RU2655750C1 - Method of adjustment and verification of radar location levels and stand for regulation and check of radar location levels - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: invention relates to the field of measurement technology and can be used to adjust and verify radar level gauges. Method of adjustment and verification of radar level gauges is based on a simulation of level measurement in a horizontal plane by successively reproducing several predetermined distances between a flat reflector and a radar level gauge. At that for adjustment and verification of radar level gauges in the range of distances exceeding the physical dimensions of the stand, increase the electrodynamic length of the transmission line of electromagnetic energy (TLEE) of the level gauge in its antenna-waveguide path, sequentially connecting additional TLEE from the TLEE set with a discrete change in length. Stand for adjustment and verification of radar level gauges contains column 1 for fixing the level gauge, that consists of a device for generating and processing signals 2, TLEE 3 and antenna 4, support 5, flat reflector 6 perpendicular to straight line 7 passing through the centers of flat reflector 6 and opening antenna 4, device for horizontal displacement 8, means for measuring distance 9 and removable additional TLEE 10 from the TLEE set with a discrete change in the electrodynamic length.

EFFECT: technical result of the invention consists in reducing the cost of the stand and eliminating the procedure for correcting the results of measurements.

9 cl, 3 dwg

Description

The invention relates to the field of measuring equipment and can be used for certification, verification and calibration of radar level meters (level meters) of liquids and bulk materials.

A known method of checking level gauges for industrial use [1, 2], based on a comparison of the reproduced and measured levels. In this method, several distances (at least five) between the radar level meter and the flat reflector are sequentially reproduced by moving the flat reflector, measuring the sequence of delay times of the reflected signal from the flat reflector and calculating the sequence of measured distances from the known propagation velocity of the radio waves and the measured delay times of the reflected signal from flat reflector. Then, the error in measuring the distance is calculated as the difference between the measured and reproduced sequences of distances. The differences obtained are used to correct the parameters of the level gauges and to determine the error of the level gauges.

The specified method can be implemented using the following known devices.

A known installation for primary and periodic verification of industrial level gauges "MICROPILOT" containing a measuring tape, a support for the level gauge, made with the possibility of discrete movement and orientation of the level gauge normal to the reflective wall [3].

The specified installation does not provide the performance necessary in an industrial environment and cannot provide a measure of the resolution of the level gauge over distance.

A well-known NIIIS stand IGND.407619.001 for adjusting and calibrating radar level gauges, comprising a movable stand mounted on a plate of a horizontal movement device and configured to mount a level gauge, a support (or other stand) made with the possibility of fixed installation, a flat reflector mounted on a support perpendicular to the straight line passing through the centers of the flat reflector and the aperture of the level gauge antenna during calibration, a means of measuring the distance from the rack to the flat reflection a body in the form of a measuring tape [4].

A number of measuring devices are known for measuring the scattering characteristics of radar targets [5, 6], containing reflectors of a given shape, placed on weakly reflecting supports covered by radar absorbing material (RPM), radar meters and devices for changing the coordinates of reflectors.

The specified method and the listed measuring installations and stands cannot provide a low measurement error of the accuracy characteristics of the level gauges over a wide range of distances. For industrial level gauges, the permissible measurement error is units and fractions of millimeters, and the required range of measured distances is from tens of centimeters to tens of meters. This leads to the need to use measuring installations for the implementation of this method of checking level gauges, the dimensions of the working zones of which significantly exceed the dimensions of the working zones of known measuring installations, which significantly increases the cost of such installations.

The closest set of essential features to the proposed method and device (prototype) is a stand for adjustment and verification of radar level gauges [7], containing a stand made with the possibility of mounting a level gauge, a support, a flat reflector mounted on a support perpendicular to the longitudinal axis that coincides with the axis of the antenna level gauge during its adjustment and verification, horizontal movement device, means of measuring the distance from the reference point to a flat reflector, additional reflector and electronic made of radar absorbing material, the support is placed on a horizontal movement device for discrete changing the distance from the reference to the flat reflector, the screen is made with the possibility of horizontal movement simultaneously with the movement of the support to shield its surface below the flat reflector, and the distance from the flat reflector to the screen is at least two resolution distances of the level gauge, the additional reflector is mounted on a rack and made in the form of a surface of the second row with a radius of curvature of 2-4 times greater than the maximum distance between the center plane and an additional reflector, wherein the rack and the additional reflector are formed with respective through-holes for mounting the transmitter antenna. An additional reflector is spherical or cylindrical in shape.

