共查询到20条相似文献，搜索用时 406 毫秒
1.
ZHANGXiaohong LIUJingnan 《地球空间信息科学学报》2004,7(3):218-224
The error sources related to the laser rangefinder, GPS and INS are analyzed in details. Several coordinates systems used in airborne laser scanning are set up, and then the basic formula of system is given.This paper emphasizes on discussing the kinematic offset correction between GPS antenna phase center and laser fired point. And kinematic time delay influence on laser footprint position, the ranging errors, positioning errors, attitude errors and integration errors of the system are also explored. Finally, the result shows that thekinematic time delay can be neglected as compared with other error sources. The accuracy of the coordinates is not only influenced by the amplitude of the error, but also controlled by the operation parameters such as flight height, scanning angle amplitude and attitude magnitude of the platform. 相似文献
2.
This paper presents a data processing strategy for GPS kinematic Positioning by using a GPS active network to model the GPS errors in double difference observable.Firstly,the double difference residuals are estimated between the reference stations in the active network.Then the errors at a user station are predicted as the network corrctions to user measurements,based on the location of the user,Finally conventional kinematic positioning algorithms can be applied to determine the position of the user station.As an example,continuous 24-hour GPS data in March 2001 has been processed by this method.It clearly demonstrates that,after applying these corrections to a user within the network,both the success rate for ambiguity resolution and the positioning accuracy have been significantly improved. 相似文献
3.
Yonghong Yang 《地球空间信息科学学报》2011,14(1):68-72
In this paper,a special geometry case of spaceborne-airborne bistatic SAR(SA-BiSAR) is considered,in which satellite and aircraft flight paths are parallel and their antennas are steering at the strip map.This case is a simple but typical application example,which is applicable for non-cooperative illumination.The integration time of SA-BiSAR system is derived via the motion of transmitter and receiver footprint.In parallel and stripmap mode,Doppler frequency is obtained through the combination be-tween spaceborne and airborne SAR.Other Doppler properties have been envisaged,including Doppler bandwidth and azimuth resolution.The overall simulation experiments are conducted and some characteristics are exhibited.The critical parameters,which have the significant effect on the SA-BiSAR Doppler properties,are extracted by analytical expressions and numerical simulations.In parallel and strip map mode and with reference to ENVISAT-1,SA-BiSAR system possesses the potential of yielding 10 m azi-muth resolution and 0.5 s integration time for C-band via the analysis of simulation results. 相似文献
4.
Dynamic characteristics of large structures,such as tall buildings,long-span suspension,cable-stayed bridges and tall chimneys,are key to assess their drift and stress conditions.The dynamic characteristics of large structures are difficult to measure directly under the condition of earthquakes or strong winds using traditional techniques such as laser collimator,total station and accelerometers.Therefore there is a great need for developing new method or technique for this purpose.Recent advances in Global Positioning System (GPS) technology provide a great opportunity to monitor long-period changes of structures reliably.GPS receivers capable to gauge the motion at the centimeter or sub-centimeter level with sampling frequency 10Hz or even 20 Hz are now available from several manufacturers.To the authors' knowledge,the capability of identifying dynamic characteristics from GPS observations has not been widely verified.For the feasibility study on using kinematic GPS technology to identify the dynamic characteristics of tall buildings,some experiments were conducted in a simulative environment.This paper discusses in detail the experiment device,and the ways through them GPS data are recorded,processed and analyzed.With post-processing version of NovAtel's Softsurv software and auto-regressive (AR) spectral analysis method,relative displacements and corresponding vibrating frequencies have been derived from GPS observations.The results indicate that the dynamic characteristics can be identified accurately by kinematic GPS technology. 相似文献
5.
