CN102385054B - TPRF method for avoiding velocity measurement obscureness of Doppler weather radar - Google Patents

Abstract

A TPRF method for avoiding velocity measurement obscureness of a Doppler weather radar belongs to the field of weather radars, and aims at solving the problem of velocity measurement obscureness of the Doppler radar. The TPRF method is a special case of multiple-pulse repetition frequency detection technology and is also the development of dipulse repetition frequency (DPRF) detection technology. In TPRF technology, three pulse repetition frequencies forming two DPRF detections are used for detection, and two results detected by the DPRF are analyzed by the DPRF again, thereby expanding a velocity measurement range for twice. The velocity measurement range expanded by the DPRF can not realize the detection without obscureness in weather with strong convection. Under the condition that the distance of the detection without obscureness is the same, the velocity measurement range of the TPRF is wider than that of the DPRF by two times at least, thereby realizing the detection without obscureness on most weather with strong convection. The key for implementing the TPRF is to choose three suitable pulse repetition frequencies and to provide a method for confirming the three pulse repetition frequencies of the TPRF so as to ensure the effectiveness of the TPRF method.

Description

The TPRF method of avoiding velocity measurement obscureness of Doppler weather radar

1. technical field

The invention belongs to the weather radar field, be directly used in the fuzzy problem that tests the speed that solves Doppler radar.

2. background technology

The fuzzy problem that tests the speed is that Doppler radar is surveyed and to be needed for a long time the technical barrier that solves.Because range finding and the contradiction that tests the speed are limited in scope in order to satisfy the requirement of certain detection range, to test the speed, be easy to occur the velocity ambiguity phenomenon when running into convection weather.In the Velocity products of Doppler radar, the velocity ambiguity district often appears.Yet Velocity products is for the product very useful with analysis and research of early warning in short-term, because the velocity ambiguity problem is very limited its application.For a long time, solve the velocity ambiguity problem and be mostly to adopt the way of software processing afterwards.Although these ways have restitution to velocity ambiguity to a certain extent, under convection weather, fuzzy region is many and in disorder, whether fuzzyly is difficult to a certain database of automatic discrimination, produces effects not quite so pure software moves back fuzzy way.For this reason, the way that some man-machine interactively softwares are processed has been proposed.This solution is more effective, but is not suitable for service application.The fuzzy way of comprehensive various software back speed degree, poor effect in general.Dipulse repetition frequency Detection Techniques (DPRF) are expansion practical in the Doppler range rate measurement scope technology that tests the speed.But the DPRF technology is not used widely in Doppler radar is surveyed.Main cause is the restriction of detection range and speed spectrum width, causes the scope that tests the speed of DPRF expansion still inadequate, surveys still existence much fuzzy under convection weather.

In order to guarantee certain detection range, pulse repetition rate can not be very high.Because the problem of speed spectrum width, in order to guarantee the validity of DPRF technology, pulse repetition rate is than generally being taken as 3: 2 (or 4: 3), and higher pulse repetition rate ratio can cause the DPRF technical failure.Such as, in order to guarantee to have the detection range of 200km, pulse repetition rate can not be higher than 750Hz.Be that the DPRF technology of 3: 2 is when being used for Doppler radar, if get PRF with the pulse repetition rate ratio ₁=750Hz, PRF ₂=500Hz can expand to 37.5m/s for the not fuzzy speed of S-band weather radar so.For stronger convection weather, easily exceed such velocity range.For the C-band Doppler radar, fuzzy problem is just more serious.Such as, in order to guarantee to have the detection range of 150km, pulse repetition rate can not be higher than 1000Hz.Get equally PRF ₁: PRF ₂=3: 2, not fuzzy speed can expand to 25m/s at most.The scope that tests the speed so also can occur fuzzy under weather more stably.Fuzzy problem is especially serious for the X-band Doppler radar.

The fuzzy problem that tests the speed is that Doppler radar is surveyed the technical barrier that exists for a long time, and the outlet of dealing with problems is how to realize without fuzzy detection.

3. summary of the invention

3.1 the technical matters that solves

The present invention is used for solving the fuzzy problem that tests the speed of Doppler radar.

