DE1900854A1 - Procedure for radar multiple target detection - Google Patents

Description

"Procedure for radar multiple target detection"

The invention relates to a method for recognizing the simultaneous presence of several radar target objects that are so closely spaced in the directional diagram of a radar antenna system that it is based on angle, distance and / or speed the evaluation side of the radar device associated with the antenna cannot be separated from one another without further auxiliary measures.

In the target tracking and targeting with the aid of radar devices, the multiple target problem is of particular importance. It is understood to mean the fact that when several closely adjacent targets are present, the respective radar device can separate them more from one another in terms of the coordinates of angle, distance and speed, but that the several existing targets are erroneously recognized as one target. The radar units speak on the radar that is common to the targets.

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Reflection focus on. When tracking the target, then therefore continuously measure a fictitious target. By targeting multiple targets, a missile is aimed at a fictitious goal steered towards. Its target separation in the angular coordinate is often only possible too late, so that a successful mission is no longer given. The respective missile can simply no longer reach a target in time be set.

The invention is based on the object of specifying a method which allows several, closely spaced targets to be recognized in good time at least as such. It would of course be desirable if a real multiple target resolution would take place. However, a multiple target resolution already brings considerable advantages.

To measure the target offset from the optical axis of a radar antenna, methods of conical roughness scanning (Conical Scan process) and Monpuls process use. Both the latter one must again between amplitude monopulse and Differentiate phase monopulse methods.

For phase monopulse methods the following ia meaning is the Invention proposed a method that allows the

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Angular coordinates of several falling in the same antenna lobe Ζ1 · 1 · see below. These measured angular coordinates (Azisrat and elevation a, ^), however, the assignment is missing. the corresponding pairs of angles (a _yt £) to bekoaaea, an additional measuring process is required. It will also be shown that this method for multi-target resolution works perfectly if fewer targets are triggered than is possible in terms of effort. It is easy to see that the effort is higher, the more goals are required as a system requirement.

In a method of the type mentioned at the outset, the invention consists in the fact that, in the case of two radar target objects, the auxiliary signals consist in that, when the phase-on-pulse principle is used, the radar antenna system has at least five receiving antennas, which are located in one, perpendicular to the optical axis of the antenna system lying level are arranged in such a way that in two menu levels standing at right angles to one another there are three receiving antennas each having the same continuous distance L from one another, so that the three receiving signals separately for each of the two measuring levels

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^iU 2

i2u i2u V ₃ .A ₁ . + A ₂ .

■ it dea indices 1 to 3 corresponding to the three lapfangfang tennen and old

A ₁ »lapfangasignalaaplitude tob goal 1 A ₂ «lapfangssignalaaplitude roe target 2

«J» K ^ · sin Ot ₁

λ s wheel length α s signal incidence angle το · target 1 in the respective measuring plane

Ot- μ signal incidence angle -roe target 2 in the respective MeA plane

can be obtained that therefrom the amounts of the signals

iu ₄ iu

(V _1. - V ₂ ) and (V ₂ β ^x - V.) are determined and that from these behaviors in connection with the relationship

i ^lu 2 i ⁽ V - ^V 2 ^{} e} " ⁽ V" ^V 3 ^} U ₁ and U ₂ , which represent a measure for α and a _g in the respective measuring plane.

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Further training courses deal with "it do" recognition of more than two target objects under the same conditions.

The invention is based on the following considerations: If only one goal is given for the measurement task according to the principle of the PhasexuBonopuls method, then both are acceptable Planes (horizontal and vertical planes) with three antennas; one of these three antennas is used for measurement in both planes.

One has a configuration of the antennas as indicated in Fig. 1 in a plan view. If one now looks at one of these planes for the angle determination, then according to FIG. 2 results from the phase relationship

^27C '' sin α (i)

for the incident wave the angle of incidence α against the op table axis of the antenna. The angle determination is via the Range »90 ° -j- + 90 ° only unambiguously if this applies

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To determine Un ψ and thus α, all that needs to be done is a phase comparison of the two antenna output signals.

If an antenna target tracking is carried out, the antenna can simply be tracked to the target by using a special regulating and control circuit to ensure that phase ψ - according to relationship (l) - has the value zero. In this case it is not important to have an entire half-room as a measuring room, but rather, in order to get the highest possible profit and to be selective, the antennas are built in a strongly bundling manner. Then you get more freedom in handling the antenna spacing.

