RU2434242C1 - Method of measuring distance and radio range finder with frequency modulation of probing radio waves (versions) - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method of measuring distance involves summation of a picked up differential frequency signal (DFS) in which, along with the information component, there may be several noise components with a generated reference signal, parameters of which are selected so as compensate for the measurement error caused by noise and distortions, particularly incidental amplitude modulation. The criterion for correct selection of reference signal parameters is minimum deviation of parameters of the spectrum of the resultant signal from parameters of the spectrum of the signal generated by echo waves reflected by a reference reflector. The disclosed method is realised by a radio range finder, having a channel for processing the information component of the DFS and a channel for processing the component of the DFS obtained from echo waves reflected by the reference reflector.

EFFECT: reduced error in measuring distance due to the effect of noise, with simultaneous signal distortion by incidental amplitude modulation.

13 cl, 5 dwg

Description

The invention relates to the field of measuring technology, in particular to measuring distance, for example, in closed tanks when measuring the liquid level, and is based on the principle of frequency-modulated (FM) radar radar sensing radio waves.

A widely used radar method for measuring the distance from the FM sounding radio waves based on spectral analysis of the difference frequency signal (RFM) in evaluating the echo delay τ _R [1, p. 316-381; 2; 3; four]. In practical use, digital spectral analysis is used. The frequency F _R = Ω _R / 2π of the information component of the RMS u _and (t, τ _R ), with the linear FM law on the interval T, is associated with the echo delay τ _R , with the measured distance R and the frequency modulation range Δf = Δω / 2π linear relationship Ω _R = Δω · τ _R / T = Δω · 2R / (v · T), where v is the propagation velocity of electromagnetic waves. However, for a signal whose spectrum contains other terms near the useful term, this linearity is violated, and the accuracy of this method is usually insufficient for most practical applications.

Therefore, in the methods of measuring distance based on the spectral analysis of digital samples of the UHF u _qi (n, τ _R ) (where n = 0, ..., N-1; N is the number of samples of the UHF in digital processing), the measurement results are refined at an additional stage HFD processing. In particular, there is a known method for measuring distance with a radio range finder with continuous emission of frequency-modulated radio waves and a two-stage signal processing procedure [5]. At the first stage, a rough estimate of the frequency and distance is performed using the Fourier transform. At the second stage, the calculation of the signal function of the UHF C (τ)

,

,

where W (n) is the weight function, for example, the Kaiser-Bessel weight function;

с единичной амплитудой, варьируемой задержкой сигнала τ, и с заданным значением его фазы φ, а также с известными значениями центральной частоты ω₀ и диапазона частотной модуляции Δω частотно-модулированного радиочастотного сигнала.u _c (n, τ) - digital samples of the basis function with the envelope of discrete samples in the form of undistorted

with a unit amplitude, variable signal delay τ, and with a given value of its phase φ, as well as with known values of the central frequency ω ₀ and the frequency modulation range Δω of the frequency-modulated radio frequency signal.

Refinement of the measured distance is performed by the delay time corresponding to the global maximum of the signal function.

The signal function has an oscillating character with an envelope, which in shape coincides with the shape of the signal spectrum. Moreover, the noise created by the interfering object distorts the shape of the envelope of the signal function, but practically does not change the position of its local maxima. If the phase of the reflection coefficient from the surface of the sensed (useful) object is determined without error, and the noise level is low, then the frequency and the corresponding delay in the region of the global maximum of the signal function practically coincide with the frequency and delay of the information component of the RMS. Therefore, when measuring the distance to the object against the background of low-level interference, the cited two-stage method provides a measurement error that is one to two orders of magnitude smaller than the one-stage methods when using the Fourier transform for processing the RPS. However, with an increase in the level of interference, the envelope of the signal function is distorted, and it becomes impossible to determine which of the local maxima corresponds to the true value of the distance. Estimating the distance from the global maximum with a large level of interference leads to the fact that the measurement error can be either less or more than the measurement error using only the Fourier transform. With a smooth change in the distance between the interfering object and the sensed object, the error abruptly changes by half the wavelength around the error of the one-stage method. Thus, if the interference level is above a certain threshold value, the above method of measuring the distance also does not provide high accuracy of measurement due to errors in determining the local maximum, which corresponds to the true value of the distance.

A known radar method of measuring the distance to the material filling the tank, with spectral analysis of the RMS and compensation of the interference components of the spectrum [6, 7]. In this case, the interfering terms of the spectrum are determined during the calibration of the radio range finder on an empty tank.

A set of essential features that is close to the claimed one (analogue) is a radar method for measuring the level of material in a tank with a radio range finder with FM probing radio waves, based on spectral analysis of the RF, taking into account the interference components of the spectrum [8]. The specified method includes the calculation of the RMS spectrum, the calculation of the reference spectrum, consisting of constant and variable terms, and the calculation of the measure of difference between the RMS spectrum from the reference spectrum. Then, the parameters of the variable term of the reference spectrum are changed until the minimum of the indicated measure of spectral difference is reached. The parameters of the constant term of the reference spectrum are determined during calibration and stored in memory. Calibration is performed at the workplace at such a level of filling the tank when the radio waves reflect all the interfering objects and there is no mutual influence of the side lobes of the terms of the UHF spectrum corresponding to the interfering objects and the term of the UHF spectrum corresponding to the reflection from the probed material.

To calculate the measured distance, the parameters of the reference spectrum are used, at which a minimum of the difference measure is found.

In the last three cited methods of measuring distance, one would expect a significant decrease in the measurement error, since the recording of the reference spectra is performed at the workplace during the calibration spill of the tank. However, in reality, a decrease in the error does not occur due to the impossibility of accurate selection of the parameters of the reference spectrum. Changing the temperature of the tank, its filling, and other factors lead to significant deformations of the tank. Due to changes in the structure of the scattered field in the tank under the influence of the deformation of the tank, as well as due to deposition of inactive fractions of the material of the probed object on the antenna and structural elements of the tank, the amplitude and phase ratios in the terms of the RMS and, accordingly, in the spectra change. In addition, the frequency modulation of the generated signal is always accompanied by spurious amplitude modulation (PAM), the parameters of which change, for example, with a change in temperature. As a result, over time, the reference spectra and signals stored in the memory cease to coincide with the spectra and signals used in the measurement.

