CN104808223B - It is a kind of suitable for spaceborne GNSS R receivers with the correlator that can suppress mirror point high dynamic - Google Patents
It is a kind of suitable for spaceborne GNSS R receivers with the correlator that can suppress mirror point high dynamic Download PDFInfo
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- CN104808223B CN104808223B CN201510218180.5A CN201510218180A CN104808223B CN 104808223 B CN104808223 B CN 104808223B CN 201510218180 A CN201510218180 A CN 201510218180A CN 104808223 B CN104808223 B CN 104808223B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/35—Constructional details or hardware or software details of the signal processing chain
- G01S19/37—Hardware or software details of the signal processing chain
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Abstract
The invention discloses it is a kind of suitable for spaceborne GNSS R receivers with the correlator that can suppress mirror point high dynamic, the correlator includes direct signal tracking module (1), time delay module (2), suppresses mirror point high dynamic control module (3), suppress mirror point high dynamic processing module (4), suppress mirror point high dynamic Fusion Module (5), carrier compensation module (6) and interference treatment module (7)；Certain time delay processing is carried out to the direct signal after carrier track first, specular reflection point high dynamic suppression treatment is then carried out again, the reflected signal after last and carrier compensation carries out interference treatment, obtains two-dimentional delay-Doppler related power.The correlator first aspect of present invention design is used to produce local replica carrier wave；Second aspect need not produce local copy codes；The third aspect is will to carry out interference treatment by direct signal after delay-Doppler compensation deals and reflected signal, so as to obtain Doppler frequency shift of the specular reflection point under different sampling stages, so as to inhibit the speckle noise in areas of specular reflection, the signal to noise ratio of signal is improve.
Description
Technical field
Refer to that one kind is applied to spaceborne GNSS-R receivers more particularly the present invention relates to a kind of GNSS-R receivers
With the correlator that can suppress mirror point high dynamic.Processed by the specular reflection point to high-speed mobile so that spaceborne
GNSS-R receivers improve sea altimetry precision in sea inverting is carried out.
Background technology
GPS (Global Navigation Satellite System, GNSS) is exactly with man-made land
Ball satellite as guidance station satellite-based radio navigation system, for all kinds of the army and the people's carriers in global land, sea, air, day provide whole day
Marquis, high-precision Position, Velocity and Time information, thus it is also called space-based positioning, navigation and time service (PNT) system.The whole world
Satellite navigation system (GNSS) is to global positioning system (GPS), glonass system (GLONASS) and Galileo
(Galileo) the unified appellation of these single satellite navigation and location systems such as system.With reference to the 1st printing of September in 2013, author
Xie Gang,《GLONASS principle --- GPS, GLONASS and Galileo system》Chapter 1, introduction, page 1.
Although GPS, GLONASS and Galileo three digest journals constitute to have to its system each slightly different determining
Justice, but can be substantially made up of three parts with a GNSS, i.e. space constellation part, ground monitoring part and user equipment portion
Point.Printed for the 1st time with reference to September in 2013, author Xie Gang,《GLONASS principle --- GPS, GLONASS and gal
Profit slightly system》Chapter 1, introduction, page 4.Fig. 1 is designated as herein, and the main body for scheming hollow constellation part is distributed across sky
Between a number of satellite that runs in track, they generally in earth middle orbit (MEO), the static earth (GEO) or are inclined
The form of geostationary orbit (IGSO) satellite occurs.As navigation positioning satellite.(or same defended to distinguish different satellites
Star) unlike signal launched, GNSS needed using a kind of multiple access technology mechanism.Multiple access technology is generally divided into CDMA
(CDMA), three kinds of frequency division multiple access (FDMA) and time division multiple acess (TDMA), wherein, CDMA can be broadcast in same carrier frequency
Unlike signal through different pseudo noise (PPN) code band spectrum modulations, FDMA is to broadcast in different carrier waves unlike signal
In frequency, and TDMA is will can to broadcast unlike signal composition in same carrier frequency to share a letter by timesharing
Road.