3.2 the technical scheme that adopts

For solving the fuzzy problem that tests the speed of Doppler radar, invented three pulse repetition rate Detection Techniques (TPRF), provide the method for three pulse repetition raties in definite TPRF technology, and provided universal calculation equation.

TPRF is also a kind of the test the speed method of scope of expansion.The TPRF method is that the special case of multiple PRF Detection Techniques is also the development of dipulse repetition frequency Detection Techniques (DPRF).The TPRF technology is surveyed with three pulse repetition raties that consist of two DPRF detections, two DPRF result of detections is carried out DPRF again analyze, and the scope of testing the speed has been carried out twice expansion.

In weather radar is surveyed the scope that tests the speed of DPRF expansion still can not satisfy under strong convective weather without fuzzy detection.The scope that tests the speed of the TPRF method of inventing is a times of DPRF method at least, can realize without fuzzy detection in most strong convective weathers.

No matter be DPRF method or TPRF method, validity is all the topic that asks with concern, and selecting suitable pulse repetition rate is the key that guarantees technical validity.On the basis that the impact of detection range requirement and meteorological target velocity and speed spectrum width is analyzed, provided the method for three pulse repetition raties of definite TPRF.

The TPRF method can be regarded the combination of DPRF method as, and the analytical approach of TPRF is identical with the DPRF technology with algorithm.For this reason, provided universal calculation equation.

The TPRF know-why

The TPRF technology adopts selected in advance three pulse repetition raties that meet certain requirements to survey successively.If three pulse repetition raties are designated as respectively from high to low: PRF ₁, PRF ₂And PRF ₃, three pulse repetition raties need to satisfy lower relation of plane:

PRF ₁: PRF ₂=q: (q-1) and PRF ₂: PRF ₃-------------------------------------(1) of=q: (q-1)

Wherein, q=3,4,5 ... positive integer.

Obviously, PRF ₁And PRF ₂Consist of a q: DPRF (q-1) surveys, and result of detection is designated as

PRF ₂And PRF ₃Consist of another q: DPRF (q-1) surveys, and result of detection is designated as

Be equivalent to PRF _a=qPRF ₂The Doppler search result, Be equivalent to PRF _b=qPRF ₃The Doppler search result.Because PRF _a: PRF _b=q: (q-1),

With

Be equivalent to respectively PRF _aAnd PRF _bResult of detection, so can be right

With

Carrying out a DPRF analyzes again.If with PRF ₁, PRF ₂And PRF ₃The fuzzyyest corresponding speed is designated as respectively V _N1, V _N2And V _N3, with PRF _aAnd PRF _bThe fuzzyyest speed be designated as respectively V _NaAnd V _Nb, the TPRF technology expands to V with the scope of testing the speed so _N=qV _Nb=q ²V _N3, it is equivalent to PRF=qPRF _b=q ²PRF ₃Doppler search.

Three pulse repetition raties of TPRF technology consist of two DPRF to be surveyed, and two DPRF result of detections is carried out DPRF again analyze, and the scope of testing the speed has been carried out twice expansion.The principle of scope is identical with the DPRF technology because the TPRF technological expansion tests the speed, so illustrate that next DPRF expands the scope principle that tests the speed.

DPRF expands the scope principle that tests the speed

The specific practice of DPRF technology is: successively survey with two pulse repetition raties that satisfy the certain proportion relation, calculate actual speed according to two measurement results.Two pulse repetition raties are designated as respectively PRF ₁And PRF ₂, the fuzzyyest speed of their correspondences is designated as respectively V _N1And V _N2, two measurement results are designated as respectively With

Both differences are designated as

PRF ₁And PRF ₂Satisfy relation:

PRF ₁∶PRF ₂＝q∶(q-1)--------------------------------------------(2)

Wherein, q=3,4,5 ... positive integer.

In Doppler range rate measurement, pulse repetition rate is determining the scope of testing the speed.In rectangular coordinate system, if with the corresponding actual speed of X-axis, with the corresponding measurement result of Y-axis, so along with the increase of actual speed, the measurement result curve be the scope of testing the speed be the saw-toothed curve on boundary.According to PRF ₁And PRF ₂Measurement result poor can be with ± qV _N2Velocity range be divided into 2q speed interval.

