How to determine the line position of the emitters

 

The invention relates to electrical engineering and can be used in installed on mobile platforms passive dynamical systems determine the line position of the emitters. How to determine the line position of the emitters, in which the movement of monopulse signal phase-type along the X axis of the XY plane with a constant speed V, the signal emitters at two spaced apart along the X-axis antenna A1and a2axes are constantly directed along the axis Y, the restriction of the antenna-received A1and a2signals S1(t) and S2(t), the dimension of the complex correlation coefficient F(t) between the received signals, determining according to F(t) of time t0the allocation of the limited signals S1(t) and S2(t) "p"-x harmonics S1p(t) and S2p(t), respectively, the measurement of instantaneous frequency(t) the complex correlation coefficient F(t), the measurement time, the measurement of the complex correlation coefficient F(t) is performed for the signals S1p(t) and S2p(t) a t0is defined as the instant frequent the Oia is to eliminate the ambiguity of the definition line the position of the source of radio emission. 4 Il.

The invention relates to electrical engineering and can be used in installed on mobile platforms passive dynamical systems determine the line position (PL) sources of radio emission (IRI).

A well-known problem of determining the PL Iran on the XY plane [1, C. 182]. One solution to this problem involves the use of a goniometer (DF) measurement devices for directions on the detected IRI [1, C. 182-183]. As goniometric devices can be used, in particular, DFS with monopulse antenna sensors, i.e., the monopulse direction finders (MP) [1, S. 405-413; 2].

For goniometric devices PL Iran is a line passing through a specific point on the XY plane in the direction of Iran. For MP, members of the stationary radar of the circular review, this is the installation location of the MP, which together with the axis of the antenna MP, aimed at Iran, determines PL Iran.

Another, in some sense, the opposite is the case when MP is installed on the platform, performing a rectilinear motion along the X-axis with constant velocity V, and the axis of the antenna system MP is recorded continuously in the Y axis direction perpendicular to tractatio side view [1, S. 393-399]. When working sideward-looking in passive mode PL Iran, we can uniquely determine the time t0in which the direction of arrival of waves from Iran coincides with the direction of the Y axis, i.e. along the axis of the antenna system MP. This time t0uniquely associated with a point trajectory MP, of which Iran is seen at right angles to the course MP (in nautical terminology - on the beam), and therefore fully determines the PL Iran.

The lack of counterparts, regardless of the method (circular or side) view of the area, is the low accuracy of determination of the PL IRI the existing constraints on the constructive dimensions of antenna sensors MP. Will illustrate this on the example of the MP, which uses a monopulse antenna phase sensor type [2, S. 67-68], consisting of two separated by distance L (base) along the X-axis antennas A1and a2axes are oriented in the direction of the axis Y. In MP this type the location of Iran along the axis of the MP means equidistance IRI from the centers of the antennas A1and a2and the deviation of the IRI from the axis of MP is determined by measuring the current values of the correlation coefficient between the signals S1(t) and S2(t) received by the antennas A1and a2sootvetstvenno basis of L/between antennas, where- wavelength Iran. This explains the desire to increase the accuracy of the measurements by increasing L (for a given). However, to make another fundamental requirement of unambiguous measurement of bearing on Iran, the growth of L must be accompanied by an increase of the diameter of the antennas And1and a2that should not be less than the distance L between them. When the construction of these antennas is limited, the contradiction between the requirements of high precision and unambiguity of the bearing measurement cannot be resolved within the traditional processing methods.

The severity of this contradiction can be partly smoothed in the method prototype, which involves a lateral view of the area. For the proposed method of passive radar side view with monopulse antenna phase sensor type are basic radio systems, and the corresponding set of operations performed in the MP over the receiving signal IRI for direction finding and determination PL Erie, is a prototype method. However, we must assume that in MP prototype measured two correlation coefficient - real F* and imaginary F** sowmya in the presence of the barrier on/2 in the channel signal processing S1(t), and imaginary F** - in its absence [2, S. 250].

The disadvantage of the prototype is the ambiguity of the definition line position of Iran in the case when the distance between antennas MP phase-type considerably exceeds the diameter of each antenna.

The purpose of the invention is to eliminate the ambiguity of the definition line position on Iran.

