Research in Communication Technique and Methods Improving Using Accuracy of Agricultural GPS

Abstract: It is certain developing trend of agricultural information technology to apply GPS and GIS to agriculture. The application of GPS in agricultural field is indivisible with GIS. Studying the using characteristic of agricultural GPS and its integration with GIS becomes a new agricultural task. AgGPS 132 is the object in this thesis and some research work is done about it.Firstly, the thesis summarizes the functions, features, application status quo and developing trend of AgGPS 132 receiver and Arc View GIS. The main supporting technologies of precision agriculture are discussed. This establishes theoretical basis for subsequent study. The communicative problem between common portable computer and AgGPS 132 receiver is developed with Visual Basic. Some points that must be paid attention to in this process have been studied. The unreliable and useless data are get rid of. That is to say, only useful data to us are reserved. Then they are saved in the database for later use. This research work completely departs from AgGPS 170 field computer. So it not only provide technical support for establishing low cost and homemade agricultural GPS system, but also settles foundation for founding new methods to handle GPS data and developing equipments of precision agriculture on the basis of AgGPS 132 ourselves. Because the data format of AgGPS 132 can't be imported to Arc View directly, we must transform it to the data format of Arc View by an interface software. So their data formats are deeply studied and the software is developed. Thus, the AgGPS 132 data can be handled using Arc View. Many functions such as field information map, contrastive map of yearly yield, prescription map, etc. can be made. In order to improve using accuracy of agricultural GPS, by analyzing the error of point, polyline, polygon, several methods are produced such as arithmetic average value, least squares, adding control points, etc. Their principles, features and limitations are also analyzed and discussed. The mathematic model of average error method included in adding control points is established. Many experiments are carried out to testify the methods above and the resules gained by them are contrasted with that gained by AgGPS 170 field computer. It is proved that these methods can improve the using accuracy of AgGPS 132. Compared with the results of AgGPS 170 field computer, the comparative position error of point is reduced by 40%, the accuracy of perimeter is inproved by above 8.75% and that of area is above 25%. This not only makes the more accurate work possible, but settles theoretical and practical basis for developing our own system to apply to precision agriculture. So it has important value…
Key words: precision agriculture; GPS; GIS; data format; precision

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