Phase method for direction finding

FIELD: radio detection and ranging, radio navigation, applicable for determining the angular co-ordinates of the signal radiation source.

SUBSTANCE: the claimed method is realized with the aid of a device having three receiving derails, three receivers, two phase-meters, computer, adder and a recording unit connected in a definite way.

EFFECT: enhanced range of one-valued measurement of angles at a small length of the rough measuring base.

3 dwg

 

The proposed method relates to the field of radar, radio navigation and can be used for determining the angular coordinates of the source signal.

Known phase methods of direction finding (patents of the Russian Federationâ„–â„–2003131, 2006872, 2010258, 2012010, 2134429, 2155352, 2175770; patents Germany No. 2127087, 2710955; patent of great Britain No. 1395599, 1598325; Kinkelin IE and other Phase method for the determination of coordinates. M: Owls. Radio, 1979; Space radio systems. Edited Shibukawa. M: Owls. radio, 1967, s-138 and others).

Known methods most similar to the present invention is a phase method of direction finding (Space radio systems. Edited Shibukawa. M: Owls. radio, 1967, s-138), which is selected as the base object.

The phase direction finding method generally inherent contradiction between the requirements of accuracy and unambiguity of the reference angle. Indeed, according to the formula

Δϕ=2π·d/λ·Cosβ,

where Δϕ - the phase difference between the signals received by two antennas, separated by distance d (measurement basis);

λ wavelength;

β - the angle of arrival of radio waves relative to the normal to the measuring base

the phase system is the more sensitive to changes in angle β, the larger the relative size of the database d/λ. However, with increasing d/λ decreases C is Uchenie angular coordinates β at which the phase difference Δϕ exceeds the value of 2πi.e. comes the ambiguity of reference.

To eliminate the phase ambiguity of the way the location of the radiation source signal are two classical methods: the use of antennas with a sharp directivity and the use of multiple measurement bases (mnogodelnosti).

The direction finding system with highly directional antennas has a large range and high resolution in the direction. However, they require a search of the source signal before the measurement and automatic tracking in the direction of the antenna beam in the measurement process, as well as deprive phase method of direction finding one of its advantages is the possibility of using non-directional (isotropic) antenna systems.

Mnogodelnosti is usually achieved by using multiple measurement bases. While a smaller base forms a rough, but unambiguous scale reference angle βand large base - accurate but ambiguous scale of reference. When choosing a value basis, as well as the number of bases originate from the following considerations.

The number of zones of ambiguity, i.e. regions where the phase difference Δϕ varies by an amount equal to 2π, is determined by the ratio

n=2 d/λ.

For a single reference, you need to choose n=1, so the. to select the database on the basis of conditions

d<λ/2.

The base object uses mnogozonnoy (multibase) antenna system (figure 1). While receiving antennas 1, 2, 3 and 4 have the classic form of the location. As an example we consider the case of four antennas. Small base d1formed by the antennas 1 and 2, provides a rough unambiguous reference large base of d2formed by the antennas 3 and 4 is the exact ambiguous reference.

However, in some cases with large ranges unambiguous measurement of angles β rough base d1may be so small that it is physically impossible to place two antennas (e.g., d1=1 m diameter antennas D=2 m).

In such cases, the formation of coarse scale indirect method.

There are two measuring unequal base d1and d2(figure 2) and on each of them measured phase shifts Δϕ1and Δϕ2. The measurement of the difference of the difference of phases Δϕp=Δϕ1-Δϕ2equivalent to measuring the phase shift on the basis of length d3=d1-d2.

Thus, choosing the difference bases d3quite small, it is possible to ensure the formation of the corresponding coarse measurement database.

It should be noted that the total phase shift Δϕ=Δϕ1Δ ϕ2can be used to generate a measurement that is equivalent to the measurement of the phase difference on the basis of the d4which length is equal to the sum of the two original databases

d4=d1+d2.

An object of the invention is to increase the unambiguous range measurement of angles with a small length rough measurement database.

The problem is solved in that phase according to the method of direction finding, based on the reception of signals from the four antennas spaced apart and located on the same line, combine two antennas forming the first antenna to form two unequal measurement bases of the first and second antennas, second and third antenna respectively measure the phase difference between the signals received by the specified antennas, determine the difference and the sum of the measured phase difference form using the difference of difference of phases rough, but unambiguous scale reference angles corresponding to small measurement basis, using the amount of phase difference accurate but ambiguous scale of reference angles corresponding to large measurement database.

The relative locations of the antennas 1, 2, 3 and 4 of the base object shown in figure 1. The relative locations of the antennas 1, 2 and 3 of the proposed method is depicted in figure 2. The structural scheme of the device that implements the proposed method is presented in figure 3.