For this purpose, in the method prototype in which: - move MP phase-type along the X axis of the XY plane with constant speed V; - reception of signals IRI two spaced apart along the X-axis antenna A1and a2axes are constantly directed along the Y axis; - the limitation of the antenna-received And1and a2signals S1(t) and S2(1); - measurement of the current values of F(t) is the complex correlation coefficient F between received signals; determining current values of the complex correlation coefficient F(t) of time t0where IRI is equidistant from the antenna (A1and a2and which uniquely characterizes PL Erie, additionally: - the allocation of limited signals S1(t) and S2(t) "p"-x harmonics S1R(t) and S2R(t), respectively; - the measurement of instantaneous castagana frequency(t) reaches its maximum valuemaxand: - measurement kompleksnogo correlation coefficient F(t) is performed for the signals S1p(t) and S2p(t);
- a t0is defined as the instantaneous frequency(t) the maximal valuemax
In Fig. 1 shows the geometrical arrangement of the IRI and MP, as well as the phase of f(x), the instantaneous frequency(x), the output signal SC of the comparator 20 and the clock pulse C as a function of spatial coordinates x=Vt.

In Fig.2 gives a magnified image of the antenna sensor MP phase type and phase front of the signal Erie in the vicinity of the antenna MP.

In Fig.3 shows a diagram of the MP phase-type, forming a real F*(t) and imaginary (F*(t) components of the complex correlation coefficient F(t). Here labeled: 1, 2 - mixer; 3, 4 - if amplifier; 5, 6 - amplifier-limiter with a bandpass filter tuned to the center frequency equal to R; 7 - lo; 8 Phaser/2; 9, 10 - phase detector. The circuit of Fig.3 differs from the type by presence of elements 5, 6.

In Fig. 4 shows a possible circuit is th frequency(t) its maximum value. Here designated: 11, 12 - multiplier products; 13 - generator harmonic oscillations; 14 - adder, 15 - frequency detector; 16 - analog-to-digital Converter (ADC); 17 - block select max (BWM); 18 - unit time recording (BRV); 19 - clock (GTI); 20 comparator; 21 - differentiating chain, 22 - meter real-time.

Consider the transformation performed on the signals IRI according to the proposed method. Let Iran is located at the point of the plane with coordinates: x= 0, y=R and emits a continuous harmonic signal. The phase front of the signal has the form of a circle with centre at the point (0, R) and the phase distribution is:
(x,y)=(2/)[x2+(y-R)2]-0,5(1)
Temporarily assume that MT is stationary and located at the observation point with coordinates (x, 0), i.e. at the point (x, 0) is the center of the base of the MP phase type. Then received by the antennas A1and A2the signals S1(t) and S2(t) are in phase, which depends on the "x" coordinate of the point of observation. Provided that the base L is not too large, so that the wave can be considered flat, the difference f(x /x (2)
which after substitution in the expression (1) gives
F(x)=(2/)L(x/R)[1+(x/R)2)0,5. (3)
The dependence of f(x) is shown in Fig.1. In the expression (3) is not entered for this parameter as the size of the antennas due to the fact that in the original assumptions antennas have poor focus, allowing you to select only one half-plane (Y0), i.e., to detect Iran's only one (left or right) side of the media MP.

After limiting signals S1(t) and S2(t) in items 5, 6 selection using bandpass filters their "R"-th harmonics of S1p(t) and S2p(t) the difference of their phases (3) is also increasing in p time. Real F*(x) and imaginary (F**(x) components of the complex correlation coefficient of F(x), considered as functions of the spatial variable x is allocated on the outputs of the phase detectors 10,9 respectively, and are expressed through the phase difference of the RF(x) from the input signals S1p(t) and S2p(t):
F*(x) =Cos[RF(x)]; F**(x) = Sin[RF(x)]. (4)
Previously introduced the assumption of immobility of the MP can be removed, if formula (3), (4) remain valid after replacing them prostranstve, during which examined as a function of time t, the phase difference of the RF(t) is changed by the value of/2 is much greater than the time interval during which the measured phase difference RF(t).

Therefore, in the future, for the moving MP we will continue to use the expression (4) for real F*(x) and imaginary (F**(x) components of the complex correlation coefficient of F(x), considering them in the variable "x" is equal to the product x=Vt. Further, when the complex correlation coefficient F real F* and imaginary F** components will not be considered as functions of the spatial variable x and as a function of time t, uses the notation F(t), F*(t) and F**(t), respectively.

The instantaneous frequency(x) the complex correlation coefficient of F(x) is obtained by differentiation of RF(x) in time taking into account the equality x=Vt:
(x)=(2/)(pLV/R)[1+(x/R)2]-1,5(5)
and this dependence is shown in Fig.1.

