RU1806384C - Method of determining distance using spectral processing of signals - Google Patents

Abstract

SUMMARY OF THE INVENTION: A device that implements a range-determining method with spectral signal processing comprises a stationary signal generator, a directional coupler, a transmitting antenna, a receiving antenna, an amplifier, an addition unit, a multi-channel splitter, a spectrum analyzer unit, a synchronization unit, an adder, a high-pass filter registering unit and calculator. 5 ill.

Description

The invention relates to radar and can be used in near radar to determine the range to an object.

The purpose of the invention is to increase sensitivity and improve energy performance while maintaining resolution.

In FIG. Figures 1-4 show examples of a device that implements the proposed method (Fig. 1), an embodiment of a device that implements the proposed method (Fig. 2), a synchronization unit (Fig. 2), a synchronization unit (Fig. 3), a switching unit (Fig. 1). 4), Fig. 5 is a diagram explaining the proposed method.

The ranging device implementing the proposed method comprises a stationary signal generator 1, a directional coupler 2, a transmitting antenna 3, a receiving antenna 4, an amplifier 5, an addition unit, a multi-channel splitter 7, a spectrum analyzer unit 8, a synchronization unit 9, an adder 10, filter 11

of high frequencies, recording unit 12 and calculator 13, an embodiment of a ranging device implementing the proposed method comprises a stationary signal generator 14, a directional coupler 15, a transmitting antenna 16, a receiving antenna 17, an amplifier 18, an addition unit 19, a multi-channel splitter 20, a unit 21 spectrum analyzers, a synchronization unit 22, an adder 23, a filter unit 24, a switching unit 25, a first and second recording unit 26.27, and a calculator 28, a synchronization unit 9 (22) contains N + 1 of the first controlled voltage sources 29; N first comparators 30, N second comparators 31, N second controlled voltage sources 32, an amplifier 33 and a sawtooth voltage generator 34, the switching unit 25 includes a timing clock 35, a frequency divider 36, a step voltage generator 37, a shift register 38 and K amplifiers 39.

A method for determining a range with spectral processing is as follows.

ABOUT

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When summing the received and reference signals, a signal is obtained with a periodic irregularity of the spectrum, from the period of which the target range is determined. The periodic waveform spectrum of the sum signal is the result of interference between the received and reference signals and is a frequency functional relationship. To get information about the range of the target, it is necessary to convert the frequency functional dependence into a temporary one. For this, several consecutive spectrum analyzes in different frequency ranges are carried out in parallel and synchronously. Then, the difference frequency signals corresponding to different parts of the spectrum of the signal under study, each of which is determined by one of the spectral analysis ranges, will fall into the passband of the filter. If, however, these ranges are determined so that the frequency difference between the extreme lowest frequencies of the neighboring ranges is equal to or a multiple of the frequency difference between adjacent maximums of the spectrum of the signal under study with periodic disruption of the spectrum, as shown in Fig. 56 and Fig. Bb, then envelope signals corresponding to different ranges of analysis will differ in phase from each other by 2 pt, where m 1,2 ... is an integer. When summing, the signals also add up in phase, which means the amplitude. the resulting envelope signal, which is the sum of all envelope signals, will increase N times as compared to the known method. Here N is the number of additional ranges of spectral analysis. The resolution will not change, but now an additional N spectral regions are additionally used to determine the target range. Accordingly, the fraction of signal energy used to obtain information about the target increases by a factor of N,

The phase summation condition will also be fulfilled for signals whose periodic irregularity of the spectrum is a multiple of the periodic irregularity of the signal under investigation (Fig. Bv). Therefore, the spectrum of the resulting signal will contain multiple frequencies corresponding to the range studied and its multiple. To unambiguously determine the presence of a target, range signals having the indicated multiple frequencies are extracted from the resulting signal. The amplitude of each range signal is measured and the presence or absence of a target at the range being studied or a multiple thereof is determined from the amplitude of the corresponding range signal. The power level of the received signal, sufficient to register the target, is defined as P min / N, where P min is the power of the received

sufficient signal to register the target in the known method. Thus, in addition to improving the energy characteristics of the device implementing the proposed method, a significant increase in sensitivity is achieved. The dynamic range of the received and reference signals, at which their interference is observed, also expands by 2N times, which provides increased reliability of the device implementing the proposed method.

A spectral processing range determining device operates as follows.

At the output of the stationary signal generator 1, a broadband noise-like signal is obtained, which is fed to the input of a directional coupler 2, where it is divided into sounding and reference signals.