LUOHeping SHIXiaoyan LIUHui 《地球空间信息科学学报》2005,8(1):19-22
Real-time kinematic GPS precise positioning has been playing an increasing role in both surveying and navigation. Based on the city‘s fibre LAN network, Shenzhen Continuous Operating Reference Stations (SZCORS) system has been established and consists of GPS reference stations, system control center, user‘s data center, and real-time datacom network. The SZCORS system provides users the real-time centimeter positioning or post-processing millimeter positioning. This paper makes discussion on the structure of SZCORS system. Some experiments have been made to test the usablity, and then the data has been analyzed. 相似文献
6.
Analyses and Solutions of Errors on GPS／GLONASS Positioning 总被引：1，自引：0，他引：1
ZHANGYongjun WANGZemin 《地球空间信息科学学报》2002,5(2):6-12
This paper focuses mainly on the major errors and their reduction approaches pertaining to combined GPS/GLONASS positioning.To determine thd difference in the time reference systems,different receiver clock offsets are introduced with respect to GPS and GLONASS system time.A more desirable method for introducing a independent unknown parameter of fifth receiver,which can be canceled out when forming difference measurements,is discussed.The error of orbit integration and the error of transformation parameters are addressed in detail.Results of numerical integration are give.To deal with the influence of ionospheric delay,a method for forming dual-frequency ionospheric free carrier phase measurements is detailed. 相似文献
7.
MWRI (MicroWave Radiation Imager) is one of the payloads on our next generation polar meteorological satellite FY-3. MWRI conically scans with a fixed incident angle on the earth surface. It is the first time for Chinese remote sensor to use this scan mode. In this work, we present a geolocation method for FY-3 MWRI’s remote sensing image based on its special scan geometry. The integrated coordinate systems and the specific relationships with these coordinate systems are defined. A spatial relationship model between the remote sensing data and the earth-based coordinate system is established. This method also includes an algorithm of satellite orbit computation, which is used to get the satellite’s instantaneous velocity vector from its position. This method has been applied to MWRI’s remote sensing image geolocation. The results show that the accuracy of this method can achieve 1 pixel. The 33 GCPs (Ground Control Points) which are in the regiones of FY-3 MWRI’s observation have been collected and used to analyze the precision of the geolocation. By statistical analysis, the error along-track is about 1.5km, and the error along-scan is about 3.0km. It is obvious that this method fulfills the requirement of precision for FY-3 MWRI whose space resolution exceeds 5km. 相似文献
8.
CHENChujiang LIDeren ZHUQing 《地球空间信息科学学报》2005,8(1):33-38
This paper presents the studies of the refining of IKONOS-2 RPC, the transform of the datum, the mode of the control point distribution and the method of IKONOS stereo triangulation, so that IKONOS imagery can be used to collect the precise geospatial data and produce the large scale map. The transform between the IKONOS-2 image space and the national coordinate system based on the RPC have been developed, and the results of block adjustment with various control schemes in a practical project near Himalayas have been examined and analysed. The encouraging results of high positioning accuracy have been obtained. 相似文献
9.
Hüseyin Baki lz 《地球空间信息科学学报》2000,3(1):66-69
1 IntroductionChnventional DGPS is limited by the range overwhich the differential corrections are valid due tothe rapid decorrelation of the error sources with in-creasing distance from the reference station to user.In wide area differential GPS (WWPS) errorsources in GPS measurements are medeled sepa-rately,on the basis of a limited number of referencestaitOns, to overcome this drawback. The main er-ror sources are regarded as broadcast ephemeris er-ror,atmospheric refraction and satel… 相似文献
10.
JIAO Wenhai GUO Hairong FU Yang WEI Ziqing 《地球空间信息科学学报》2005,8(3):220-224
The absolute rate of mean sea level of Xiamen area is derived from the data of Xiamen tide gauge station and Xiamen GPS fiducial station of crustal movement observation network of China（CMONC）. The height variation is discussed deeply in this paper, h is shown that height has periodic variations. So the rate of vertical land movement can not be precisely obtained only from several GPS campaigns. It is pointed out that the vertical crustal movement of tide gauge station should be monitored by using long-term continuous GPS observations. 相似文献
11.
