

[0012]

[0013] Among them, s(t) is the radar transmission signal, t is the time, A s (t) is the signal amplitude, N is the number of pulses, rect() is the rectangular function, T r is the pulse repetition period, τ is the pulse width, f c is the carrier frequency of the transmitted signal, f s (t) is the time-varying frequency of the transmitted signal, is the initial phase of the transmitted signal, is the time-varying phase of the transmitted signal;

[0014] Step S13: When the radar simulator is working, the radar transmit signal is continuously transmitted at a fixed time. When encountering a target, the radar simulator will generate target echo data. Since the echo signal travels back and forth between the radar and the target, it will lag the transmission pulse t r , then by the formula:

[0015] 2R=ct r

[0016] The relationship between distance and time can be known; where c is the speed of light propagation in the air, the distance R of the target on the echo can be calculated at this time;

[0017] The echo signal h(t) scattered back by the target can be calculated according to the formula:

[0018]

[0019] Find, where N T is the target echo pulse number, G i (t) is the modulation function of the target on the transmitted signal, is the modulation function of the target on the phase of the transmitted signal, n h (t) is the environmental noise;

[0020] When the target is not encountered, only the ambient noise n is received h (t).

[0021] Preferably, the step S13 further includes the following steps:

[0022] Step S14: loop through steps S11, S12 and S13 for multiple times.

[0023] Preferably, step S2 comprises the following steps:

[0024] Step S21: when the antenna rotates for the first circle, the azimuth and same-azimuth radar video echo data generated by the radar echo simulator are saved, and when the antenna rotates for the sth circle (s≠1), the same-azimuth radar video echo data of the previous circle is multiplied by the attenuation factor α, and compared with the amplitude of each point of the current azimuth data, and the video echo data with a larger amplitude is retained;

[0025] Step S22: using a data space that only needs to store one circle, the video echo data of each circle is continuously updated to the data space;

[0026] Step S23: Execute steps S22 and S23 in a loop until the radar P display simulation is completed.

[0027] Preferably, step S3 includes the following steps: introducing a threshold low value and a threshold high value to perform a double threshold decision: normalizing the video echo data for processing, if the data amplitude in the echo data is lower than the low value, it is set to 0; if the data amplitude in the echo data is higher than the high value, it is set to 1; if the data amplitude in the echo data is between low and high, selecting and amplifying the data amplitude in the echo data to make the video echo at the target the brightest in the P display.

[0028] Preferably, the selection and enlargement process is one of linear mapping, convexity mapping and concavity mapping, and the transformation formula of the linear mapping is as follows:

[0029]

[0030] The transformation formula of the convexity mapping is as follows:

[0031]

[0032] The transformation formula of the concave mapping is as follows:

[0033]

[0034] Among them, V after is the amplitude after mapping, V former is the amplitude before mapping.

[0035] Preferably, step S4 comprises the following steps:

[0036] Step S41: Calculate the distance r of each point of the radar echo data by the following formula:

[0037] r=(ncT r ) / M, n=1,2,3,…,M;

[0038] Step S42: Display the radar video echo data on the radar P display according to the azimuth and distance of each point.

[0039] Compared with the prior art, the beneficial effects of the present invention include: a schematic diagram of a radar P-display afterglow simulation method based on a double threshold of the present invention, the method processes the corresponding radar video echo data according to the azimuth generated by the radar echo simulator for P-display display; by introducing an attenuation factor, the amplitude of the displayed radar video echo is attenuated, the amplitude of the video echo data at the current azimuth is compared with the attenuated echo data of the same azimuth and distance in the previous circle, and the echo data with a larger amplitude is retained; a double threshold judgment method is given to adjust the brightness of the radar video echo on the P-display; the processed radar echo data is displayed on the P-display using the double threshold judgment method; after this method, the P-display afterglow simulation effect and implementation efficiency are further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flow chart of the simulation method of the present invention;

