CN104297730A - Method for obtaining radar clutter image - Google Patents

Abstract

The invention provides a method for obtaining a radar clutter image. Radar clutter data are obtained for non-cooperative circumferential scanning radar through passive detection, the clutter data are converted into polar coordinates through signal processing, and the radar clutter image is drawn on a polar coordinate system. By means of the method, the clutter image of non-cooperative circumferential scanning radar can be obtained, the shape of the image and the shape of the real radar clutter image are similar to a large extent, and therefore the problem that a traditional radar clutter forming method has defects is solved.

Description

A kind of method obtaining radar clutter image

Technical field

The invention belongs to Radar Clutter Signal process field, particularly a kind of method obtaining radar clutter image based on passive detection.

Background technology

Have a lot to the document that radar clutter figure studies, as document " the CFAR algorithm based on radar clutter figure " (" fire control radar technology ", the 4th phase in 2010) is described below: radar clutter figure is mainly used to clutter distribution and the Strength Changes thereof of real time record radar site surrounding environment; It processes based on to the value of repeatedly scanning of the same space unit the average amplitude estimating this element clutter, thus provide two hierarchical informations of radar site surrounding environment.

Radar clutter figure normally by radar by scanning surrounding environment, and signal transacting carried out to echoed signal formed, have not yet to see the document record being obtained radar clutter figure by passive detection and signal transacting.

Summary of the invention

The object of the invention is to utilize passive detection means to obtain radar clutter image, is a kind of new tool of electronic warfare passive detection.Obtain after clutter image, may be used for measuring the position of radar, to nose into arround radar the purposes such as landform.

Content of the present invention is to provide a kind of new method being obtained radar clutter image by passive detection and signal processing means.The method, for non-cooperation circular scan radar, utilizes passive detection to obtain radar clutter data, by signal transacting, clutter data is converted to polar coordinates, and in polar coordinate system, draw radar clutter image.

Technical scheme of the present invention is:

A kind of described method obtaining radar clutter image, is characterized in that: comprise the following steps:

Step 1: utilize the orientation of passive detection device measuring radar, antenna scan period T;

Step 2: according to the orientation of the radar that step 1 obtains, using the position of target radar as the limit of polar coordinate system, the pole axis being polar coordinate system to the line of passive detection equipment with limit, sets up polar coordinate system;

Step 3: measure the moment that radar main lobe irradiates passive detection equipment, will now engrave as T0;

Step 4: utilize passive detection equipment within antenna scan period T0 ~ T0+T period, detects and receives noise signal t time of arrival of instrumentation radar and the clutter amplitude A of correspondence;

Step 5: make k=1 successively, 2 ... 359, repeat following process, complete the drafting of whole clutter map:

At t _k~ t _k+1period, select the clutter amplitude data A in the radar pulse repetition period for drawing clutter map when polar angle is k, wherein t _k=T0+T/720+T* (k-1)/360, method for drafting is: arrive the initial time of passive detection equipment reconnaissance antenna at first for time reference with radar signal in the selected radar pulse repetition period, noise signal is designated as TOA relative to the time of arrival of time reference, the signal amplitude that TOA moment passive detection equipment receiver receives is converted to gradation of image, be plotted in coordinate position { k, c*TOA} place, wherein c is the light velocity.

Beneficial effect

Adopt the method, can obtain the clutter image of non-cooperation circular scan radar, this image and real radar clutter image have similarity largely in shape, thus solve the imperfect problem of conventional radar clutter formation method tool.

Accompanying drawing explanation

Fig. 1: the implication of limit, pole axis, DOA;

Fig. 2: based on the radar clutter image acquiring method process flow diagram of passive detection;

Fig. 3: the true clutter image of radar;

Fig. 4: the radar clutter image that passive detection obtains.

Embodiment

Below in conjunction with specific embodiment, the present invention is described:

See Fig. 3, solid line be depicted as one " M " and the true clutter image of the clutter reflector space of shape, wherein radar is positioned at center, passive detection equipment in the front-right of radar site, apart from distance by radar 400Km.

The each pixel of this clutter image (because quantity is more, the having done extraction here) coordinate in polar coordinate system (being counterclockwise the positive dirction of polar angle) is for shown in table 1.