Printed for the 1st time with reference to September in 2013, author Xie Gang,《GLONASS principle --- GPS, GLONASS
And Galileo system》Chapter 1, introduction, the 8-12 pages.In the design of GNSS receiver, Fig. 2 is designated as herein.In figure
Correlator is that local replica pseudo-code carries out related calculation with signal is received, and satellite-signal is de-spread and is improved reception signal immediately
Signal to noise ratio.
In the application field of numerous GNSS-R receivers, what is also had is mounted with GNSS-R receivers on low orbit satellite.
Tested by airborne, land and obtain the big discharge observation data such as Ocean Wind-field, soil moisture, sea ice, have studied corresponding inverting
Model.GNSS-R is Global Navigation Satellite System-Reflection, and translation is based on reflected signal
GPS.
Traditional spaceborne GNSS-R receivers receive, treatment ocean surface reflected signal carry out surveying high when, compared to sea
(region of the fixed gain isopleth definition less than the maxgain value 3dB of antenna boresight direction claims the 3dB areas of coverage on foreign surface
It is the 3dB areas of coverage) and ocean surface reflected signal rOceanIt is not fully utilized, the minute surface especially in the case of spaceborne is anti-
The high dynamic movement of exit point.The speckle noise existed in area of glittering belonging to specular reflection point is to traditional spaceborne GNSS-R receivers
Process signal will produce influence, and this can produce larger time delay error, and speckle noise reduces the signal to noise ratio of signal, so as to drop
Low ocean altimetry precision.
The content of the invention
In order that spaceborne GNSS-R receivers in sea refutation process is carried out to the raising of sea altimetry precision, the present invention
Devise it is a kind of suitable for spaceborne GNSS-R receivers with the correlator that can suppress mirror point high dynamic.The correlator is on the one hand
Make full use of the ocean surface reflected signal r in antenna 3dB overlay areasOcean, on the other hand using specular reflection point Doppler frequently
Rate (fa, fb) carries out frequency compensation to direct signal d, and the third aspect is by the direct signal after delay-Doppler is compensatedWith noise ZdReflected signal after (t) and carrier compensationWith speckle signal ZrT () is carried out at interference
Reason, so as to be conducive to improving altimetry precision.
The present invention design it is a kind of suitable for spaceborne GNSS-R receivers with the correlator that can suppress mirror point high dynamic,
It is characterized in that：The correlator includes direct signal tracking module (1), time delay module (2), suppresses mirror point high dynamic control mould
Block (3), suppress mirror point high dynamic processing module (4), suppress mirror point high dynamic Fusion Module (5), carrier compensation module (6) and do
Relate to processing module (7)；
Direct signal tracking module (1) is for digital direct projection intermediate-freuqncy signalEnter
Line trace；
Time delay module (2) is according to delay volume τ to digital direct projection intermediate-freuqncy signal
Time delay is carried out, direct signal is delayed when obtaining
Suppress to delay direct signal when mirror point high dynamic processing module (3) is received firstScattering point-Doppler
Difference on the frequencyIt is poor with pip-Doppler frequencyThen, it is poor using scattering point-Doppler frequencyAnd reflection
Point-Doppler frequency is poorCarry out direct signal after delay compensationDirect signal after must compensating
Suppress mirror point high dynamic control module (4) first aspect and receive navigation data Na (t)；Second aspect, according to navigation
Data Na (t) obtain the number and a specular reflection point sp of the scattering point sa in scattering region；The third aspect, using based on line
The specular reflection point algorithm for estimating of section dichotomy obtains the position of specular reflection point sp, and the position of specular reflection point sp is designated as (xsp,
ysp)；Fourth aspect, calculates scattering point-Doppler frequency poor；5th aspect, calculates pip-Doppler frequency poor；
Suppress mirror point high dynamic Fusion Module (5) to be covered in a N number of shift position for specular reflection point, and antenna 3dB
M scattering point in cover area is averagely added up, and the direct signal for being exported is
