WO2017067033A1 - 一种gnss-r地表探测装置和方法 - Google Patents

一种gnss-r地表探测装置和方法 Download PDF

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Publication number
WO2017067033A1
WO2017067033A1 PCT/CN2015/094525 CN2015094525W WO2017067033A1 WO 2017067033 A1 WO2017067033 A1 WO 2017067033A1 CN 2015094525 W CN2015094525 W CN 2015094525W WO 2017067033 A1 WO2017067033 A1 WO 2017067033A1
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Prior art keywords
gnss
signal
direct
signals
intermediate frequency
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PCT/CN2015/094525
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English (en)
French (fr)
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叶雷
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叶雷
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Publication of WO2017067033A1 publication Critical patent/WO2017067033A1/zh
Priority to US15/954,107 priority Critical patent/US20180231667A1/en

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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
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • 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
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • 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
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/003—Bistatic radar systems; Multistatic radar systems
    • 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
    • G01S19/14—Receivers specially adapted for specific applications
    • 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
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO

Definitions

  • the invention relates to the field of remote sensing technology, and in particular relates to a GNSS-R surface detecting device and method.
  • GNSS Global Navigation Satellite System
  • US GPS Global Navigation Satellite System
  • GLONASS Global Navigation Satellite System
  • Beidou China
  • GNSS-R GNSS Reflection
  • the ground device collects navigation broadcast signals on the one hand and reflects the GNSS on the Earth's surface.
  • GNSS homologous signal synchronization passive observation similar to multi-band radar interference.
  • the basic principle is to perform a variety of comparative phase analysis by using the data formed by the GNSS right-handed circularly polarized direct signal and the left-handed circularly polarized reflected signal, using L-band 1575MHz for liquid water and other substances (including ice).
  • the characteristics of the boundary line sensitivity, real-time capture, acquisition, analysis, processing of the formation of the surface interference data are important to perform a variety of comparative phase analysis by using the data formed by the GNSS right-handed circularly polarized direct signal and the left-handed circularly polarized reflected signal.
  • GNSS-R surface detection devices mostly use omnidirectional antennas for signal acquisition, and usually require baseband decoding of GNSS signals, and GNSS-R technology for remote sensing detection based on reflected signal C/A code or P(Y) code.
  • the signal needs to be decoded, which makes the existing technology generally only capable of surface detection based on the signals of the GPS system.
  • the present invention provides a GNSS-R surface detection apparatus and method for surface detection while being compatible with a plurality of different GNSS system signals.
  • the present invention provides a GNSS-R surface detecting apparatus, comprising:
  • a first receiving antenna for receiving a GNSS direct signal at a corresponding frequency of at least two different GNSS systems
  • a second receiving antenna for receiving a GNSS reflected signal at a corresponding frequency of at least two different GNSS systems
  • An intermediate frequency signal acquisition device configured to separately acquire the GNSS direct signal and the GNSS reflected signal The digital intermediate frequency signal; wherein the intermediate frequency signal acquisition device separately collects the digital intermediate frequency signals of the GNSS direct signals received by the frequencies of different GNSS systems through independent channels, and separately collects the GNSS reflections received by the frequencies of different GNSS systems through independent channels.
  • Digital intermediate frequency signal of the signal
  • Data processing means for selecting the GNSS direct signal and the GNSS reflected signal of the corresponding frequency according to the detected intensity or predetermined setting of the intermediate frequency signal at different GNSS system frequencies, and according to the selected number of the GNSS direct signal
  • the intermediate frequency signal and the digital intermediate frequency signal of the GNSS reflected signal acquire multi-channel Doppler shift and multi-path delay of the GNSS reflected signal relative to the GNSS direct signal, and further invert the acquired surface parameters.
  • the first receiving antenna is a directional right-handed antenna
  • the second receiving antenna is a directional right-handed antenna
  • the first receiving antenna and the second receiving antenna are phased array antennas, and the GNSS signals are received by scanning to obtain a beam direction with the strongest received signal strength.
  • the first receiving antenna and the second receiving antenna comprise:
  • An antenna unit arranged in a plurality of arrays, wherein the antenna unit comprises: a substrate; a radiation pattern formed on the first surface of the substrate, including four sub-patterns enclosing a rectangular shape; and a feed line pattern formed on a second side of the substrate;
  • a low noise amplifier connected to a feeder pattern of the antenna unit
  • each of the sub-patterns includes a first portion, a second portion, and a third portion that are in communication with each other; the first portion is in communication with the second portion, and the second portion is in communication with the third portion, the first portion and The third portion is a rectangle symmetrically disposed with respect to the second portion and having the same shape; an end portion of the third portion of each sub-pattern is disposed opposite to a side portion of the first portion of the adjacent next sub-pattern such that the four sub-patterns It is enclosed in a rectangular shape, and the four sub-images are not connected to each other.
  • the different GNSS systems comprise at least two of a Global Positioning System, a Beidou system, a Galileo system, and a Glonass system.
  • the data processing apparatus is configured to acquire a Doppler shift and a delay of the GNSS direct signal according to the digital intermediate frequency signal of the GNSS direct signal, and to perform a Doppler shift of the GNSS direct signal and The delay is used as the local code of the GNSS reflected signal, and the multi-channel Doppler shift and the multi-path delay of the GNSS reflected signal relative to the GNSS direct signal are obtained according to the digital intermediate frequency signal of the GNSS reflected signal.
  • the present invention provides a GNSS-R surface detection method, including:
  • GNSS Receiving GNSS direct and reflected signals at corresponding frequencies of at least two different GNSS systems
  • Digital IF signals of GNSS direct signals and GNSS reflected signals are respectively collected, wherein digital IF signals of GNSS direct signals received at frequencies of different GNSS systems are acquired through independent channels, and numbers of GNSS reflected signals received at frequencies of different GNSS systems are obtained.
  • the IF signal is obtained through an independent channel;
  • the surface parameters are obtained according to the multi-channel Doppler shift and the multi-path delay inversion of the GNSS reflected signal with respect to the GNSS direct signal.
  • the GNSS direct signal is received by a left-handed directional antenna
  • the GNSS reflected signal is received by a right-handed directional antenna.
  • receiving the GNSS direct and reflected signals at corresponding frequencies of the at least two different GNSS systems comprises:
  • the GNSS direct signal and the GNSS reflected signal are received by the phased array antenna by obtaining the beam direction with the strongest received signal strength.
  • the multi-channel Doppler shift and the multi-path delay of the GNSS reflected signal relative to the GNSS direct signal are obtained according to the selected digital intermediate frequency signal of the GNSS direct signal and the digital intermediate frequency signal of the GNSS reflected signal.