It should also be borne in mind that there are interference terms in the RMS and, accordingly, in the spectrum, which appear only in the presence of a useful signal. Examples of such interfering signals are signals generated by higher types of waves when measuring the level of material in the outlet pipes of the tanks or in the guide pipes of the pontoons, as well as when taking measurements near the side wall of the tank when the interfering signals arise due to echo waves from the angle formed by the probed material and vertical wall of the tank. The delay of such interfering signals differs slightly from the delay of the useful signal and varies in accordance with the change in the measured distance. In both examples, the interference components cannot be extracted from the signal, because usually not allowed by delay with a useful signal and lead to measurement errors.

Closest to the claimed method (prototype for the method) in terms of essential features is a method for measuring the electrophysical parameters of the sensed material and the distance to it [9], including generating a radio frequency signal with a periodic frequency modulation with known values of the center frequency and frequency modulation range, generation and radiation radio waves in the direction of the probed object, the allocation of part of the generated RF signal, reception, after the propagation time, echo ln and the formation of the reflected signal from them, mixing it with the extracted part of the generated radio frequency signal, extracting the low-frequency components of the resulting signal, extracting them from the RMS and extracting from it the information component of the RMS containing information about the distance to the probed object, analog processing of the information component of the RMS, calculation the spectrum of the information component of the RMS and calculating the center frequency of the spectrum, calculating the distance from the known propagation velocity of radio waves center frequency spectrum information component MPS, MPS shaping reference and the calculation parameters of its spectrum, the correction of the measured distance.

In this method, zero components are additionally extracted from the low-frequency components of the resulting signal, due to the parasitic passage of the probe signal into the receiving path, reflection from the inhomogeneities of the antenna-waveguide path and the precipitation layer on the antenna, the spectrum of zero components is calculated, and a measure of its difference from the reference recorded in the conditions is calculated lack of interference. When the difference in the spectra of the control level is exceeded, an undistorted low-frequency component is formed with a delay corresponding to the central frequency of the spectrum of the extracted information component, and the sum of the spectra is calculated, the first term of which is formed by the spectrum of the undistorted component, and the second term is formed by the signal spectrum with amplitude equal to the product of the correction coefficient and amplitude measured zero components and the amplitude of the formed undistorted component, a phase equal to zero, and a delay corresponding to the delay difference of the undistorted low-frequency component and the zero component. Next, the resulting sum is compared with the spectrum of the extracted information component, the amplitude, delay and phase of the generated undistorted component are changed to the best match the formed sum of the spectra with the spectrum of the extracted information component. The center frequency and phase of the generated undistorted low-frequency component of the signal are taken as the frequency of the spectrum of the information component of the RMS, corresponding to the range to the probed material, with the best coincidence of the spectra of the information component of the RMS and the generated sum.

The cited method is implemented by a device (the closest to the claimed device in terms of essential features - a prototype of the device) containing a digital signal processing circuit, an antenna-waveguide device, a controlled radio frequency signal generator, a frequency synthesizer with two inputs and one output, a power divider with one input and two outputs, directional coupler with one input and two outputs, mixer with two inputs and one output, two controlled filters connected in series, circuits preliminary analog processing, analog-to-digital converter, a control circuit with one input and two outputs. In this case, the input of the controlled generator of the radio frequency signal is connected to the output of the frequency synthesizer, the inputs of which are connected, respectively, with the first output of the controlled generator of the radio frequency signal and the first output of the digital signal processing circuit, and the output of the controlled generator of the radio frequency signal is connected to a series-connected power divider and directional coupler, the first output of which is connected to the input of the antenna-waveguide device. The inputs of the mixer are connected, respectively, with the second output of the power divider and with the second output of the directional coupler, and the output is connected to series-connected controlled filters. The output of the second controlled filter is connected to a preliminary analog processing circuit, the output of which is connected to the input of the analog-to-digital converter, and the output of the analog-to-digital converter is connected to the input of the digital signal processing circuit. The input of the control circuit is connected to the second output of the digital signal processing circuit, and its two outputs are connected to the second inputs of the respective controlled filters.

The cited method for measuring distance and a device for its implementation do not provide high measurement accuracy with the simultaneous influence of PAM and interfering signals that are not related to the inhomogeneities of the antenna-waveguide device.

The technical result of the invention is the reduction of the error of distance measurement due to the influence of interference while distorting the PAM signal.

The technical result is achieved by the fact that in the method of measuring distance by a radio range finder with frequency modulation of the probe radio waves, including generating a radio frequency signal with a periodic frequency modulation with known values of the center frequency and the frequency modulation range, generating and emitting radio waves in the direction of the probed object, isolating a portion of the generated radio frequency signal, reception, after the propagation time, of the echo waves and the formation of the reflected signal from them, mixing it with you divided by the generated RF signal, the selection of the low-frequency components of the resulting signal, the separation of the difference frequency signal (RMS) from them and the separation of the information component of the RMS, containing information about the distance to the probed object, analog processing of the information component of the RMS, the calculation of the spectrum from digital samples of the information component RF and calculation of the center frequency of the spectrum, calculation of the distance from the known propagation velocity of the radio waves and the center h The spectrum of the information component of the RMS, the formation of the spectrum of the first reference RMS, the calculation and recording of the parameters of the spectrum of the first reference RMS, updating the measured distance, subject to the following conditions, additionally perform the following set of actions. The spectrum of the first reference RF system is formed using echo waves reflected by the reference reflector with a delay time less than the minimum propagation time of the echo waves from the sensed object, as well as using a priori information about the complex transmission coefficient of the device for extracting and processing the first reference RPS and a priori information about the complex transmission coefficient of the device for extracting and processing the information component of the RMS. A measure of the difference in the information component of the RF system from the first reference RF system is calculated. If the measure exceeds the control level differences, the second reference signal is repeatedly generated in the form of digital samples from the known values of the frequency modulation range of the generated radio frequency signal and its center frequency, as well as from the given values of the delay time, amplitude and phase, the resulting signal is calculated from the sum of the information component of the RMS and the second reference signal, calculate the resulting spectrum of the sum of the spectrum of the information component of the RMS with the spectrum of the second reference signal, calculate the measure of difference of the resulting signal from the first reference RF system, the delay and amplitude of the second reference signal are changed until the smallest measure of difference is obtained, and the resulting spectrum and signal at which a minimum of the measure of difference is found are used in calculating the exact distance value.