Carrier compensation module (6) reflects intermediate-freuqncy signal R to the numeral for receivingrT () carries out carrier compensation；
Interference treatment module (7) is by what is receivedWithInterference treatment is carried out, delay-Doppler two is obtained
Dimension related power
The present invention design the correlator for having the advantages that mirror point high dynamic can be suppressed be：
1. correlator of the invention estimates the how general of specular reflection point by the calculating to specular reflection point position, speed
Strangle frequency n Δs fs(the n times movement of specular reflection point within N number of sampling period, and the minute surface obtained after n times movement is anti-
The Doppler frequency shift n Δs f of exit points), whereinIt is right using above-mentioned frequency displacement as after the Doppler effect correction of reflected signal
N number of different specular reflection point reflector space carries out average adding up and makes full use of sea echo resource；For individual reflection
For region, reception device, according to receiver speed, position and satellite velocities, positional information, is estimated using known navigation information
Count out the M Doppler frequency mf relative to specular reflection point in the reflector spaces, wherein, Doppler frequency is ahead of minute surface
The number of the scattering point of pip sp is designated as mIn advance, the number that Doppler frequency lags behind the scattering point of specular reflection point sp is designated as
mIt is delayed, and mIn advance+mIt is delayed=M, m represent the summing target of scattering point, can be reduced after averagely being added up along track Doppler effect correction
Speckle noise power, improves signal to noise ratio.
2. in " suppressing mirror point high dynamic Fusion Module " of present invention design, enter in the two-dimentional delay-Doppler to gained
After row integral mean, the speckle noise in different reflector spaces can be effectively reduced.
3. specular reflection point high dynamic suppression module is increased on the basis of conventional receiver device, reception device is optimized
The performance of resource and raising reception device, allows reception device to make full use of the aeronautical satellite in antenna 3dB overlay areas
Reflected signal, compensate for producing Doppler frequency shift due to mirror point high dynamic, it is suppressed that the speckle noise in areas of specular reflection, carry
The signal to noise ratio of signal high.
Brief description of the drawings
Fig. 1 is three schematic diagrames of part of passive type GNSS.
Fig. 2 is the baseband digital signal treatment block diagram of GNSS receiver.
Fig. 3 is the structured flowchart with the correlator that can suppress mirror point high dynamic of the invention.
Fig. 4 is the sea altimetry precision simulated effect figure under the irrelevant cumulative points of different sampled points.
Specific embodiment
Below in conjunction with drawings and Examples, the present invention is described in further detail.
When spaceborne GNSS-R receivers are operated on the low orbit satellite of high-speed flight, the environment of work, state and
GNSS receiver of many conditions such as position all with ground general work is entirely different, and these factors determine and spaceborne GNSS-R is connect
The technical requirements of receipts machine are somewhat different with the conventional GNSS receiver for using on the ground.
Shown in Figure 3, the present invention devises a kind of high with that can suppress mirror point suitable for spaceborne GNSS-R receivers
Dynamic correlator, the correlator includes direct signal tracking module 1, time delay module 2, suppresses mirror point high dynamic control module
3rd, suppress mirror point high dynamic processing module 4, suppress mirror point high dynamic Fusion Module 5, carrier compensation module 6 and interference treatment module
7.The correlator first aspect of present invention design is used to produce local replica carrier waveSecond aspect need not be produced
Raw local copy codes；The third aspect is will to be interfered by direct signal d after delay-Doppler compensation deals and reflected signal r
Treatment, so that Doppler frequency shift of the specular reflection point under different sampling stages is obtained, so as to inhibit mirror-reflection area
Speckle noise in domain, improves the signal to noise ratio of signal.