The analytical approach of DPRF is with two result of detections

With

Ask poor According to Δ V judgement measurement result

With

Fall which speed interval, then according to speed interval and result of detection

Or

Calculate doppler velocity.The present invention has provided following general reckoning doppler velocity formula:

$V_D=\left\{\begin{array}{c}(i-1)V_{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HSB00000415641400011.png,HSB00000415641400021.png"\; state="\{\{state\}\}">N</figure-callout>}2}+{\tilde{V}}_{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HSB00000415641400011.png,HSB00000415641400021.png"\; state="\{\{state\}\}">D</figure-callout>}2},...i>0,i=\mathrm{1,2},...,q\\ (i+1)V_{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HSB00000415641400011.png,HSB00000415641400021.png"\; state="\{\{state\}\}">N</figure-callout>}2}+{\tilde{V}}_{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HSB00000415641400011.png,HSB00000415641400021.png"\; state="\{\{state\}\}">D</figure-callout>}2},...,i<0,i=-1,-2,...,-q\end{array}\right.---\left(3\right)$

Wherein, Int () represents rounding operation, and i represents the speed interval sequence number.V _N2In two pulse repetition raties, the fuzzyyest speed of the correspondence that frequency is lower,

It is its measurement result.V _DThe doppler velocity that expression obtains according to the DPRF technology.

DPRF successively adopts two pulse repetition raties to survey, although two measurement results

With

May be fuzzy, but poor by them

Judge which speed interval they fall, and still can recover actual doppler velocity, the test the speed principle of scope of DPRF technological expansion that Here it is.The DPRF technology expands to the not fuzzy scope of testing the speed ± qV _N2, such scope of testing the speed is equivalent to Sing plus repetition frequency PRF=qPRF ₂=(q-1) PRF ₁Effect on Detecting.

According to the relation of two pulse repetition raties in the DPRF technology and the relation between pulse repetition rate and the fuzzyyest speed, can derive following formula:

$V_N=\frac{\mathrm{\&lambda;}}{4}\frac{{\mathrm{<figure-callout\; id="1"\; label="PRF"\; filenames="HSB00000415641400011.png"\; state="\{\{state\}\}">PRF</figure-callout>}}_1\&times;{\mathrm{<figure-callout\; id="2"\; label="PRF"\; filenames="HSB00000415641400011.png,HSB00000415641400021.png"\; state="\{\{state\}\}">PRF</figure-callout>}}_2}{{\mathrm{PRF}}_1-{\mathrm{PRF}}_2}---\left(4\right)$

Can obtain thus important inference: DPRF to the expansion of the scope of testing the speed and amassing with poor relevant of two pulse repetition raties, the scope that tests the speed long-pending larger, the DPRF expansion of two pulse repetition raties is larger; The difference of two pulse repetition raties is less, the scope that tests the speed of DPRF expansion is larger.Therefore, adopting high pulse repetition rate and little pulse repetition rate poor is to improve test the speed two approach of scope of DPRF.

In addition, according to the proportionate relationship of two pulse repetition raties, can also derive following formula:

PRF ₁-PRF ₂＝PRF ₁/q --------------------------------------------(5)

Available inference is thus: at PRF ₁After determining, q is less, PRF ₁-PRF ₂Larger.Because minimum q value is q=3, so work as PRF ₁: PRF ₂=3: 2 o'clock, the two poor maximums of pulse repetition rate.

In order further to explain the DPRF technology.The below is with PRF ₁: PRF ₂=3: 2 DPRF is that example explanation DPRF expands test the speed scope principle and speed interval division.As Fig. 1, dotted line represents PRF ₁The measurement result curve, solid line represents PRF ₂The measurement result curve.According to Δ V, general ± 3V _N2Velocity range be divided into 6 speed intervals.Can analyze table 1 according to Fig. 1.As can be seen from Table 1 at ± 3V _N2Scope in, Δ V and speed interval are one to one.Therefore, even if

With

Be fuzzy, by the speed interval that judges rightly, can recover original actual speed.Above example has ubiquity, for the situation of other ratio, analytical approach is similarly arranged.