The spectrum of the first reference RF system is formed by extracting the reference component of the RF system corresponding to the distance to the reference reflector, calculating the spectrum of digital samples of this component, multiplying the calculated spectrum by the ratio of the complex transmission coefficient of the device for extracting and processing the information component of the RF system of the radio range finder, determined for the calculated distance to the sensed object, to the complex transfer coefficient of the device for separation and processing of the reference component of the RF system of the radio range pa

It is advisable to use a single inhomogeneity in the antenna-waveguide device as a reference reflector, while this heterogeneity should be removed from the neighboring inhomogeneities in the antenna-waveguide device by more than twice the resolution of the radio range finder.

It is preferable to use the aperture of the aperture antenna as a reference reflector, for example, the edge of an axisymmetric conical horn antenna, while the filter component of the RMS corresponding to the range to the specified aperture is isolated.

The formation of the spectrum of the first reference RF system is performed under the influence of interfering terms below the control level.

The second reference signal is generated in the form of digital samples with an envelope of discrete samples in the form of a segment of a harmonic signal that corresponds to a difference frequency signal that is not distorted by interference and spurious amplitude modulation, with a frequency determined by a given delay time different from the center frequency of the main lobe of the spectrum of the RMS information component less than half the width of the main lobe of the spectrum of the information component of the RMS.

The measure of difference between the information component of the RMS from the first reference RMS is calculated by the spectral parameters as the sum of terms with the given weight coefficients, including: the modulus of the difference in the width of the main lobe of the spectrum of the first reference RMS and the width of the main lobe of the resulting spectrum, the module of the difference in the asymmetry coefficients of the main lobes of the spectrum of the first reference RMS and of the resulting spectrum, the module of the difference in phase spectra of the first reference RF system and the resulting spectrum and their derivatives of lower orders by the center frequencies of the spectrum of the first reference RF system and the resulting spectrum.

It is advisable, with a minimum of a measure of difference, to additionally calculate the signal function of the resulting signal with a basic function in the form of an undistorted RF system with a variable delay of the reflected signal and with a given value of its phase, as well as with known values of the central frequency and frequency modulation range of the frequency-modulated radio frequency signal and specify the measured distance of the delay time corresponding to the global maximum of the signal function.

It is possible to calculate the measure of difference by the difference in the spectrum of the resulting signal function, normalized to its maximum value, from the spectrum of the signal function of the first reference RF system, normalized to its maximum value. In this case, the spectrum of the signal function of the first reference MFR is calculated using the signal samples calculated by the inverse Fourier transform of the digital samples of the main lobe and the nearest side lobes of the spectrum of the first reference MFR.

The technical result is also achieved by the fact that in a radio range finder with frequency modulation of the probing radio waves, comprising: a controlled radio frequency signal generator with one input and two outputs, a digital signal processing circuit, an antenna-waveguide device, a power divider with one input and two outputs, a directional coupler with one input and two outputs, a mixer with two inputs and one output, a frequency synthesizer with one output connected to the input of a controlled radio-frequency signal generator, and two inputs dams connected to the first outputs, respectively, of a digital signal processing circuit and a controlled radio-frequency signal generator, the second output of which is connected to a power divider and a directional coupler in series, the first output of which is connected to an antenna-waveguide device, and the second outputs of a power divider and a directional coupler connected, respectively, with the first and second inputs of the mixer, the output of which is connected to a series-connected filter, a preliminary anal processing and an analog-to-digital converter, the output of which is connected to the first input of the digital signal processing circuit, and the second input of the analog-to-digital converter is connected to the second output of the digital signal processing circuit, one of the outputs of which is the information output of the radio range finder, the second filter output is additionally introduced, a second analog pre-processing circuit; and a second analog-to-digital converter. Moreover, the second filter output is connected to the second analog pre-processing circuitry and the second analog-to-digital converter connected in series, the output and the second input of which are connected, respectively, to the second input and the third output of the digital signal processing circuit, and the antenna-waveguide device is made with uniform sections, the electrical length of at least one of which is at least twice the distance permitted by the radio range finder.

It is advisable that the antenna of the antenna-waveguide device be made in the form of an axisymmetric conical horn with an axial length of at least twice the resolution of the rangefinder in range and with an aperture edge made in a plane normal to its axis.

It is advisable to make the filter in the form of a high-pass filter and a band-pass filter connected in parallel with their inputs, while the high-pass filter output is connected to a series-connected pre-analog processing circuit and an analog-to-digital converter, and the output of the band-pass filter is connected to a series-connected second pre-analog processing circuit and a second analog-to-digital conversion.

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 prototypes of the method and device made it possible to identify a set of essential (with respect to the technical result perceived by the applicant) distinctive features in the claimed objects 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 method and device, there is no positive effect. Based on this, it was concluded that the proposed technical solution meets the criterion of "inventive step".

A comparison of the features of the known and proposed methods for analyzing the inventive step shows a significant difference in conditions, modes of operations on electrical signals (both continuous and in the form of digital samples), which are characterized by amplitude, frequency and phase.

In the prototype, a reference signal is formed from a segment of a harmonic term generated with a given amplitude, frequency and phase, and a term similar to “virtual reflectors”, so that the spectrum of the generated signal coincides in position (frequency), shape and amplitude with the term in the spectrum of the information component of the RMS . The main action is to evaluate the frequency according to the known frequency of the generated segment of the harmonic reference signal (in the prototype text - “undistorted low-frequency component with a delay corresponding to the center frequency of the spectrum, the selected information component”) with the best coincidence of the spectra of the information component and the generated sum. It follows that the known method cannot be implemented in the presence of interference.

In the proposed method, the generated second reference signal is varied in delay (frequency) and amplitude, i.e., in order to reduce the distortion of the spectrum of the information component of the RMS caused by interference, of which there may be several. Moreover, neither the delay (frequency), nor the amplitude, nor the phase of the generated second reference signal can match the information component of the RMS. And an accurate estimate of the frequency is performed by the resulting signal after its correction, when the distortions of its spectrum are the smallest. In this case, to determine the correction results, the spectrum of the first reference RF system is formed, the parameters of which coincide with the spectrum parameters of the sensed object when it is not distorted by noise and, therefore, its center frequency is determined exactly.

In addition, the conditions and modes of implementing the set of actions are interconnected with the dimensions of the antenna-waveguide device of the radio range finder, because the resolved distance by the radio range finder is determined by the frequency modulation range, and the antenna-waveguide device must be made with homogeneous sections, the electric length of at least one of which is at least twice the resolved distance.

