CN113359204A - Underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay - Google Patents

Underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay Download PDF

Info

Publication number
CN113359204A
CN113359204A CN202110616658.5A CN202110616658A CN113359204A CN 113359204 A CN113359204 A CN 113359204A CN 202110616658 A CN202110616658 A CN 202110616658A CN 113359204 A CN113359204 A CN 113359204A
Authority
CN
China
Prior art keywords
gnss
pseudo
receiver
signal
antenna
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202110616658.5A
Other languages
Chinese (zh)
Inventor
李超超
刘伟铭
钱学武
徐飞
兰骧
于亦龙
赵毛毛
吕志彬
沈翔
季鲁敏
刘建国
佟国栋
葛飞
许永涛
文张建
王怀康
杨皓明
张扬
黄轩
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ningxia University
Original Assignee
Ningxia University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ningxia University filed Critical Ningxia University
Priority to CN202110616658.5A priority Critical patent/CN113359204A/en
Publication of CN113359204A publication Critical patent/CN113359204A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V7/00—Measuring gravitational fields or waves; Gravimetric prospecting or detecting

Landscapes

  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)

Abstract

The invention provides an underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay, wherein the method comprises the following steps: receiving a direct signal by using an RHCP antenna of a GNSS-R receiver, and receiving a reflected signal by using an LHCP antenna; the GNSS-R receiver copies the local PRN code; acquiring pseudo-range multipath errors of the direct signals and the reflected signals; inverting elevation anomaly according to pseudo-range multipath errors of the direct signals and the reflected signals; and inverting the underwater gravity field according to the elevation anomaly. The underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay provide a new reference thought for gravity anomaly measurement, complement the advantages of other measurement means, increase the measurement diversity and robustness and make up for the situation of insufficient local measurement means.