Table 1:PRF ₁: PRF ₂=3: 2 DPRF surveys

Beneficial effect

The TPRF method has the very strong extended capability that tests the speed, and can realize without fuzzy detection for most strong convective weathers.Because be without fuzzy detection, so fundamentally avoided software in the past to move back the uncertainty of blur method.

Because the impact of detection range and meteorological target velocity spectrum width makes the scope that tests the speed of DPRF expansion inadequate.In order to guarantee certain detection range, pulse repetition rate can not be very high.Because the speed spectrum width have pulse repetition rate than generally being taken as 3: 2 (or 4: 3), higher pulse repetition rate ratio can cause the DPRF technical failure.Yet the TPRF technology has been carried out twice expansion to the scope of testing the speed, can satisfy most strong storms without fuzzy detection requirement.

The pulse repetition rate setting of TPRF is equivalent to two DPRF, therefore when comparing TPRF and DPRF performance, should separately consider.

At first with TPRF and PRF ₁: PRF ₂=q: DPRF (q-1) compares.The scope of testing the speed of DPRF is ± qV _N2, the scope of testing the speed of TPRF is ± q ²V _N3, because

So the scope of testing the speed of TPRF is DPRF test the speed scope q-1 doubly.If get the pulse repetition rate ratio of 3: 2, i.e. q=3, the scope that tests the speed of TPRF has increased by one times than the DPRF scope of testing the speed so.At this moment, both not fuzzy detection ranges are identical.

Then with TPRF and PRF ₂: PRF ₃=q: DPRF (q-1) relatively.The scope of testing the speed of DPRF is ± qV _N3, the scope of testing the speed of TPRF is ± q ²V _N3So, the scope of testing the speed of TPRF be DPRF test the speed scope q doubly.If get the pulse repetition rate ratio of 3: 2, i.e. q=3, the scope that tests the speed of TPRF increases twice than the DPRF scope that tests the speed so.At this moment, the not fuzzy detection range of TPRF is 2/3 of DPRF.

As seen, under the identical condition of not fuzzy detection range, the scope that tests the speed of TPRF doubles at least than the DPRF scope that tests the speed.

In addition, because TPRF uses three pulse repetition raties, DPRF to use two pulse repetition raties, so the TPRF technology has increased approximately 1/3 than the detection time of DPRF technology.

4. description of drawings

Fig. 1: PF ₁: PF ₂=3: 2 DPRF surveys

Fig. 1 is PRF ₁: PRF ₂=3: 2 DPRF detection principle figure.Directions X represents tested speed, and Y-direction represents measured value.Broken line a1a2-a2a3-... pulse repetition rate PRF ₁The measurement curve, V _N1PRF ₁The fuzzyyest corresponding speed along with the increase of speed, is measured curve at ± V _N1Between indentation.Broken line b1b2-b2b3-... pulse repetition rate PRF ₂The measurement curve, V _N2PRF ₂The fuzzyyest corresponding speed.± 3V _N2Velocity range be the not fuzzy interval that DPRF measures.According to PRF ₁And PRF ₂Article two, measure the poor of curve, can be with ± 3V _N2Velocity range be divided into (from-3 to+3) 6 speed intervals.If with PRF ₁Measured value be designated as PRF ₂Measured value be designated as

With

Poor

Corresponding one by one with 6 speed intervals, referring to table 1.For example, Δ V=2V _N2Corresponding is speed interval 2, Δ V=-V _N2Corresponding is speed interval-3.Although

Or

May be fuzzy, but as long as judge them according to Δ V and drop on that speed interval, utilize formula (3) just can the back speed degree fuzzy.The back speed degree is fuzzy to be limited to ± 3V _N2Velocity range in, exceed this scope DPRF and will occur fuzzy.For example, if actual speed is in interval 4, interval 4 Δ V=V _N2, identical with the Δ V value of speed interval-3, therefore can't carry out speed and recover.So the not fuzzy interval of DPRF is ± 3V _N2This example is PRF ₁: PRF ₂=3: 2 situation, but have ubiquity for explanation DPRF principle and way.