Direct signal tracking module 1
Direct signal tracking module 1 is used for digital direct projection intermediate-freuqncy signal RdT () is tracked, wherein Represent that digital direct penetrates the amplitude leyel of intermediate-freuqncy signal, Sd(t) table
The carrier wave of registration word direct projection intermediate-freuqncy signal, DdT () represents that digital direct penetrates the range finding spreading code of intermediate-freuqncy signal.In the present invention, lead to
Crossing the tracking in sampling time t makes local replica carrier waveWith the RdThe carrier wave S of (t)dT () has identical
Doppler frequency and phase.
It is describedJ represents the imaginary part of plural number, and t represents present sample time point, and π represents pi, value
3.14, fdThe frequency reproduction of locally generated direct signal is represented,Represent that the duplication of locally generated direct signal is initial
Phase.
In the present invention, direct signal tracking module 1 be used for the navigation direct signal that is received to antenna carry out carrier wave with
Track, and extract local replica carrier wave, then carries out coherent integration using coherent accumulation to local replica carrier wave, using integration-
Remover eliminates radio-frequency component and noise in coherent signal by integrating low-pass filter, to improve signal to noise ratio, makes to be concerned with
Local replica carrier wave after integration has identical Doppler frequency with the navigation direct signal for receiving.But carrier tracking loop
Road carries out the tracking of carrier wave using the third order pll under second order FLL auxiliary to coherent integration results, and the phase that will be obtained is inclined
Used as phase compensation, the final local carrier for causing to replicate has and the direct signal identical frequency for receiving and identical shifting amount
Phase.
Time delay module 2
In the present invention, time delay module 2 is according to delay volume τ to digital direct projection intermediate-freuqncy signal RdT () carries out time delay, obtain time delay
Direct signal afterwards
It is described
In the present invention, using delay volume τ (t) to digital direct projection intermediate-freuqncy signal RdT () carries out time delay processing, be for
The related power associated with reflected signal is obtained in follow-up interference treatment module.
Suppress mirror point high dynamic control module 4
It is shown in Figure 3, suppress the first aspect of mirror point high dynamic control module 4 and receive navigation data Na (t)；
In the present invention, navigation data Na (t) is that the satellite ephemeris that calculate of spaceborne GNSS-R receivers, clock are repaiied
Just, amendment, the almanac of interior other satellites of GPS constellation and working condition etc. during ionosphere.Spaceborne GNSS-R receivers are by docking
The satellite-signal for receiving carries out carrier modulation and pseudo-code despreading, and form according to navigation message can finally compile it into navigation
Text, the navigation message is mainly used to determine customer location, speed and the data basis of time.
Suppress the second aspect of mirror point high dynamic control module 4, dissipating in scattering region is obtained according to navigation data Na (t)
The number of exit point sa and a specular reflection point sp；
If scattering point is designated as sa, the number of scattering point is designated as M, then all scattering points in scattering region are designated as SA=
{sa1,sa2,…,saM}。sa1It is first scattering point, sa2It is second scattering point, saMIt is last scattering point, for side
Just sa is illustratedMAlso referred to as any one scattering point.Any one scattering point saMPosition coordinates in scattering region is designated as
In the present invention, a satellite only corresponds to a specular reflection point.
Suppress the third aspect of mirror point high dynamic control module 4, using the mirror-reflection point estimation based on line segment dichotomy
Algorithm obtains the position of specular reflection point sp, and the position of specular reflection point sp is designated as (xsp,ysp)；
The Euclidean distance between all scattering points in specular reflection point sp and scattering region is calculated, is then had：
Specular reflection point sp and scattering point sa1Between Euclidean distance be designated asAnd
Specular reflection point sp and scattering point sa2Between Euclidean distance be designated asAnd
Specular reflection point sp and scattering point saMBetween Euclidean distance be designated asAnd
In the present invention, specular reflection point is to the Euclidean distance of scattering point
Suppress the fourth aspect of mirror point high dynamic control module 4, calculate scattering point-Doppler frequency poor；
In the present invention, the Euclidean distance to specular reflection point to scattering point carries out derivation, obtains scattering point-Doppler frequently
Rate is poorλ represents carrier wavelength,Represent to the differential of two point distances, dt is micro- to the sampling time
Point, t represents present sample time point.