The device comprises series-connected first antenna 1, the first receiver 4, the first phase meter 7, the second input is via a second receiver 5 is connected to the output of the second antenna 2, myCitadel 9 and the block 11 registration of series-connected third antenna 3, the third receiver 6, the second phase meter 8, a second input connected to the output of the second receiver 5, and the adder 10, a second input connected to the output of the first phase meter 7, and the output connected to the second input unit 11 of the Desk, a second input vicites 9 is connected to the output of the second phase meter 8.

The proposed method is implemented as follows.

The received signals are:

U1(t)=υ1·Cos(ωct+ϕ1),

U2(t)=υ2·Cos(ωct+ϕ2),

U3(t)=υ3·Cos(ωct+ϕ3), 0≤t≤Tc,

where υ1that υ2that υ3that ωcthat ϕ1that ϕ2that ϕ3Tc- amplitude, carrier frequency, initial phase, and the duration of the signals;

output from the receiving antennas 1, 2, 3 through the receivers 4, 5, 6 are received at the two inputs of the phase meter 7 and 8, respectively. And receiving antennas 1, 2, 3 spaced apart and are located on the same line (figure 2). Antennas 1 and 2 is formed by first measuring the base of the d1and antennas 2 and 3, the second measuring BA is and d 2respectively (d1≠d2). The phase meter 7 and 8 measured phase shifts, respectively:

Δϕ112=2π·d1/λ·Cosβ,

Δϕ223=2π·d2/λ·Cosβ,

where d1d2measuring base formed by the antennas 1, 2 and 2, 3 respectively;

λ wavelength;

β - the angle of arrival of radio waves relative to the normal to the measurement database.

The measured shifts of phases Δϕ1and Δϕ2fed to two input vicites 9 and the adder 10.

The measurement of the difference of the difference of phases

Δϕp=Δϕ1-Δϕ2

equivalent to measuring the phase shift on the basis of which length

d3=d1-d2.

Thus, choosing the difference bases d3quite small, it is possible to ensure the formation of an appropriate measurement base.

The total phase shift

ΔϕΣ=Δϕ1+Δϕ2,

obtained at the output of the adder 10 is used to generate measurements, equivalent to measuring the phase difference on the basis of the d4which length is equal to the sum of the two original databases

d4=d1+d2.

Thus formed between measurement bases is the following nerves is in:

d3/λ<1/2≤d4/λ.

The lowest base d3determining the interval unambiguous measurement direction is determined from the condition

d3=λ/|umax-umin|,

where |umaxumin| - interval unambiguous measurement guide cosine.

The largest database of d4determines the accuracy of the measurement directions

d4=SΔϕ·λ/2πSu,

where SΔϕ - error phasemeter,

Su - measurement direction.

When negotiating measurement bases should be condition

ufrom≥2Sug,

i.e. twice the maximum error of measurement areas on a rough basis of d3should not exceed the interval unambiguous measurement of the exact directions on the basis of the d4.

To perform the matching conditions database, you must provide certain ratio between coarse and fine databases

d4/d3·SΔϕp<π.

Thus, the proposed method is compared with the reference object and other technical solutions for a similar purpose provides increased range unambiguous measure angles with a small length rough measurement base. This is achieved by the formation of coarse scale indirect method. Technical implementation of the proposed method requires less to the number of receiving antennas and receivers. This is especially important when the location of sources of radiation signals in a wide frequency range.

The phase method of direction finding, based on the reception of signals from three antennas, spaced apart and located on the same line, characterized in that form two unequal measuring base d1and d2the first and second antennas, the second and third antennas, respectively, measure the phase difference Δϕ1and Δϕ2between the signals received in the first and second, second and third antennas, respectively, determine the difference Δϕ R=Δϕ1-Δand2and the amount of ΔϕΣ=Δϕ1+Δϕ2the measured phase difference form using the difference of difference of phases ΔϕR. gross, but unambiguous scale reference angles corresponding to the small measuring the basis of the d2using the sum of the difference of phases ΔϕΣ- accurate but ambiguous scale of reference angles corresponding to large measurement database d1while the measurement of the difference of the difference of phases Δϕp is equivalent to the measurement of phase shift measurement basis, the length of which d3=d1-d2the measurement of the total phase shift ΔϕΣequivalent to measuring the phase difference on the measuring base, the length of which d4= 1+d2subject to the fulfillment of the inequality d3/λ<1/2≤d4/λ and approval of measuring bases, which doubled the maximum measurement error on the basis of the d3should not exceed the interval unambiguous direction measurement on the basis of the d4that is provided by the ratio of d4/d3·SΔϕ≤πwhere SΔϕ - error phasemeter.



 

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