RU2402041C2 - Radar energy potential correction method - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: along with an existing real radar channel, a virtual reference channel with a given radar energy potential value is formed, as well as a calibration target in form of a virtual cloud medium with an invariably known level of radar reflectivity. When correcting the radar energy potential, the cloud medium is probed, from which the distance to the analysed local volume of the cloud is determined and the projection of the envelope of the video pulse on the axis of the distance in the real and reference channels respectively is found. Further, the difference in electromagnetic density of the cloud medium between the virtual reference and real channels is found using a calculation method. The radar energy potential is then corrected by determining its true value using the corresponding formula.

EFFECT: more accurate radar measurements through correction of the radar energy potential in each measurement cycle.

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Description

The invention relates to the field of radar meteorology and can be used in both civilian and military meteorology to correct the value of the energy potential of ground and airborne radars.

There are various methods of monitoring and correcting the energy potential of the radar by the following methods:

- the magnitude of the reflected signal from local objects;

- by separately measuring the technical parameters of the radar;

- using a standard reflector;

- using a control resonator (echo camera).

(Latinsky S.M., Sharapov V.I., Ksendz S.P., Afanasyev S.S. Theory and practice of operating radar systems, ed. -36).

The disadvantages of the known methods include low accuracy of measurements due to the influence of uncontrolled factors and the difficulty of their implementation in practice.

Closest to the claimed object is a method of correcting the energy potential of a radar from a standard conductive target, for which the cross-sectional value of the backscattering is known (Guidance on the use of radars MRL-4, MRL-5 and MRL-6. / M.T. Abshaev, I. I. Burtsev, S. I. Vaksenburg, G. F. Shevela. - L .: Gidrometeoizdat, 1980, p.138-145. Prototype).

In practice, when determining the energy potential of a radar, it is calibrated against a standard target. The meaning of calibrating a radar against a standard target is to determine its energy potential, which allows us to further measure the radar reflectivity of the target relative to the known backscattering cross section of the conductive target.

When calibrating the radar according to the known method, a standard target is used in the form of a metallized sphere with a diameter of at least 30.5 cm. When calibrating the radar, a standard target is installed at a distance of 3-10 km from the radar and raised using a special cable to a height of 500-1000 meters above the ground . For this purpose, as a rule, pilot balls are used, and the process itself is carried out in calm weather. Then, the distance to the target and the power of the radio echo at the receiving end of the radar are determined by radar sensing. Then determine the value of the energy potential of the radar (C _λ ) according to the well-known formula.

A significant disadvantage of this method is that under the influence of a number of uncontrolled factors, the value (C _λ ) is not constant, and the procedure for measuring it is associated with significant labor costs, because It requires special transport, a winch holding the ball pilot at an altitude of 500-1000 m using a special cable. In addition, the relief of the underlying surface and climatic conditions (snow, dirt, fog, wind) do not always provide the possibility of correcting the value (C _λ ) in this way. Therefore, in practice, this procedure is performed once a year, and then, during operation of the radar, periodically correct the value (C _λ ) for reference targets (mountain, various artificial elevations, etc.). However, it is not possible to carry out regular correction of the value (C _λ ) for benchmark purposes in each measurement cycle in the online mode. As a result, the accuracy of radar measurements is significantly reduced.

The technical result of using the claimed technical solution is to increase the accuracy of radar measurements by correcting the energy potential of the radar in each measurement cycle.

The technical result is achieved by the fact that in the known method of correcting the energy potential of a radar using a calibration target, along with the existing real radar channel, a virtual reference channel is formed with a given value of the energy potential of the radar (C _λo ), and a calibration target, which is used as a virtual cloud environment , with a known level of radar reflectivity (η _o ), then, when correcting the energy potential of the radar in a real channel, sounding of a cloud medium, in which a local test volume is extracted, and from the radar screen for a given volume, using the envelope of the video pulse, determine the maximum value of the echo intensity under the envelope of the video pulse (Z _R.1 ), the distance to the cloud (R ₁ ), corresponding to this value, the maximum value of the echo signal intensity (Z _{max. 1} ) from the local test volume at a distance from the radar equal to a unit distance (R _e ) in 1 km, and the length of the projection of the envelope of the video pulse (ΔR ₁ ) on the distance axis, P After that, for the virtual reference channel, where the value of the energy potential of the radar (C _λ.o ) and the value of the radar reflectivity of the virtual cloud environment (η _o ) are specified, the maximum range of the hardware contact (R _max.o ) is _determined by the formula