The greater / effort with double goals compared to the single goal procedure is that the number of required Receiving antennas increases. So one needs in the to be described System per level at least one more antenna, so that a receiving system of five antennas uses the two-target method must be taken as a basis. In Fig. 3 one is suitable for this Antenna arrangement can be seen in plan view. An antenna, in the example the antenna 2 is again used to determine the direction in both eps Levels used. Since the procedure is identical on both levels, one consideration is sufficient for the basic explanation of the same in one plane. In the horizontal plane result

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On the basis of Fig. k , the following voltages are applied to the antennas in the presence of two targets:

«· A ₂ e ^iUa (3)

ι i2u
V ₃ «A _t e * ♦ A ₂ e ²

It means:

A ₁ «amplitude of the signal from target 1 A_ κ amplitude of the signal from target 2 U ₁ m Kjt · a α ₄

n _n . κ / an α ₂

Vellensahl

a _t κ Angle of incidence (azimuth) of the signal from target 1 Ot- ν Angle of incidence (azimuth) of the signal from target 2

The relationships are now the starting point for the following Separation Failures.

First, the phase of signal V. is changed by the value u and then subtract the signal V from it:

iu ₄ iu iu

^V l ° - ^V 2 = ^A 2 ^{(ee} (/ i)}

Like Y., V is shifted in the phase ura u and then from which V subtracted:

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iu iu Xu ₁ xu

V ₂ e ¹ - V ₃ = A ₂ e ² (e * - e ² ) (5)

From the two relationships (4) and (5) one obtains a third,

iu
One shifts (Ve - V) in the phase by the value u _o and

^lu i

subtracted from this (Ve - V), we get:

δ j

iu iu iu
(V ₁ C ^α - V ₂ ) e ² - (V ₂ e ^α - V ₃ ) = 0 (6)

An interpretation of the three relationships (k) , (5) and (6) already leads to the fundamentals of the method according to the invention. FIG. 5 shows an advantageous implementation possibility of the method according to the invention for the recognition of two objectives.

If V and V have been shifted in phase according to the instructions and the corresponding differences formed, it is found that the two signals according to relations (4) and (5) are equal in terms of magnitude. If one forms the amounts of (k) and (5) i then one receives directly a control signal for the phase shifters. If the control signal is zero, the position of the phase shifter is directly proportional to the sine of the angle of incidence of target 1. For small? Angle is sin o. "S &<x.

The further processing of the signals according to equation (6) finally results in a hatred for -len angle of incidence Cos. Target 2 in the position of a further phase shifter.

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The two elevation values of the targets are obtained in the same way in the vertical plane. However, it is an assignment of the Coordinates α, £ to the destinations are not always possible.

An assignment of the specific coordinates is always not possible if cc ia _o and Z. f = c _o . There are two possible assignments, which are indicated in FIG. 6 by circles or crosses. In order to achieve an assignment, the antenna arrangement can be pivoted in a first step so that CX .. = - GC and £. = - £, so that in Fig. 6 the

X £ X £

The dashed coordinate system must be taken into account «If V = 11.6 · sin J 'and V = ll £ * sin C _n , then the following

XX do cu

£ oiid ο definition:

u + u _o = 0

(7) ο

In the second and last step, the antenna arrangement is now ent ^ O '/ ei! Deni rotated clockwise around its optical axis until the coordinate values in a plane become I.'u'Ll. If this is the case first for the α ¹ -plane, then;: iLt the configuration denoted by id'ouzen, if this is true for the cue t ¹ -plane, then the one indicated by Ki eisen is:; ', uo! '('; umr, '^ ültis. The reception arrangement can now be restored

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be brought back to the starting position and according to a predetermined program one of the two run in the coordinates given goals for target pursuit or target acquisition to be selected. It is only necessary to ensure that the antenna arrangement with its optical axis is via a tracking circuit always points to the selected target, so that the corresponding 'coordinates Ot, c are zero.

If there is only one target, the antenna voltages are:

V - A - e ¹ * ^ίδ)

V ₂ -A e

V ₃ = A * e ^i2Cp

The equations corresponding to relations (4) and (5) in this case:

- Y ₉ = A (e ¹ * - e ¹ «-)

(9) - V, = Αβ ^χς: (e ¹ * - e ^iC:) ,

where -γ is any value.

One can now see immediately that the two relationships (9) are identical in terms of amount, regardless of which one

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Owns value ^. If it is found that a change in the position of the first phase shifter has no effect on the readjustment variable, ie that the readjustment variable has the value zero regardless of the phase setting, then there can only be one target . The further relationship

(Y _t e ^if - V ₂ ) e ^{i <P} - (V ₂ e ^if - V ₃ ) = O (10)

it then finally results that the coordinate values of the target are obtained by the phase shifters located after the formation of the absolute value .