These differences lead to the appearance of qualitatively new properties of the claimed method and device — the ability to accurately measure distance in the presence of several interfering objects and distortion of the PAM signals.

The essence of the proposed method is illustrated by the graphs depicted in figure 1, figure 2, figure 3 and figure 5, as well as using the device schematically depicted in figure 4.

Figure 1 shows the dependence of the error of the measured distance to the probed object from the distance in the wavelengths between the probed object and a single interfering object. Figure 2 shows the dependence of the error of the measured distance to the probed object from the delay of the second reference signal in the presence of two interfering objects. Figure 3 shows the dependence of the measure of difference from the delay of the second reference signal when sensing a useful object and in the presence of two interfering objects. Figure 5 shows the dependence of the error of the measured distance to the probed object in the presence of two interfering objects for the prototype and for the proposed method.

The essence of the method is that the shift of the center frequency of the spectrum due to the influence of interference created by interfering objects can be reduced with the introduction of an additional signal. The radar method of measuring distance, based on spectral analysis, provides high accuracy of measurements in the absence of interfering objects and distortion of the RF. The presence of a single interfering object leads to a measurement error, the dependence of which on the distance between the interfering and probed objects is oscillatory in nature (Fig. 1) around a zero value (when the distance is measured without error) with an oscillation period equal to half the average length of the radio wave and a varying oscillation amplitude . Figure 1 shows the dependence of the error of the measured distance to the sensed object on the distance in the wavelengths between the sensed object and a single interfering object, creating an interfering signal with an amplitude of 0.1 from the useful one. The FM band is Δf = 1 GHz, the center frequency of the modulation range is 10 GHz. If the UHF is formed by a useful probed object and several interfering objects, then each interfering object, regardless of the presence of other objects, leads to measurement error. The full value of the error depends on the ratio of the amplitudes of the useful and interfering terms, phase relations, the distance distribution of the interfering objects, as well as on the magnitude of the SAM and other signal distortions. With a constant interference environment and a constant distance to the probed object, the error in measuring the distance is unchanged.

The summation of the information component of the RMS with the generated reference signal (the second reference signal, with the given values of the delay time, amplitude, phase, carrier frequency and frequency deviation of the frequency-modulated signal, whose parameters are similar to the parameters of the RMS undistorted by interference) and a change in the delay of this reference signal lead to the fact that the dependence of the measured distance to the probed object from the delay of the reference signal and, accordingly, the measurement error will also be oscillatory character, but around the value of the error due to interference (figure 2). Figure 2 shows the dependence of the error of the measured distance to the sensed object, remote at a distance of 3 meters from the radio range finder, on the delay of the second reference signal in the presence of two interfering objects, remote from the radio range finder, respectively, by 3.0375; 3,077 meters and creating interfering signals with an amplitude of 0.1 of the useful. The dependence of the resulting measurement error on the delay of the second reference signal, shown by a solid line, corresponds to the amplitude of the second reference signal, equal to 0.158 from the useful one. At a certain value of the amplitude of the second reference signal, the dependence of the resulting measurement error of the distance on the delay of the second reference signal reaches zero (in Fig. 2, point 1 is the dependence of the resulting error on the delay of the second reference signal).

An increase in the amplitude of the second reference signal leads to the fact that zero values of the measurement error can be obtained with several delay values of the second reference signal (in Fig. 2, the dotted dependence on the resulting error on the delay of the second reference signal).

It is obvious that one segment of the harmonic term cannot compensate for several interference terms. However, at point 1, the error is completely compensated, while the delay of the second reference signal and its other parameters do not coincide with the interference parameters, but the parameters of the resulting spectrum become close to the spectrum parameters of the first reference signal. Also close to each other are the normalized spectra of the signal function of the first reference signal and the signal function of the information component of the RMS. Accordingly, the measure of difference in both cases is close to minimal.

The dependence of the measure of difference from the delay of the second reference signal is also oscillatory in nature. Figure 3 shows an example of the dependence of the measure of difference from the delay of the second reference signal relative to the delay of the useful signal in the presence of two interfering objects. The measurement conditions correspond to those shown in figure 2. A change in the amplitude of the second reference signal leads to a change in the amplitude of the oscillations of the measure of difference. The selection of the delay of the second reference signal and its amplitude allows us to find the global minimum of the measure of difference, at which the error in measuring the distance is also close to the minimum. The reduction in error is due to a decrease in the distortion of the spectrum and the signal function due to the influence of interference. In turn, reducing the distortion of the signal function eliminates the error in determining the maximum of the signal function, which corresponds to the true value of the distance, which allows accurate measurement.

A radio range finder with frequency modulation of the probe radio waves (FIG. 4) comprises: a controllable generator of a radio frequency signal (UGRS) 2 with one input and two outputs; a digital signal processing circuit (DSP) 3 with four outputs and two inputs; antenna waveguide device (AVU) 4; power divider (DM) 5 with one input and two outputs; directional coupler (NO) 6 with one input and two outputs; mixer 7 with two inputs and one output; frequency synthesizer (MF) 8 with one output and two inputs; filter 9 with one input and two outputs; the first pre-analog processing circuitry (SPAO) 10; the first analog-to-digital converter (ADC) 11 with two inputs and one output; the second SPAO 12 and the second ADC 13.

The output of the midrange 8 is connected to the input of the UGRS 2. The inputs of the midrange 8 are connected, respectively, with the first output of the UGRS 2 and with the first output of the SCS 3. The output of the UGRS 2 is connected to the DM 5 and HO 6 connected in series, and the first output of HO 6 is connected to the AVU 4 The second outputs of DM 5 and HO 6 are connected, respectively, with the first and second inputs of the mixer 7, the output of which is connected to the input of the filter 9. The first output of the filter 9 is connected to series-connected SPAO 10 and ADC 11, and the output of ADC 11 and its second input connected, respectively, with the first input and the second output of the alarm system 3. The second output of the filter 9 is connected to a series-connected SPAO 12 and ADC 13, and the output of the ADC 13 and its second input are connected, respectively, to the second input and the third output of the alarm center 3. The fourth exit of the alarm center 2 is the information output of the radio range finder.

Antenna АВУ 4 is made in the form of an axisymmetric conical horn with an axial length of at least twice the resolution of the rangefinder in range, while the mouth of the mouth is made in a plane normal to its axis.

The filter 9 can be made in the form of the well-known [10, pp. 93-129] high-pass filter and a band-pass filter, connected in parallel with their inputs, highlighting, respectively, the information component of the RMS and the reference component of the RMS.