The probe signal from the output of the directional coupler 2 is fed to a transmitting antenna 3, by which it is radiated towards the target. The signal reflected from the target is received by the receiving antenna 4 and

they are then sent to the input of amplifier 5, where it is amplified to the power level necessary for further signal processing. The received and amplified signal is fed to the first input of the addition unit 6, to the second

the input of which simultaneously feeds the reference signal from the output of the directional coupler 2. As a result of the addition of the received and reference signals, the sum signal

which has periodic ruggedness and is determined by the formula

Ф (Г) Фо (0 1 + COS

(1)

45

where Φι (τ) is the spectrum of the sounding signal.

To convert the frequency functional dependence of the form (1) into a temporary functional dependence,

0 it is necessary to carry out spectral processing of the total signal. To this end, the total signal from the output of the addition unit 6 is sent to the input of the multi-channel splitter 7, where it is divided into N equal

5 parts corresponding to N frequency ranges of spectral analyzes. The obtained N signals are fed to the N inputs of block 8 of spectrum analyzers, where N spectral analyzes of the total signal are synchronously performed in different frequency ranges. For the proposed spectral processing, it is necessary that the frequency difference between the lowermost frequencies of the neighboring ranges is equal to or a multiple of the C / 2R ratio, where R is the studied discrete range. Moreover, to study other discrete ranges, the frequency difference between the extreme frequencies of adjacent ranges is changed. In order to realize such spectral processing, N control signals are required to determine the range of each of the N spectrum analyzers (not shown in Fig. 1,2) of the spectrum analyzer unit 8, as well as a signal enabling synchronization of these spectrum analyzers. The necessary control signals are obtained in the synchronization unit 9, the N outputs of which are connected to the control inputs of the spectrum analyzer unit 8, while a frequency sweep signal and a control signal determining the analysis range are supplied to each spectrum analyzer. As a result of such spectral analysis, the output of each spectrum analyzer receives a signal of the envelope of the spectrum of the corresponding range of spectral analysis. These N envelope signals from the outputs of block 8 of the spectrum analyzers are fed to the inputs of a multi-channel adder 10, at the output of which a resulting signal is obtained, which is the sum of all envelope signals. Since the frequency ranges of the spectrum analyzers of block 8 of the spectrum analyzers are shifted relative to each other in this way, the signals of the spectral envelopes will also be phase shifted relative to each other by

DRP 2L :(

2R Afa

-m)

where m is the order of multiplicity;

fa is the frequency difference between the extreme lower frequencies of adjacent ranges; m 2RAfa / c.

Therefore, the resulting signal will have the following form:

M N, ATT R

U (t) 2 2 Amn cos f 1 (St

m 1n + PDGa), (3)

where 5 is the sweep speed in the frequency of spectrum analyzers, Hz / C;

p is the number of the range of spectral analysis;

Agg - the amplitude of the signal of the envelope of the spectrum.

It follows from formulas (2) and (3) that the envelope signals, for which condition 5 is performed outside C / 2Rm Afa (4), are summed in the multi-channel adder 10 in phase and, thus, are amplified N times, and the signals corresponding to other ranges are summed up with a random phase, which is equivalent to

10 attenuation of the signal. As a result, the resulting signal will contain only those signals whose frequencies correspond to the studied range and ranges that are multiples of it. The resulting resulting signal15 is fed to the input of the high-pass filter 11, where the spurious low-frequency components that occur during non-phase addition of the envelope signals are cut off. Dedicated High Frequency Signal

20 is fed to the input of the recording unit 12, which can be used as a low-frequency spectrum analyzer or frequency meter. Using the recording unit 12, the frequency f of the high frequencies of the 25rd signal is measured. The measurement results are fed to the calculator 13, where the target range is determined by the formula R fc / 2S, after which the frequency difference between

30 extreme lower frequencies of adjacent ranges of spectral analysis using block 9 synchronization and repeat all the above operations, while exploring a different range .-,

35 The resulting resulting signal is fed to the input of block 24 filters, where, using band-pass filters, signals corresponding to different multiplicities of the studied range R are extracted. The frequencies of the selected range signals will also be multiple and equal to fqm - 2m RS / c, where m 1.2 ... M is an order of multiplicity. The range signals from the output of the filter unit 24 are sequentially supplied to the first recording unit 26,

45 where they measure the amplitude of the range signal and determine the presence or absence of the target at the target and its multiple ranges from the amplitude of the corresponding range signal. Moreover, if there is a goal, the court

50 exceeding the amplitude of the range signal of a certain amplitude level, which is established experimentally. The measurement signals from the second recording unit 26 are supplied to the computer 28, where

55 simultaneously with the switching unit 25, they give signals about the frequency difference between the extreme lower frequencies of the neighboring spectral analysis ranges and about connecting one or another band-pass filter to the recording unit 15 (in FIG.

shown) block 14 filters. The target range in this case is determined by the formula

R

where Afar is the frequency difference between the center frequencies of the bandpass filters of block 14;

D fai - the frequency difference between the extreme lower frequencies of adjacent ranges, corresponding to the studied range;

K is the number of the filter, when turned on, the presence of a target is detected and which determines the multiplicity m, eliminating the associated ambiguity in (3) and (4).