To specular reflection point sp and scattering point sa1Between Euclidean distanceDerivation, obtains scattering point-Doppler frequency
DifferenceRepresent specular reflection point sp and scattering point sa1Between Euclidean distanceDifferential；
To specular reflection point sp and scattering point sa2Between Euclidean distanceDerivation, obtains scattering point-Doppler frequency
DifferenceRepresent specular reflection point sp and scattering point sa2Between Euclidean distanceDifferential；
To specular reflection point sp and scattering point saMBetween Euclidean distanceDerivation, obtains scattering point-Doppler frequency
DifferenceRepresent specular reflection point sp and scattering point saMBetween Euclidean distanceDifferential.
In the present invention, scattering point-Doppler frequency is poorIt refer to the scattering point in scattering region
Reflected signal and specular reflection point reflected signal Doppler frequency between difference.
Suppress the 5th aspect of mirror point high dynamic control module 4, calculate pip-Doppler frequency poor；
The ephemeris in navigation data Na (t) is calculated using the computational methods of satellite velocity, obtains minute surface anti-
The speed of service v of exit point spsp；
In the present invention, the computational methods of satellite velocity refer to the 3rd printing of December in 2012《GPS principles
Designed with receiver》The contents of page the 63rd, 64,65, author Xie Gang.
In the present invention, specular reflection point sp will be moved in a sampling period T, move to the minute surface of next position
Pip is designated as spIt is mobile(referred to as mirror point movement spIt is mobile), mirror point movement spIt is mobilePosition be designated asAnd mobile
Distance is designated as(referred to as mirror point displacement), it is describedIn the present invention, a sampling week
Include multiple sampling time point t in phase T.
In the present invention, in N number of sampling period T, specular reflection point sp will have n times to move to spaceborne GNSS-R receivers,
The then movement of all specular reflection points is designated asIt is specular reflection point sp through first
Position (referred to as first mirror point movement after the individual sampling period),It is that specular reflection point sp samples through second
Position (referred to as second mirror point movement after cycle),It is specular reflection point sp through last sampling period
Position (referred to as last mirror point movement afterwards), for convenience of explanation,Referred to as any one mirror point movement.
The present invention is moved under the conditions of spaceborne in order to suppress the specular reflection point in the antenna 3dB areas of coverage, for the different sampling periods
All with specular reflection point sp as reference point.
The Euclidean distance between mobile front and rear specular reflection point is calculated, is then had：
Specular reflection point sp and first mirror point movementBetween Euclidean distance be designated asAnd
First mirror point movementMoved with second mirror pointBetween Euclidean distance be designated asAnd
Second mirror point movementMoved with last mirror pointBetween Euclidean distance be designated asAnd
To mirror point displacementDerivation is carried out, pip-Doppler frequency is obtained poor
λ represents carrier wavelength,The differential to mirror point displacement is represented, dt is the differential to the sampling time, and T represents sampling week
Phase.
It is rightDerivation is carried out, pip-Doppler frequency is obtained poorRepresent
To the differential of mirror point displacement.
It is rightDerivation is carried out, pip-Doppler frequency is obtained poorRepresent
To the differential of mirror point displacement.
It is rightDerivation is carried out, pip-Doppler frequency is obtained poorRepresent
To the differential of mirror point displacement.
In the present invention, pip-Doppler frequency is poorRefer to anti-movement former and later two minute surfaces in scattering region
Difference between the Doppler frequency of the reflected signal of exit point.