The practical implementation of the device is not difficult and is carried out on the basis of widely distributed electronic elements, for example, manufactured by ANALOG DEVICES, MOTOROLA, MICRONETICS, PEREGRINE, etc.

The method of measuring the distance is carried out using a radio range finder with frequency modulation of the probe radio waves as follows.

A part of the generated radio frequency signal with periodic frequency modulation in the form of a sequence of radio frequency signals, the known discrete frequencies in which are equidistantly distributed over the frequency modulation range, from UGRS 2 (Fig. 4) controlled by MF 8, through DM 5 and HO 6 enters the antenna АВУ 4 , which generates directional radiation in the direction of the probed object. After reflection from the surface of the probed object, the echo waves are received by the antenna АВУ 4 and converted into a reflected signal, which through НО 6 is supplied to the second input of the mixer 7. The selected part of the generated signal is used as the heterodyne signal. The output signal of the mixer is filtered by filter 9 and from the first output is fed to the input of SPAO 10, where it is processed by a given gain and additional suppression of high-frequency components. As a result, the low-frequency components of the resulting signal are extracted, from which the information component of the RMS u _and (t, τ _R ), which contains information about the distance to the probed object, is extracted. The information component of the UHF u _and (t, τ _R ) are used to calculate the distance. Moreover, it may also contain interference components created by interfering objects, which lead to measurement errors.

At the second output of the filter 9, the reference component of the RMS u _e (t, τ _A ) is selected, corresponding to the distance to the reference reflector, which can be used, in particular, a single inhomogeneity in the antenna-waveguide device. The specified heterogeneity should be removed from neighboring inhomogeneities in the antenna-waveguide device by more than twice the resolution of the radio range finder. As a reference reflector, it is preferable to use the opening edge of the conical horn antenna, when using the latter in a radio range finder. This is explained by the fact that the complex reflection coefficient of radio waves from an aperture with a diameter of several wavelengths is practically independent of frequency [11, pp. 122-142], as well as the complex reflection coefficient of radio waves from the probed surface of a liquid in a tank under normal incidence of radio waves.

The selected informational component of the UHF u _and (t, τ _R ) through the ADC 11 is fed to the first input of the SCE 3. And the reference component of the UHF u _e (t, τ _R ) from the second output of the filter 9 through the second SPAO 12 and the second ADC 13 is fed to the second input SCOS 3. Using SCPS 3 perform all actions on the components of the RF system, control the synthesizer midrange 8 setting codes of discrete frequencies and synchronize the operation of the ADC 11 and ADC 13.

устройства выделения и обработки информационной составляющей u_и(t, τ_R) СРЧ радиодальномера (фильтром 9 и СПАО 10) и его форма зависит не только от наличия помех, но и от измеряемого расстояния.Using digital samples u _qi (n, τ _R ) (where n = 0, ..., N-1; N is the number of samples) of the information component of the RMS u _and (t, τ _R ) using SCE 3 calculate the spectrum S _and (τ _R ), the center frequency of the spectrum is calculated, for example, by the frequency of the maximum of the spectrum, the distance is calculated and recorded in the memory of SCE 3 according to the known propagation velocity of the radio waves and the center frequency of the spectrum. This spectrum is distorted by the frequency dependence of the complex transfer coefficient

devices for extracting and processing the information component u _and (t, τ _R ) of the RF system of the radio range finder (filter 9 and SPAO 10) and its shape depends not only on the presence of interference, but also on the measured distance.

When calculating the measure of difference in the spectrum parameters, the spectrum parameters S _and (τ _R ) (the width of the main lobe, the asymmetry coefficient, the phase and the values of the derivatives of the lower-order phase spectra at the center frequency of the spectrum) are calculated and stored in the memory of the center.

устройства выделения и обработки эталонной составляющей u_э(t, τ_A) СРЧ радиодальномера (фильтром 9 и СПАО 12). Используя записанные в памяти СЦОС 3, априорные сведения о комплексном коэффициенте передачи устройства выделения и обработки информационной составляющей СРЧ радиодальномера (фильтра 9 и СПАО 10) и априорные сведения о частотной зависимости комплексного коэффициента передачи устройства выделения и обработки эталонной составляющей СРЧ радиодальномера (фильтра 9 и СПАО 12), умножают вычисленный спектр S_э(τ_A) цифровых отсчетов u_цэ(n, τ_A) на отношение комплексного коэффициента передачи устройства выделения и обработки информационной составляющей СРЧ радиодальномера, определенного для вычисленного расстояния до зондируемого объекта, к комплексному коэффициенту передачи устройства выделения и обработки эталонной составляющей СРЧ радиодальномера. В результате получают спектр первого эталонного сигнала

, который используют для вычисления меры отличия. Этот спектр аналогичен спектру сигнала, полученному в условиях отсутствия неразрешаемых помех при зондировании одиночного отражателя. При этом в нем учитываются искажения как за счет ПАМ, так и за счет частотной зависимости комплексного коэффициента передачи устройства выделения и обработки информационной составляющей СРЧ радиодальномера. Используя спектр первого эталонного сигнала S_э0(τ_A), вычисляют его параметры (ширину основного лепестка, коэффициент асимметрии, фазу и величины производных низших порядков фазового спектра на центральной частоте спектра) и записывают в память СЦОС 3. Затем, используя записанные в памяти СЦОС 3 параметры спектра S_и(τ_R) и параметры спектра S_э0(τ_A), вычисляют меру их отличия. При превышении мерой отличия контрольного уровня с помощью СЦОС 3 многократно генерируют второй эталонный сигнал в форме цифровых отсчетов u_цijkэ(n, τ_iэ) (n=0, …, N-1.) с огибающей дискретных отсчетов в виде отрезка гармонического сигнала