Moreover, for this, the measurement of the amplitude of the range signals is carried out by sequentially connecting the band-pass filters of the filter unit 14 both to the output of the multi-channel adder 10 and to the input of the first recording unit 26. Such a serial connection is made using the signals that are received in the switching unit 16, Block 14 filters is a set of bandpass filters, the input of each of which is connected through an electronic key to the input of the unit, and the output to the output of the unit (not shown in Fig. 2). The control inputs of the electronic keys are connected to the switching unit 16, from which signals are received that open or close the electronic keys. When the electronic key is opened, the corresponding band-pass filter of the filter unit 14 is connected to the first recording unit 26.

In order to more accurately measure the range, if the target is detected on the studied or one of its multiple ranges, measure the frequency fg of the range signal using the recording unit 12 and calculate the range using the formula

R fgc / 2S

The introduction of discrete and continuous range measurements allows combining the high speed of studying the entire range of ranges for the purpose of the first method with the high accuracy of the second.

After the presence or absence of a target is determined at the target and its multiples, the region of another discrete range Ri, as well as the multiples of it, is examined for the target. To do this, the frequency difference Afa between the lowermost frequencies of adjacent ranges is changed so that the ratio Afa C / 2R

Already performed for the RI range, after which all the above operations are repeated.

The frequency difference between the ranges is changed using signals that are generated in the synchronization unit 9, which operates as follows.

Using N + 1 controlled voltage sources 29, a lower frequency limit is set for the N ranges of spectral analysis in block 8 of the spectrum analyzers. In this case, between the adjacent ranges there should be a certain frequency difference, which for research

15 different ranges, in addition, it is necessary to change. Since the dependence of the local oscillator frequency (not shown in Figs. 1, 2) of each spectrum analyzer of spectrum analyzer unit 8 is known in advance, the problem is reduced to generating control signals in block 9, the voltage difference between which corresponds to the frequency difference between adjacent spectral ranges analysis.

25 To establish a certain voltage difference between the control signals and to change them, N first and N second analog comparators 30, 31, as well as an amplifier 33 are used, where a search signal 30 is generated.

Consider an example of obtaining the first control signals. The first control signal U0 is set independently

35 from the rest of the signals. The second control signal Ui is set in such a way that it differs from the first Uo in voltage by a certain value A U. To ensure a given difference

40 voltages between the control signals, they are fed to the inputs of the first of the N first comparators 30, the output of which receives a signal UOL proportional to the voltage difference between the signals U0 and

45 Ui. Using the search signal Un, which is generated in the amplifier 33, and the first of the N second comparators 31, the first of the N voltage sources 29 is controlled so that the signal Ui obtained at its output,

50 differed in voltage from signal U0 by a certain amount of AU. To this end, the signal Uoi from the output of the first of the N second comparators 30 and the search signal Un are simultaneously supplied to the outputs of the first of the N second 55 comparators 31, where they are compared, as a result of which the auto-adjustment signal Ua, proportionally different are the voltages between the signals Uoi and Un.

The auto-adjustment signal Ua is supplied to the control input of the second of N + 1 controlled voltage sources 29. As a result of the action of the auto-adjustment signal Ua, the voltage Ui at the output of the second of N controlled voltage sources 29 changes so that Uoi becomes equal to Un according to voltage. If we now change the voltage of the search signal 1) n, then, as a result of the described auto-adjustment process, the voltage of the control signal is again changed so that Uoi is equal to un. Thus, changing the voltage of the search signal Un. it is possible to vary the voltage difference between the control signals, and hence the frequency difference between adjacent ranges of the spectral analysis.

.Other control signals are obtained in a similar manner. In this case, the voltage of the signal U2 is set relative to the voltage of the signal Ui, and the voltage of the signal Uz relative to the signal U2, etc.