Description

Underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay
Technical Field
The invention relates to the technical field of navigation, in particular to an underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay.
Background
The GNSS-R (GNSS-Reflection) technology is a new branch of GNSS that has been developed since the 90 s of the 20 th century. The GNSS-R technology has the characteristics and advantages of no need of a transmitter, large number of signal sources, wide application range and the like, and is one of the research hotspots in the technical fields of remote sensing detection and navigation at home and abroad along with the development and continuous perfection of a global navigation satellite system. The GNSS receiver receives a GNSS signal reflected by the reflecting surface while receiving a GNSS direct signal, and parameters such as polarization characteristic, frequency, phase, amplitude and the like of the signal reflected by the reflecting surface are changed, so that the reflected signal contains physical characteristic information of the reflecting surface, and if the interaction between the signal and the reflecting surface is not considered, signal delay and Doppler frequency shift can be accurately mapped on the reflecting surface, so that physical parameter information of the reflecting surface can be inverted, and the technology is called as a GNSS reflected signal technology.
The application of the global navigation satellite system reflected signal can be said to be organic combination of navigation and remote sensing, and is a typical innovation of the navigation satellite signal. The main application can be divided into two modes of a scatterometer and an altimeter, wherein the scatterometer is mainly used for remotely sensing sea surface wind fields, sea surface roughness and the like, and the altimeter is mainly used for sea surface height measurement. The method can realize inversion of the physical characteristics of the reflecting surface by accurately predicting and processing the reflected signals, and the GNSS-R is widely applied to the fields of sea surface height measurement, sea surface wind speed and wind direction inversion, sea surface effective wave height measurement, sea ice thickness, soil humidity detection, target imaging and the like.
The global navigation satellite system reflection signal technology (GNSS-R) is a novel, low-cost and high-mobility microwave remote sensing technology, has complementary advantages with other measuring means, can increase the diversity and robustness of measurement, and makes up for the situation of insufficient local measuring means.
Disclosure of Invention
Based on the above, the invention aims to provide an underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay, which provide a new reference idea for gravity anomaly measurement, complement the advantages of other measurement means, increase the measurement diversity and robustness, and make up for the situation of insufficient local measurement means.
In order to achieve the above object, the present invention provides an underwater gravitational field inversion method based on GNSS-R pseudo random noise code delay, the method comprising:
step S1: receiving a direct signal by using an RHCP antenna of a GNSS-R receiver, and receiving a reflected signal by using an LHCP antenna;
step S2: the GNSS-R receiver copies the local PRN code;
step S3: acquiring pseudo-range multipath errors of the direct signals and the reflected signals;
step S4: inverting elevation anomaly according to pseudo-range multipath errors of the direct signals and the reflected signals;
step S5: and inverting the underwater gravity field according to the elevation anomaly.
Optionally, the receiving a direct signal by using an RHCP antenna of the GNSS-R receiver, and receiving a reflected signal by using an LHCP antenna specifically include:
a low gain Right Hand Circularly Polarized (RHCP) antenna is pointed upward for receiving direct signals.
The other high-gain left-handed circularly polarized (LHCP) antenna faces downward for receiving the reflected signal.
After the direct signal is reflected by the reflecting surface, when the reflecting surface and the reflecting angle meet certain conditions, the polarization characteristic of the signal is gradually changed from right rotation to left rotation, and the polarization change degree is related to factors such as surface medium characteristics, radio wave incident angle and the like. The signals are transmitted to a receiver for data processing, and the receiver can estimate the ionospheric delay related to the reference frequency by adopting a multi-frequency receiver, so that the pseudo range can be measured more accurately.
Optionally, the obtaining of the pseudorange multipath error of the direct signal and the reflected signal may be performed by the following specific formula:
pseudo-range multi-path error rhoEExpressed by the product of the time difference Δ t and the speed of light c, i.e.:
ρE＝c·Δt；
at any time trAt time, the local pseudo-random noise replica code a and the receiving antenna in the GNSS reflected signal receiver are at trThe correlation function of the reflected signal output at time + Δ t is:
Figure BDA0003097851200000021
in the formula, TiTo integration time, Es(U,tr+ t' + Δ t) is trThe reflected field of the receiver at U at time + t' + Δ t, j2＝-1，fcTo compensate for the doppler shift of the received signal. Changing the integration order and simplifying, we can:
Figure BDA0003097851200000031
a is signal amplitude, D (-) is navigation data bit information, R is reflection unit, Rt(. R) is the distance from the navigational satellite to the specular reflection pointrDistance from the receiver antenna phase center to the point of specular reflection, g (·) is a function of the receiver, transmitter and surface reflector motion with respect to time, fD(. cndot.) is the total Doppler shift.
Optionally, according to the obtained pseudorange multipath error of the direct signal and the reflected signal, a specific formula is as follows:
pseudo-range multi-path error rho which is propagation path difference of GNSS direct signal and reflection signalECan be expressed as:
ρE＝(2hr+d)·sinθ＝c·Δt；
in the formula, hrThe height from the receiver RHCP antenna to the reflecting surface; d is the distance between the phase center of the RHCP antenna and the phase center of the LHCP antenna of the receiver; c is the propagation speed of light in vacuum; theta is the satellite altitude at the specular reflection point;
optionally, inverting the elevation anomaly according to the pseudorange multipath error based on the direct signal and the reflected signal by using a specific formula:
when determining ρEThen h is obtainedrComprises the following steps:
Figure BDA0003097851200000032
zeta elevation anomaly is defined as geoid-like elevation to parameterDistance of the test ellipsoid, hpFor the height of the altimetric platform to the reference ellipsoid,
Figure BDA0003097851200000041
for measuring the distance from the receiving platform to the reflecting surface, there are:
Figure BDA0003097851200000042
thus, using GNSS reflected signals to measure hrAnd obtaining h through navigation positioning information of the receiver platformpAnd then the elevation abnormity can be obtained.
Optionally, inverting the underwater gravitational field according to the elevation anomaly according to the following specific formula:
when the observed value is gravity anomaly, the following value condition under the sphere approximation condition can be expressed as:
Figure BDA0003097851200000043
in the formula, R is the average radius of the earth, T is the disturbance position, L is the earth center diameter, and g is the gravity anomaly on the quasi-geoid S, and can be calculated by gravity measurement and gravity regression. The expression for calculating the gravity anomaly is:
Figure BDA0003097851200000044
where γ represents the normal gravity of the ground point, ψ is the spherical angular distance between the calculation point and the integration point, and σ is the unit sphere. The formula maps the gravity level fluctuation N on the boundary surface to a gravity anomaly Δ g on or off the boundary surface. The expression for Q (L, ψ) is as follows:
Figure BDA0003097851200000045
wherein l is the distance between the calculation point and the flow point,
Figure BDA0003097851200000046
in order to evaluate the point(s),
Figure BDA0003097851200000047
is the quasi-geoid surface relief at that point.
Combining the above results, we obtained:
Figure BDA0003097851200000048
and solving the gravity anomaly on the earth surface by the above formula so as to determine the underwater gravity field.
The invention also provides an underwater gravity field inversion system based on GNSS-R pseudo-random noise code delay, which comprises:
and the right-hand circularly polarized receiving antenna is used for receiving the direct signal.
The left-handed circularly polarized receiving antenna is used for receiving and reflecting the direct radiation signal.
And the antenna cable is used for connecting the antenna and the receiver board card.
The GNSS-R receiver board card is used for signal sampling and signal processing. The receiver board card has low noise interference and has the functions of monitoring and preventing multipath and other environmental influences and the like. GNSS signal loss-of-lock often occurs in urban canyons, tunnels, and other GNSS shielded environments. In order to improve the performance of GNSS in an outage environment, the receiver employs an improved technique for ensuring. The receiver can provide a plurality of hardware data acquisition channels, is widely used in many measurement fields, and can simultaneously track all visible GNSS satellite signals (including GPS, GLONASS, Galileo, Beidou and the like).
And the upper computer is used for data processing. The direct and reflected signals are received by the antenna and then are down-converted by the radio frequency front end, and the original sampling data are transferred to the upper computer through the RS232 interface and are processed and analyzed by the software part of the receiver. According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides an underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay, wherein the method comprises the following steps: receiving a direct signal by using an RHCP antenna of a GNSS-R receiver, and receiving a reflected signal by using an LHCP antenna; the GNSS-R receiver copies the local PRN code; acquiring pseudo-range multipath errors of the direct signals and the reflected signals; inverting elevation anomaly according to pseudo-range multipath errors of the direct signals and the reflected signals; and inverting the underwater gravity field according to the elevation anomaly.
According to the method, the observed GNSS pseudo-random noise code delay is used as the delay amount of a direct signal and a reflected signal, the height measurement is completed according to the geometric relation formed by a GNSS satellite, a GNSS receiver and a mirror reflection point, the pseudo-range multi-path error is measured by utilizing the PRN code copied by the GNSS satellite and the receiver, and the elevation abnormity of a point to be measured is solved. The method for inverting the gravity anomaly by the GNSS-R with the quasi-geoid as the reference surface utilizes the elevation anomaly obtained by the measurement of the GNSS-R to invert the gravity anomaly of the point to be measured. And the influence of the change of the satellite altitude angle on the inversion result is reduced by utilizing the joint observation of the multiple navigation systems.
The underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay provide a new reference thought for gravity anomaly measurement, complement the advantages of other measurement means, increase the measurement diversity and robustness and make up for the situation of insufficient local measurement means.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flowchart of an underwater gravitational field inversion method based on GNSS-R pseudo-random noise code delay according to an embodiment of the present invention;
FIG. 2 is a block diagram of an underwater gravitational field inversion system based on GNSS-R pseudo-random noise code delay in accordance with an embodiment of the present invention;
FIG. 3A is a diagram of a space satellite view of a GNSS system at a certain time in accordance with an embodiment of the present invention;
FIG. 3B illustrates a change in the pitch angle of a satellite for an exemplary time period;
FIG. 4 is a multi-system pseudorange multi-path error experimental result according to an embodiment of the invention;
FIG. 5 shows experimental results of a GPS single system according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide an underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay. The method for inverting the gravity anomaly by the GNSS-R with the quasi-geoid as the reference surface utilizes the elevation anomaly obtained by the measurement of the GNSS-R to invert the gravity anomaly of the point to be measured. And the influence of the change of the satellite altitude angle on the inversion result is reduced by utilizing the joint observation of the multiple navigation systems. A new reference idea is provided for the gravity anomaly measurement, the advantages of the gravity anomaly measurement are complemented with those of other measurement means, the measurement diversity and robustness are increased, and the condition that the local measurement means is insufficient is made up.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The GNSS in the invention is a global navigation satellite system, the GNSS-R is a global navigation satellite system reflection signal technology, the BDS is a Beidou satellite navigation system, the GLONASS is a Glonass satellite navigation system, the Galileo is a Galileo satellite navigation system, the RHCP is right-hand circular polarization, the LHCP is left-hand circular polarization, and the PRN is a pseudo-random noise code.