со спектром S_ijkэ(τ_iэ), который соответствует спектру СРЧ, неискаженному помехами и ПАМ. Второй эталонный сигнал генерируют по известным значениям диапазона частотной модуляции Δω генерируемого радиочастотного сигнала и его центральной частоты ω₀, а также по заданным значениям времени задержки τ_iэ отраженного сигнала, амплитуды U_jэ и фазы φ_kэ. Вычисляют результирующий спектр S_рез(τ_R)=[S_и(τ_R)+S_ijkэ(τ_iэ)] суммы спектра S_и(τ_R) со спектром S_ijkэ(τ_iэ) цифровых отсчетов u_цijkэ(n, τ_iэ) второго эталонного сигнала, вычисляют его параметры, вычисляют и записывают в память СЦОС 3 меру отличия параметров результирующего спектра от записанных в память СЦОС 3 параметров первого эталонного спектра и записывают также заданные значения времени задержки τ_iэ, амплитуды U_jэ и фазы φ_kэ, соответствующие указанной мере отличия. Многократным изменением времени задержки τ_iэ и амплитуды U_jэ второго эталонного сигнала u_ijkэ(n, τ_iэ) изменяют его форму до получения наименьшего значения меры отличия, а результирующие спектр и сигнал u_црез(n, τ_R)=[u_ци(n, τ_R)+u_цijkэ(n, τ_iэ), при которых обнаружен минимум меры отличия, используют при расчете точного значения расстояния.From digital samples u _ce (n, τ _A ) (n = 0, ..., N-1.) Of the reference component of the RMS u _e (t, τ _A ) using SCOC 3, using the direct Fourier transform, the spectrum S _e (τ _A ). This spectrum is distorted by the frequency dependence of the complex transfer coefficient

devices for isolating and processing the reference component u _e (t, τ _A ) of the RF rangefinder (filter 9 and SPAO 12). Using a priori information on the complex transfer coefficient of the device for extracting and processing the informational component of the RF system of the radio range finder (filter 9 and SPAO 10) stored in the memory of SCE 3, a priori information about the complex dependence of the transmission coefficient of the device for extracting and processing the reference component of the RFE of the radio range finder (filter 9 and SPAO) 12), multiply the calculated spectrum S _e (τ _A ) of digital samples u _ce (n, τ _A ) by the ratio of the complex transfer coefficient of the device for extracting and processing the information content the effective RFM of the radio range finder, determined for the calculated distance to the probed object, to the complex transmission coefficient of the device for extracting and processing the reference component of the RFM of the radio range finder. The result is a spectrum of the first reference signal

, which is used to calculate the measure of difference. This spectrum is similar to the signal spectrum obtained in the absence of unresolved interference when probing a single reflector. At the same time, it takes into account distortions both due to PAM and due to the frequency dependence of the complex transfer coefficient of the device for extracting and processing the information component of the RMS of the radio range finder. Using the spectrum of the first reference signal S _e0 (τ _A ), its parameters are calculated (the width of the main lobe, the asymmetry coefficient, the phase and the values of the derivatives of the lower orders of the phase spectrum at the center frequency of the spectrum) and are recorded in the memory of the center of reference 3. Then, using the memory of the center of reference. 3, the spectrum parameters S _and (τ _R ) and the spectrum parameters S _e0 (τ _A ), calculate the measure of their difference. If the measure exceeds the control level difference using SCE 3, a second reference signal is repeatedly generated in the form of digital samples u _cijke (n, τ _ie ) (n = 0, ..., N-1.) With an envelope of discrete samples in the form of a harmonic signal segment

with the spectrum S _ijke (τ _iе ), which corresponds to the RMS spectrum undistorted by interference and PAM. The second reference signal is generated by known values of the frequency modulation range Δω of the generated radio frequency signal and its center frequency ω ₀ , as well as by given values of the delay time τ _{i e of the} reflected signal, amplitude U _{j e} and phase φ _ke . The resulting spectrum S _res (τ _R ) = [S _and (τ _R ) + S _ijke (τ _iе )] is calculated for the sum of the spectrum S _and (τ _R ) with the spectrum S _ijke (τ _i ) of digital samples u _cijke (n, τ _i ) of the second reference signal, its parameters are calculated, the measure of difference in the parameters of the resulting spectrum from the parameters of the first reference spectrum recorded in the memory of the third reference signal is calculated and recorded in the memory of the center of reference 3 and the specified values of the delay time τ _i , amplitude U _jе and phase φ _ke corresponding to indicated measure of difference. Repeatedly changing the delay time τ _iе and the amplitude U _{jе of the} second reference signal u _ijke (n, τ _iе ) change its shape until the smallest measure of difference is obtained, and the resulting spectrum and signal u _cres (n, τ _R ) = [u _qi (n , τ _R ) + u _zijke (n, τ _iе ), at which a minimum of the measure of difference is found, is used in calculating the exact value of the distance.

When using a reference reflector with a frequency-dependent reflection coefficient of radio waves and when probing an object with a frequency-dependent reflection coefficient of radio waves, a priori information about these reflection coefficients is obtained, written to the memory of the sensor 3 and used in the formation of the reference signal.

The delay time of the second reference signal τ _{iе is} set so that the center frequency of the spectrum S _ijke (τ _ie ) of the digital samples of the second reference signal differs from the center frequency of the main lobe of the spectrum of digital samples u _qi (n, τ _R ) of the information component of the RMS by less than half the width main lobe of the specified spectrum.

The measure of difference in the spectral parameters is calculated as the sum of terms with the given weight coefficients, including: the modulus of the difference in the width of the main lobe of the spectrum of the first reference signal S _e0 (τ _A ) and the width of the main lobe of the resulting spectrum S _res (τ _R ), the modulus of the difference in the asymmetry coefficients of the main spectrum lobes the first reference signal and the resulting spectrum, the phase difference module of the first reference signal and the resulting spectrum and their lower-order derivatives at the center frequencies of the spectrum the first- reference signal and the resultant spectrum, the phase spectrum is determined taking into account the measured distance to the test object and the previously measured and stored in the memory 3 STSOS phase characteristic DME.

With a minimum of the measure of differences, it is advisable to additionally calculate the signal function C _res (τ) of the resulting signal u _cres (n, τ _R )

,

,

с варьируемой задержкой отраженного сигнала τ и с заданным значением его фазы φ, а также с известными значениями центральной частоты ω₀ и диапазона частотной модуляции Δω частотно-модулированного радиочастотного сигнала;where u _c (n, τ) - digital samples of the basis function with the envelope of discrete samples in the form of undistorted

with a variable delay of the reflected signal τ and with a given value of its phase φ, as well as with known values of the central frequency ω ₀ and the frequency modulation range Δω of the frequency-modulated radio frequency signal;

W (n) is the weight function, for example, the Kaiser-Bessel weight function;

and specify the measured distance according to the delay time corresponding to the global maximum of the signal function.

