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Interference phase assistance-based height measuring method for delay doppler radar altimeter

A technology of Doppler radar and interferometric phase, which is applied in the altimetry field of delayed Doppler radar altimeter and radar altimeter. , unable to obtain high positioning accuracy and other problems, to achieve the effect of improving measurement accuracy and resolution, reducing the amount of calculation, and improving measurement accuracy

Active Publication Date: 2018-01-19
XIDIAN UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

As a result, high positioning accuracy cannot be obtained when matching positioning
However, the interferometric delay Doppler radar altimeter system developed by the United States is only a dual-antenna system. Since the echoes of the equidistant ground units on the left and right sides of the route will overlap in one range unit, the dual-antenna system faces the problem of positive and negative interference phase differences. Due to the problem of coherent superposition, it is difficult to effectively extract the angle information of ground units, it is impossible to distinguish the position information of equidistant ground units on the left and right sides of the route, and it is impossible to improve the resolution of the vertical heading of the radar altimeter

Method used

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  • Interference phase assistance-based height measuring method for delay doppler radar altimeter
  • Interference phase assistance-based height measuring method for delay doppler radar altimeter
  • Interference phase assistance-based height measuring method for delay doppler radar altimeter

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Embodiment 1

[0026] In the existing dual-antenna interferometric delay Doppler radar altimeter system, since the echoes of equidistant ground units on the left and right sides of the route will overlap in one range unit, the dual-antenna system faces the problem of non-coherent superposition of positive and negative interference phases , it is difficult to effectively extract the angle information of the ground unit, and it is impossible to distinguish the position information of the equidistant ground units on the left and right sides of the route, and thus it is impossible to improve the resolution of the vertical heading of the radar altimeter.

[0027] In addition, traditional altimetry algorithms such as the half-power point method, WSG method, and the least mean square error fitting height estimation method have low precision and a large amount of calculation.

[0028] For this present situation, the present invention has carried out discussion and research, proposes a kind of delay D...

Embodiment 2

[0040] The delay Doppler radar altimeter altimeter method based on the interferometric phase assistance is the same as embodiment 1, and the echo signal model based on the interferometric phase auxiliary delay Doppler radar altimeter is set up in the step (1) of the present invention:

[0041] refer to figure 2 , figure 2 It is a schematic diagram of any channel among the three antennas. Three antennas are arranged at the same interval along the vertical direction. Antenna 1 sends and receives signals, and antennas 2 and 3 are used to receive signals.

[0042] The echo signal model of antenna 1:

[0043]

[0044] Echo signal model of antenna 2:

[0045]

[0046] The echo signal model of antenna 3:

[0047]

[0048] In the formula, c is the speed of light, λ is the wavelength, and L P is the propagation attenuation, H is the height of the carrier aircraft, G(ρ, φ) is the antenna gain of the ground unit corresponding to the polar coordinates ρ, φ, σ(ρ, φ) is the g...

Embodiment 3

[0052] The delay Doppler radar altimeter altimeter method based on interferometric phase assistance is the same as embodiment 1, the noise power calculation of any antenna in step 2, in this example with the noise power of antenna 1 For example:

[0053]

[0054] Among them, N1 is the starting distance unit number of the noise window, M is the length of the noise window, s 1 is the received signal of antenna 1, and l is the serial number of the distance unit in the noise window;

[0055] Determine the threshold U of subsequent detection according to the detection probability T :

[0056]

[0057] where P fa is the detection probability.

[0058] In this example, although the output signal of antenna 1 is used to calculate the noise power, in actual operation, the output signal of antenna 2 or antenna 3 can also be used to calculate the noise power. The calculation formula is the same as that of antenna 1, and the noise power calculated by antenna 2 or antenna 3 It ...

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Abstract

The invention discloses an interference phase assistance-based height measuring method for a delay doppler radar altimeter, wherein the problems that the traditional algorithm is low in resolution andprecision and the angle information of a ground unit is difficult to extract due to the non-coherent superposition of the positive and negative interference phases of a double-antenna system in the prior art can be solved. The method comprises the following steps of establishing a signal model of a delay doppler radar altimeter based on interference phase assistance; processing an echo signal: estimating the noise power and calculating a detection threshold; defining a an interference window; extracting an interference phase angle, namely the included angle between a ground unit relative to the normal line of an antenna array; calculating the height, and estimating the height of an aerial carrier according to the corresponding distances of all distance units in the interference window, and the included angle of the corresponding ground unit relative to the normal line of the antenna array. According to the invention, the angle information of the ground unit can be effectively extracted through three antennas, so that the height measuring precision and the resolution of the radar altimeter are remarkably improved. The method is stable, reliable and low in calculation amount, and can be used for the terrain matching of the interference doppler radar altimeter.

Description

technical field [0001] The invention belongs to the technical field of radar, and in particular relates to a radar altimeter height measurement method, in particular to an interference phase-assisted delayed Doppler radar altimeter height measurement method, which can be used for terrain matching based radar altimeter height measurement. Background technique [0002] When the traditional radar altimeter is applied to terrain matching navigation, its main impact on the performance of terrain matching is: the traditional radar altimeter has a large ground footprint, and the measured height is all the ground within the entire ground footprint (pulse limited or beam limited). average height. Therefore, the measurement accuracy and ground resolution of traditional radar altimeters are low. As a result, high positioning accuracy cannot be obtained during matching positioning. However, the interferometric delay Doppler radar altimeter system developed by the United States is only...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S13/88G01S7/292
Inventor 刘楠刘战范振林任义何星瑶
Owner XIDIAN UNIV
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