In the GNSS-R double-antenna observation mode, the time delay difference of a reflected signal relative to a direct signal is obtained through the cooperative processing of the direct signal and the reflected signal, and the code delay height measurement, the carrier phase delay height measurement and the carrier frequency height measurement are mainly included. The carrier phase height measurement requires that the signal be coherent, at least need to contain strong coherent components. When the surface of the water surface is rough, the coherent component of the GNSS scattering signal is small, the signal correlation is poor, so that the receiver cannot complete phase locking, and effective phase data cannot be obtained, especially for the conditions of space-based or satellite-borne high dynamics. The pseudo-random code delay height measurement technology is the most commonly used GNSS-R height measurement technology at present, has the characteristics of convenient realization and strong anti-interference capability compared with other height measurement methods, and for water surface reflection signals, under the condition that the altitude angle of a satellite is larger, surface reflection signals are usually incoherent signals, so the carrier phase height measurement technology is mainly used for low altitude angles, the pseudo-random code delay height measurement technology is mainly used for the condition that the altitude angle is larger, and the pseudo-random code delay height measurement technology is widely applied to the water surface monitoring field of the GNSS-R shore base. The GNSS is an important outdoor navigation technology, and is a system for realizing positioning by transmitting high-frequency modulation signals through a satellite constellation. Each satellite transmits electromagnetic wave signals to the ground, which include pseudorandom noise codes (PRN). Using the PRN code, the receiver can obtain the signal travel time and multiply the speed of light to obtain the satellite-to-receiver distance. The measured distance between the satellite and the receiver is called pseudorange. The signal transmitting time is calculated by navigation message, and the receiving time can be obtained only by carrying out correlation operation on the replica code received by the receiver and the satellite signal.
Aiming at the problems that the conventional method for inverting the gravity anomaly is single and has certain limitation, the invention provides an underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay.
As shown in fig. 1, the present invention provides an underwater gravitational field inversion method based on GNSS-R pseudo random noise code delay, the method comprising:
step S1: receiving a direct signal by using an RHCP antenna of a GNSS-R receiver, and receiving a reflected signal by using an LHCP antenna;
step S2: the GNSS-R receiver copies the local PRN code;
step S3: acquiring pseudo-range multipath errors of the direct signals and the reflected signals;
step S4: inverting elevation anomaly according to pseudo-range multipath errors of the direct signals and the reflected signals;
step S5: and inverting the underwater gravity field according to the elevation anomaly.
The individual steps are discussed in detail below:
step S1: the method for receiving the direct signal by utilizing the RHCP antenna of the GNSS-R receiver and the reflection signal by utilizing the LHCP antenna specifically comprises the following steps:
the navigation satellite transmits right-hand polarized signals, and a pair of low-gain right-hand circularly polarized (RHCP) antennas face upward for receiving direct signals.
The other high-gain left-handed circularly polarized (LHCP) antenna faces downward for receiving the reflected signal.
After the direct signal is reflected by the reflecting surface, when the reflecting surface and the reflecting angle meet certain conditions, the polarization characteristic of the signal is gradually changed from right rotation to left rotation, and the polarization change degree is related to factors such as surface medium characteristics, radio wave incident angle and the like. The signals are transmitted to a receiver for data processing, and the receiver can estimate the ionospheric delay related to the reference frequency by adopting a multi-frequency receiver, so that the pseudo range can be measured more accurately.
Step S2: the GNSS-R receiver copies the local PRN code, and specifically includes:
each satellite transmits electromagnetic wave signals to the ground, which include pseudorandom noise codes (PRN). Using the PRN code, the receiver can obtain the signal travel time and multiply the speed of light to obtain the satellite-to-receiver distance. The measured distance between the satellite and the receiver is called pseudorange. The signal transmitting time is calculated by navigation message, and the receiving time can be obtained only by carrying out correlation operation on the replica code received by the receiver and the satellite signal. Pseudo-range multi-path error rhoEExpressed by the product of the time difference Δ t and the speed of light c, i.e.:
ρE＝c·Δt；
and further obtaining a path difference value through the time corresponding to each peak value by utilizing the correlation power peak value of the direct signal C/A code and the cross-correlation power peak value of the reflected signal C/A code. At any time trAt time, the local pseudo-random noise replica code a and the receiving antenna in the GNSS reflected signal receiver are at trThe correlation function of the reflected signal output at time + Δ t is:
Figure BDA0003097851200000081
in the formula, TiTo integration time, Es(U,tr+ t' + Δ t) is trThe reflected field of the receiver at U at time + t' + Δ t, j2＝-1，fcTo compensate for the doppler shift of the received signal. Changing the integration order and simplifying, we can:
Figure BDA0003097851200000091
a is signal amplitude, D (-) is navigation data bit information, R is reflection unit, Rt(. R) is the distance from the navigational satellite to the specular reflection pointrDistance from the receiver antenna phase center to the point of specular reflection, g (·) is a function of the receiver, transmitter and surface reflector motion with respect to time, fD(. cndot.) is the total Doppler shift.
Step S3: the method for acquiring the pseudo-range multipath error of the direct signal and the reflected signal comprises the following steps:
the height of the shore-based experimental receiver is generally low, and the effective surface scattering area is determined by the relative irradiation area of the antenna. The LHCP antenna receives mainly coherent reflection components from around the point of specular reflection, maintaining the pseudo-random noise code-correlated triangular waveform. Because the peak point of the relevant waveform of the reflected signal is not a mirror reflection point due to the factors of the scattering influence of the water surface, the free space loss, the antenna directional diagram and the like, but for the condition of relatively low height, the influence of the factors on the reflection relevant waveform is much smaller than the code delay observation noise, so that the relative code delay can be obtained by obtaining the accurate code delay of the peak values of the reflection signal and the direct signal to directly invert the height of the water surface. In shore-based GNSS-R measurements, the earth's surface can be considered approximately horizontal, ignoring the effects of the earth's curved surface.
Pseudo-range multi-path error rho which is propagation path difference of GNSS direct signal and reflection signalECan be expressed as:
ρE＝(2hr+d)·sinθ＝c·Δt；
in the formula, hrThe height from the receiver RHCP antenna to the reflecting surface; d is the distance between the phase center of the RHCP antenna and the phase center of the LHCP antenna of the receiver; c is the propagation speed of light in vacuum; theta is the satellite altitude at the specular reflection point;
step S4: inverting elevation anomaly according to pseudo-range multipath errors of the direct signals and the reflected signals, specifically comprising the following steps:
in actual measurement, the surface of the ocean is rough due to the existence of wind waves, and the peak value point of the correlation result after the correlation processing does not correspond to the time delay of the specular reflection point. Although the time delay corresponding to the specular reflection point is minimum, due to the existence of diffuse reflection, the correlation result peak with different delays is superposed on the correlation result peak obtained by specular reflection, so that the maximum reflection correlation peak is moved backwards, and the shape of the correlation peak is also changed. However, the position corresponding to the rise of the slope of the reflection correlation peak to the maximum value is the time delay of the specular reflection point. And calculating the slope change of the correlation result to obtain the delay time corresponding to the real specular reflection, and further deducing the height of the receiver antenna. Performing conventional navigation calculation of software receiver on direct signals of effective satellite in a period of time, calculating pseudo-random noise code delay from peak positions of direct and reflected correlation waveforms, and calculating multipath error delta rho according to pseudo-range multipath error between direct signals and reflected signalsEFind hr。
When determining ρEThen h is obtainedrComprises the following steps:
Figure BDA0003097851200000101
zeta elevation anomaly is defined as the distance from the geoid to the reference ellipsoid, hpFor the height of the altimetric platform to the reference ellipsoid,
Figure BDA0003097851200000102
for measuring the distance from the receiving platform to the reflecting surface, there are:
Figure BDA0003097851200000103
thus, using GNSS reflected signals to measure hrAnd obtaining h through navigation positioning information of the receiver platformpAnd then the elevation abnormity can be obtained.
Step S5: inverting the underwater gravity field according to the elevation anomaly, specifically:
knowing the gravity and the gravity potential on the quasi-geoid surface shape S and knowing the rotation angular velocity of the earth, the disturbance potential outside the quasi-geoid surface satisfies the Laplace equation, and when the observed value is gravity anomaly, the lower value condition under the sphere approximation condition can be expressed as:
Figure BDA0003097851200000111
in the formula, R is the average radius of the earth, T is the disturbance position, L is the earth center diameter, and g is the gravity anomaly on the quasi-geoid S, and can be calculated by gravity measurement and gravity regression. The expression for computing gravity anomaly using Stokes principle is:
Figure BDA0003097851200000112
the formula is a generalized inverse Stokes formula, wherein gamma represents the normal gravity of a ground point, psi is the spherical angular distance between a calculation point and an integral point, and sigma is a unit sphere. The formula maps the gravity level fluctuation N on the boundary surface to a gravity anomaly Δ g on or off the boundary surface. The expression for Q (L, ψ) is as follows:
Figure BDA0003097851200000113
wherein l is the distance between the calculation point and the flow point,
Figure BDA0003097851200000114
in order to evaluate the point(s),
Figure BDA0003097851200000115
is the quasi-geoid surface relief at that point.
Combining the above results, we obtained:
Figure BDA0003097851200000116
and solving the gravity anomaly on the earth surface by the above formula so as to determine the underwater gravity field.
As shown in fig. 2, the present invention further provides an underwater gravitational field inversion system based on GNSS-R pseudo random noise code delay, the system comprising:
and the right-hand circularly polarized receiving antenna is used for receiving the direct signal.
The left-handed circularly polarized receiving antenna is used for receiving and reflecting the direct radiation signal.
And the antenna cable is used for connecting the antenna and the receiver board card.
The GNSS-R receiver board card is used for signal sampling and signal processing. The receiver board card has low noise interference and has the functions of monitoring and preventing multipath and other environmental influences and the like. GNSS signal loss-of-lock often occurs in urban canyons, tunnels, and other GNSS shielded environments. In order to improve the performance of GNSS in an outage environment, the receiver employs an improved technique for ensuring. The receiver can provide a plurality of hardware data acquisition channels, is widely used in many measurement fields, and can simultaneously track all visible GNSS satellite signals (including GPS, GLONASS, Galileo, Beidou and the like).
And the upper computer is used for data processing. The direct and reflected signals are received by the antenna and then are down-converted by the radio frequency front end, and the original sampling data are transferred to the upper computer through the RS232 interface and are processed and analyzed by the software part of the receiver.
Experimental verification
FIG. 3A is a diagram of a GNSS satellite sky at a certain time, and FIG. 3B is a diagram of changes in the elevation angle of GNSS satellites at a certain measurement time. Because the relative position of the satellite in the measurement time period is constantly changed, the pitch angle is also constantly changed, the data signals of the GPS satellites PRN5 and PR8, the Beidou satellites PRN10 and PRN12, the GLONASS satellites PRN14 and PRN15, the Galileo satellites PRN20 and PRN21 can be analyzed by comparing and analyzing the GNSS satellite sky diagram and the pitch angle change diagram, the data signals of the satellite are good in continuity, the altitude change meets the experimental requirements, and the altitude of the satellite selected in the experiment is not lower than 20 degrees. Because the lobe width of the antenna is narrow and the inversion accuracy is related to the signal SNR, good results can be obtained by selecting a plurality of satellites to be concentrated in the main lobe section of the antenna. In summary, data of the GPS satellites PRN5, PR8, Beidou satellites PRN10, PRN12, GLONASS satellites PRN14, PRN15, Galileo satellites PRN20, and PRN21 are selected as experimental data of the experiment.
The receiver adopted in the experiment is compatible with Beidou satellite signals, GLONASS satellite signals, GPS satellite signals and Galileo satellite signals, the size of an ionospheric error can be obtained in real time through measurement, most ionospheric errors are eliminated, and atmospheric delay errors are reduced, so that the measurement precision is improved. In the multisystem experiment, a Beidou system, a Glonass system and a Galileo system are selected for research, and the data acquisition time is 90 minutes.
Combining the satellite space diagram and the satellite pitch angle change conditions in the measurement time period, two satellites with the numbers PRN10 and PRN12 in the Beidou system are selected, two satellites with the numbers PRN14 and PRN15 in the Glonass system are selected, and two satellites with the numbers PRN20 and PRN21 in the Galileo system are selected. After filtering processing, obtaining pseudo-range multi-path error delta rho of each satellite for multi-system height measurementEThe variation is shown in fig. 4.
Measurement in the fieldIn the experiment, a C/A code delay ranging method is used for obtaining pseudo-range multi-path errors, and original data path difference value points are removed by combining the position change condition of the reflection points of the water surfaces of the satellites so as to eliminate multi-path error interference. And Gaussian smoothing filtering is carried out to obtain pseudo-range multipath error delta rhoEThe variation is shown in fig. 5 (top). The continuously changing water level height curve is shown in fig. 5 (lower).
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (6)