GPS单点测速的误差分析及精度评价 总被引：6，自引：0，他引：6
首先从理论和实测数据模拟两方面分析了SA取消后各类误差源对GPS测速的影响,推导并计算了GPS单点测速可能达到的精度水平。然后用静态数据模拟动态测速试验和实测动态数据测速与同步高精度惯导测速的动态试验进行验证。结果表明,采用载波相位导出的多普勒观测值使用静态数据模拟动态测速,其精度可以达到mm/s级;用接收机输出的多普勒观测值进行测速时,其精度为cm/s级。在动态测速试验中,GPS单点测速方法（即多普勒观测值测速与导出多普勒观测值测速）间的符合精度达到cm/s级,与高精度的惯导测速结果的符合精度为dm/s级,而且和运动载体的动态条件（如加速度和加速度变化率的大小）具有很强的相关性。 相似文献
12.
13.
Since the Selective Availability was turned off, the velocity and acceleration can be determined accurately with a single GPS receiver using raw Doppler measurements. The carrier-phase-derived Doppler measurements are normally used to determine velocity and acceleration when there is no direct output of the raw Doppler observations in GPS receivers. Due to GPS receiver clock drifts, however, a GPS receiver clock jump occurs when the GPS receiver clock resets itself (typically with 1 ms increment/decrement) to synchronize with the GPS time. The clock jump affects the corresponding relationship between measurements and their time tags, which results in non-equidistant measurement sampling in time or incorrect time tags. This in turn affects velocity and acceleration determined for a GPS receiver by the conventional method which needs equidistant carrier phases to construct the derived Doppler measurements. To overcome this problem, an improved method that takes into account, GPS receiver clock jumps are devised to generate non-equidistant-derived Doppler observations based on non-equidistant carrier phases. Test results for static and kinematic receivers, which are obtained by using the conventional method without reconstructing the equidistant continuous carrier phases, show that receiver velocity and acceleration suffered significantly from clock jumps. An airborne kinematic experiment shows that the greatest impact on velocity and acceleration reaches up to 0.2 m/s, 0.1 m/s2 for the horizontal component and 0.5 m/s, 0.25 m/s2 for the vertical component. Therefore, it can be demonstrated that velocity and acceleration measurements by using a standalone GPS receiver can be immune to the influence of GPS receiver clock jumps with the proposed method. 相似文献
14.
15.
GPS多普勒频移测量速度模型与误差分析 总被引：10，自引：0，他引：10
利用GPS多普勒频移观测量可以获得高精度的速度测量结果。文中先给出GPS载波相位观测方程，在此基础上，详细推导了GPS多普勒频移测量载体速度的数学模型。然后在相对测量模式下，讨论各种误差对速度的影响。 相似文献
16.
Hung Lee Jinling Wang Chris Rizos Dorota Grejner-Brzezinska Charles Toth 《GPS Solutions》2002,6(1-2):34-46
This paper discusses the introduction of pseudolites (ground-based GPS-like signal transmitters) into existing integrated
GPS/INS systems in order to provide higher availability, integrity, and accuracy in a local area. Even though integrated GPS/INS
systems can overcome inherent drawbacks of each component system (line-of-sight requirement for GPS, and INS errors that grow
with time), performance is nevertheless degraded under adverse operational circumstances. Some typical examples are when the
duration of satellite signal blockage exceeds an INS bridging level, resulting in large accumulated INS errors that cannot
be calibrated by GPS. Such a scenario, unfortunately, is a common occurrence for certain kinematic applications. To address
such shortcomings, both pseudolite/INS and GPS/pseudolite/INS integration schemes are proposed here. Typically, the former
is applicable for indoor positioning where the GPS signal is unavailable for use. The latter would be appropriate for system
augmentation when the number and geometry of visible satellites is not sufficient for accurate positioning or attitude determination.
