CN102385054A - 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 that Doppler radar back speed degree is fuzzy

1. technical field

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

2. background technology

The fuzzy problem that tests the speed is that Doppler radar is surveyed the technical barrier that need solve for a long time.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 to be used 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 processes afterwards.Though these ways have restitution to velocity ambiguity to a certain extent, under convection weather, fuzzy region is many and in disorder, and whether fuzzy, produce effects not quite so pure software moves back fuzzy way if being difficult to differentiate a certain database automatically.The way of some man-machine interactively software processes has been proposed for this reason.This solution is more effective, but is not suitable for service application.The way that comprehensive various software back speed degree is fuzzy, 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 not enough, under convection weather, surveys still to have lot of fuzzy.

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.With the pulse repetition rate ratio is that 3: 2 DPRF technology is when being used for Doppler radar, if get PRF 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, exceed such velocity range easily.For the C-band Doppler radar, then 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 PRF equally 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 bluring under the weather more stably.Then 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 not having fuzzy the detection.

3. summary of the invention

3.1 the technical matters that solves

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

The scope that tests the speed of DPRF expansion still can not satisfy fuzzy detection of nothing under the strong convective weather in weather radar is surveyed.The scope that tests the speed of the TPRF method of being invented is a times of DPRF method at least, can realize not having fuzzy the detection in most strong convective weathers.

No matter be DPRF method or TPRF method, validity all is the topic that asks with concern, and selecting suitable pulse repetition rate is the key that guarantees technical validity.On the basis that the influence 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, then three pulse repetition raties need satisfy relation of plane down:

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 ₂Constitute a q: DPRF (q-1) surveys, and result of detection is designated as PRF ₂And PRF ₃Constitute 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 PRF respectively _aAnd PRF _bResult of detection, so can be right

With

Carrying out a DPRF again analyzes.If with PRF ₁, PRF ₂And PRF ₃The fuzzyyest corresponding speed is designated as V respectively _N1, V _N2And V _N3, with PRF _aAnd PRF _bthe fuzzyyest speed be designated as V respectively _NaAnd V _Nb, the TPRF technology will test the speed range expansion to V 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 constitute two DPRF to be surveyed, and two DPRF result of detections is carried out DPRF once more 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, and expands the scope principle that tests the speed so next DPRF is described.

DPRF expands the scope principle that tests the speed

The specific practice of DPRF technology is: two pulse recurrence frequencies with satisfying the certain proportion relation are successively surveyed, and calculate actual speed based on two measurement results.Two pulse repetition raties are designated as PRF respectively ₁And PRF ₂, their the fuzzyyest corresponding speed is designated as V respectively _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 the 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 axle, with the corresponding measurement result of Y axle, along with the increase of actual speed, the measurement result curve is to be the saw-toothed curve on boundary with the scope of testing the speed so.According to PRF ₁And PRF ₂Measurement result poor can be with ± qV _N2Velocity range be divided into 2q speed interval.

DPRF analytical approach is to ask poor to judge according to Δ V which speed interval is measurement result and

fall with two result of detections

and

, then according to speed interval and result of detection

or

& CAT[NGeneral reckoning doppler velocity formula below the present invention has provided:

$V_D=\left\{\begin{array}{c}(i-1)V_{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="DEST\_PATH\_HSB00000415641400011.png"\; state="\{\{state\}\}">N</figure-callout>}2}+{\tilde{V}}_{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DEST\_PATH\_HSB00000415641400011.png"\; state="\{\{state\}\}">D</figure-callout>}2},...i>0,i=\mathrm{1,2},...,q\\ (i+1)V_{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="DEST\_PATH\_HSB00000415641400011.png"\; state="\{\{state\}\}">N</figure-callout>}2}+{\tilde{V}}_{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DEST\_PATH\_HSB00000415641400011.png"\; state="\{\{state\}\}">D</figure-callout>}2},...,i<0,i=-1,-2,...,-q\end{array}\right.---\left(3\right)$

Wherein, Int () representes rounding operation, and i representes the speed interval sequence number.V _N2Be in 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; Though two measurement results

and

possibly blur; But poor

through them judges which speed interval they fall; Still can recover actual doppler velocity, the test the speed principle of scope of DPRF technological expansion that Here it is.The DPRF technology will not blured the range expansion that tests the speed and arrived ± qV _N2, such scope of testing the speed is equivalent to single pulse repetition rate PRF=qPRF ₂=(q-1) PRF ₁Effect on Detecting.

Based on the relation of two pulse recurrence frequencies in the DPRF technology and the relation between pulse recurrence frequency and the fuzzyyest speed, can derive following formula:

$V_N=\frac{\mathrm{\&lambda;}}{4}\frac{{\mathrm{<figure-callout\; id="1"\; label="PRF"\; filenames="DEST\_PATH\_HSB00000415641400011.png"\; state="\{\{state\}\}">PRF</figure-callout>}}_1\&times;{\mathrm{<figure-callout\; id="2"\; label="PRF"\; filenames="DEST\_PATH\_HSB00000415641400011.png"\; state="\{\{state\}\}">PRF</figure-callout>}}_2}{{\mathrm{PRF}}_1-{\mathrm{PRF}}_2}---\left(4\right)$

Can obtain important inference: DPRF thus 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 bigger, the DPRF expansion of two pulse repetition raties is big more; The difference of two pulse repetition raties is more little, the scope that tests the speed of DPRF expansion is big more.Therefore, adopting high pulse repetition rate and little pulse repetition rate difference 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 thus inference is: at PRF ₁After confirming, more little, the PRF of q ₁-PRF ₂Big more.Because minimum q value is q=3, so work as PRF ₁: PRF ₂=3: 2 o'clock, two pulse repetition rate differences were maximum.