Compared to the double target case, the number of antennas in the triple target according to FIG. 7 increases by two; One more antenna is therefore required per level. 7 shows a possible antenna arrangement. As one can easily imagine, several equivalent anticine arrangements are possible. For further considerations one restricts oneself again to a single level

Corresponding to the two-goal case, the following results arise • nominal voltages (Λ.-above where comparable quantities are apostrophized):

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V ₁ = A _{1 +} A « ₊ A ·

iu · iu «

V «= A'e + Ale * + A'e

i2u 'x2u' i2u

V »= Ate * + ale + ale

Jl ti J

The following symbols have been introduced:

A '= amplitude of the signal from target 3

u = k £ sin α

α '= Eiiifallswinlccl (Ar.inut) of the signal from target 3

The phase of the signal V is changed by the value u ' and then V ^ is subtracted from it:

iu iu 'iu' iu iu '

V'e - V «= A ₀ (c - e) + Al (e - e ^J ) (12)

Corresponding to that, V _{0 is} changed by u 'in the phase and then V is subtracted from it:

• iu 'iu _o iu' iuj !, ^lu o i- ^ll \ i ^u o

VIe ^X - Vl = A; o "ie * - e ^) ₊ AIe ^J (e ^X - e ³ ) (I3)

_{The Sif-jnal Vj 1 is also} subjected to the same phase shift (u ') uii'"is then subtracted from V /:

iu 'i2u _o iu · iu' i2u 'iu' iu ^

V'e - ν, ', = AIc - (c - o. ^Z ) + Ale ³ (e ^X - e ^J ) (l')

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The three relationships (12), (13) and (14) become two

^iu i

won more. On the one hand, Hein shifts (V 'e - V ·)

iuj in the phase uri u and subtracts from it (V 'e - V'):

in 'iu' iu 'iu' iu 'iu' iu

(V'e ¹ - V ') e ² - (VJ ^ e * - V') = A '(e ^X - β ³ ) (e ² - e ³ ) (15)

X <i " YY

and toii others (V'e - V ·) in the phase also by u

^iu l
and then subtract from it (V'e - Vi):

iu 'iujl, iu' iu 'iul iu' iu iu

fv'e. Vi] p "-fV'f - VM = A'e ^ (ρ _ ρ ^) (ο _e> ^)

VV ₁ ^ t- v ^ -jrt; \ ^ν Λ ^ ί / l O / V ^ ¹ ^ /

Finally, the two relationships (15) and (l6) further processed. If we move the expression in (15) to the Phase by u "and subtracts from it the expression in (16), see above b elcoriu.it man:

Eiu 'iu,!, Iu' η iu · (VIe ^% - V;) e "- (V'e ¹ - V ·) e - *

iu iu iu '

The procedure is again obtained by interpreting the relationships (12) to (17) and Fig. 8. If the antenna voltages have been shifted in phase according to the instructions and subtracted accordingly, then equations (15) and (16) result from deti, that the expressions given in them are identical in absolute terms. The difference between these two amounts yields

- Ik -

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thus a control signal for the two phase shifter groups. If the phase shifter groups are set with the help of search and tracking logic so that the position of the first group is proportional to sin (X. and the position of the second group is proportional to sin 0C ₀ , the control signal has the value zero already the greater difficulties in comparison to Zweif aclizielf all. This is because the control signal cannot be clearly assigned to the two phase shifter groups.

One is generally dependent on a} ** kind of search process, the Of course, when tracking can be kept much narrower within the limits than when purely looking for a destination, the regulation for preservation the third angular coordinate can be read off directly from relation (17). The elevation angles can be the same Determine way. Again, this is not a general one Allocation of the Winlcelcoordinates to the three destinations, possible.

To achieve a target coordinate assignment, ζ * B. the following path should be taken. Zn a special circuit arrangement the target coordinates found must first be examined to determine whether an assignment is possible from the outset is possible without having to perform further operations. This applies to three cases:

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• f

• ff • · ff

9 ff

• ff

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α «,

α

For all other possible triple-goal fillings are special To go through the allocation program. First of all, it must be established «which angle configuration is present:

1) ct> * α * * cc »i € 'Φ 6« Φ έ · · χ · & j χ * s j

The choice of the angle depends on the angular configuration using assignments epi-ogi-aiuns.

