自动与人工土壤水分观测数据对比分析研究—以西宁市二十里铺气象站为例

通过选取2020年7月至2020年9月期间西宁市二十里铺气象站DZN2、DZN3两种型号的土壤水分自动站土壤体积含水量数据与人工观测土壤体积含水量数据进行统计和一致性分析,验证两种型号自动土壤水分自动站数据的一致性、差异性。通过数据比较分析得出：DZN2型与DZN3型土壤水分自动站的数据与人工观测数据均存在较好的相关性,较DZN3型自动站,DZN2型自动站数据与人工观测数据一致性更好。分析结果可为评估两种型号自动土壤水分站的监测能力提供客观依据。     

自动与人工土壤水分观测数据对比分析研究——以西宁市二十里铺气象观测站为例

通过选取2020年7—9月西宁市二十里铺气象观测站DZN2型、DZN3型2种土壤水分自动站土壤体积含水率数据与人工观测土壤体积含水率数据进行统计和一致性分析,验证2种型号土壤水分自动站数据的一致性、差异性。结果表明:DZN2型、DZN3型土壤水分自动站的测定数据与人工观测数据均存在较好的相关性,其中DZN2型自动站数据与人工观测数据一致性更好。分析结果可为评估2种型号土壤水分自动站的监测能力提供参考。     

前向散射能见度仪应用情况分析

主要介绍了能见度仪的性能与工作原理,分析了在人工与自动2种不同观测方式下所得到的能见度观测数据的差异及原因,以期为合理引用自动能见度仪数据提供参考。     

DSG5型降水现象仪平行观测数据应用评估及误差分析

本文利用营口市气象观测站DSG5型降水现象仪平行观测数据与人工观测数据进行应用评估及误差分析,了解降水现象仪观测结果与人工观测记录的差异,给出针对性建议,以供其他气象台站参考。     

对利用GPS观测值建立区域VTEC模型的研究

本文根据区域电离层延迟模型的原理与方法,利用载波相位、伪距两种GPS观测值建立了区域VTEC电离层模型,并利用地壳网络观测数据对模型的精度进行了检核.     

基于RTK-GNSS和MEMS陀螺仪的车辆航向角测量技术

【目的】更好地满足车辆自动驾驶时航向角测量的精度要求。【方法】提出卡尔曼滤波算法,把实时动态–全球导航卫星系统(RTK-GNSS)测量出来的经纬度和高程经过高斯投影转换为高斯平面坐标,和微电子机械系统(MEMS)陀螺仪测得的累积航向角进行融合处理,最终得到车辆更为精准的航向角。【结果】融合后的航向角度曲线既保持了GNSS航向的整体变化趋势,也保持了陀螺仪航向的细部变化趋势,且较GNSS和陀螺仪所得曲线更为平滑,可以跟踪车辆180°调头的转弯动作。【结论】卡尔曼滤波算法可以实时在线且精准地测得车辆航向角数据,精度较GNSS测量结果提高80%以上。     

探究在降水观测过程中降水现象仪与人工数据观测精度差别

降水观测主要是为了能够提供更加精准的气象信息,目前常用的观测手段分为降水现象仪及人工观测。近几年随着降水现象仪与人工数据观测的综合应用,人们在降水观测中的工作效率得到明显提升,但是为了使其数据信息的精确度更准确。本次对降水现象仪与人工数据观测的精度差别进行分析,人工观测过程中使用雨量筒来实现,通过对雨量筒的定期观察进行记录;自动观测使用的是DSG4降水现象仪,该设备能够对多种降雨类型进行区分。为了增加数据对比的明显性,选择了本地汛期6月、7月、8月进行观察。通过长达3个月的时间进行数据搜集,统计相关数据的精确度,进而使降水观测工作更加顺利的得以开展。     

GPS经典相对静态定位已知数据利用研究

从我国测绘采用的坐标系统与GPS定位的坐标系统的转换分析着手,对坐标转换和距离约束进行了理论研究;同时设计了相关实验,分析比较了实验数据;得到GPS经典相对静态定位有效利用原有对已知点同步观测数据的方法。     