Fig. 2: TPRF technical schematic diagram

In figure, broken line 1 (a1a2-a2a3-a3a4-a4a5-a5a6) is PRF ₁Slotted line.Broken line 2 (b1b2-b2b3-b3b4-b4b5-b5b6) is PRF ₂Slotted line.Broken line 3 (c1c2-c2c3-c3c4-c4c5-c5c6) is PRF ₃Slotted line.PRF ₁: PRF ₂The DPRF that consists of 3: 2 surveys, and with the DPRF principle, not fuzzy velocity range is expanded to (± 3V between A2A3-A4A5 _N2), be equivalent to PRF _aDetection.PRF ₂: PRF ₃The DPRF that consists of 3: 2 surveys, and not fuzzy velocity range expands to (± 3V between B2B3-B4B5 _N3), be equivalent to PRF _bDetection.PRF _a: PRF _bConsist of DPRF and survey, not fuzzy scope is further expanded to (± 9V between EF _N3).V _N1, V _N2, V _N3, V _NaAnd V _NbRespectively pulse repetition rate PRF ₁, PRF ₂, PRF ₃, PRF _aAnd PRF _nThe fuzzyyest corresponding speed.

5. embodiment

The TPRF technology has the test the speed ability of scope of very strong expansion, but will guarantee in strong convective weather is surveyed effectively must to propose restriction to the pulse repetition rate of selecting.The Key of Implementation of TPRF technology is to select three suitable pulse repetition raties.The various restrictions of paired pulses repetition frequency mainly require and the speed of meteorological target and the impact of speed spectrum width from detection range.Now detection range is required to be designated as R, the speed spectrum width is designated as σ _v, horizontal wind is designated as V _h, these three parameters are to determine the Main Basis of pulse repetition rate.

Detection range requires to have limited operable high pulse repetition frequency.The weather radar of different-waveband has different requirements to detection range, so when implementing the TPRF technology, select available high pulse repetition frequency according to specific requirement.Parameter σ _vAnd V _hBe to affect the main factor that pulse repetition rate is selected, relate to range of pulse repetition frequency, pulse repetition rate is poor and the selection of pulse repetition rate ratio.Generally, the stronger σ of storm _vAnd V _hLarger.U.S. meteorologist has carried out statistical research to a strong storm example seventies in last century, and its statistics can be used as σ _vAnd V _hThe reference of index.Its statistics shows: the spectrum width for strong storm 15% surpasses 6m/s, and horizontal wind can surpass 50m/s.

Determine operable high pulse repetition frequency in TPRF

Require and require size without the horizontal wind of fuzzy detection according to detection range, determine the pulse repetition rate upper limit.

PRF _max1＝c/(2R)

PRF _max2＝4V _h/λ

Wherein, c is velocity of electromagnetic wave, and R is the detection range of requirement, V _hBe requirement without the size of the horizontal wind of fuzzy detection, λ is radar wavelength.Operable high pulse repetition frequency is for lower one in both.

Determine the poor and operable minimum pulse repetition rate of pulse repetition rate in TPRF

Determine pulse repetition rate poor (and minimum pulse repetition rate) according to the speed spectrum width parameter of setting.Two pulse repetition raties poor (and minimum pulse repetition rate) should satisfy:

ΔPRF≥2σ _v/λ

PRF _min≥2σ _v/λ

Wherein, Δ PRF=PRF ₁-PRF ₂, or Δ PRF=PRF ₂-PRF ₃, σ _vBe the speed spectrum width, λ is radar wavelength.Effective in order to guarantee the detection TPRF technology of most strong storm, desirable σ _v〉=6 (m/s).Like this, (get λ=10cm) for the S-band weather radar, pulse repetition rate poor (and minimum pulse repetition rate) need to be more than or equal to 120Hz, (getting λ=5cm) need to be more than or equal to 240Hz, (gets λ=3cm) need to be more than or equal to 400Hz for the X-band weather radar for the C-band weather radar.