then for this channel, using the found value (R _max.o ), determine the maximum value of the intensity of the echo signal (Z _max.o ) from the virtual cloud environment, at a distance from the radar, equal to a unit distance (R _e ) of 1 km, according to the formula

and the maximum value of the echo signal intensity (Z _R.0 ) corresponding to the distance found in the real channel (R ₁ ), according to the formula

then, using the obtained values of Z _R.0 , Z _max.0 and Z _max.1 , determine the length of the projection of the envelope of the video signal on the distance axis in the virtual reference channel (ΔR _o ) according to the formula

and, using the values of the found values (ΔR _o , ΔR ₁ , Z _max.o and Z _R.1 ), find the difference in the electromagnetic density of the cloud between the virtual reference and real channels (ΔD), according to the formula

then carry out the correction of the energy potential of the radar (C _λ.1 ), determining its true value by the formula

The technical result is achieved by the fact that the maximum value of the intensity of the echo signal (Z _{max. 1} ) at a distance (R _e ) from the radar in a real channel is determined by the formula

The technical result is also achieved by the fact that when determining the projection of the envelope of the video pulse on the distance axis in each channel, the initial section of the envelope of the echo signal is taken, limited by the maximum intensity of the echo signal.

The proposed method for correcting the energy potential of the radar has significant advantages compared with known methods, which can significantly improve the accuracy of radar measurements without the use of complex calibration targets.

The invention is illustrated in the drawing, which schematically presents a system that implements the proposed method.

The drawing schematically depicts a cloud 1, in which the local studied area 2 of the cloud environment is highlighted. The real channel is indicated by I, and the virtual reference channel by II. The radar in channels I and II is indicated by 3. In the real channel I, the video signal received from the local area of interest 2 is schematically represented as the envelope 4, and in the virtual reference channel II as the envelope 5. The maximum values of the echo intensity under the envelopes 4 and 5 in channels I and II are indicated, respectively, by (Z _R.1 ) and (Z _R.0 ), and the distance from the radar 3 to the central part of the local area 2 in the channels is indicated by R ₁ and R _0, respectively.

The projections of the envelopes of the echo signals 4 and 5 onto the distance axis (oh) in the real I and virtual reference channel II are denoted by ΔR ₁ and ΔR _0, respectively.

When determining the projections of the envelopes of the echo signal ΔR ₁ and ΔR _{0, the} initial sections of the envelopes 4 and 5 are taken, limited by the maximum levels of the intensity of the echo signal under the envelopes (Z _R.1 ) and (Z _R.0 ). In the drawing, the sections ΔR ₁ and ΔR ₀ , as well as the maximum levels of the echo intensity under the envelopes (Z _R.1 ) and (Z _R.0 ) are shown in bold.

A method of correcting the energy potential of a radar is implemented as follows.

Previously, along with the existing real radar channel (I), a virtual reference channel (II) is formed with a given value of the energy potential of the radar (C _λo ), in which a virtual cloud medium with a known level of radar reflectivity (η _o ) is used as a calibration target. Then, to correct the energy potential of the radar (C _λ.1 ) in the real channel (I), a cloud 1 is probed, in which the local volume of the cloud medium 2 is then extracted. After that, the maximum value of the echo signal intensity is determined from the radar screen 3 (Z _{R .1} ) under the envelope of the video pulse 4, and the distance (R ₁ ) to this level in the cloud. At the same time, the maximum value of the echo signal intensity (Z _{max. 1} ) is _determined at a distance of the local test volume 2 from the radar of 1 km, and the length of the projection of the envelope of the video pulse (ΔR ₁ ) on the distance axis (oh). Then, for the virtual reference channel (II), where the values of the radar energy potential (C _λ.o ) and the radar reflectivity of the virtual cloud environment (η _o ) are specified, the maximum range of the hardware contact (R _max.o ), the maximum echo intensity signal (Z _max.o ) at a distance of the local test volume 2 from the radar in 1 km, and the maximum value of the echo signal intensity (Z _R.0 ) corresponding to the distance found in the real channel (R ₁ ). Then, using the obtained values of Z _R.0 , Z _max.0 and Z _max.1 , determine the length of the projection of the envelope of the video signal on the distance axis (ΔR _o ) and the difference in the electromagnetic density of the cloud environment (ΔD) between the virtual reference and real channels. Then carry out the correction of the energy potential of the radar (C _λ.1 ), determining its true value by the formula

An example of a specific implementation of the method.

As an example, the result of the correction of the energy potential (C _λ.1 ) of a meteorological radar of the MPL-5 type, having in the normal mode C _λ.1 = 10 ²⁶ cm ³ and a radiation wavelength λ = 10 cm, is given.