人工观测与自动观测气象数据差异的原因分析

DZZ1-2型自动站自2005年开始试运行,06年正试投入业务运作,本文通过对紫金县气象站人工观测数据与DZZ1-2型自动站数据进行对比,从中找出人工观测与自动观测两种观测体系所获的观测数据存在的差异。     

GPS在定位和面积量测中的误差分析

以河南农业大学校区为研究区域,通过手持GPS仪探讨了不同观测时长、不同观测时间以及不同区域面积对GPS精密度和稳定性的影响。结果表明:不同观测时长对GPS定位的坐标没有影响;不同观测时段中,定位时长为60 s和120 s的稳定度相差不大,而实时定位的稳定度比120 s的稳定度高3倍以上;当地块面积在3 600 m2以下时,GPS测量结果的变化幅度较大,呈不稳定状态,当地块面积在3 600 m2以上时,GPS测量结果的变化幅度逐渐变小,呈现面积越大、误差越小、精度越高的趋势。     

Error Sources Affecting Variable Rate Application of Nitrogen Fertilizer

The accuracy and interaction among global positioning system (GPS) horizontal accuracy, differential GPS (DGPS) sampling frequencies and machine delay times of a hypothetical variable rate applicator for nitrogen (N) fertilizer application based on an application map in Florida citrus were studied. Parameters studied included: five GPS horizontal accuracy levels, two levels of DGPS horizontal accuracy, two DGPS sampling frequencies and two machine delay times. Two integrated models were developed which documented the effects of the parameters. Machine delay time was the most important factor and GPS horizontal accuracy was the second most important.     

DGPS数据分析及定位精度研究

本文进行了DGPS数据分析及定位精度研究。通过试验分析表明，Ag132GPS接收机接收到的卫星信号数可以满足使用卫星数量的要求。采用伪距差分纠偏后，Ag132GPS接收机的DGPS单点定位精度可以达到0．232m，满足亚米级的定位精度。     

GPS在南方林区的应用试验

应用Ｍａｇｅｌｌａｎ Ｐｒｏｍａｒｘ Ｘ－ＣＭ ＧＰＳ接收机在广东省新丰县小镇镇林区进行野外样地定位等试验,结果表明,林冠郁闭度、天线类型、天线高度对卫星信号的接收均有一定的影响;ＧＰＳ在杉木林中基本能定位;ＧＰＳ与ＴＭ卫星影象套合误差小于一上象元;差分ＧＰＳ定位技术在南方山区林业调查应用是可行的。     

天宝Trimble 5800单点定位在林业测量中的应用探析

检测了全球定位系统（GPS）接收机天宝Trimble 5800在复杂地形中的定位精度和在林业测量中应用的可行性。研究表明：天宝Trimble 5800 GPS接收机在不同地形中单点定位时，WGS-84坐标的内符合精度为0 ～ 2 m占65％，2 ～ 5 m占30％，最大偏差＜8 m；经坐标转换后，各历元观测平均值的BJ-54坐标外符合精度都＜5 m，在0 ～ 5 m分布均匀，因此，在同一作业时间段，以在已知点上获得观测值与已知值的偏差值作为其他观测点观测值的改正参数，将有效提高定位精度；在距离和面积测量中，以全站仪测量数据为参考值，天宝Trimble 5800单点定位的相对误差分别优于1/300和1%，比手持GPS定位精度高。图1表8参8     

Centimetre-precision guidance of moving implements in the open field: a simulation based on GPS measurements

High quality and sustainable agricultural production in the open field will be supported by centimetre-precision guidance of agricultural implements. In this paper, a complete guidance system is proposed and simulated using real sensor data obtained from a real time kinematic (RTK) differential global positioning system (DGPS). This type of the satellite navigation system became available commercially in 1997 and is claimed to reach cm accuracy. It uses real time kinematics to improve the accuracy of a position fix by phase comparison of the carrier signal. The simulation primarily aims to investigate the accuracy of the guidance system that can be obtained with RTK DGPS. Using real DGPS measurement errors the simulated system showed a tracking error less than 0.005 m when the PID-controller had settled.     