[0041] Figure 2 is a flow chart of the simulation method of the present invention;

[0042] Figure 3 It is a waveform diagram of the radar transmission signal of the present invention;

[0043] Figure 4 is a waveform diagram of the echo signal of the present invention;

[0044] Figure 5 It is a polar coordinate diagram of the radar P display of the present invention;

[0045] Figure 6 It is the radar P display interface without any data processing;

[0046] Figure 7 It is the radar P display interface of the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0048] Example 1

[0049] The present invention provides a radar P display afterglow simulation method based on double thresholds. Figure 1 ,2 , Figure 1 , 2 Flow chart of the simulation method of the present invention; the method of the present invention comprises the following steps:

[0050] Step S1: The radar echo simulator generates the azimuth and corresponding radar video echo data.

[0051] Specifically, the steps include:

[0052] S11: The radar echo simulator generates azimuths at a fixed time; the radar antenna has a fixed rotation speed, and each rotation of the radar antenna is 360 degrees, which is divided into M azimuths on 360 degrees. According to the above division of azimuths, (0-360) degrees correspond to (0, 1, 2, ..., M-1) azimuths respectively.

[0053] S12: The radar transmission signal is generated according to the following formula:

[0054]

[0055] Among them, s(t) is the radar transmission signal, t is the time, A s (t) is the signal amplitude, N is the number of pulses, rect() is the rectangular function, T r is the pulse repetition period, τ is the pulse width, f c is the carrier frequency of the transmitted signal, f s (t) is the time-varying frequency of the transmitted signal, is the initial phase of the transmitted signal, is the time-varying phase of the transmitted signal.

[0056] For example, A s (t) is 1, T r for e -4 s,τ is 1*e -6 s, its transmission signal is as follows Figure 3 shown.

[0057] S13: When the radar simulator is working, the radar transmit signal is continuously transmitted at a fixed time. When encountering a target, the radar simulator will generate target echo data. Since the echo signal travels back and forth between the radar and the target, it will lag the transmission pulse t r , then by the formula:

[0058] 2R=ct r

[0059] The relationship between distance and time can be known; where c is the speed of light propagation in the air, the distance R of the target on the echo can be calculated at this time;

[0060] The echo signal h(t) scattered back by the target can be calculated according to the formula:

[0061]

[0062] Find, where N T is the target echo pulse number, G i (t) is the modulation function of the target on the transmitted signal, is the modulation function of the target on the phase of the transmitted signal, n h (t) is the environmental noise;

[0063] When the target is not encountered, only the ambient noise n is received h (t).

[0064] If the radar transmission signal encounters the target, the radar receiver will receive the radar echo signal, otherwise it will only receive environmental noise and clutter.

[0065] For example, A s (t) is 1, T r for e -4 s,τ is 1*e -6 s, when the target distance is 19km, the echo signal is as follows Figure 4 shown.

[0066] According to steps S11, S12 and S13, the azimuth and the same azimuth echo video data can be obtained. If the echo video data is to be continuously obtained, the azimuth and the video echo data need to be generated regularly, that is, steps S11, S12 and S13 are repeatedly executed. Preferably, the following steps are also included after steps S11, S12 and S13:

[0067] S14: Execute steps S11, S12 and S13 repeatedly.

[0068] Step S2: Introduce the attenuation factor. When the antenna rotates to the sth circle (s≠1), multiply the radar video echo data of the previous circle in the same direction by the attenuation factor α, compare it with the amplitude of each point of the current direction data, and retain the video echo data with a larger amplitude.

[0069] The attenuation factor α is introduced for the following purposes: Usually, the rotation speed of the radar antenna is from several revolutions per minute to dozens of revolutions per minute, so the antenna rotates once in several seconds to dozens of seconds; the fastest speed for the target is the speed of sound, and after the radar antenna rotates once, the target is near the target of the previous circle, so the attenuation factor α is introduced to simulate the real scene.