  • a GNSS signal receiving antenna that can receive signals at corresponding frequencies of different GNSS systems, and simultaneously acquiring direct and reflected signals of different frequencies through independent channels in the intermediate frequency extraction phase to obtain digital intermediate frequency signals, based on user settings or Signal strength is selected for the GNSS system for data processing.
  • the ground data is obtained based on the inversion. .
  • multiple different GNSS system signals can be simultaneously compatible for surface detection.
  • FIG. 1 is a schematic diagram of a principle of performing GNSS-R surface detection according to an embodiment of the present invention
  • FIG. 2 is a schematic diagram of a GNSS-R surface detecting device according to an embodiment of the present invention
  • FIG. 3 is a schematic diagram of a preferred receiving antenna according to an embodiment of the present invention.
  • FIG. 4 is a schematic diagram of an antenna unit of the antenna shown in FIG. 3;
  • FIG. 5 is a schematic diagram of a human-machine interaction interface of a data processing apparatus according to an embodiment of the present invention.
  • FIG. 7 is a flow chart of a GNSS-R surface detection method according to an embodiment of the present invention.
  • FIG. 1 is a schematic diagram of the principle of performing GNSS-R surface detection according to an embodiment of the present invention.
  • the GNSS-R detecting device disposed above the ground or above the water surface includes a first antenna for receiving a GNSS direct signal and a second antenna for receiving a GNSS reflected signal.
  • the difference in propagation path between specular reflection and direct signal is:
  • h is the height of the first receiving antenna to the reflecting surface (ie, the ground or the water surface);
  • ⁇ is the pitch angle of the reflecting point to a satellite;
  • d is between the two antenna phase centers of the GNSS-R detecting device Distance;
  • D is The geometric distance between the satellite and the first receiving antenna of the GNSS direct signal;
  • R is the signal path geometric length of the reflected signal received by the second receiving antenna.
  • d dif can be estimated by measuring the difference in propagation time between the signals transmitted by the satellite and the direct and reflected paths respectively reaching the receiver.
  • the effective wave height of the reflecting surface is relatively small, the coherence of the reflected signal is maintained, and the propagation time difference between the direct path and the reflected path is obtained by measuring the carrier phase state of the reconstructed direct and reflected signals.
  • the ground receiver can track the phase of the direct signal carrier generally for 0.01 weeks.
  • the carrier phase observation is a carrier phase (or phase pseudorange) extracted at a certain time interval when the receiver reaches the carrier phase tracking state, and is applied to the positioning calculation of the carrier phase.
  • the carrier phase observation value for a certain satellite consists of three parts: the initial whole week unknown number N 0 , the whole week count C(n) from the start of locking to n, the phase mantissa
  • the carrier phase observation of the direct and reflected signals (with full-circumference ambiguity) of the nth epoch is actually extracted. with The ambiguities for the whole week are N 0r and N 0d , respectively .
  • x(n) is the observation of the physical quantity x in the nth epoch
  • D tro is the error in the propagation distance caused by tropospheric refraction to direct signal propagation
  • D ion is the error in the propagation distance caused by the ionospheric refraction to the direct signal propagation;
  • ⁇ uclock is the user's clock difference;
  • ⁇ dsclock is the satellite clock difference corresponding to the observed direct signal
  • R tro is the error in the propagation distance caused by the tropospheric propagation of the reflected signal
  • R ion is the error in the propagation distance caused by the ionosphere to the reflection signal propagation
  • ⁇ rsclock is the clock difference of the satellite corresponding to the reflected signal
  • the time-synchronized user clock is basically eliminated.
  • the satellite clock corresponding to the reflected signal and the reflected signal in the epoch n is not fully synchronized, so the difference is ⁇ rsclock (n)- ⁇ dsclock (n), which only weakens the influence of the long-term stability of the satellite clock , did not eliminate the impact of short-term stability.
  • the propagation distance error caused by the troposphere since the propagation paths through which the direct signal and the reflected signal pass are close to each other ( ⁇ 20km), the physical characteristics of the troposphere at similar distances are similar, so the approximate synchronous observation value of the same satellite is found to be poor. Attenuate the influence of tropospheric refraction, but the refractive index value of the troposphere close to the lake surface is the largest in the troposphere. Considering the propagation path of the direct and reflected signals near the lake surface, the influence of the troposphere is not completely eliminated, especially when the direct and reflected signals travel distance. When the difference is large.
  • the physical properties of the ionosphere in close proximity to space are similar.
  • the ionospheric error is significantly weakened. due to with The randomness is relatively strong, and the correlation between them is weak, and it can be considered that it is basically not weakened by the difference.
  • the difference between the epochs is further performed.
  • the satellite clock is basically eliminated, and the ambiguity is eliminated throughout the week, resulting in:
  • the elevation angle is obtained by solving the receiver by using a direct signal. Since only a small change is possible in the short-time (0.1 s) elevation angle, when n 2 Tn 1 T ⁇ 0.1 s (T represents the time interval between adjacent epochs), it can be assumed that sin ⁇ (n 2 ) ⁇ sin ⁇ (n 1 ), d is known and determined. Equation (9) can be approximated as:
  • the carrier phase observation obtained by the epoch n 1 , n 2 calculates the change of the lake height between the epochs n 1 , n 2 .
  • the acquisition of the surface parameters can be performed without decoding the GNSS signal.
  • the GNSS-R surface detecting device includes a first receiving antenna 1, a second receiving antenna 2, an intermediate frequency signal collecting device 3, and a data processing device 4.
  • the first receiving antenna 1 and the second receiving antenna 2 are respectively connected to the intermediate frequency signal collecting device 3 via a radio frequency cable.
  • the intermediate frequency signal acquisition device 3 is connected to the data processing device 4 via a serial port or other digital signal transmission interface.
  • the first receiving antenna 1 is configured to receive GNSS direct signals at corresponding frequencies of at least two different GNSS systems.
  • the second receive antenna 2 is for receiving GNSS reflected signals at corresponding frequencies of at least two different GNSS systems.
  • the first receiving antenna 1 and the second receiving antenna 2 may be directional antennas or omnidirectional antennas.
  • the first receiving antenna 1 is a directional right-handed antenna, and can be oriented to receive a right-handed circularly polarized GNSS direct signal.
  • the second receiving antenna 2 is a directional left-handed antenna, and can receive the left-handed circularly-polarized GNSS reflected signal.