Suppress mirror point high dynamic processing module 3
Suppress to delay direct signal when mirror point high dynamic processing module 3 is received firstScattering point-Doppler is frequently
Rate is poorIt is poor with pip-Doppler frequencyThen, it is poor using scattering point-Doppler frequencyWith pip-
Doppler frequency is poorCarry out direct signal after delay compensationDirect signal after must compensating
In the present invention,
Suppress mirror point high dynamic Fusion Module 5
Reflected signal processing procedure is the process of coherently despreading, and the cycle in the present invention with navigational range code is as correlation intergal
Time span Tc(referred to as coherent accumulation time Tc), it is contemplated that movements of the specular reflection point sp under Different sampling period away from
From in order to suppress the influence of specular reflection point high dynamic during correlation intergal, the Tc=T.
In the present invention, the frequency bandwidth of spaceborne GNSS-R receivers is designated as Bw, according to frequency bandwidth Bw and sampling period
Relation, obtain the number in sampling period, i.e. N=Bw × T.Then there is suppression mirror point high dynamic Fusion Module 5 anti-in a minute surface
N number of shift position (movement of mirror point) of exit point, and M scattering point in antenna 3dB overlay areas is averagely added up, and is obtained
The direct signal of output is
In the present invention, Doppler frequency is ahead of the number of the scattering point of specular reflection point sp and is designated as mIn advance, Doppler is frequently
The number that rate lags behind the scattering point of specular reflection point sp is designated as mIt is delayed, and mIn advance+mIt is delayed=M.M represents the summing target of scattering point,
N represents the summing target in sampling period.
The presence of consideration thermal noise is needed when being processed for direct signal, it is assumed that the additive noise of input signal is Z (n),
It is that average is 0, variance is σ2White Gaussian noise, then by mirror point high dynamic suppression module treatment after, the noise of output isU represents the discrete element of scattering point, W represent the sampling period it is discrete because
Son.
According to white noise feature, each sampled point is separate, the noise after the treatment of mirror point high dynamic suppression module
Variance is
In the present invention, the coherent accumulation time T in mirror point high dynamic Fusion Module 5 is suppressedcWill be high as mirror point is suppressed
The time span foundation in the sampling period of Dynamic control module 4.
Carrier compensation module 6
The numeral reflection intermediate-freuqncy signal R that carrier compensation module 6 pairs is receivedrT () carries out carrier compensation.In the present invention, make
Reflected signal after compensationWith direct signal after trackingWith identical Doppler frequency.
In the present invention, the carrier compensation module of reflected signal is used to enter depending on the navigation reflected signal that antenna is received to lower
Row carrier compensation, the method for carrier compensation is mainly produced using traditional coherent accumulation, carrier tracking loop and carrier wave NCO modules
The carrier compensation component of signal of reflected signal.Carrier wave NCO produces local replica carrier wave by traditional LUT Method, and is concerned with
It is cumulative that the local replica carrier wave that carrier wave NCO is produced is carried out into traditional coherent integration, using integration-remover by integrating low pass
Wave filter eliminates the radio-frequency component in coherent signal and noise, to improve signal to noise ratio, navigation after carrier compensation is reflected letter
Number with direct signal there is identical Doppler frequency.Carrier tracking loop is using three ranks under traditional second order FLL auxiliary
Phaselocked loop carries out the tracking of carrier wave to coherent integration results, and the phase pushing figure that will be obtained feeds back to carrier wave NCO and mended as phase
Repay, the final local carrier for causing to replicate has and receives reflected signal identical frequency and identical phase.
Interference treatment module 7
Referring to accompanying drawing 3, interference treatment module 7 will be receivedWithInterference treatment is carried out, when obtaining
Prolong Doppler's two-dimensional correlation power
It is described
τ is the time delay relative to specular reflection point；
F is relative to the Doppler frequency shift of reflected signal frequency at specular reflection point；
TcIt is the coherent accumulation time；
Link thermal noise is regarded for upper in GNSS-R receiver direct projection passages；
ZrT () regards link thermal noise for lower in GNSS-R receiver reflectance passages.