林冠与山地对GPS定位精度的影响及消减对策

为解决林冠与山地对RTDGPS定位精度影响的难题 ,作者在不同地类、不同地形、不同测程、不同林冠下进行RTDGPS复测实验 ,并获得数据 .通过数据统计分析 ,得出RTDGPS定位精度随上述因素变化的具体规律 .提出了应用高增益天线法、砍树剥枝法、升高天线高于树冠法、伪卫星法、GLONASS法、差分GPS +气压计法、延长观测时间法、插转台法等多种对策 ,在测区内高处设置插转台进行观测、选取适当的觇标高、选用适当的历元数等手段 ,通过增强GPS接收卫星的信号 ,提高定位精度 ,消减林冠、地形、测程等因素对RTDGPS定位效果的影响     

GPS卫星定位导航系统飞播造林试验研究

采用美国国防部星座式全球生卫星定位导航系统和ＧＡＲＭＩＮＧＰＳ９５型接收机进行飞播林导航试验，结果表明，采用ＧＰＳ导航试验，播区平均有效落种率为８６．７％，超过了８５％的国家标准，飞行作业日减少３５％，节省飞播作业导航投工，投资７８％。     

农机直线行走作业DGPS导航软件开发

对于大中型宽幅农业机组的田间行走作业,利用DGPS进行导航具有很多优点,本研究利用VB6.0编程语言,对农机直线行走作业DGPS导航涉及的GPS定位信息的获取、坐标投影变换、导航AB线的确定等编制了相应的程序,开发了应用软件。农业生产中可利用触摸屏计算机实现对机组田间直线行走作业导航。田间作业记录进行模拟试验表明,此软件可有效地实现导航功能,并同时具有作业行走记录和行走距离、作业面积实时显示的功能。     

Performance of two low-cost GPS receivers for ground speed measurement under varying speed conditions

A global positioning system (GPS) receiver is an important sensor used in modern farming, particularly in precision agriculture to determine geographic location and ground speed. The aim of this study was to investigate the effectiveness of two low-cost GPS receivers for measuring ground speed under varying speed conditions on four different dates. A rotary shaft encoder on an auxiliary wheel mounted on an agricultural tractor was used as a reference. A significant time lag between the rotary encoder speed and the GPS speed was found over a range of speeds. It was observed that the GPS speed lagged the encoder speed in both increasing and decreasing speeds. The average time lag was found to be between 3.6 and 5.2 s for Receiver 1 while Receiver 2 had a time lag from 1.7 to 2.5 s. A significant difference was found between the two receivers for increasing and decreasing speeds in terms of time lags (P < 0.05). A post correction by shifting the GPS speed increased the accuracy of the speed measurement capability of both receivers resulting in an average correlation coefficient of 0.30–0.90 for Receiver 1 and 0.65–0.98 for Receiver 2. Effect of USB-to-COM converter was also studied and it did not have a significant effect on time delay. The GPS receivers provided reliable data during constant speed operating conditions; however, caution should be exercised in varying speed conditions when using low-cost GPS receivers. Also, the companies that produce GPS-based speed sensors should supply technical specifications related to velocity estimates during acceleration and deceleration.     

Evaluation of Sub-Meter and 2 to 5 Meter Accuracy GPS Receivers to Develop Digital Elevation Models

The digital elevation model (DEM) is considered by many to be an important base map for a precision farming GIS (Geographic Information System). Previous work has shown that dual-frequency survey grade GPS (Global Positioning System) receivers are capable of rapidly producing accurate positional data from a moving vehicle from which DEM's can be developed. However, this type of GPS receiver is expensive and somewhat difficult to use properly. This paper presents the results of a study to evaluate the potential of using single frequency sub-meter and 2–5 meter horizontal accuracy GPS receivers to enable the farmer to collect multiple passes of GPS data during normal field operations from which DEM's can be developed. The results show that when using a single frequency sub-meter GPS receiver: (1) it is possible to develop a DEM with standard deviation of the elevation accuracy on the order of 0.12–0.14 m, (2) in order to collect data with this level of elevation accuracy, data should only be collected when the GDOP (Geometric Dilution Of Precision) is less than 5.0, (3) at least 10 passes of data with appropriate data averaging is required to produce this level of elevation accuracy. The results also indicate that the vertical error associated with a 2–5 meter horizontal accuracy GPS receiver is such that it is not recommended for use in collecting data to develop DEM's in this application.