In order further to explain the DPRF technology.Below with PRF ₁: PRF ₂=3: 2 DPRF is that example explanation DPRF expands test the speed scope principle and speed interval division.Like Fig. 1, dotted line is represented PRF ₁The measurement result curve, solid line is represented 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.Can find out at ± 3V by table 1 _N2Scope in, Δ V and speed interval are one to one.Therefore; Even if

and blurs; Through 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 not having fuzzy the detection for most strong convective weathers.Because be not have fuzzy the detection, so fundamentally avoided software in the past to move back the uncertainty of blur method.

Because the influence of detection range and meteorological target velocity spectrum width makes the scope that tests the speed of DPRF expansion not enough.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, and can satisfy the fuzzy detection of the nothing requirement of most strong storms.

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 3: 2 pulse repetition rate ratio, 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 3: 2 pulse repetition rate ratio, 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.

It is thus clear that under the identical condition of not fuzzy detection range, the scope that tests the speed of TPRF doubles than the DPRF scope that tests the speed at least.

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

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 is represented tested speed, Y direction indication measured value.Broken line a1a2-a2a3-... Be pulse repetition rate PRF ₁The measurement curve, V _N1Be PRF ₁The fuzzyyest corresponding speed along with the increase of speed, is measured curve at ± V _N1Between indentation.Broken line b1b2-b2b3-... Be pulse repetition rate PRF ₂The measurement curve, V _N2Be PRF 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

Then

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.Though

or

possibly blur; But, utilize formula (3) just can to blur by the back speed degree as long as judging them according to Δ V drops on that speed interval.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

Among the 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 constitutes 3: 2 surveys, and will not blur velocity range with the DPRF principle and expand to (± 3V between the A2A3-A4A5 _N2), be equivalent to PRF _aDetection.PRF ₂: PRF ₃The DPRF that constitutes 3: 2 surveys, and not fuzzy velocity range expands to (± 3V between the B2B3-B4B5 _N3), be equivalent to PRF _bDetection.PRF _a: PRF _bConstitute DPRF and survey, the scope of bluring does not further expand to (± 9V between the EF _N3).V _N1, V _N2, V _N3, V _NaAnd V _NbBe respectively pulse repetition rate PRF ₁, PRF ₂, PRF ₃, PRF _aAnd PRF _bThe 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 enforcement key 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 influence of speed spectrum width from detection range.Detection range is required to be designated as R, the speed spectrum width is designated as σ at present _v, horizontal wind is designated as V _h, these three parameters are to confirm the main foundation of pulse repetition rate.

Detection range requires to have limited operable high pulse repetition frequency.The weather radar of different-waveband has different requirement 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 influence the main factor that pulse repetition rate is selected, relate to the selection of range of pulse repetition frequency, pulse repetition rate difference and pulse repetition rate ratio.Generally, the stronger σ of storm _vAnd V _hBig more.U.S. meteorologist has carried out NULL 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.

Confirm operable high pulse repetition frequency among the TPRF

According to the size that detection range requires and requires not have the fuzzy horizontal wind of surveying, confirm the pulse repetition rate upper limit.

PRF _max1＝c/(2R)

PRF _max2＝4V _h/λ

Wherein, c is a velocity of electromagnetic wave, and R is the detection range of requirement, V _hBe the size that requirement does not have the fuzzy horizontal wind of surveying, λ is a radar wavelength.Operable high pulse repetition frequency is for lower one among both.

Confirm pulse repetition rate difference and operable minimum pulse repetition rate among the TPRF

Speed spectrum width parameter according to setting is confirmed pulse repetition rate poor (and minimum pulse repetition rate).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 a radar wavelength.Effective in order to guarantee to 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 be more than or equal to 120Hz; (getting λ=5cm) need be more than or equal to 240Hz, (gets λ=3cm) need be more than or equal to 400Hz for the X-band weather radar for the C-band weather radar.

Pulse repetition rate ratio among the TPRF

Based on the analysis of front, when the pulse recurrence frequency ratio was 3: 2, the pulse recurrence frequency difference was maximum.So, the validity of TPRF in order to guarantee strong storm surveyed, generally getting the pulse repetition rate ratio is 3: 2.That is, the pulse repetition rate ratio among the 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 found out easily 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, be that example provides set of pulses repetition frequency data with the C-band Doppler radar here.Get radar wavelength λ=5cm, the speed spectrum width is got σ _v=6m/s, three pulse repetition rate PRF ₁, PRF ₂And PRF ₃Be respectively 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 V respectively _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, confirm

With The place speed interval is used PRF according to following universal calculation equation calculating 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 () representes rounding operation, and i representes the speed interval sequence number.

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

With

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

Carry out DPRF according to

once more and analyze, the gained result is actual doppler velocity.

Claims (3)

1. the fuzzy TPRF method of Doppler radar back speed degree; It is characterized in that; Three pulse repetition raties with meeting certain requirements are surveyed successively, and three pulse repetition raties constitute two dipulse repetition frequencys and survey (DPRF), and two DPRF analyze the scope of testing the speed is carried out the expansion first time; Two DPRF analysis results constitute a DPRF again and survey; Two DPRF analysis results are carried out DPRF once more analyze, the scope of testing the speed is carried out the expansion second time, three pulse repetition raties are designated as PRF from high to low respectively ₁, PRF ₂, PRF ₃, their measurement result is designated as V respectively 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, pass through V with the DPRF analytical approach once more _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 PRF from high to low respectively 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 3,4,5 ... Positive integer.

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

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