, вычисляют спектр S_сэ(τ_n) полученной эталонной сигнальной функции, нормируют его к максимальному значению и записывают нормированные отсчеты S_сэн(τ_n) в память СЦОС 3.When calculating the measure of difference in the spectra of signal functions, using the spectrum of the first reference signal S _e0 (τ _A ) and using the inverse Fourier transform, digital samples of the first reference signal u _ce0 (n, τ _A ) are calculated. Then calculate the reference signal function

, calculate the spectrum S _ce (τ _n ) of the obtained reference signal function, normalize it to the maximum value, and write the normalized samples S _sen (τ _n ) in the memory of SES 3.

информационной составляющей СРЧ, вычисляют спектр S_си(τ_n) полученной сигнальной функции, нормируют его к максимальному значению и записывают нормированные отсчеты S_си(τ_n) в память СЦОС 3. Используя нормированные спектры сигнальных функций первого эталонного сигнала и информационной составляющей СРЧ, вычисляют меру их отличия. При превышении мерой отличия контрольного уровня с помощью СЦОС 3 многократно генерируют второй эталонный сигнал в форме цифровых отсчетов u_цijkэ(n, τ_iэ), вычисляют цифровые отсчеты результирующего сигнала u_црез(n, τ_R) и вычисляют результирующую сигнальную функцию результирующего сигнала. Затем вычисляют спектр результирующей сигнальной функции, нормируют его к максимальному значению, вычисляют и записывают в память СЦОС 3 меру отличия спектра результирующей сигнальной функции от записанного в память СЦОС 3 спектра сигнальной функции первого эталонного сигнала и записывают также заданные значения времени задержки τ_iэ, амплитуды U_jэ и фазы φ_kэ, соответствующие указанной мере отличия. Многократным изменением задержки τ_iэ и амплитуды U_iэ второго эталонного сигнала u_цijkэ(n, τ_iэ) изменяют его форму до получения наименьшего значения меры отличия, а результирующий сигнал, при котором обнаружен минимум меры отличия, используют при расчете точного значения расстояния.Then, using digital samples of the information component of the RMS u _qi (n, τ _R ), the signal function is calculated

the information component of the RHF, calculate the spectrum S _si (τ _n ) of the obtained signal function, normalize it to the maximum value and write the normalized samples S _si (τ _n ) in the memory of the SCE 3. Using the normalized spectra of the signal functions of the first reference signal and the information component of the RHF, calculate measure of their differences. If the measure exceeds the control level difference using SCE 3, a second reference signal is repeatedly generated in the form of digital samples u _cijke (n, τ _iе ), digital samples of the resulting signal u are _cut (n, τ _R ) and the resulting signal function of the resulting signal is calculated. Then, the spectrum of the resulting signal function is calculated, normalized to the maximum value, the measure of the difference between the spectrum of the resulting signal function and the spectrum of the signal function of the first reference signal recorded in the memory of the SCE 3 is calculated, and the set delay values τ _iе , amplitudes U _jе and phases φ _ke corresponding to the indicated measure of difference. _By repeatedly changing the delay τ _iе and the amplitudes U _{ie of the} second reference signal u _cijke (n, τ _iе ), they change their shape until the smallest measure of difference is obtained, and the resulting signal, at which the minimum of the measure of difference is found, is used in calculating the exact value of the distance.

As a measure of the difference between the normalized spectra and the signal ones, any mathematical metric can be used to assess the difference between the two functions. For example, the Euclidean metric [12] ρ:

,

,

where N is the total number of discrete frequencies in the spectrum of the signal function.

From the fourth output of SCE 3, the result of calculating the exact distance is fed to the output of the device.

5, the thick line 14 shows the dependence of the error of the measured distance to the probed object, moving within 2.85 ... 3.15 meters, in the presence of two interfering objects remote from the radio range finder, respectively, by 3.0375; 3,077 meters and creating interfering signals with an amplitude of 0.1 of the useful, obtained as a result of the implementation of the method. Thin line 15 shows the dependence of the error of the measured distance when measuring in a known manner (prototype). From the drawing it follows that in the presence of interference, the implementation of the method reduces the maximum error values from 5 to 60 times.

Information sources

1. Vinitsky A.S. "Essay on the fundamentals of radar in the continuous emission of radio waves" M .: "Soviet Radio", 1961.

2. US patent No. 5546088 08/13/1996.

3. US patent No. 6107957 08/22/2000.

4. US patent No. 5504490 A, G01S 13/08 from 04/02/1996.

5. Davydochkin V.M., Parshin B.C. Distance measurement with a level meter with frequency modulation of the emitted signal in the presence of interfering reflections of low intensity. // Proceedings of the Russian NTO RES named after Popova. Series: Digital signal processing and its application. 8th International Conference Vol. VIII - 2. Moscow. 2006. S.530-533.

6. Brumbi D. Fundamentals of Radar Technology for Level Gauging. 3-rd Revision, Krohne Messtechnik, Duisburg. 1999.

7. Bruimbi D. Low power FMCW radar system for level gauging // 2000 IEEE MTT-S International microwave symposium digest, vol. 3, 2000. P.1559-1562.

8. RF patent No. 224268, MKI G01F 23/28, G01S 13/08. Claim March 4, 2003; No. 2003105994; Publ. January 10, 2005 Bull. No. 1. A method of measuring the level of material in a tank. B.A. Atayants, V.V.Ezersky, V.S. Parshin.

9. Patent 2234688 of the Russian Federation, MKI G01F 23/28, G01N 27/26. A method for measuring the electrophysical parameters of the sensed material and the distance to it (options), a device for its implementation and a method for calibrating this device / B.A. Atayants, V.M. Davydochkin, V.V. Ezersky, V.A. Pronin. No. 2003101694/09; Claim 01/23/2003; Publ. 08/20/2004, Bull. Number 23.

10. A.J. Peyton, W. Walsh. Analog electronics on operational amplifiers. (Translated from English): M .: BINOM, 1994.352 s.