In the present invention, by delay-Doppler two-dimensional correlation powerLaunched, be respectively：
The coherent component W of direct signal and reflected signald_r, and
The coherent component W of direct projection passage thermal noise and reflection channel speckle noisedz_rz, and
The coherent component W of direct signal and reflection channel speckle noised_rz, andWith
Direct projection passage thermal noise and reflected signal coherent component Wdz_r, and
In spaceborne GNSS-R receivers, it is contemplated that direct signal white Gaussian noise and reflected signal speckle noise are mutually only
It is vertical, it is uncorrelated, assembly average is obtained to above-mentioned four components, i.e.,<|Wd_r|2>、<|Wdz_rz|2>、<|Wd_rz|2>With<|Wdz_r|2
>, four assembly averages are also the output result of interference treatment correlator of the present invention.
In the present invention<|Wdz_rz|2>、<|Wd_rz|2>With<|Wdz_r|2>It is containing noise component(s), according to signal to noise ratio formula
Can be in the hope of the output signal-to-noise ratio of interference treatment module 7It is for average
0, variance is σ2White Gaussian noise for, its watt level be equal to variance, so by specular reflection point high dynamic suppression after
Its direct signal output noise power can reduce.After signal to noise ratio is improved, altimetry precision can be also correspondingly improved.
Embodiment 1
In order to where advantage of the correlator compared to conventional correlator for better illustrating present invention design, first by simulated environment
It is described as follows：
| Parameter | Numerical value | Unit |
| Orbit altitude | 756 | Km |
| The minute surface launch point elevation angle | 28 | Deg |
| Wind speed | 6.5 | m/s |
| Significant wave height | 1.5 | m |
| It is upper regarding antenna and lower regarding antenna gain | 25 | dBi |
| Receiver bandwidth | 50 | MHz |
| It is upper to regard antenna noise temperature | 40 | K |
| Antenna noise temperature is regarded down | 120 | K |
| Receiver noise temperature | 280 | K |
| Receiver noise value | 3 | dB |
| Satellite signal transit power | 26 | dBW |
| In-orbit spatial resolution | 100 | Km |
Elevation of satellite wherein at specular reflection point is between 29~32 degree.Sea echo reception antenna is using high
Gain (12dB), narrow beam (38 degree) left-hand circular polarization antenna.It is right under conditions of the related cumulative points using different samplings
Sea altimetry precision is emulated, and obtains simulation result as shown in figure 4, in figure, the correlator of present invention design improves sea
Altimetry precision.
The present invention design it is a kind of suitable for spaceborne GNSS-R receivers with the correlator that can suppress mirror point high dynamic,
To be solved is traditional spaceborne GNSS-R receivers when receiving, treatment ocean surface reflected signal carrying out surveying high, in star
The technical problem of the high dynamic movement of the specular reflection point in the case of load, correlator of the present invention depending on direct signal on by first entering
Row carrier compensation and time delay, and the direct signal after compensation is carried out to suppress the treatment of specular reflection point high dynamic, obtain the suppression of mirror point
Direct signal after system treatment, then carries out relevant treatment, to obtained by treatment to the direct signal after treatment and reflected signal
Two-dimentional delay-Doppler is integrated average technological means, so as to inhibit the speckle noise in areas of specular reflection to two dimension
The influence of related power, improves the technique effect of the signal to noise ratio of signal.