Harmonic model of the signal IRI is obviously an idealization of real signals IRI. For a more General signal model of IRI in the form of a continuous photomanipulating sparoga law changes from time to time, of the form (4) can be observed the emission of the pulsed nature (different polarity). However, if the duration of elementary parcels photomanipulating signal significantly exceeds the propagation time of radio waves along the base L, then, by choosing the time constant of the smoothing filter at the output of the phase detectors 10, 9 commensurate with the duration of elementary parcels, these emissions in the output signal F*(t), F**(t) will be eliminated.

Watching the change of the instantaneous frequency(x) and considering it as a function of(t) of time t, we can determine the time t0at which it reaches its maximum valuemax. It was at this point Iran is on the beam MP, i.e., equidistant from the antenna A1and a2. This can be done automatically using the device of Fig.4. In it of the two quadrature components of the complex correlation coefficient F(t)=F*(t)+jF**(t) with generator 13 frequency, multiplier products 11, 12 and adder 14 is formed of a high-frequency signal S(t), modulated by the phase of the RF(t):
S(t)=F*(t)Sint+F**(t)Cost=Sin[t+RF(t)] (6)
The instantaneous frequency(t) this signal is frequency 32D/chr/969.gif">and the other frequency+maxwheremaxmaximum frequency of the complex correlation coefficient F(t). The output signal of the frequency detector 15 is shape-based(x) Fig.1. Time t0it reaches a maximum value determined by the elements 16-22 circuit of Fig.4.

The operation of the device of Fig.4, includes items 16, 17, 18 and 19, described in detail in [3] and essentially boils down to measuring the time delaythe output signal of the frequency detector 15 (or more precisely, of its maximum value) relative to the auxiliary synchronizing pulse C applied to the control inputs of the blocks 17 and 18 before the appearance of this maximum value. Using SI is cleared included in blocks 17, 18 registers and counter delay time. T* the occurrence of SI can be fixed using the absolute time counter 22, and then the absolute time t0achieve instant frequency(t), its maximum value is defined as
t0=t*+. (7)
Thus, the pair of values

The clock pulse C is expedient to form at time t*, close to the time t0(but not later) to reduce the amount (capacity) included in BRW 18 counter delay time. This is part of the schema of Fig.4, includes items 20 and 21. The output signal of the frequency detector 15 that is proportional to(t), is fed to the signal input of the comparator 20, the reference input of which receives the reference voltage, selectable, for example, at the level of 0.35 from the maximum values ofmax. At the output of the comparator 20 is formed by the signal SK constant amplitude Fig.1, throughout which frequency(t) exceeds a threshold of 0.35max. Clock pulse C is generated at the output of differentiating network 21, and coincides with the leading edge of the output signal SC of the comparator 20.

Measurement procedureends after filling of the counter delay timein block BRW 18. It is assumed that the volume of this counter is filled approximately to the end of the observation interval IRI.

We now illustrate this specific PR is the values of radio and daleste-speed parameters: R=5-7, L/=30-100; V=20 m/s, R=40 m, the Maximum value of the frequency is: (1/2)max= 75-350 Hz. Linear observation interval IRI chosen equal to the distance to the IRI: x=R. the Value of instantaneous frequency(x) at x/R=1, corresponding according to (5) level of 0.35maxlies in the interval (1/2))(=26-125 Hz. Thus, during the time of observation IRI equal to 2R/V=4, the variation of the instantaneous frequency(t) is either 26-75 Hz (p=5, L/=30), or 125-350 Hz (p=7, L/=100).

On the detected value of t0PL is defined in relative (moving) coordinate system associated with the MP. In the presence of SSO (absolute) time and navigation systems, provide "anchor" moving platform MP for the area, you can define a PL in absolute (earth) coordinate system.

Note that the problem of determining the PL IRI often help solve the more General problem of identifying the object on which you installed the IRI. Show how it can be resolved which can be recorded in real time by a human operator "by ear" without the use of additional devices of Fig.4, which is enough play time dependence of the complex correlation coefficient F(t) by connecting the output of one of the phase detectors 9, 10 to the headphones of the operator.

If, moreover, on a mobile platform MP have the option to install an optical device for monitoring an area, the axis of which is directed along the Y axis, the operator can carry out a rough "anchor" of the passing of the instantaneous frequency(t) its maximum value to a specific object on the ground (vehicle, building, house window, and so on) and identify thus the option to install or media IRI.