To correct the energy potential of the radar (C _λ.1 ) in the real channel (I), radar sounding of cloud 1 was carried out, in which the investigated local volume 2 was then allocated, which creates an echo signal at the receiving point with the following parameters:

R ₁ = 30 km; Z _R.1 = 25 dB (in one direction of movement of the electromagnetic wave); ΔR ₁ = 5 km. These values of R ₁ , Z _R and ΔR ₁ determined from the radar screen using the envelope of the echo signal 4 are the source for the channel (I) under consideration.

The initial data for the virtual reference channel (II): With _λ.0 = 10 ²⁶ cm ³ and η _o = 10 ^-8 cm ^-1 . The values of C _λ.0 and η _o in this channel are taken corresponding to the order of magnitude observed in practice.

Using the source data, we determine:

For a real channel.

The maximum value of the intensity of the echo signal from the local volume of the cloud medium studied at a distance of 1 km from the radar

For the reference channel.

1. The maximum range of the hardware contact (R _max.o ), according to the formula

2. The maximum value of the intensity of the echo signal (Z _max.o ), according to the formula

3. The maximum value of the echo intensity (Z _R.0 ) for the distance found in the real channel (R ₁ ) according to the formula

Then, using the values of Z _R.0 , Z _max.0 and Z _max.1 obtained above, we determine the length of the projection of the envelope of the video signal on the distance axis (ΔR _o ) in the virtual reference channel according to the formula

After that, using the found values (ΔR ₁ ), (ΔR ₀ ), (Z _max.1 ) and (Z _R.1 ), we find the difference in the electromagnetic density of the cloud environment (ΔD) between the virtual reference (II) and real (I) channels according to the formula

and then we carry out the correction of the energy potential of the radar (C _λ.1 ), determining its true value by the formula

Using a virtual cloud environment with known parameters as a standard calibration target allows monitoring the radar energy potential in the operational mode and in each measurement cycle. In this case, all errors are taken into account, including errors due to the influence of uncontrolled factors, which ensures high accuracy of radar measurements.

Claims (3)

1. A method for correcting the energy potential of a radar using a calibration target, characterized in that, along with the existing real radar channel, a virtual reference channel is formed with a given value of the energy potential of the radar (C _λ0 ) and a calibration target, which is used as a virtual cloud environment with a known level of radar reflectivity (η ₀ ), then, when correcting the energy potential of the radar in a real channel, a cloud medium is probed, in which the local test volume is extracted with rum, and the maximum value of the echo signal intensity (Z _R.1 ) of the echo signal under the envelope of the video pulse is determined from the radar screen for the given test volume, the distance to the cloud environment (R ₁ ) corresponding to this value, the maximum value of the echo signal (Z _max.1) of the local test volume at a distance from the radar it is equal to the unit distance (R _e) 1 km, and the length of the projection of a video envelope (ΔR ₁₎ on the distance axis, then for a virtual reference channel, which is set receptacle chenie radar energy potential (P _λ0) and the value of radar reflectivity virtual cloud (η ₀₎ calculated by determining the maximum range of the radar to a local test volume probed cloud (R _max.0) by the formula

,
then for the given channel, using the found value (R _max.0 ), determine the maximum value of the echo signal intensity (Z _max.0 ) from the virtual cloud environment, at a distance from the radar equal to a unit distance (R _e ) of 1 km, according to the formula

,
and the maximum value of the echo signal intensity (Z _R.0 ) corresponding to the distance found in the real channel (R ₁ ), according to the formula

,
then, using the obtained values of Z _R.0 , X _max.0 and Z _max.1 , determine the length of the projection of the envelope of the video signal on the distance axis in the virtual reference channel (ΔR ₀ ) by the formula

,
then, using the values of the found values (ΔR ₀ , ΔR ₁ , Z _max.0 and Z _R.1 ), the difference in the electromagnetic density of the cloud medium between the virtual reference and real channels (ΔD) is found by the formula

,
then carry out the correction of the energy potential of the radar (C _λ.1 ), determining its true value by the formula

. 2. The method of correction of the energy potential of the radar according to claim 1, characterized in that the maximum value of the intensity of the echo signal (Z _{max. 1} ) at a distance (R _e ) from the radar in a real channel is determined by the formula

. 3. The method of correcting the energy potential of the radar according to claim 1, characterized in that when determining the projection of the envelope of the video pulse on the distance axis in each channel, the initial portion of the envelope of the echo signal, limited by the maximum intensity of the echo signal, is taken.

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