  • the advantage of using a directional antenna is that after adjusting to a better receiving direction, the directional antenna can receive GNSS direct and reflected signals with higher gain, and at the same time, its pitch angle is relatively determined, which can better perform subsequent delay acquisition.
  • the first receiving antenna 1 and the second receiving antenna 2 may be phased array antennas, and the received signal with the strongest received signal strength can be obtained by scanning the received signals of different azimuths by adjusting the directivity of the phased array antenna.
  • FIG. 3 is a schematic diagram of a preferred receiving antenna in accordance with an embodiment of the present invention.
  • 4 is a schematic diagram of an antenna unit of the antenna shown in FIG.
  • the antenna shown in FIG. 3 can receive either a right-hand circularly polarized signal or a left-handed circularly polarized signal.
  • the preferred receive antenna includes four antenna elements and a low noise amplifier.
  • Each antenna unit includes a substrate 11, a radiation pattern 12, and a feed pattern 13.
  • a radiation pattern 12 is formed on the first side of the substrate 11, which includes four sub-patterns 121, 122, 123, and 124 that are enclosed in a rectangular shape.
  • each of the sub-patterns includes a first portion a, a second portion b, and a third portion c that are in communication with each other.
  • the first portion a is in communication with the second portion b
  • the second portion b is in communication with the third portion c
  • the first portion a and the third portion c being rectangularly disposed symmetrically with respect to the second portion b and having the same shape.
  • the axes of the first portion a, the second portion b, and the third portion c are arranged in a straight line.
  • the second portion b is also formed in a rectangular shape having a smaller width than the first portion a and the third portion c, so that the sub-patterns 121-124 are respectively formed as dumbbell-shaped patterns composed of rectangles.
  • the sub-patterns 121-124 are hollowed out to form a pattern on the conductive material layer.
  • the conductive material may be a metal conductive material such as gold, silver or copper or an oxide conductive material such as ITO.
  • the four sub-patterns 121-124 are circumferentially encircled. Specifically, one end of one sub-pattern is disposed opposite to a portion of the side of the next adjacent sub-pattern near the end.
  • each sub-pattern is disposed opposite to the side of the first portion a of the adjacent next sub-pattern such that the four sub-patterns enclose a rectangular shape and between the four sub-patterns Not connected to each other.
  • the antenna unit thus formed can receive either a right-handed circularly polarized signal or a left-handed circularly polarized signal.
  • the feed pattern 13 is disposed on the second surface of the substrate 11 opposite to the first surface. At least a conductive pattern at a corresponding location of the first portion a of each sub-pattern is included.
  • the low noise amplifier 2 is electrically connected to the feed pattern 13, receives the GNSS electromagnetic signal received via the radiation pattern, is amplified, and is transmitted to a signal processing system connected to the GNSS receiving antenna.
  • the low noise amplifier 2 may be a low noise amplifier employing an SMA interface.
  • the low noise amplifier 2 can be mounted on the side of a support member to extract signals received by the antenna unit.
  • the first receiving antenna receiving the right circular polarization and the second receiving antenna receiving the left circular circular polarization can be formed by the antenna of the same structure.
  • the antenna adopting the above structure can simultaneously receive signals at a plurality of different frequencies, thereby realizing receiving GNSS direct signals or GNSS reflected signals at corresponding frequencies of at least two different GNSS systems.
  • the first receiving antenna 1 and the second receiving antenna 2 can simultaneously receive GNSS signals at the L frequency point of the GPS system and the B1, B2, and B3 frequency points of the Beidou system. It should be understood that the present invention is also applicable to receiving, collecting, and processing signals based on at least two systems of a GPS system, a Beidou system, a Galileo system, and a Glonass system.
  • the intermediate frequency signal collecting device 3 is configured to respectively acquire the digital intermediate frequency signals of the GNSS direct signals and the GNSS reflected signals; wherein the intermediate frequency signal collecting devices respectively collect the numbers of the GNSS direct signals received by the frequencies of different GNSS systems through independent channels.
  • the intermediate frequency signal and the digital intermediate frequency signals of the GNSS reflected signals received by the frequencies of different GNSS systems are respectively collected through independent channels.
  • the intermediate frequency signal acquisition device 3 of the embodiment of the present invention can operate in the following frequency bands.
  • GPS L1 frequency band 1575.42MHz ⁇ 0.05MHz;
  • BD2B1 frequency band 1561.098MHz ⁇ 0.05MHz;
  • BD2B2 frequency band 1207.14MHz ⁇ 0.05MHz;
  • BD2B3 frequency band 1268.52MHz ⁇ 0.05MHz;
  • the intermediate frequency signal acquisition device of the embodiment separately collects the direct signal, the reflected signal of the GPS system, and the digital intermediate frequency signal of the direct signal and the reflected signal of the Beidou system through four independent channels. Therefore, under the premise of not involving Beidou ICD, the dual-mode unified IF signal acquisition and processing of Beidou+GPS is realized.
  • the data processing device 4 is configured to select the GNSS direct signal and the GNSS reflected signal of the corresponding frequency according to the detected intensity or predetermined setting of the intermediate frequency signal at different GNSS system frequencies, and according to the selected number of the GNSS direct signal.
  • the intermediate frequency signal and the digital intermediate frequency signal of the GNSS reflected signal acquire multi-channel Doppler shift and multi-path delay of the GNSS reflected signal relative to the GNSS direct signal, and further invert the acquired surface parameters.
  • the data processing device 4 can perform surface detection using the GNSS signal of the highest quality, or perform surface detection according to the user's selection.
  • the data processing apparatus 4 may acquire a Doppler shift and a delay of the GNSS direct signal according to the digital intermediate frequency signal of the GNSS direct signal, and transmit a Doppler frequency shift of the GNSS direct signal.
  • the multi-channel Doppler shift and the multi-path delay of the GNSS reflected signal relative to the GNSS direct signal are obtained according to the digital intermediate frequency signal of the GNSS reflected signal.
  • the data processing device 4 can be implemented by a general-purpose computer system carrying a data processing program, that is, multi-channel Doppler shift and multiplexing of GNSS reflected signals with respect to GNSS direct signals in a manner that the general computer system executes program instructions. The delay is sought.
  • FIG. 5 is a schematic diagram of a human-computer interaction interface of a data processing apparatus according to an embodiment of the present invention
  • FIG. 6 is a Doppler frequency shift-time delay diagram acquired by the GNSS-R surface detecting apparatus according to an embodiment of the present invention.