1. An underwater gravity field inversion method based on GNSS-R pseudo-random noise code delay is characterized by comprising the following steps:
step S1: receiving a direct signal by using an RHCP antenna of a GNSS-R receiver, and receiving a reflected signal by using an LHCP antenna;
step S2: the GNSS-R receiver copies the local PRN code;
step S3: acquiring pseudo-range multipath errors of the direct signals and the reflected signals;
step S4: inverting elevation anomaly according to pseudo-range multipath errors of the direct signals and the reflected signals;
step S5: and inverting the underwater gravity field according to the elevation anomaly.
2. The underwater gravity field inversion method based on GNSS-R pseudo-random noise code delay is characterized in that the RHCP antenna of the GNSS-R receiver is used for receiving a direct signal, and the LHCP antenna is used for receiving a reflected signal; the method specifically comprises the following steps:
step S11: a pair of low-gain right-hand circularly polarized (RHCP) antennas facing upward for receiving direct signals;
step S12: the other high-gain left-hand circularly polarized (LHCP) antenna faces downwards and is used for receiving a reflected signal;
3. the underwater gravity field inversion method based on GNSS-R pseudo-random noise code delay as claimed in claim 1, wherein the GNSS-R receiver copies local PRN code, and the specific formula is:
and further obtaining a path difference value through the time corresponding to each peak value by utilizing the correlation power peak value of the direct signal C/A code and the cross-correlation power peak value of the reflected signal C/A code. At any time trAt time, the local pseudo-random noise replica code a and the receiving antenna in the GNSS reflected signal receiver are at trThe correlation function of the reflected signal output at time + Δ t is:
Figure FDA0003097851190000011
in the formula, TiTo integration time, Es(U,tr+ t' + Δ t) is trThe reflected field of the receiver at U at time + t' + Δ t, j2＝-1，fcTo compensate for the doppler shift of the received signal.
4. The underwater gravitational field inversion method based on GNSS-R pseudo-random noise code delay according to claim 1, wherein according to the pseudo-range multi-path error of the obtained direct signal and reflected signal, the specific formula is as follows:
pseudo-range multi-path error rho which is propagation path difference of GNSS direct signal and reflection signalECan be expressed as:
ρE＝(2hr+d)·sinθ＝c·Δt
in the formula, hrThe height from the receiver RHCP antenna to the reflecting surface; d is the distance between the phase center of the RHCP antenna and the phase center of the LHCP antenna of the receiver; c is transmission of light in vacuumThe playing speed; theta is the satellite altitude at the specular reflection point.
5. The underwater gravity field inversion method based on GNSS-R pseudo-random noise code delay as claimed in claim 1, wherein according to the pseudo-range multi-path error inversion elevation anomaly according to the direct signal and the reflected signal, the specific formula is as follows:
when determining ρEThen h is obtainedrComprises the following steps:
Figure FDA0003097851190000021
zeta elevation anomaly is defined as the distance from the geoid to the reference ellipsoid, hpFor the height of the altimetric platform to the reference ellipsoid,
Figure FDA0003097851190000022
for measuring the distance from the receiving platform to the reflecting surface, there are:
Figure FDA0003097851190000023
measurement of h using GNSS reflected signalsrAnd obtaining h through navigation positioning information of the receiver platformpAnd then the elevation abnormity can be obtained.
6. An underwater gravitational field inversion system based on GNSS-R pseudo-random noise code delays, the system comprising:
a right-hand circularly polarized receiving antenna for receiving a direct signal;
the left-handed circularly polarized receiving antenna is used for receiving and reflecting the direct incident signal;
the antenna cable is used for connecting the antenna and the receiver board card;
a GNSS-R receiver board card;
and (4) an upper computer.
CN202110616658.5A 2021-06-02 2021-06-02 Underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay Pending CN113359204A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110616658.5A CN113359204A (en) 2021-06-02 2021-06-02 Underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110616658.5A CN113359204A (en) 2021-06-02 2021-06-02 Underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay

Publications (1)

Publication Number Publication Date
CN113359204A true CN113359204A (en) 2021-09-07

Family

ID=77531410

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110616658.5A Pending CN113359204A (en) 2021-06-02 2021-06-02 Underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay

Country Status (1)

Country Link
CN (1) CN113359204A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114690212A (en) * 2022-03-18 2022-07-01 中国科学院国家空间科学中心 Method and system for carrying out interference early warning by utilizing DDM data quality monitoring

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6137433A (en) * 1999-03-18 2000-10-24 The United States Of America As Represented By The Secretary Of Commerce Scatterometer with adaptable spatial resolution
EP1262792A1 (en) * 2001-05-31 2002-12-04 Starlab Barcelona SL System for monitoring a feature of a surface by reflected satellite navigation signals
CN101339018A (en) * 2008-08-13 2009-01-07 广州市城市规划勘测设计研究院 Remote mode three-dimensional coordinate conversion method
CN101713649A (en) * 2009-11-05 2010-05-26 中国测绘科学研究院 Disturbing gravity-based quasi-geoid land-sea seamless splicing method
CN104765032A (en) * 2015-04-21 2015-07-08 山东省科学院海洋仪器仪表研究所 Shore-based array GNSS reflected signal tide and multi-wave-parameter comprehensive detection system
CN105334510A (en) * 2015-10-19 2016-02-17 叶雷 GNSS-R ground surface detection apparatus and method
CN108761510A (en) * 2018-04-09 2018-11-06 中铁二局集团有限公司 The method for carrying out height differences by leveling measurement using the gravity field model based on topographic correction
CN111045099A (en) * 2019-12-27 2020-04-21 武汉大学 Method for inverting ocean gravity field by imaging type altimeter data
CN112818285A (en) * 2021-02-08 2021-05-18 中国人民解放军92859部队 Method for calculating central area effect of external disturbance gravity north component