Secondly, the procedure of identifying the location of the IRI can be done more accurately in a hospital after a review of space for what platform MP must be set to video camera, fixing, in addition to the image location along the Y axis, also the absolute time t* from the counter 22. Given a set of data obtained by the device of Fig.4, consisting of various pairs of values {t*,} explored IRI, it is possible to identify objects-native Iran while watching a video, perform a "bind" the data to image objects on Feedlounge method (Fig.4) turned out to be quite simple because what range to Iran was assumed approximately known (precision = 30-50%), because information about R was used in the frequency detector 15, the comparator 20, and also when selecting the volume (capacity) included in BRW 18 counter delay time.

However, in the considered situation - intelligence on Iran in an urban environment, this assessment of the range R can be easily obtained, because the potential installation sites identified leads may contain Iran - along streets, buildings, cars, etc. is easily observed visually and distance to them can be measured with the use of assistive devices or passive optical system, or active radar system. Given that at a sufficiently large distance intervals, comparable to the length of the street, the distance R remains approximately constant, the update data about R in the processing device should be fairly rare.

Decoding used letter symbols:
V is the velocity of the platform, on which is mounted a MP;
L is the distance (baseline) between the antennas A1and a2q-switched signal, the phase type;
S1(t) and S2(t) the signals received by the antennas A1and arespectively after limiting signals S1(t) and S2(t);
S(t) - a high-frequency signal generated at the output of the adder 14 of the meter of Fig.4;
F is the complex correlation coefficient between the signals S1p(t) and S2p(t);
F* is the real part of the complex correlation coefficient F;
F** is the imaginary part of the complex correlation coefficient F;
F(t) is the complex correlation coefficient between the signals S1p(t) and S2p(t), considered as a function of time t;
F(x) is the complex correlation coefficient between the signals S1p(t) and S2p(t), considered as function of coordinates x;
F*(t) is the real part of the complex correlation coefficient between the signals S1p(t) and S2p(t), considered as a function of time t;
the same output signal of the phase detector 10;
F**(t) is the imaginary part of the complex correlation coefficient between the signals S1p(t) and S2p(t), considered as a function of time t;
the same output signal of the phase detector 9;
F*(x) is the real component of the complex correlation coefficient of F(x);
F**(x) is the imaginary component of the complex correlation coefficient of F(x);
(x) is the instantaneous frequency of the complex correlation coefficient of F(x) viewed as a function of the coordinates x;
max- the maximum value of instantaneous frequency(t);
F(t) is the phase difference of the signals S1(t) and S2(t), considered as a function of time t;
F(x) is the phase difference between signals S1(t) and S2(t), considered as function of coordinates x;
RF(t) is the phase of the signal S(t), considered as a function of time t;
RF(x) is the phase of the signal S(t), considered as function of coordinates x;
- wavelength IRI;
R is the distance measured from the MP in the direction perpendicular to the trajectory MP and coinciding with the axis of the MP. On the other: it is the distance between two straight lines, one of which is the trajectory of the MP and the other is a set of points, each of which can be located IRI;
(x, y) is the phase distribution of the signal IRI on the XY plane;
t is the absolute time;
t0- the time at which the IRI is equidistant from the antenna (A1and a2and at which instant cha is t* - when SI;
the time between the moment of achievement of output signal(t) of the frequency detector 15 its maximum valuemaxand the moment of occurrence of t* sync, C;
/x is the operation of taking private derivative of the variable "x";
x is the spatial coordinate.

Sources of information
1. Y. P. Grishin and other Radio system / Ed. by Y. M. Kazarinov. - M., 1990.

2. Leonov, A. I., Fomichev K. I. Monopulse radar. - M., 1984.

3. Auth. mon. 1824596, G 01 R 29/02 (Meter pulse delay).


Claims

How to determine the line position of the emitters, in which the movement of monopulse signal phase-type along the X axis of the XY plane with a constant speed V, the signal emitters at two spaced apart along the X-axis antenna A1and a2axes are constantly directed along the axis Y, the restriction of the antenna-received A1and a2signals S1(t) and S2(t), the dimension of the complex correlation coefficient F(t) between the accepted of signalmen And1and a2and which uniquely characterizes the line the position of the source of radio emission, characterized in that additionally the allocation of limited signals S1(t) and S2(t) "p"-x harmonics S1p(t) and S2p(t), respectively, the measurement of instantaneous frequency(t) the complex correlation coefficient F(t), the measurement of the point in time when the instantaneous frequency(t) reaches its maximum value, and the measurement of complex correlation coefficient F(t) is performed for the signals S1p(t) and S2p(t) and t0is defined as the instantaneous frequency(t) its maximum value.

 

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