The coordinate (after extracting) of the true clutter point of table 1 radar

Polar angle (degree)	168	167	165	164	163	161	160	158	156	155	153
												Footpath, pole (rice)	50990	50220	49477	48765	48083	47434	46819	46239	45695	45188	44721
Polar angle (degree)	153	153	153	153	153	153	153	153	153	153	153
												Footpath, pole (rice)	44721	43603	42485	41367	40249	39131	38013	36895	35777	34659	33541
Polar angle (degree)	153	151	150	148	146	145	143	141	139	137	135
												Footpath, pole (rice)	33541	32882	32249	31643	31064	30516	30000	29517	29069	28657	28284

Polar angle (degree)	135	135	135	135	135	135	135	135	135	135	135
												Footpath, pole (rice)	28284	26870	25456	24042	22627	21213	19799	18385	16971	15556	14142

This radar clutter image is obtained, process following (shown in Fig. 2) according to method of the present invention:

Step 1: utilize the orientation DOA of passive detection device measuring radar, antenna scan period T;

Step 2: with reference to accompanying drawing 1, according to the orientation of the radar that step 1 obtains, using the position of target radar as the limit of polar coordinate system, the pole axis being polar coordinate system to the line of passive detection equipment with limit, sets up polar coordinate system;

Step 3: measure the moment that radar main lobe irradiates passive detection equipment, will now engrave as T0;

Step 4: utilize passive detection equipment within antenna scan period T0 ~ T0+T period, detects and receives noise signal t time of arrival of instrumentation radar and the clutter amplitude A of correspondence;

Step 5: make k=1 successively, 2 ... 359, repeat following process, complete the drafting of whole clutter map:

At t _k~ t _k+1period, select the clutter amplitude data A in a radar pulse repetition period (PRI) for drawing clutter map when polar angle is k, wherein t _k=T0+T/720+T* (k-1)/360, method for drafting is: arrive the initial time of passive detection equipment reconnaissance antenna at first for time reference with the interior radar signal of selected radar pulse repetition period (PRI), noise signal is designated as TOA relative to the time of arrival of time reference, the signal amplitude that TOA moment passive detection equipment receiver receives is converted to gradation of image, and (amplitude is larger, color is darker), be plotted in coordinate position { k, c*TOA} place, wherein c is the light velocity.

For the present embodiment, for 168 degree of directions, can obtain noise signal relative to the time that reaches of time reference is 3.3719 × 10 ^-4second, if light velocity value 299792458 meter per second, the distance that can be calculated between noise signal reflection spot and radar is 101087 meters.By that analogy can table 2.

Table 2 is according to the coordinate (after extracting) of the radar clutter point of the data acquisition measured

Polar angle (degree)	168	167	165	164	163	161	160	158	156	155	153
												Footpath, pole (rice)	101087	99341	97625	95941	94290	92674	91095	89552	88049	86586	85164
Polar angle (degree)	153	153	153	153	153	153	153	153	153	153	153
												Footpath, pole (rice)	85164	83025	80886	78748	76610	74473	72336	70200	68064	65929	63794
Polar angle (degree)	153	151	150	148	146	145	143	141	139	137	135
												Footpath, pole (rice)	63794	62154	60540	58953	57396	55869	54375	52914	51490	50102	48754
Polar angle (degree)	135	135	135	135	135	135	135	135	135	135	135

Footpath, pole (rice)

48754

46295

43838

41383

38930

36480

34031

31585

29142

26700

24261

Ignore the fluctuating of the intensity of each clutter reflection spot, radar clutter image can be obtained as shown in Figure 4.

By comparison diagram 3 and Fig. 4 visible, passive detection obtain radar clutter image and real radar clutter image there is similarity in shape largely.

Claims (1)

1. obtain a method for radar clutter image, it is characterized in that: comprise the following steps:

Step 1: utilize the orientation of passive detection device measuring radar, antenna scan period T;

Step 2: according to the orientation of the radar that step 1 obtains, using the position of target radar as the limit of polar coordinate system, the pole axis being polar coordinate system to the line of passive detection equipment with limit, sets up polar coordinate system;

Step 3: measure the moment that radar main lobe irradiates passive detection equipment, will now engrave as T0;

Step 4: utilize passive detection equipment within antenna scan period T0 ~ T0+T period, detects and receives noise signal t time of arrival of instrumentation radar and the clutter amplitude A of correspondence;

Step 5: make k=1 successively, 2 ... 359, repeat following process, complete the drafting of whole clutter map:

At t _k~ t _k+1period, select the clutter amplitude data A in the radar pulse repetition period for drawing clutter map when polar angle is k, wherein t _k=T0+T/720+T* (k-1)/360, method for drafting is: arrive the initial time of passive detection equipment reconnaissance antenna at first for time reference with radar signal in the selected radar pulse repetition period, noise signal is designated as TOA relative to the time of arrival of time reference, the signal amplitude that TOA moment passive detection equipment receiver receives is converted to gradation of image, be plotted in coordinate position { k, c*TOA} place, wherein c is the light velocity.