  • the human-machine interaction interface of the data processing apparatus of the present invention can display the current position, different signal strengths, and surface parameters obtained based on the acquired signal inversion (for example, wave height, wind speed, wind direction, etc. of the sea surface, etc.) Inversion based on time delay and Doppler shift map can be performed using various existing surface parameter inversion methods.
  • the embodiment of the present invention uses the carrier phase detection method to acquire the difference between the GNSS reflected signal and the GNSS direct signal, decoding is not required, and thus, the carrier signal reception, the intermediate frequency acquisition, and the processing can be implemented for multiple Compatible with different GNSS systems. At the same time, it can accept both right circular and circular The signal can also receive the directional reception of the GNSS signal by the array of antenna elements receiving the left-hand circularly polarized signal, which enhances the signal quality and simplifies the system structure. Further, according to the signals of different GNSS systems, the best quality signal can be selected for inversion, thereby improving the accuracy of GNSS-R surface detection.
  • a GNSS signal receiving antenna that can receive signals at corresponding frequencies of different GNSS systems, and simultaneously acquiring direct and reflected signals of different frequencies through independent channels in the intermediate frequency extraction phase to obtain digital intermediate frequency signals, based on user settings or Signal strength is selected for the GNSS system for data processing.
  • the ground data is obtained based on the inversion. .
  • multiple different GNSS system signals can be simultaneously compatible for surface detection.
  • FIG. 7 is a flow chart of a GNSS-R surface detection method according to an embodiment of the present invention.
  • the GNSS-R surface detection method includes the following steps:
  • Step 100 Receive GNSS direct signals and reflected signals at corresponding frequencies of at least two different GNSS systems.
  • the GNSS direct signal is received by a left-handed directional antenna
  • the GNSS reflected signal is received by a right-handed directional antenna.
  • step 100 includes:
  • the GNSS direct signal and the GNSS reflected signal are received by the phased array antenna by obtaining the beam direction with the strongest received signal strength.
  • Step 200 Collect digital IF signals of GNSS direct signals and GNSS reflected signals respectively, wherein digital IF signals of GNSS direct signals received at different GNSS systems are acquired through independent channels, and GNSS reflections received at frequencies of different GNSS systems The digital IF signal of the signal is acquired through a separate channel.
  • Step 300 Select the GNSS direct signal of the corresponding frequency and the digital intermediate frequency signal of the GNSS reflected signal according to the detected intensity or predetermined setting of the intermediate frequency signal at different GNSS system frequencies.
  • Step 400 Acquire multi-channel Doppler shift and multipath delay of the GNSS reflected signal relative to the GNSS direct signal according to the selected digital intermediate frequency signal of the GNSS direct signal and the digital intermediate frequency signal of the GNSS reflected signal. .
  • step 400 may include:
  • Step 410 Acquire a Doppler shift and a delay of the GNSS direct signal according to the digital intermediate frequency signal of the GNSS direct signal.
  • Step 420 The Doppler frequency shift and the delay of the GNSS direct signal are used as GNSS reflection signals.
  • the native code acquires a multi-channel Doppler shift and a multi-path delay of the GNSS reflected signal relative to the GNSS direct signal according to the digital intermediate frequency signal of the GNSS reflected signal.
  • Step 500 Acquire surface parameters according to multi-channel Doppler shift and multi-path delay inversion of the GNSS reflected signal with respect to the GNSS direct signal.
  • a GNSS signal receiving antenna that can receive signals at corresponding frequencies of different GNSS systems, and simultaneously acquiring direct and reflected signals of different frequencies through independent channels in the intermediate frequency extraction phase to obtain digital intermediate frequency signals, based on user settings or Signal strength is selected for the GNSS system for data processing.
  • the ground data is obtained based on the inversion. .
  • multiple different GNSS system signals can be simultaneously compatible for surface detection.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
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  • Geophysics And Detection Of Objects (AREA)
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  • Position Fixing By Use Of Radio Waves (AREA)

Abstract

本发明公开了一种GNSS-R地表探测装置和方法，通过设置可以在不同GNSS系统的对应频率进行信号接收的GNSS信号接收天线，同时在中频提取阶段通过独立通道对每个不同频率的直射和反射信号进行采集以获取数字中频信号，基于用户设定或信号强度选定用于进行数据处理的GNSS系统，通过对数字中频信号的多普勒频移和时延进行分析以获得GNSS反射信号相对于GNSS直射信号的区别，从而基于此反演获取地表数据。由此，可以同时兼容多种不同的GNSS系统信号进行地表探测。

Description

一种GNSS-R地表探测装置和方法
本申请要求了2015年10月19日提交的、申请号为2015106798344、发明名称为“一种GNSS-R地表探测装置和方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及遥感技术领域，具体涉及一种GNSS-R地表探测装置和方法。
背景技术
全球导航卫星系统(GNSS)星座(美国GPS；俄罗斯的GLONASS；中国北斗)的发展为我们提供了一个可连续、丰富、覆盖扫描全球的L波段信号源。在地球表面的任一地方，如今均可同时收到10-20颗GNSS卫星信号。GNSS-R(GNSS反射)的概念最初由法国科学家M.Martin-Neira在1993提出，它利用全球GNSS信号作为遥感发射信号源，地面装置一方面收集导航广播信号，同时对GNSS在地球表面反射的GNSS同源信号同步，进行类似多波段雷达干涉的被动方式观测。其基本原理是通过将GNSS右旋圆极化的直射信号与左旋圆极化的反射信号进行正相交后形成的数据进行多种比较相位分析，利用L波段1575MHz对液态水与其它物质(包括冰)分界线敏感的特点，实时捕捉、采集、分析、处理形成的面状干涉数据。
现有的GNSS-R地表探测装置多采用全向天线进行信号采集，同时通常需要对GNSS信号进行基带解码，基于反射信号C/A码或者P(Y)码进行遥感探测的GNSS-R的技术则需要对信号进行解码，这使得现有的技术通常仅能基于GPS系统的信号进行地表探测。
发明内容
有鉴于此，本发明提供一种GNSS-R地表探测装置和方法，以同时兼容多种不同的GNSS系统信号进行地表探测。
第一方面，本发明提供一种GNSS-R地表探测装置，包括：
第一接收天线，用于在至少两种不同GNSS系统的对应频率接收GNSS直射信号；
第二接收天线，用于在至少两种不同GNSS系统的对应频率接收GNSS反射信号；
中频信号采集装置，用于分别采集所述GNSS直射信号和所述GNSS反射信号 的数字中频信号；其中，中频信号采集装置分别通过独立的通道采集不同GNSS系统的频率下接收的GNSS直射信号的数字中频信号，并分别通过独立的通道采集不同GNSS系统的频率下接收的GNSS反射信号的数字中频信号；
数据处理装置，用于根据检测到不同GNSS系统频率下的中频信号的强度或预定设置选择对应频率的所述GNSS直射信号和所述GNSS反射信号，并根据选定的所述GNSS直射信号的数字中频信号和所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延，并进而反演获取地表参数。
优选地，所述第一接收天线为定向右旋天线，所述第二接收天线为定向右旋天线。
优选地，所述第一接收天线和所述第二接收天线为相控阵天线，其通过扫描获取接收信号强度最强的波束方向进行GNSS信号的接收。
优选地，所述第一接收天线和所述第二接收天线包括：
多个阵列方式排布的天线单元，其中，所述天线单元包括：基板；辐射图案，形成在所述基板的第一面，包括围成矩形形状的四个子图案；以及，馈线图案，形成在所述基板的第二面；
低噪声放大器，与所述天线单元的馈线图案连接；
其中，每个所述子图案包括相互连通的第一部分、第二部分和第三部分；所述第一部分与所述第二部分连通，第二部分相对于第三部分连通，所述第一部分和第三部分为相对于第二部分对称设置且形状相同的矩形；每个子图案的第三部分的端部与相邻的下一个子图案的第一部分的侧部相对设置以使得所述四个子图案围成矩形形状，且四个子图像之间相互不连通。
优选地，所述不同GNSS系统包括全球卫星定位系统、北斗系统、伽利略系统和Glonass系统中的至少两种。
优选地，所述数据处理装置用于根据所述GNSS直射信号的数字中频信号获取所述GNSS直射信号的多普勒频移和时延，并将所述GNSS直射信号的多普勒频移和时延作为GNSS反射信号的本机码，根据所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延。
第二方面，本发明提供一种GNSS-R地表探测方法，包括：
在至少两种不同GNSS系统的对应频率接收GNSS直射信号和反射信号；
分别采集GNSS直射信号和GNSS反射信号的数字中频信号，其中，不同GNSS系统的频率下接收的GNSS直射信号的数字中频信号通过独立的通道获取，不同GNSS系统的频率下接收的GNSS反射信号的数字中频信号通过独立的通道获取；