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6137433A (en) * 1999-03-18 2000-10-24 The United States Of America As Represented By The Secretary Of Commerce Scatterometer with adaptable spatial resolution
EP1262792A1 (en) * 2001-05-31 2002-12-04 Starlab Barcelona SL System for monitoring a feature of a surface by reflected satellite navigation signals
CN101339018A (en) * 2008-08-13 2009-01-07 广州市城市规划勘测设计研究院 Remote mode three-dimensional coordinate conversion method
CN101713649A (en) * 2009-11-05 2010-05-26 中国测绘科学研究院 Disturbing gravity-based quasi-geoid land-sea seamless splicing method
CN104765032A (en) * 2015-04-21 2015-07-08 山东省科学院海洋仪器仪表研究所 Shore-based array GNSS reflected signal tide and multi-wave-parameter comprehensive detection system
CN105334510A (en) * 2015-10-19 2016-02-17 叶雷 GNSS-R ground surface detection apparatus and method
CN108761510A (en) * 2018-04-09 2018-11-06 中铁二局集团有限公司 The method for carrying out height differences by leveling measurement using the gravity field model based on topographic correction
CN111045099A (en) * 2019-12-27 2020-04-21 武汉大学 Method for inverting ocean gravity field by imaging type altimeter data
CN112818285A (en) * 2021-02-08 2021-05-18 中国人民解放军92859部队 Method for calculating central area effect of external disturbance gravity north component

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
程芦颖等: "广义逆stokes公式、广义逆vening-meinesz公式及广义molodensky公式", 《地球科学》 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114690212A (en) * 2022-03-18 2022-07-01 中国科学院国家空间科学中心 Method and system for carrying out interference early warning by utilizing DDM data quality monitoring
CN114690212B (en) * 2022-03-18 2024-05-14 中国科学院国家空间科学中心 Method and system for performing interference early warning by using DDM data quality monitoring

Similar Documents

Publication Publication Date Title
Groves et al. A portfolio approach to NLOS and multipath mitigation in dense urban areas
CN110824510B (en) Method for increasing number of sea surface reflection signals received by GNSS-R height measurement satellite
Braasch Multipath
Kos et al. Effects of multipath reception on GPS positioning performance
US6421003B1 (en) Attitude determination using multiple baselines in a navigational positioning system
RU2615984C2 (en) Assessment method of arrival navigation signals direction to receiver after reflection from walls in satellite positioning system
Ban et al. GEO-satellite-based reflectometry for soil moisture estimation: Signal modeling and algorithm development
CN105334510A (en) GNSS-R ground surface detection apparatus and method
Bahrami et al. Instantaneous Doppler-aided RTK positioning with single frequency receivers
CN107561562A (en) Specular reflection point fast determination method in a kind of GNSS R remote sensing
Hobiger et al. GLONASS-R: GNSS reflectometry with a frequency division multiple access-based satellite navigation system
JP2017111112A (en) Ppp and magnetic compass integration system for compensating phase wind-up of receiver in gnss base buoy for measuring long period wave height (ppp and magnetic compass integration system for measuring of long period wave in buoy's wind-up)
Gowdayyanadoddi et al. A Ray‐Tracing Technique to Characterize GPS Multipath in the Frequency Domain
EP1262792A1 (en) System for monitoring a feature of a surface by reflected satellite navigation signals
Wang et al. Sea-state observation using reflected BeiDou GEO signals in frequency domain
Collett et al. Phase coherence of GPS signal land reflections and its dependence on surface characteristics
Kucwaj et al. Accurate pseudorange estimation by means of code and phase delay integration: Application to GNSS-R altimetry
Serrano Carrier-phase multipath mitigation in RTK-based GNSS dual-antenna systems
CN113359204A (en) Underwater gravity field inversion method and system based on GNSS-R pseudo-random noise code delay
Rajabi et al. Polarimetric GNSS-R sea level monitoring using I/Q interference patterns at different antenna configurations and carrier frequencies
Wang et al. Analysis of GNSS-R Code-Level Altimetry using QZSS C/A, L1C, and BDS B1C signals and their Combinations in a Coastal Experiment
Palamartchouk et al. Dual-polarization GNSS observations for multipath mitigation and better high-precision positioning
CN113589350B (en) Sea surface wind speed measuring method based on measuring GNSS receiver
He et al. Coastal GNSS-R phase altimetry based on the combination of L1 and L5 signals under high sea states
Smyrnaios Carrier-phase multipath in satellite-based positioning

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
WD01 Invention patent application deemed withdrawn after publication

Application publication date: 20210907

WD01 Invention patent application deemed withdrawn after publication