In addition to the control signals by which the frequency ranges of the spectral analyzes are set, in the synchronization unit 9, a sweep signal Up is also generated, with which all spectral analyzes are synchronized. The sweep signal is obtained at the output of a sawtooth voltage generator 34 and is supplied simultaneously with control signals to the local oscillators of all spectrum analyzers of block 8 of the spectrum analyzers. In order to prevent the influence of the sweep signal on the autoregulation circuit of the control signals, the latter are supplied to the local oscillator inputs through the voltage controlled 31 sources from the M sources. In this case, the control signals are supplied to the control inputs of these N sources 31, the output of which receives a voltage proportional to the voltage of the corresponding control signal. Thus, the control signals are transmitted through the corresponding from N sources of controlled voltage, which are non-reciprocal elements and protect the control inputs of the corresponding from N + 1 controlled voltage sources 29 from the action of the scan signal.

The change in the frequency difference between the ranges of the spectral analysis should occur only at certain points when the sequential on-off of the bandpass filters of the filter unit 14 is completed. For this, in the switching unit 25, a shift signal of the spectral analysis ranges is generated, which is a stepwise varying voltage, which is supplied to the control input of the amplifier 33 of the synchronization unit 9.

5 The switching unit operates as follows.

In the master clock 25, which can be used as a multivibrator or any other pulse generator, a signal is generated representing a periodic sequence of pulses; the repetition period of which Ti is equal to the time required to measure the amplitude of the range signal, and thus determines the switching speed of the filters in the filter unit 24. This signal is fed through a frequency divider 36 to the read input of the shift register 38 and directly to the clock input

0 register 38 shift. In this case, a logical unit is written to the first output of the shift register 38. The high level signal from the first output of the register 38 through the first of the K amplifiers 39 is fed to the control

5 input block 24 filters, thereby connecting the first filter in block 24 filters. The pulses arriving at the clock input of the shift register 38 will move the high level signal from the first to the last outputs of the shift register 38. In this case, the filters in block 24 of filters are respectively turned on and off sequentially. The output of the frequency divider 36 receives a signal with a pulse repetition period,

5 equal to T2 Ti / K, where K is the number of filters in the block of 24 filters. This signal is fed to the synchronizing input of the step voltage generator 37, where a range offset signal is generated, which is a 0 stepwise varying voltage. Due to this synchronization, a step change in voltage will occur only after switching all the filters of the block 24 filters 5, In the block 8 (21) spectrum analyzers, C4-60 instruments were used, the recording unit 12 (second recording unit 27) was used. Frequency meter 3-34, as

0 of the first recording unit 26 - voltmeter V7-27.

Consider a specific application of the proposed method and device for its implementation. Range of probed

5 ranges from 15 to 1000 m. In this case, the maximum frequency difference fpmax between adjacent maximums of the spectrum of the total signal will be no more than 10 MHz. Therefore, the spectrum width of the DR of the probing signal should be at least 30 MHz. Of

Claims (1)

of the range of probed ranges, we single out the ranges for the sensing of which a relative increase in sensitivity will be required. We limit this range to ranges from 100 to 1000 m. This bandwidth corresponds to fpmax 1.5 MHz. Then, the spectrum of the AF signal of 30 MHz can be divided into approximately 20 frequency ranges of synchronous spectral processing, which will give, according to formula (3), an increase in sensitivity by 13 dB and expansion of the dynamic range of the received signals, in which interference of the received and reference signals is observed, approximately forty times. SUMMARY OF THE INVENTION A method for determining a range with spectral processing of a signal, which comprises generating a stationary signal with a spectral width of at least the ratio of the speed of light C to the distance to the target R, dividing said signal into sounding and reference signals, emitting a sounding signal, receiving the reflected signal, the received and Reference signals are summarized, the total signal is spectrally processed, the distance to the target is determined by the frequency difference between adjacent maximums of the spectrum, characterized in that in order to increase the sensitivity and improve energy characteristics while maintaining the resolution, N similar spectral treatments of the total signal in different frequency ranges are performed simultaneously with the first one, the frequency ranges of these spectral treatments being chosen so that the frequency difference between the extreme lower frequencies of adjacent ranges is equal to or a multiple of the C / 2R ratio, a resulting signal is obtained, which is the sum of the spectral processing signals, each of which corresponds to uet spectrum envelope of the sum signal in one of the spectral ranges processing of the resultant signal is isolated by a high frequency signal and low-frequency filtering the permanent constituents determined range of frequency fen drove high frequency according to the formula R fC / 2S, where S is the frequency sweep speed for spectrum analysis. Ryg / A of / M FIG. 4 S) B 1 & / KauKuu / ЈЛ