根据检测到不同GNSS系统频率下的中频信号的强度或预定设置选择对应频率的所述GNSS直射信号和所述GNSS反射信号的数字中频信号；
根据选定的所述GNSS直射信号的数字中频信号和所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延；
根据所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延反演获取地表参数。
优选地，所述GNSS直射信号通过左旋定向天线接收，所述GNSS反射信号通过右旋定向天线接收。
优选地，在至少两种不同GNSS系统的对应频率接收GNSS直射信号和反射信号包括：
通过相控阵天线通过获取接收信号强度最强的波束方向进行GNSS直射信号和GNSS反射信号的接收。
优选地，根据选定的所述GNSS直射信号的数字中频信号和所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延包括：
根据所述GNSS直射信号的数字中频信号获取所述GNSS直射信号的多普勒频移和时延；
将所述GNSS直射信号的多普勒频移和时延作为GNSS反射信号的本机码，根据所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延。
通过设置可以在不同GNSS系统的对应频率进行信号接收的GNSS信号接收天线，同时在中频提取阶段通过独立通道对每个不同频率的直射和反射信号进行采集以获取数字中频信号，基于用户设定或信号强度选定用于进行数据处理的GNSS系统，通过对数字中频信号的多普勒频移和时延进行分析以获得GNSS反射信号相对于GNSS直射信号的区别，从而基于此反演获取地表数据。由此，可以同时兼容多种不同的GNSS系统信号进行地表探测。
附图说明
通过以下参照附图对本发明实施例的描述，本发明的上述以及其它目的、特征和优点将更为清楚，在附图中：
图1是本发明实施例进行GNSS-R地表探测的原理示意图；
图2是本发明实施例的GNSS-R地表探测装置的示意图；
图3是本发明实施例的一个优选的接收天线的示意图；
图4是图3所示天线的天线单元的示意图；
图5是本发明实施例的数据处理装置人机交互界面的示意图；
图6是本发明实施例的GNSS-R地表探测装置获取的多普勒频移-时延图；
图7是本发明实施例的GNSS-R地表探测方法的流程图。
具体实施方式
以下基于实施例对本发明进行描述，但是本发明并不仅仅限于这些实施例。在下文对本发明的细节描述中，详尽描述了一些特定的细节部分。对本领域技术人员来说没有这些细节部分的描述也可以完全理解本发明。为了避免混淆本发明的实质，公知的方法、过程、流程、元件和电路并没有详细叙述。
此外，本领域普通技术人员应当理解，在此提供的附图都是为了说明的目的，并且附图不一定是按比例绘制的。
除非上下文明确要求，否则整个说明书和权利要求书中的“包括”、“包含”等类似词语应当解释为包含的含义而不是排他或穷举的含义；也就是说，是“包括但不限于”的含义。
在本发明的描述中，需要理解的是，术语“第一”、“第二”等仅用于描述目的，而不能理解为指示或暗示相对重要性。此外，在本发明的描述中，除非另有说明，“多个”的含义是两个或两个以上。
图1是本发明实施例进行GNSS-R地表探测的原理示意图。
如图1所示，设置于地面或水面上方的GNSS-R探测装置包括用于接收GNSS直射信号的第一天线和用于接收GNSS反射信号的第二天线。根据空间几何学原理，不考虑大气层等空间传播的不理想因素，镜面反射和直射信号的传播路径差最小为：
R-D＝(2h+d)·sinθ   (1)
其中，h为第一接收天线到反射面(也即，地面或水面)的高度；θ为反射点到某颗卫星的俯仰角；d为GNSS-R探测装置的两个个天线相位中心之间的距离；D为 GNSS直射信号在卫星与第一接收天线之间的几何距离；R为第二接收天线接收的反射信号的信号路径几何长度。
精确测量出直射和反射信号的传播几何路径差ddif＝R-D，即可获得观测到的反射面至接收平台反射天线的垂直高度h为：
Figure PCTCN2015094525-appb-000001
ddif可以通过测量卫星发射的信号经过直射与反射路径分别到达接收机的传播时间差来推算。对于比较平静的湖面或者海面，反射面的有效波高比较小时，反射信号的相干性被保持，直射路径和反射路径的传播时间差通过测量重建直射、反射信号的载波相位状态得到。地面接收机在常规的GPS信号接收强度下，对直射信号载波相位的跟踪精度一般能达到0.01周。
载波相位观测量是在接收机达到载波相位跟踪状态下，隔一定的时间间隔提取的载波相位(或测相伪距)，应用于载波相位的定位解算中。对某一卫星的载波相位观测值由3部分组成：初始整周未知数N0，从开始锁定至n时刻的整周计数C(n)，相位尾数
Figure PCTCN2015094525-appb-000002
在测高应用中，实际提取在第n个历元的直射信号和反射信号的(带有整周模糊度)载波相位观测量
Figure PCTCN2015094525-appb-000003
和
Figure PCTCN2015094525-appb-000004
整周模糊度分别为N0r和N0d。
考虑一颗卫星和一个接收机的情况，这个时候，直射和反射信号的伪距观测方程分别为：
Figure PCTCN2015094525-appb-000005
其中，x(n)为在第n个历元对物理量x进行观测；
Figure PCTCN2015094525-appb-000006
为直射信号载波相位观测量；
Dtro为对流层折射对直射信号传播造成的传播距离上的误差；
Dion为电离层折射对直射信号传播造成的传播距离上的误差；δuclock为用户钟差；
δdsclock为观测直射信号对应的卫星钟差；
Figure PCTCN2015094525-appb-000007
为卫星钟和接收机时钟相噪、接收机硬件相延迟、周跳等对直射信号的载波测量所产生的误差的综合，以周为单位；
Figure PCTCN2015094525-appb-000008
为反射信号载波相位观测量；
Rtro为对流层对反射信号传播造成的传播距离上的误差；
Rion为电离层对反射信号传播造成的传播距离上的误差；
δrsclock为反射信号对应的卫星的钟差；
Figure PCTCN2015094525-appb-000009
为卫星钟和接收机时钟相噪、接收机硬件相延迟、周跳等对反射信号的载波测量所产生的误差的综合，以周为单位。
对同一颗星的直射和反射信号的原始伪距观测方程求差得：
Figure PCTCN2015094525-appb-000010
通过求差，时间同步的用户钟差基本消除。于历元n进行观测直射信号与反射信号对应的卫星钟差由于不是全同步的，故通过δrsclock(n)-δdsclock(n)求差，只削弱了长期稳定度的卫星钟差的影响，没有消除短期稳定度的影响。
对于由对流层造成的传播距离误差，由于直射信号和反射信号通过的传播路径相距较近(<20km)，对流层在距离相近处的物理特性相近，因此将同一卫星的近似同步观测值求差，明显减弱对流层折射的影响，不过对流层接近湖面的折射率值是对流层中最大的，考虑接近湖面处直射和反射信号的传播路径不同，对流层的影响并未完全消除，尤其当直射和反射信号的传播距离差较大的时候。
电离层在空间相近处的物理特性也相近，通过对同一卫星观测的直射和反射信号近似同步观测值求差，电离层的误差获得明显的削弱的效果。由于
Figure PCTCN2015094525-appb-000011
和
Figure PCTCN2015094525-appb-000012
的随机性都比较强，而且它们之间相关性较弱，可以认为基本没有通过求差而削弱。
对式(5)进行简化，表示为：
Figure PCTCN2015094525-appb-000013
其中，
Figure PCTCN2015094525-appb-000014
为直射与反射信号的测相伪距之差，ΔN0＝N0r-N0d为直射与反射信号的整周模糊度的差值，ddif(n)＝R(n)-D(n)为直射与反射信号的几何空间上传播距离的差值，ΔE＝Rtro(n)-Dtro(n)为由于直射和反射信号的传播路径不同，对流层对信号传播造成的影响，这个值可近似求出。Δδsclock(n)＝δrsclock(n)-δdsclock(n)为对应于直射信号与反射信号的卫星钟的差值，
Figure PCTCN2015094525-appb-000015