The disadvantage of this stand for adjusting and calibrating radar level gauges is the complexity of the shape of the additional reflector, which significantly increases the cost of the stand and necessitates an additional correction of the results for the level gauge antennas of various sizes and types.

The technical result of the invention consists in reducing the cost of the stand and eliminating the procedure for correcting measurement results.

The technical result is achieved by the fact that in the method of adjustment and verification of radar level gauges, including the first sequential reproduction of several predetermined distances between the level gauge, which contains interconnected device for generating and processing signals, an electromagnetic energy transmission line (LET) and an antenna, and a flat reflector by moving a flat reflector, measuring the first sequence of delay times of the reflected signal from a flat reflector, calculating the first the sequence of the measured distances, which is performed according to the known propagation velocity of the radio waves and the measured delay times of the reflected signal from the flat reflector, reproducing the second sequence of additional specified distances by sequentially moving the flat reflector to the second sequence of distances, measuring the second sequence of signal delays, calculating the second sequence of measured distances, calculating errors in the form of the difference between both Using the reproduced and measured distances of the same name, and using the calculated error to correct the level gauge parameters and to determine the level gauge error with the following conditions, additionally perform the following set of actions. For measurements in the range of distances exceeding the length of the bench, the electrodynamic length of the LET of the level gauge is increased, including the additional LET from the discrete set of LET, with the electrodynamic length shorter than the maximum reproduced distance from the previous sequence of given distances by the minimum reproducible distance, move the flat reflector in the direction of the antenna until the result matches measurements from the current additional LET with the maximum measurement result of the previous sequence The accuracy of the measured distances takes the found position of the flat reflector as the initial one for the new sequence of additional specified distances and reproduces the next sequence of additional specified distances, selects the signal corresponding to the current reproduced distance to the flat reflector taking into account the electrodynamic length of the current additional LET, measures a new additional sequence of signal delays up to flat reflector taking into account current electrodynamic lengths s additional LETE, calculate the corresponding additional sequence of measured distances, and the measurement of sequences of delay times of the reflected signal from the flat reflector is performed at the level of noise not resolved by distance, not exceeding the permissible, and deviation from the uniform dependence of the speed of electromagnetic energy in additional LETE on the oscillation frequency exceeding permissible.

In these measurements, the allowable level of interference not resolved over the distance is specified by the allowable signal-to-noise ratio, q _nc , defined by the expression

q _nc ≤ (1,2 ÷ 2,5) K _m ΔR _norms / N,

where ΔR _norms is the normalized value of the permissible error equal to the ratio of the absolute permissible error to the resolution of the radar level gauge;

K _m - coefficient taking into account the signal processing method (when estimating the distance from the signal spectrum K _m = 1 and using the maximum likelihood method to clarify the result K _m = 5 ÷ 7);

N is the multiplicity of reflections used.

The change in the propagation velocity of electromagnetic energy in additional LETE with a change in the oscillation frequency in the frequency band of the probe signal should not exceed one percent.

The technical result is also achieved by the fact that in the stand for adjustment and calibration of radar level gauges, comprising a stand made with the possibility of mounting a level gauge, which includes interconnected signal conditioning and processing devices, LET and antenna, support, a flat reflector mounted perpendicular to the support a straight line passing through the centers of the flat reflector and the aperture of the antenna, a horizontal displacement device, a means of measuring the distance from the reference point associated with the rack to a flat reflector, a removable additional LETE from a set of LETE with a discrete change in the electrodynamic length was introduced. Moreover, the discrete change in the electrodynamic length of the removable additional LET in the LETE set is less than the difference between the maximum and minimum distances to the flat reflector.

It is possible to perform additional LETE in the form of a waveguide with matching devices.

It is advisable to carry out additional LETE in the form of two first and second three-arm circulators connected in series through partial LETEs, with the first arm of the first circulator connected to the signal conditioning and processing device, the second and third arms of the first circulator connected through partial LETE, respectively, with the first and third arms the second circulator, and the second shoulder of the second circulator is connected to the antenna.

The analysis of the prior art, including a search by patent and scientific and technical sources of information and identification of sources containing information about analogues of the claimed invention, allows us to establish that the applicant has not found technical solutions characterized by features identical to all the essential features of the claimed invention. The definition from the list of identified analogues of the prototype made it possible to identify a set of essential (in relation to the technical result perceived by the applicant) distinctive features in the claimed object set forth in the claims. Therefore, the claimed technical solution meets the requirement of "novelty" under the current law. Information about the fame of the distinguishing features in the totality of the characteristics of the known technical solutions with the achievement of the same as the claimed device, there is no positive effect. Based on this, it was concluded that the proposed technical solution meets the criterion of "inventive step".