[0070] Specifically, step S2 includes the following steps:

[0071] S21: When the antenna rotates for the first circle, the azimuth and co-azimuth radar video echo data generated by the radar echo simulator are saved. When the antenna rotates for the sth circle (s≠1), the co-azimuth radar video echo data of the previous circle is multiplied by the attenuation factor α and compared with the amplitude of each point of the current azimuth data, and the video echo data with a larger amplitude is retained.

[0072] S22: A data space that only needs to store one circle is used, and the video echo data of each circle is continuously updated to the data space.

[0073] S23: Steps S22 and S23 are executed in a loop until the radar P display simulation is completed.

[0074] As the number of circles increases, the amplitude of the target's video echo signal is much larger than the noise. After comparison, the target echo data is saved until it decays to the size of the noise and disappears.

[0075] Step S3: Use a dual threshold decision method to adjust the brightness of the radar video echo on the P display.

[0076] Specifically, step S3 includes the following steps: introducing a threshold low value and a threshold high value to perform a double threshold decision: normalizing the video echo data for processing, if the data amplitude in the echo data is lower than the low value, it is set to 0; if the data amplitude in the echo data is higher than the high value, it is set to 1; if the data amplitude in the echo data is between low and high, selecting and amplifying the data amplitude in the echo data to make the video echo at the target the brightest in the P display.

[0077] Preferably, the selection and enlargement process is one of linear mapping, convexity mapping and concavity mapping, and the transformation formula of the linear mapping is as follows:

[0078]

[0079] The transformation formula of the convexity mapping is as follows:

[0080]

[0081] The transformation formula of the concave mapping is as follows:

[0082]

[0083] Among them, V after is the amplitude after mapping, V former is the amplitude before mapping.

[0084] The transformed video echo data is the selected and amplified video echo data before the transformation. This mapping can enhance the brightness of the higher amplitude of the radar data. By selecting a suitable double threshold decision method, the radar P display afterglow can be clearly displayed in the end.

[0085] Step S4: Display the radar echo data on the P display.

[0086] like Figure 5 As shown, the coordinates of the radar display are polar coordinates, where the dot is the radar position. The radar display position of the target can be accurately confirmed by knowing the direction and distance.

[0087] Specifically, step S4 includes the following steps:

[0088] S41: Calculate the distance r of each point of radar echo data by the following formula:

[0089] r=(ncT r ) / M, n=1,2,3,…,M.

[0090] S42: Display the radar video echo data on the radar P display according to the azimuth and distance of each point.

[0091] Figure 6 This is the radar P display interface without any data processing. Figure 6 As shown in the figure, without any data processing, the radar P display interface cannot see the afterglow phenomenon, and the bright arc at the radar target is dim; if the clutter or noise amplitude is too large, the interface will be full of dim bright spots, which brings difficulties to the identification of the target and the judgment of the target related parameters.

[0092] like Figure 7 The radar P display interface of the present invention is shown. Figure 7 As shown, the afterglow phenomenon of the radar target can be seen on the radar P display interface of the present invention, and the bright arc presented at the target is clear and easy to identify; if there is clutter or the noise amplitude is large, it can also be clearly displayed.

[0093] Figure 7 In the display, the antenna rotates four circles. Among the ten targets, the target movement track can be seen when the moving speed is relatively fast, such as the target at 45 degrees and 85km away from the radar station, and the bright arc at the center of the target is retained longer.

[0094] The present invention is a schematic diagram of a radar P-display afterglow simulation method based on double thresholds. The method processes the corresponding radar video echo data according to the azimuth generated by the radar echo simulator for P-display display; by introducing an attenuation factor, the amplitude of the displayed radar video echo is attenuated, the amplitude of the video echo data at the current azimuth is compared with the attenuated echo data at the same azimuth and distance in the previous circle, and the echo data with a larger amplitude is retained; a double threshold judgment method is provided to adjust the brightness of the radar video echo on the P-display; the processed radar echo data is displayed on the P-display by using the double threshold judgment method; after the method is used, the P-display afterglow simulation effect and the implementation efficiency are further improved.