为直射信号与反射信号的随机观测误差的差值。
对上述单差观测值，进一步进行历元之间求差。求差之后，卫星钟差基本消除，整周模糊度被消除，得到:
Figure PCTCN2015094525-appb-000016
其中，
Figure PCTCN2015094525-appb-000017
ddif(n1,n2)＝ddif(n2)-ddif(n1)     (8b)
Figure PCTCN2015094525-appb-000018
把式(1)带入式(8a)得到
ddif(n1,n2)＝2h(n2)sinθ(n2)-2h(n1)sinθ(n1)+d[sinθ(n2)-sinθ(n1)]  (9)
高度角是利用直射信号对接收机进行定位求解后得到的。由于短时间内(0.1s)高度角只可能产生微小的变化，当n2T-n1T<0.1s时(T代表相邻历元之间的时间间隔)，可以假设sinθ(n2)≈sinθ(n1)，d已知且确定。式(9)可以近似为：
ddif(n1,n2)＝2hddif(n1,n2)sinθ(n1)   (10)
其中h ddif(n1,n2)＝h(n2)-h(n1)。
由式(7)和式(10)得到估计的历元间的湖面高度变化为：
Figure PCTCN2015094525-appb-000019
可见，由于历元n1,n2得到的载波相位观测量计算出湖面高度在历元n1,n2之间的变化。
用上标i,j,…表示由卫星i,j,…的观测值估计出的历元间的湖面高度变化
Figure PCTCN2015094525-appb-000020
Figure PCTCN2015094525-appb-000021
利用一段时间(如历元间隔[n1,nN]之间)内由不同的卫星的观测量得到的高度变化估计值，根据估计质量(由信号的信噪比等判断)进行加权平均，得到平均的高度变化轨迹
Figure PCTCN2015094525-appb-000022
利用信息的冗余性提高系统的可靠性和精度。
由以上方法的求差过程,由电离层、对流层、卫星钟差、卫星星历、接收机钟差等造成的影响基本被消除，得到是残留的较随机误差影响下的高度变化的估计值。
基于以上原理，不需要对GNSS信号进行解码即可以进行地表参数的获取。
图2是本发明实施例的GNSS-R地表探测装置的示意图。如图2所示，所述GNSS-R地表探测装置包括第一接收天线1、第二接收天线2、中频信号采集装置3和数据处理装置4。第一接收天线1和第二接收天线2分别通过射频线缆与所述中频信号采集装置3连接。中频信号采集装置3通过串口或其他数字信号传输接口与数据处理装置4连接。
其中，第一接收天线1用于在至少两种不同GNSS系统的对应频率接收GNSS直射信号。
第二接收天线2用于在至少两种不同GNSS系统的对应频率接收GNSS反射信号。
第一接收天线1和第二接收天线2可以为定向天线也可以为全向天线。
优选地，第一接收天线1为定向右旋天线，可以定向接收右旋圆极化的GNSS直射信号。同时，第二接收天线2为定向左旋天线，可以定向接收左旋圆极化的GNSS反射信号。使用定向天线的好处在于在调节到较好的接收方向后，定向天线可以以更高的增益接收GNSS直射和反射信号，同时，其俯仰角相对确定，可以更好地进行后续时延获取。
更优选地，第一接收天线1和第二接收天线2可以为相控阵天线，通过调节相控阵天线的方向性对不同的方位的接收信号进行扫描，可以获取接收信号强度最强的波束方向，在接收方向确定在该方向来进行GNSS信号的接收以获得最佳的信号接收效果。
图3是本发明实施例的一个优选的接收天线的示意图。图4是图3所示天线的天线单元的示意图。如图3示的天线既可以接收右旋圆极化信号，也可以接收左旋圆极化信号。该优选的接收天线包括四个天线单元以及低噪声放大器。每个天线单元包括基板11、辐射图案12以及馈电图案13。辐射图案12形成在所述基板11的第一面，其包括围成矩形形状的四个子图案121、122、123和124。
其中，每个所述子图案包括相互连通的第一部分a、第二部分b和第三部分c。所述第一部分a与所述第二部分b连通，第二部分b与第三部分c连通，所述第一部分a和第三部分c为相对于第二部分b对称设置且形状相同的矩形。第一部分a、第二部分b和第三部分c的轴线沿直线排列。在本实施例中，第二部分b也形成为矩形，其宽度小于第一部分a和第三部分c，从而使得子图案121-124分别形成为由矩形组成的哑铃状图案。在本实施例中子图案121-124为在导电材料层上镂空形成图案。所述导电材料可以为金、银、铜等金属导电材料也可以为ITO等氧化物导电材料。
在相互位置设置上，四个子图案121-124以循环方式围成矩形。具体地，一个子图案的一侧端部与下一个相邻的子图案的侧边靠近端部的部分相对设置。
更具体地，每个子图案的第三部分c的端部与相邻的下一个子图案的第一部分a的侧部相对设置以使得所述四个子图案围成矩形形状，且四个子图案之间相互不连通。
由此形成的天线单元既可以接收右旋圆极化信号，也可以接收左旋圆极化信号。
同时，馈电图案13设置在基板11上与第一面相对的第二面上。至少包括位于每个子图案的第一部分a的对应的位置的导电图形。
低噪声放大器2与所述馈电图案13导电连接，接收经由辐射图案接收的GNSS电磁信号，进行放大后传输到与所述GNSS接收天线连接的信号处理系统中。优选地，所述低噪声放大器2可以为采用SMA接口的低噪声放大器。低噪声放大器2可以安装在一个支撑部件的侧面，将天线单元接收的信号引出。
由此，通过相同结构的天线既可以形成接收右旋圆极化的第一接收天线和接收左旋圆极化的第二接收天线。同时，采用上述结构的天线可以同时在多个不同频率进行信号接收，从而实现在至少两种不同GNSS系统的对应频率接收GNSS直射信号或GNSS反射信号。
在本实施例中，所述第一接收天线1和第二接收天线2可以同时在GPS系统的L频点，北斗系统的B1、B2和B3频点接收GNSS信号。应理解，本发明也可以适用于基于GPS系统、北斗系统、伽利略系统和Glonass系统中的至少两种系统的信号进行接收、采集和处理。
中频信号采集装置3用于分别采集所述GNSS直射信号和所述GNSS反射信号的数字中频信号；其中，中频信号采集装置分别通过独立的通道采集不同GNSS系统的频率下接收的GNSS直射信号的数字中频信号，并分别通过独立的通道采集不同GNSS系统的频率下接收的GNSS反射信号的数字中频信号。
本发明实施例的中频信号采集装置3可以工作于如下频段。
GPS L1频段：1575.42MHz±0.05MHz；
BD2B1频段：1561.098MHz±0.05MHz；
BD2B2频段：1207.14MHz±0.05MHz；
BD2B3频段：1268.52MHz±0.05MHz；
GLONASS频段：1602±0.05MHz
具体地，本实施例的中频信号采集装置通过四个独立通道分别采集GPS系统的直射信号、反射信号以及北斗系统的直射信号和反射信号的数字中频信号。由此，在不涉及北斗ICD前提下，实现北斗+GPS的双模统一中频信号采集、处理。
数据处理装置4用于根据检测到不同GNSS系统频率下的中频信号的强度或预定设置选择对应频率的所述GNSS直射信号和所述GNSS反射信号，并根据选定的所述GNSS直射信号的数字中频信号和所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延，并进而反演获取地表参数。
由此，数据处理装置4可以利用质量最高的GNSS信号来进行地表探测，也可以根据用户的选定进行地表探测。
具体地，数据处理装置4可以采用根据所述GNSS直射信号的数字中频信号获取所述GNSS直射信号的多普勒频移和时延，并将所述GNSS直射信号的多普勒频移和时延作为GNSS反射信号的本机码，根据所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延。数据处理装置4可以通过承载有进行数据处理程序的通用计算机系统实现，也即，以通用计算机系统执行程序指令的方式进行GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延的求取。
图5是本发明实施例的数据处理装置人机交互界面的示意图；图6是本发明实施例的GNSS-R地表探测装置获取的多普勒频移-时延图。如图5-6所示，本发明的数据处理装置人机交互界面可以显示当前位置，不同的信号强度，以及基于采集的信号反演获得的地表参数(例如，海面的波高、风速、风向等)，基于时延和多普勒频移图进行反演可以采用各类现有的地表参数反演方法进行。