In FIG. 1 shows a stand for adjusting and calibrating radar level gauges without an additional waveguide.

In FIG. 2 shows a stand for adjusting and checking radar level gauges with an additional waveguide.

In FIG. 3 shows an additional LETE.

The stand (Fig. 1) for adjusting and calibrating radar level gauges contains a rack 1 made with the possibility of mounting a level gauge containing a signal generation and processing device (UFOS) 2, LET 3 and antenna 4, support 5, a flat reflector 6, mounted on the support perpendicular to the straight line 7 passing through the centers of the flat reflector 6 and the aperture of the antenna 4, the horizontal displacement device 8, the means 9 for measuring the distance from the reference point associated with the rack 1 to the flat reflector 6 and an additional LETE 10 (Fig. 2) with the electrode the shortest maximum reproducible distance.

It is possible to perform additional LPEE 10 in the form of a waveguide with matching devices.

Preferably, the additional LETE 10 (Fig. 3) is made in the form of two serially connected through two partial LETEs 11 and 12 of the first 13 and second 14 three-arm circulators, with the first shoulder 15 of the first circulator 13 connected to UFOS 2, the second 16 and third 17 shoulders of the first circulator 13 are connected through partial LETEs, respectively, with the first 18 and third 19 arms of the second circulator 14, and the second arm 20 of the second circulator 14 is connected to the antenna 6.

The proposed method for adjusting and calibrating radar level gauges is implemented using a stand for adjusting and calibrating radar level gauges as follows. In accordance with FIG. 1 using a horizontal moving device 8 and means 9 for measuring the distance from the reference point associated with the rack 1 to the flat reflector 6, the first sequential reproduction of several predetermined distances between the antenna 4 and the flat reflector 6 is made. At each reproduced distance, radio waves are generated and emitted in the direction a flat reflector 6, receive, after the propagation time, the echo of the wave and form a reflected signal from them, a signal corresponding to the reproduced distance to flat reflector 6, measure the first sequence of delay times of the reflected signal from the flat reflector 6, calculate the first sequence of measured distances from the known propagation velocity of the radio waves and the measured delay times of the reflected signal from the flat reflector 6.

Then, an additional LETE 10 is installed between the antenna 4 and LETE 3 in accordance with FIG. 2, move the flat reflector 6 in the direction of the antenna 4 until the distance measurement result coincides with the included additional LETE 10 with the measurement result at the maximum reproduced distance without additional LETE 10, take the found position of the flat reflector 6 as the initial position and reproduce the second sequence of additional specified distances, select the signal corresponding to the distance to the flat reflector 6, taking into account the electrodynamic length of the additional LETE 10, measure the additional sequence In order to determine the accuracy of the signal delays, an additional sequence of measured distances is calculated and the measurement error is calculated as the difference between both sequences of the reproduced and measured distances of the same name and the calculated error is used to correct the parameters of the radar level gauge and to determine the error of the radar level gauge.

Tests and operation of the inventive level gauge calibration bench showed that the measurement error due to the structural elements of the bench when measuring the characteristics of continuous-wave level gauges and periodic triangular frequency modulation of the probe waves does not exceed 0.002δ _R , where δ _R = c / 4Δƒ is the value of the discrete error, c is the speed of light, Δƒ is the frequency modulation range. The longitudinal size of the anechoic chamber is 17 m. With a greater distance for checking the level gauge, the cost of the proposed stand is at least 1.5 times less than the cost of a known stand [4].

When using additional LLEE, there is no need for additional correction of results for level gauge antennas of various sizes and types, which simplifies and speeds up the procedure for adjusting and calibrating level gauges.

Information sources

1. GOST 8.321-2013. State system for ensuring the uniformity of measurements. Level gauges for industrial use. Verification method: M. Standartinform. 2015.

2. Level gauges radio wave "BARS". Verification procedure YuYaIG.407629.009 MP.

3. Microwave level meters "MICROPILOT". Verification technique. G.R. No. 17672-02. State system for ensuring the uniformity of measurements. All-Russian Research Institute of Metrological Service (VNIIMS), Moscow, 2002.

4. Description of the calibration bench of the IGND.407619.001 level gauges (developed by the NIIIS), State Register No. 18237-99.