[0095] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A radar P display afterglow simulation method based on double thresholds, characterized in that: The steps include: Step S1: The radar echo simulator generates the azimuth and corresponding radar video echo data; Step S2: introducing the attenuation factor, when the antenna rotates to the sth circle (s≠1), multiplying the radar video echo data of the previous circle in the same direction by the attenuation factor α, and comparing it with the amplitude of each point of the current direction data, retaining the video echo data with a larger amplitude; The step S2 comprises the following steps: Step S21: when the antenna rotates for the first circle, the azimuth and same-azimuth radar video echo data generated by the radar echo simulator are saved, and when the antenna rotates for the sth circle (s≠1), the same-azimuth radar video echo data of the previous circle is multiplied by the attenuation factor α, and compared with the amplitude of each point of the current azimuth data, and the video echo data with a larger amplitude is retained; Step S22: using a data space that only needs to store one circle, the video echo data of each circle is continuously updated to the data space; Step S23: cyclically executing step S22 and step S23 until the radar P display simulation is completed; Step S3: using a double threshold decision method to adjust the brightness of the radar video echo on the P display; The step S3 comprises the following steps: introducing a threshold low value and a threshold high value to perform a double threshold decision: normalizing the video echo data for processing, and if the data amplitude in the echo data is lower than the low value, setting it to 0; If the data amplitude in the echo data is higher than the high value, it is set to 1; If the data amplitude in the echo data is between low and high, the data amplitude in the echo data is selected and amplified so that the video echo at the target is the brightest in the P display; Step S4: Display the radar echo data on the P display.

2. The simulation method according to claim 1, wherein: The step S1 comprises the following steps: Step S11: The radar echo simulator generates a direction at regular intervals; The radar antenna has a fixed rotation speed. Each rotation of the radar antenna is 360 degrees, which is divided into M directions. Step S12: Generate the radar transmission signal according to the following formula: Among them, s(t) is the radar transmission signal, t is the time, A s (t) is the signal amplitude, N is the number of pulses, rect() is the rectangular function, T r is the pulse repetition period, τ is the pulse width, f c is the carrier frequency of the transmitted signal, f s (t) is the time-varying frequency of the transmitted signal, is the initial phase of the transmitted signal, is the time-varying phase of the transmitted signal; Step S13: When the radar simulator is working, the radar transmit signal is continuously transmitted at a fixed time. When encountering a target, the radar simulator will generate target echo data. Since the echo signal travels back and forth between the radar and the target, it will lag the transmission pulse t r , then by the formula: 2R=ct r The relationship between distance and time can be known; where c is the speed of light propagation in the air, the distance R of the target on the echo can be calculated at this time; The echo signal h(t) scattered back by the target can be calculated according to the formula: Find, where N T is the target echo pulse number, G i (t) is the modulation function of the target on the transmitted signal, is the modulation function of the target on the phase of the transmitted signal, n h (t) is the environmental noise; When the target is not encountered, only the ambient noise n is received h (t).

3. The simulation method according to claim 2, characterized in that: The step S13 further includes the following steps: Step S14: loop through steps S11, S12 and S13 for multiple times.

4. The simulation method according to claim 1, wherein: The selection and enlargement process is one of linear mapping, convexity mapping, and concavity mapping. The transformation formula of the linear mapping is as follows: The transformation formula of the convexity mapping is as follows: The transformation formula of the concave mapping is as follows: Among them, V after is the amplitude after mapping, V former is the amplitude before mapping.

5. The simulation method according to claim 1, wherein: The step S4 comprises the following steps: Step S41: Calculate the distance r of each point of the radar echo data by the following formula: r=(ncT r ) / M,n=1,2,3,…,M; Step S42: Display the radar video echo data on the radar P display according to the azimuth and distance of each point.

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