由于本发明实施例采用载波相位检测的方式来获取GNSS反射信号和GNSS直射信号的不同，因此，不需要进行解码，由此，通过对载波信号的接收、中频采集以及处理既可以实现对于多个不同GNSS系统的兼容。同时，采用既可以接收右旋圆极 化信号又可以接收左旋圆极化信号的天线单元构成的阵列进行GNSS信号的定向接收，增强了信号质量，简化了系统结构。进一步地，根据不同GNSS系统的信号，可以选择质量最优的信号进行反演，从而提高了GNSS-R地表探测的准确性。
通过设置可以在不同GNSS系统的对应频率进行信号接收的GNSS信号接收天线，同时在中频提取阶段通过独立通道对每个不同频率的直射和反射信号进行采集以获取数字中频信号，基于用户设定或信号强度选定用于进行数据处理的GNSS系统，通过对数字中频信号的多普勒频移和时延进行分析以获得GNSS反射信号相对于GNSS直射信号的区别，从而基于此反演获取地表数据。由此，可以同时兼容多种不同的GNSS系统信号进行地表探测。
图7是本发明实施例的GNSS-R地表探测方法的流程图。
如图7所示，所述GNSS-R地表探测方法包括如下步骤：
步骤100、在至少两种不同GNSS系统的对应频率接收GNSS直射信号和反射信号。
优选地，GNSS直射信号通过左旋定向天线接收，所述GNSS反射信号通过右旋定向天线接收。
更优选地，步骤100包括：
通过相控阵天线通过获取接收信号强度最强的波束方向进行GNSS直射信号和GNSS反射信号的接收。
步骤200、分别采集GNSS直射信号和GNSS反射信号的数字中频信号，其中，不同GNSS系统的频率下接收的GNSS直射信号的数字中频信号通过独立的通道获取，不同GNSS系统的频率下接收的GNSS反射信号的数字中频信号通过独立的通道获取。
步骤300、根据检测到不同GNSS系统频率下的中频信号的强度或预定设置选择对应频率的所述GNSS直射信号和所述GNSS反射信号的数字中频信号。
步骤400、根据选定的所述GNSS直射信号的数字中频信号和所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延。
其中，步骤400可以包括：
步骤410、根据所述GNSS直射信号的数字中频信号获取所述GNSS直射信号的多普勒频移和时延。
步骤420、将所述GNSS直射信号的多普勒频移和时延作为GNSS反射信号的 本机码，根据所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延。
步骤500、根据所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延反演获取地表参数。
通过设置可以在不同GNSS系统的对应频率进行信号接收的GNSS信号接收天线，同时在中频提取阶段通过独立通道对每个不同频率的直射和反射信号进行采集以获取数字中频信号，基于用户设定或信号强度选定用于进行数据处理的GNSS系统，通过对数字中频信号的多普勒频移和时延进行分析以获得GNSS反射信号相对于GNSS直射信号的区别，从而基于此反演获取地表数据。由此，可以同时兼容多种不同的GNSS系统信号进行地表探测。
以上所述仅为本发明的优选实施例，并不用于限制本发明，对于本领域技术人员而言，本发明可以有各种改动和变化。凡在本发明的精神和原理之内所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种GNSS-R地表探测装置，包括：
    第一接收天线，用于在至少两种不同GNSS系统的对应频率接收GNSS直射信号；
    第二接收天线，用于在至少两种不同GNSS系统的对应频率接收GNSS反射信号；
    中频信号采集装置，用于分别采集所述GNSS直射信号和所述GNSS反射信号的数字中频信号；其中，中频信号采集装置分别通过独立的通道采集不同GNSS系统的频率下接收的GNSS直射信号的数字中频信号，并分别通过独立的通道采集不同GNSS系统的频率下接收的GNSS反射信号的数字中频信号；
    数据处理装置，用于根据检测到不同GNSS系统频率下的中频信号的强度或预定设置选择对应频率的所述GNSS直射信号和所述GNSS反射信号，并根据选定的所述GNSS直射信号的数字中频信号和所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延，并进而反演获取地表参数。
  2. 根据权利要求1所述的GNSS-R地表探测装置，其特征在于，所述第一接收天线为定向右旋天线，所述第二接收天线为定向右旋天线。
  3. 根据权利要求2所述的GNSS-R地表探测装置，其特征在于，所述第一接收天线和所述第二接收天线为相控阵天线，其通过扫描获取接收信号强度最强的波束方向进行GNSS信号的接收。
  4. 根据权利要求3所述的GNSS-R地表探测装置，其特征在于，所述第一接收天线和所述第二接收天线包括：
    多个阵列方式排布的天线单元，其中，所述天线单元包括：基板；辐射图案，形成在所述基板的第一面，包括围成矩形形状的四个子图案；以及，馈线图案，形成在所述基板的第二面；
    低噪声放大器，与所述天线单元的馈线图案连接；
    其中，每个所述子图案包括相互连通的第一部分、第二部分和第三部分；所述第一部分与所述第二部分连通，第二部分相对于第三部分连通，所述第一部分和第三部分为相对于第二部分对称设置且形状相同的矩形；每个子图案的第三部分的端部与相邻的下一个子图案的第一部分的侧部相对设置以使得所述四个子图案围成矩形形状，且四个子图像之间相互不连通。
  5. 根据权利要求1所述的GNSS-R地表探测装置，其特征在于，所述不同GNSS系统包括全球卫星定位系统、北斗系统、伽利略系统和Glonass系统中的至少两种。
  6. 根据权利要求1所述的GNSS-R地表探测装置，其特征在于，所述数据处理装置用于根据所述GNSS直射信号的数字中频信号获取所述GNSS直射信号的多普勒频移和时延，并将所述GNSS直射信号的多普勒频移和时延作为GNSS反射信号的本机码，根据所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延。
  7. 一种GNSS-R地表探测方法，包括：
    在至少两种不同GNSS系统的对应频率接收GNSS直射信号和反射信号；
    分别采集GNSS直射信号和GNSS反射信号的数字中频信号，其中，不同GNSS系统的频率下接收的GNSS直射信号的数字中频信号通过独立的通道获取，不同GNSS系统的频率下接收的GNSS反射信号的数字中频信号通过独立的通道获取；
    根据检测到不同GNSS系统频率下的中频信号的强度或预定设置选择对应频率的所述GNSS直射信号和所述GNSS反射信号的数字中频信号；
    根据选定的所述GNSS直射信号的数字中频信号和所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延；
    根据所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延反演获取地表参数。
  8. 根据权利要求7所述的GNSS-R地表探测方法，其特征在于，所述GNSS直射信号通过左旋定向天线接收，所述GNSS反射信号通过右旋定向天线接收。
  9. 根据权利要求7所述的GNSS-R地表探测方法，其特征在于，在至少两种不同GNSS系统的对应频率接收GNSS直射信号和反射信号包括：
    通过相控阵天线通过获取接收信号强度最强的波束方向进行GNSS直射信号和GNSS反射信号的接收。
  10. 根据权利要求7所述的GNSS-R地表探测方法，其特征在于，根据选定的所述GNSS直射信号的数字中频信号和所述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延包括：
    根据所述GNSS直射信号的数字中频信号获取所述GNSS直射信号的多普勒频移和时延；
    将所述GNSS直射信号的多普勒频移和时延作为GNSS反射信号的本机码，根据所 述GNSS反射信号的数字中频信号获取所述GNSS反射信号相对于GNSS直射信号的多路多普勒频移和多路时延。
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