The following program could be used for the most general case (1) introduce:

1) Adjust the antenna neatly so that .. ' - -' -. \

2) Setting the antenna arrangement. so that ti = -v \

3) Rotation of the Aiitennenanordimng uri their optical axis dom clockwise

4) Check whether the "rotation: '+ \ = 0 4.1 if yes, after 10.

¹ 1.2 MCA :: -κ ir., -Lach 5 ·

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5) Adjusting the antenna arrangement so that o! = - C '

6) Rotation of the antennae-dmmg around its optical axis counter clockwise

7) Check whether c + CfA = 0 during the rotation

7.1 if yes, after 10.

7.2 if no, after u.

0) Adjustment of the arrangement of the units so that 6 ή = -Cl

9) Counter-rotation of the antenna arrangement about its optical axis clockwise

10) Check whether S ^% = -6 * "♦ 0 V £ .u

10.1 if yes, then assignment a'lf ¹ y a '/ f'

XI #U ä5 f V

10.2 if no, so first c: '= -c.A -> 0, then assignment

After completing this program, the measured Coordinates clearly assigned to the three goals. The allocation program for the other two cases they are simpler, but still similar to what has been discussed, so that a description the same is waived.

If there are only two goals, they stand for triple goals suitable antennas the voltages:

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^A 2

iu '
= A'e ^X +

JL

iu,

V '=

x2u '
A'e ^α + A'e

x3u «

i2u '

The ('cn Gl ei dm; it on (12) to (l'i) corresponding ri 1aut en now:

ic;

icp ¹

icp

iu

V'e - V '= A' (e - ο

d. 1

χ ep ¹

- e

in 'χς ¹

iu in

- V «= A'e ^τ (e - e ^τ ) + Ale ^ (e

V'c - V ^ = A ^ c

i2u χφ ' ¹ i2u'

- e ^X ) + A ^ e ". (e

iu, !!, e ")

- e

A: istel? .E dor Gj oichungea (15) and (l6) ei "one holds:

φ - V ^) c - (V ^ o - V »)

iV

A '(e

- c

) (e

χφ '

- e

- e

iu

- e

ic

- V «) e - (V'e

iu

iu

(e

Vi) ic;

- e iu 'e ^X ) +

iu

iu

- e

χφ

(O

iu

- e

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From the last two relationships it follows that both amounts are only identical if φ '= u'. The setting the second phase shifter group can be any. With the help of a logic, however, it can be determined at any time that the adjustment signal for the phase shifter from ^ finally depends on the position of a phase shifter group. u is obtained from the position of the last phase shifter in the circuit arrangement according to Fig. 8. So you can see that the process works even when there are only two targets.

If there is only one target, then you get a loira triple target system the antenna sparings:

V = A ¹

Vl Al ^iU '

V = A'e

(21)

^V 3 = ^A ' ^e

// = A'e

Now you have to form lying expressions again:

V'e ^T - V '= A ¹ (e ^Y - e)

X Ct

V'e ^{i (pl} - V »= A'e ^iu ' (o ¹ ^ - e ^iu ') (22)

... iffl ¹ ",., i2u ^! / ϊφ ¹ iu ¹ χ

V'e ^Y - Vi = A'e (e ^Ύ - e)

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-V) β Α ¹ ί

(Vie ^ - VJ) β A'e (e -e) (e ^T -e )

(23)

Bine formation of amounts results in equality of the last two relationships completely independent of the positions of the first two phase shifter groups. Determining this is again the task of the logic mentioned above. The only measurable coordinate is known again from the position of the last phase shifter (Fig. 8). With this method, the single target case can also be resolved.

From the explanation given above, it can be seen that the effort basically increases the bit of the number of targets to be resolved. This applies to both the number of antennas and the required external circuitry. The number η of antennas required is related to the number ν of targets to be resolved as follows:

for one level: η = ν + 1 for both levels: η = 2υ + 1

With the increase of effort and the complexity of the procedure increases as you could see quite substantial. Expedient

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In some cases, it is used for on-board systems of the method according to the invention has little more than a double objective solution in question.

The tracking logic for the phase shifter groups - z. B. Triple Target Case - is built up as a learning circuit, those from the previous phase changes to the expected closes.

The required antenna spacing Jf for a clear angle measurement always results from the relationship:

(24)

2 sin

where 20L is the angle measurement range of the system and in most cases corresponds to the width of the value. Do you work z. B, ita Ku-band at λ = 1.82 cm and requires a half-width of 20L _T = 20, this results in the required antenna spacing:

J> L 5.25 cm «3 λ (25)

The invention is also advantageous in the objective

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Application, when you have found a target and for whatever reason - sj. B, for fire control - determine must, whether it is a multiple objective. Chew must then just a target resolution phase in the acquisition process slide in.