11. Weinstein L.A. The theory of diffraction and the method of factorization. M .: Soviet radio. 1966.431 s.

12. Gorelik A.L., Skripkin V.A. Recognition methods. Uch. manual for universities: M .: Higher. School., 1977, 208 p.

Claims (13)

1. A method of measuring distance with a radio range finder with frequency modulation of the probing radio waves, including generating a radio frequency signal with a periodic frequency modulation with known values of the center frequency and the frequency modulation range, generating and emitting radio waves in the direction of the probed object, extracting a part of the generated radio frequency signal, receiving after the propagation time of the echo waves and the formation of the reflected signal from them, mixing it with the selected part of the generated radio frequency about the signal, extracting the low-frequency components of the resulting signal, extracting the difference frequency signal (RMS) from them and extracting from it the information component of the RMS containing information about the range to the probed object, analog processing of the RMS information component, calculating the spectrum from digital samples of the RMS information component and calculating the center frequency of the spectrum, calculating the distance from the known propagation velocity of the radio waves and the center frequency of the spectrum of the information component C H, the formation of the spectrum of the first reference RF system, the calculation and recording of the parameters of the spectrum of the first reference RF system, the refinement of the measured distance, characterized in that the spectrum of the first reference RF system is formed using echo waves reflected by the reference reflector, with a delay time less than the minimum propagation time of the echo waves from the probed object, and also, using a priori information about the complex transfer coefficient of the device for extracting and processing the first reference RF system and a priori information about the complex coefficient transmitting the device for extracting and processing the information component of the RMS, calculate the difference between the information component of the RMS from the first reference RMS, if the measure exceeds the control level, the second reference signal is repeatedly generated in the form of digital samples from the known values of the frequency modulation range of the generated RF signal and its center frequency, and also, using the given values of the delay time, amplitude and phase, the resulting signal of the sum of the information component of the RMS is calculated the second reference signal, calculate the resulting spectrum of the sum of the spectrum of the information component of the RMS with the spectrum of the second reference signal, calculate the difference between the resulting signal from the first reference RMS, change the delay and the amplitude of the second reference signal to obtain the lowest value of the measure of difference, and the resulting spectrum and signal, in which a minimum of a measure of difference was found; they are used in calculating the exact distance value. 2. The method according to claim 1, characterized in that the spectrum of the first reference RF system is formed by extracting the reference component of the RF system corresponding to the distance to the reference reflector, computing the spectrum of digital samples of this component and multiplying the calculated spectrum by the ratio of the complex transmission coefficient of the device for extracting and processing the information component The RF system of the radio range finder, defined for the calculated distance to the probed object, to the complex transfer coefficient of the device for selection and processing of reference component of the RF system of the radio range finder. 3. The method according to claim 2, characterized in that as a reference reflector use a single heterogeneity in the antenna-waveguide device, while this heterogeneity should be removed from neighboring inhomogeneities in the antenna-waveguide device by more than twice the resolution of the radio range finder. 4. The method according to claim 3, characterized in that as the reference reflector use the aperture of the aperture antenna, for example, the edge of an axisymmetric conical horn antenna, while filtering distinguishes the reference component of the RMS corresponding to the range to the specified aperture. 5. The method according to claim 2, characterized in that the formation of the spectrum of the first reference RF system is performed under the influence of interfering terms below the control level. 6. The method according to claim 1, characterized in that the second reference signal is generated in the form of digital samples with an envelope of discrete samples in the form of a segment of a harmonic signal that corresponds to a difference frequency signal not distorted by noise and spurious amplitude modulation, with a frequency determined by a given time a delay different from the center frequency of the main lobe of the spectrum of the information component of the RMS by less than half the width of the main lobe of the spectrum of the information component of the RMS. 7. The method according to claim 1, characterized in that the measure of difference between the information component of the RMS from the first reference RMS is calculated by the spectral parameters as the sum of terms with predetermined weighting factors, including the modulus of the difference in the width of the main lobe of the spectrum of the first reference RMS and the width of the main lobe of the resulting spectrum, the module of the difference in the asymmetry coefficients of the main lobes of the spectrum of the first reference RF system and the resulting spectrum, the module of the difference of the phase spectra of the first reference RF system and the resulting spectrum and their derivatives of lower orders at the central frequencies of the spectrum of the first reference RMS and the resulting spectrum. 8. The method according to claim 1, characterized in that, with a minimum of the measure of differences, the signal function of the resulting signal with the basic function in the form of an undistorted RF system with a variable delay of the reflected signal and with a given value of its phase, as well as with known values of the center frequency and range, is additionally calculated frequency modulation of the frequency-modulated radio frequency signal and specify the measured distance by the delay time corresponding to the global maximum of the signal function. 9. The method according to claim 1, characterized in that the measure of difference is calculated by the difference in the spectrum of the resulting signal function, normalized to its maximum value, from the spectrum of the signal function of the first reference RMS, normalized to its maximum value. 10. The method according to claim 9, characterized in that the spectrum of the signal function of the first reference MFR is calculated using signal samples calculated by the inverse Fourier transform of the digital samples of the main lobe and the nearest side lobes of the spectrum of the first reference MFR. 11. A radio range finder with frequency modulation of the probing radio waves, comprising a controlled radio frequency generator with one input and two outputs, a digital signal processing circuit, an antenna-waveguide device, a power divider with one input and two outputs, a directional coupler with one input and two outputs, a mixer with two inputs and one output, a frequency synthesizer with one output connected to the input of a controlled radio-frequency signal generator, and two inputs connected to the first outputs respectively This is a scheme of digital signal processing and a controlled generator of an RF signal, the second output of which is connected to a power divider and a directional coupler, the first output of which is connected to an antenna-waveguide device, and the second outputs of the power divider and a directional coupler are connected respectively to the first and second inputs of the mixer the output of which is connected to a series-connected filter, a preliminary analog processing circuit and an analog-to-digital converter the output of which is connected to the first input of the digital signal processing circuit, and the second input of the analog-to-digital converter is connected to the second output of the digital signal processing circuit, one of the outputs of which is the information output of the radio range finder, characterized in that the filter is made with an additional output connected in series connected by a second circuit for preliminary analog processing and a second analog-to-digital converter, the output and second input of which are connected respectively to the second input and t the third output of the digital signal processing circuit, and the antenna-waveguide device is made with homogeneous sections, the electric length of at least one of which is at least twice the distance allowed by the radio range finder. 12. The radio range finder according to claim 11, characterized in that the antenna of the antenna-waveguide device is made in the form of an axisymmetric conical horn with an axial length of at least twice the resolution of the radio range finder in range, while the mouth of the mouth is made in a plane normal to its axis. 13. The radio range finder according to claim 11, characterized in that the filter is made in the form of a high-pass filter and a band-pass filter connected in parallel with their inputs, while the output of the high-pass filter is connected to a series-connected analog pre-processing circuit and an analog-to-digital converter, and the output a bandpass filter is connected to the second analogue pre-processing circuitry and the second analog-to-digital converter connected in series.

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