In this paper, some technical issues concerned with implementing these two integration schemes are described, including the
measurement model, and the appropriate integration filter for INS error estimation and correction through GPS and pseudolite
(PL) carrier phase measurements. In addition, the results from the processing of simulated measurements, as well as field
experiments, are presented in order to characterize the system performance. As a result, it has been established that the
GPS/PL/INS and PL/INS integration schemes would make it possible to ensure centimeter-level positioning accuracy even if the
number of GPS signals is insufficient, or completely unavailable.
Electronic Publication 相似文献
17.
Due to their low cost and low power consumption, single-frequency GPS receivers are considered suitable for low-cost space applications such as small satellite missions. Recently, requirements have emerged for real-time accurate orbit determination at sub-meter level in order to carry out onboard geocoding of high-resolution imagery, open-loop operation of altimeters and radio occultation. This study proposes an improved real-time kinematic positioning method for LEO satellites using single-frequency receivers. The C/A code and L1 phase are combined to eliminate ionospheric effects. The epoch-differenced carrier phase measurements are utilized to acquire receiver position changes which are further used to smooth the absolute positions. A kinematic Kalman filter is developed to implement kinematic orbit determination. Actual flight data from China’s small satellite SJ-9A are used to test the navigation performance. Results show that the proposed method outperforms traditional kinematic positioning method in terms of accuracy. A 3D position accuracy of 0.72 and 0.79 m has been achieved using the predicted portion of IGS ultra-rapid products and broadcast ephemerides, respectively. 相似文献
18.
19.
Dong-Hwan Hwang Sang Heon Oh Sang Jeong Lee Chansik Park Chris Rizos 《GPS Solutions》2005,9(4):294-311
Due to their complementary features of GPS and INS, the GPS/INS integrated navigation system is increasingly being used for
a variety of commercial and military applications. An attitude determination GPS (ADGPS) receiver, with multiple antennas,
can be more effectively integrated with a low-cost IMU since the receiver gives not only position and velocity data but also
attitude data. This paper proposes a low-cost attitude determination GPS/INS integrated navigation system. The proposed navigation
system comprises an ADGPS receiver, a navigation computer unit (NCU), and a low-cost commercial MEMS IMU. The navigation software
includes a fault detection and isolation (FDI) algorithm for integrity. In order to evaluate the performance of the proposed
navigation system, two flight tests have been performed using a small aircraft. The first flight test confirmed the fundamental
operation of the proposed navigation system and the effectiveness of the FDI algorithm. The second flight test evaluated the
performance of the proposed navigation system and demonstrated the benefit of GPS attitude information in a high dynamic environment.
The flight test results show that the proposed ADGPS/INS integrated navigation unit gives reliable navigation performance
even when anomalous GPS data is provided and gives better navigation performance than a conventional GPS/INS unit. 相似文献
20.
The Global Differential GPS (GDGPS) system developed by JPL aims at seamless global real-time positioning at the dm accuracy level for dual-frequency receivers either fixed or mobile, anywhere and at any time. The GDGPS system relies on GPS data transmitted in real-time to a central processing center at JPL from a global network of permanently operating GPS dual-frequency receivers. At the processing center, the Internet-based Global Differential GPS (IGDG) system, the heart of JPLs GDGPS, generates and disseminates over the open Internet special 1-s global differential corrections (IGDG corrections) to the GPS broadcast ephemerides. The IGDG corrections enhance the accuracy of GPS broadcast orbits and clocks down to the dm level and serve as the key-factor for high-precise real-time positioning of a stand-alone receiver. An experimental verification of the dm positional accuracy of the IGDG system was carried out in the Netherlands, by means of both a static and a kinematic test. During the static test GPS data were collected for 5 consecutive days using a fixed immobile receiver and processed as if in real-time. Within the framework of the kinematic test, an experiment was carried out using a kinematic platform. Our tests confirmed the dm accuracy of stand-alone receiver positioning with IGDG. The standard deviation for positioning both in static and kinematic mode appears to be 10 cm in each horizontal component and 20 cm in the vertical component. More than 99% of the IGDG corrections were received with the expected 1-s interval in the field via mobile communication, the latency of the corrections was generally from 7 to 8 s. 相似文献