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Claims (1)

- 22 - U 10/68 Pat 1. Ancestors for recognizing the simultaneous presence of several radar target objects that are so closely spaced in the directional diagram of a radar antenna system that they cannot be separated from one another in terms of angle, distance and / or speed on the evaluation side of the radar device belonging to the antenna without further auxiliary measures. In the case of two target objects, the auxiliary measures consist in the fact that, when the phase monopulse principle is used, the Hadaraut term system has at least five receiving antennas, which are arranged in a common plane perpendicular to the optical axis of the antenna system so that there are two on one side to this plane and on the other hand, there are three right-angled letting planes each having the same continuous spacing from one another, possibly multiple uses, so that the three received signals are separated for each of the two kessing planes V ₁ = A + A
1 1 i mi. ι. (Ou Xnr.'ii; jj! Es 1 to 3 o: itspi'och ;; iic1 den Ci-i üpCa!:; 'Santon: ie: i 009833/0908 - -3 - BATH ORIGINAL - ZJ - U 10 / 6G and with λ. s Reception signal amplitude from target 1 Ag * Reception signal amplitude from target 2 U ₁ β % .ß "Hin Ot ₁ U ₂ β Kjt ·" in Ot ₂ π - 3.14 λ * radar wavelength OC ₁ «signal angle of incidence from target 1 in the respective M <f plane α, s signal incidence angle from target 2 in the respective measuring plane, so that the amounts of the signals are obtained therefrom Iu ₁ iuj (V ^ e - Vg) and (V.e - V-) can be determined and that from these amounts in connection with the relationship itt. iUj, iu. ^(V l ^{e ¥} 1 ^{) β β (V} 2 ^{e V} 3 ^} U ₁ and U _{2 are} determined, which represent a measure for Ct ₁ and a "in the respective Heßplane. 2 · The method according to claim 1, characterized in that im In the case of three radar target objects, the auxiliary measures consist in the fact that, when the phase monopulse principle is used, the radar antenna system has at least seven, i.e. at least two, additional receiving antennas in the common plane - 2k - 009833/0908 ORIGINAL INSPECTED - 2k - U 10/68 which, if necessary, had an antenna that was used and functionally four in each of the two measuring planes with the continuous spacing ß * that for each of the two measuring planes . ^ r / iu »iu,?, iu ' V £ = AJe + A ^ e "+ A ^ e ^J i2u 'i2ui i2u' ΛΤ \ V / = A'e ^X + A'e ^ ₊ A «e A 'X ώ J) with A '= Receive ansssigna Lnr.iplitude from goal 1 A,!, = Eripfangssio'naianiplitude from goal 2 A' = Eiiipfn: icssi ~ iia! Anp7.i "cuc! E from I ^ iel 3 - · j. . & • si : i rj ! ^L1 2 = JL- 'J' • si η ^α 2 3 _ Τ " • si C. ¹ = oi ^ 'inl nini'al Is'. "V!: GI. Vo:; i TMoI 1 in c'gi · j cireili ^ en h'eßebene α,!, = Sisnaleinfailsv.-iii ^ ol vom Goal 2 in 'lor respective l-ie α '= signal incident-i. ^r in!: el of goal 3 ii of the respective runners let oil those jeironrca uertlc: ¹ that from it the 3eträ, vo el er Jiniale "l ^c " ^V n ^{} c} '"- ^(V 2 ^{e V} 3 ^} ; i 'iu; iu V /. oin ::. ;, '-! r
the; '. (.'_ Loi.Uti Ou 9833/0 90 8 " ^J '^:> " BATH ORIGINAL - 25 - U 10/63 [iu «iuj, iti '" 1 iu · ^(V i ^e - ^V 2 ^{} C} "" ^(V 2 ^e " ⁷ ^ J ^C iu 'iu iu' - (V ^ c ^α - VJ) c ** ~ (VJc ^X - V ^ = ui, uj ^ and ul have been determined, which represent a measure for OC *, CtJ !, and (X ' _{in the respective I 1} Cf level. 3 · Verfaliren according to claim 1 or 2, characterized in that for recognizing more than three, namely V adjacent Radnrzielobjokten containing Radarantonnensysteni Fuei 'a plane (v + 1) and for both planes (2v + 1) antennas. 009833/0908 BATH ORIGINAL