Pulse repetition rate ratio in TPRF

According to the analysis of front, when the pulse repetition rate ratio is 3: 2, the poor maximum of pulse repetition rate.So, the validity of TPRF in order to guarantee strong storm is surveyed, generally getting the pulse repetition rate ratio is 3: 2.That is, the pulse repetition rate ratio in TPRF is, PRF ₁: PRF ₂=PRF ₂: PRF ₃=q: (q-1)=3: 2.

Because the requirement of paired pulses repetition frequency is relevant with radar wavelength, so the pulse repetition rate that can meet the demands is different because of the difference of radar wavelength.The S-band Doppler radar is easily found out the pulse repetition rate combination of satisfying above-mentioned requirements.The X-band Doppler radar is difficult to find out the pulse repetition rate combination of satisfying above-mentioned requirements, generally needs to reduce a certain requirement.According to the method for above-mentioned definite pulse repetition rate, provide set of pulses repetition frequency data here as an example of the C-band Doppler radar example.Get radar wavelength λ=5cm, the speed spectrum width is got σ _v=6m/s, three pulse repetition rate PRF ₁, PRF ₂And PRF ₃Respectively 1125Hz, 750Hz and 500Hz.Carry out TPRF with such pulse repetition rate combination and survey, the fuzzyyest speed can expand to 56m/s, and detection range is about 133km.

The calculating of TPRF

Remember that three pulse repetition raties are respectively PRF ₁, PRF ₂And PRF ₃, the fuzzyyest corresponding speed is designated as respectively V _N1, V _N2And V _N3, three measurement results are designated as respectively

With

And note

Three pulse repetition raties satisfy relation: PRF ₁: PRF ₂=q: (q-1) and PRF ₂: PRF ₃=q: (q-1).

According to Δ V ₁₂Carry out DPRF and analyze, determine

With

The place speed interval calculates according to following universal calculation equation and uses PRF ₁And PRF ₂The doppler velocity that measures, and result of calculation is designated as

$V_D=\left\{\begin{array}{c}(i-1)V_N+{\tilde{V}}_D,...i>0,i=\mathrm{1,2},...,q\\ (i+1)V_N+{\tilde{V}}_D,...,i<0,i=-1,-2,...,-q\end{array}\right.$

Wherein, Int () represents rounding operation, and i represents the speed interval sequence number.

According to Δ V ₂₃Carry out DPRF and analyze, determine

With The place speed interval calculates according to top universal calculation equation and uses PRF ₂And PRF ₃The doppler velocity that measures, and result of calculation is designated as

According to

Again carry out DPRF and analyze, acquired results is actual doppler velocity.

Claims (2)

1. three pulse repetition rate TPRF methods of avoiding velocity measurement obscureness of Doppler weather radar, it is characterized in that, survey successively with three pulse repetition raties, three pulse repetition raties consist of two dipulse repetition frequencys and survey DPRF, two DPRF analyze the scope of testing the speed are expanded for the first time, two DPRF analysis results consist of again a DPRF and survey, two DPRF analysis results are carried out DPRF again to be analyzed, the scope of testing the speed is expanded for the second time, and three pulse repetition raties are designated as respectively PRF from high to low ₁, PRF ₂, PRF ₃, pulse repetition rate compares PRF ₁/ PRF ₂And PRF ₂/ PRF ₃Satisfy identical proportionate relationship q/ (q-1), q is 3,4, the positive integer of 5..., and the measurement result of three pulse repetition raties is designated as respectively V ₁, V ₂, V ₃, pass through V with the DPRF analysis calculation method ₁And V ₂Difference analysis obtain speed V _a, pass through V with the DPRF analysis calculation method ₂And V ₃Difference analysis obtain speed V _b, again pass through V with the DPRF analytical approach _aAnd V _bDifference analysis obtain actual tested speed.

2. method according to claim 1, three pulse repetition raties in the TPRF method are designated as respectively PRF from high to low ₁, PRF ₂, PRF ₃, the poor PRF of pulse repetition rate ₁-PRF ₂And PRF ₂-PRF ₃All be greater than and equal 2 σ _v/ λ, wherein, σ _v〉=6m/s is meteorological target velocity spectrum width, and λ is the Doppler radar wavelength.

Images