In the present invention, the alphabetical physical significance of reference is：
Claims (4)
1. it is a kind of suitable for spaceborne GNSS-R receivers with the correlator that can suppress mirror point high dynamic, it is characterised in that：Should
Correlator includes direct signal tracking module (1), time delay module (2), suppresses mirror point high dynamic control module (4), suppresses mirror
Point high dynamic processing module (3), suppression mirror point high dynamic Fusion Module (5), carrier compensation module (6) and interference treatment module
(7)；
Direct signal tracking module (1) is for digital direct projection intermediate-freuqncy signalEnter
Line trace；Represent that digital direct penetrates the amplitude leyel of intermediate-freuqncy signal, SdT () represents that digital direct penetrates the carrier wave of intermediate-freuqncy signal,
DdT () represents that digital direct penetrates the range finding spreading code of intermediate-freuqncy signal；
Time delay module (2) is according to delay volume τ to digital direct projection intermediate-freuqncy signalEnter
Row time delay, delays direct signal when obtainingIt is describedJ represents the imaginary part of plural number, and t represents present sample time point, and π represents pi, value 3.14, fdRepresent this
The frequency reproduction of the direct signal that ground is produced,Represent the duplication initial phase of locally generated direct signal；
Suppress to delay direct signal when mirror point high dynamic processing module (3) is received firstScattering point-Doppler frequency is poorIt is poor with pip-Doppler frequencyThen, it is poor using scattering point-Doppler frequencyWith pip-Doppler frequently
Rate is poorCarry out direct signal after delay compensationDirect signal after must compensating
Suppress mirror point high dynamic control module (4) first aspect and receive navigation data Na (t)；Second aspect, according to navigation data
Na (t) obtains the number and a specular reflection point sp of the scattering point sa in scattering region；The third aspect, using based on line segment two
The specular reflection point algorithm for estimating of point-score obtains the position of specular reflection point sp, and the position of specular reflection point sp is designated as (xsp,
ysp)；Fourth aspect, calculates scattering point-Doppler frequency poor；5th aspect, calculates pip-Doppler frequency poor；
Suppress mirror point high dynamic Fusion Module (5) in a N number of shift position of specular reflection point sp, and antenna 3dB overlay areas
M interior scattering point is averagely added up, and the direct signal for being exported isIt is many
The general number for strangling the scattering point that frequency is ahead of specular reflection point sp is designated as mIn advance, Doppler frequency lags behind specular reflection point sp
The number of scattering point be designated as mIt is delayed, and mIn advance+mIt is delayed=M；M represents the summing target of scattering point, and n represents the summation in sampling period
Index；TcRepresent the coherent accumulation time；
Carrier compensation module (6) reflects intermediate-freuqncy signal R to the numeral for receivingrT () carries out carrier compensation；
Interference treatment module (7) is by what is receivedWithInterference treatment is carried out, delay-Doppler two-dimensional phase is obtained
Close power For GNSS-R connects
It is upper in receipts machine direct projection passage to regard link thermal noise, ZrT () regards link thermal noise, Z for lower in GNSS-R receiver reflectance passagesr(t+
It is τ) to regard link thermal noise in the presence of lower in a GNSS-R receiver reflectance passage relative to specular reflection point time delay,It is the reflected signal after compensation,It is in the presence of a compensation relative to specular reflection point time delay
Reflected signal afterwards.
2. it is according to claim 1 it is a kind of suitable for spaceborne GNSS-R receivers with the phase that can suppress mirror point high dynamic
Close device, it is characterised in that：Suppress the coherent accumulation time T in mirror point high dynamic Fusion Module (5)cWill be high dynamic as mirror point is suppressed
The time span foundation in the sampling period of state control module (4).
3. it is according to claim 1 it is a kind of suitable for spaceborne GNSS-R receivers with the phase that can suppress mirror point high dynamic
Close device, it is characterised in that：By delay-Doppler two-dimensional correlation powerLaunched, be respectively：
The coherent component W of direct signal and reflected signald_r, and
The coherent component W of direct projection passage thermal noise and reflection channel speckle noisedz_rz, and
The coherent component W of direct signal and reflection channel speckle noised_rz, andWith
Direct projection passage thermal noise and reflected signal coherent component Wdz_r, and
4. it is according to claim 3 it is a kind of suitable for spaceborne GNSS-R receivers with the phase that can suppress mirror point high dynamic
Close device, it is characterised in that：<|Wdz_rz|2>、<|Wd_rz|2>With<|Wdz_r|2>Be containing noise component(s), can according to signal to noise ratio formula
It is in the hope of interference treatment module (7) output signal-to-noise ratio
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