5. Mitsmakher M.Yu., Torgovanov V.A. Microwave anechoic chambers. - M .: Radio and communications, 1982. - 128 p.

6. Mayzels E. N., Torganov V.A. Measuring the dispersion characteristics of radar targets. Ed. M.A. Kolosova, M. Publishing House "Soviet Radio", 1972, p. 232, p. 138-143.

7. RF patent No. 2298770. Stand for adjustment and verification of radar level gauges. Atayants B.A., Davydochkin V.M., Yezersky V.V., Bologin V.A., Mazalov Yu.V., Markin S.A., Nagorny D.Ya. (prototype).

Claims (13)

1. The method of adjustment and verification of radar level gauges, including the first sequential playback of several predetermined distances between a flat reflector and a radar level gauge, which contains interconnected device for generating and processing signals, an electromagnetic energy transmission line (LET) and an antenna, ranging from minimum to maximum reproducible distances by moving a flat reflector, measuring the first sequence of delay times of the reflected signal from the plane the first reflector, calculating the first sequence of measured distances, which is performed according to the known propagation velocity of the radio waves and the measured delay times of the reflected signal from the flat reflector, reproducing the second sequence of given distances by sequentially moving the flat reflector to the second sequence of distances, measuring the second sequence of signal delays, calculating the second sequence the measured distances, the calculation of the error in the form of differences between sequences of reproduced and measured distances of the same name and using the calculated error to correct the parameters of the radar level gauge and to determine the error of the radar level gauge, characterized in that for reproducing the second and subsequent sequences of additional specified distances between the LET and the antenna include an additional LET from a discrete set of LET, with electrodynamic less than the maximum reproduced distance from the previous last The set distances are taken for the value of the minimum reproducible distance, the flat reflector is moved in the direction of the antenna until the measurement result matches the current additional LET with the maximum measurement result of the previous sequence of measured distances, the found position of the flat reflector is taken as the initial one for the new sequence of additional specified distances and the next sequence of additional given distances, emit a signal corresponding to the current reproducible distance to the flat reflector, taking into account the electrodynamic length of the current additional LET, measure a new additional sequence of signal delays to the flat reflector, taking into account the current electrodynamic length of the additional LET, calculate the corresponding additional sequence of measured distances, and measure the sequences of delay times of the reflected signal from the flat reflector at the level of interference not resolved by distance, not exceeding x permissible, and the deviation from the uniform velocity dependence of the electromagnetic energy in additional LPEE the oscillation frequency does not exceed the permissible. 2. The method according to p. 1, characterized in that the permissible interference level specified by the allowable signal-to-noise ratio is determined by the noise immunity of radar level gauges. 3. The method according to p. 2, characterized in that the permissible interference-signal ratio

defined by the expression

, where ΔR _norms is the normalized value of the permissible error equal to the ratio of the absolute permissible error to the resolution of the radar level gauge;

- coefficient taking into account the signal processing method (when estimating the distance from the signal spectrum

and when using the maximum likelihood method to refine the result

); N is the multiplicity of reflections used. 4. The method according to p. 1, characterized in that the change in the speed of propagation of electromagnetic energy in additional LET when changing the oscillation frequency in the frequency band of the probe signal does not exceed one percent. 5. The method according to p. 1, characterized in that the total reproduced sequence of distances is equal to the sum of the first sequence of reproduced distances and the difference between the maximum and minimum reproduced distances at each sequence of reproduced distances. 6. A stand for adjusting and calibrating radar level gauges, comprising a rack configured to mount a radar level gauge, which contains interconnected signal conditioning and processing devices, LETE and antenna, a support, a flat reflector mounted on a support perpendicular to a straight line passing through the centers of the flat reflector and aperture of the antenna, a horizontal movement device, a means of measuring the distance from the reference point associated with the rack to a flat reflector, distinguishing I'm in that between LPEE and antenna included detachable additional LPEE LPEE of a set of discrete changes in the electrodynamic length. 7. The stand according to claim 6, characterized in that the discrete change in the electrodynamic length of the removable additional LET in the LET set is less than the difference between the maximum and minimum distances to the flat reflector. 8. The stand according to claim 6, characterized in that the additional LETE is made in the form of a waveguide with matching devices. 9. The stand according to claim 6, characterized in that the additional LETE is made in the form of two series-connected LETEs of the first and second three-arm circulators, the first arm of the first circulator connected to the signal generation and processing device, the second and third arms of the first circulator connected through partial LETEs, respectively, with the first and third arms of the second circulator, and the second arm of the second circulator is connected to the antenna.

Images