| Precision Agriculture (PA), as modern high-tech information agriculture, has made arapid process. Now it is considered as an efficient development mode of the worldwideagriculture and a very hot domain of agriculture high-tech research in the 21st century. However,a great deal of high dense and all-sided farmland information in details must be provided to us.Global Position System (GPS) is a very wonderful method to show farmland's locationinformation synchronously. As the base and important technology sustain of PA, GPS has agreat application foreground and inestimable action on modern agriculture practice.GPS receiver, user's equipment, has some questions in application of PA, such as costly,big and difficult to be carried, hard to be developed and integrated. So GPS-OEM moduleprevails and be used widely because of its good performance, low price, small and light, easilyto be integrated. Lower than GPS receiver and to be developed easily, GPS data acquisition andcommunication system has been developed with small OEM module and IT, which has been anew trend.With OEM as GPS signals sensor and ARM SCM as CPU, the design was put forward,joined with electronics, computer and communication technology. GPS information(mainlyGPGGA) from OEM was proceeded according to design demands step by step to realizefarmland's exact orientation at adequate setting accuracy with difference and no differenceworking mode, at the same time matched with relevant users' terminals, such as LCD,keyboards. The system possesses many advantages: small and light, simply operation, low costand easy to be integrated.The paper first summarizes the generally internal and overseas situation of GPSapplication in PA, as well as GPS-OEM's situation. Next introduces GPS theory and ARMtechnology. Based on GPS-OEM principles, hardware circuits design and software programs ofthis system are put forward, focus on GPS data acquisition part, including ARM SCM samplingdata, storing and display. At last, this developed GPS-OEM system was practiced and tested,following data processing, precision of system estimating and performance analysis, etc.Based on secondary development of OEM, by the type of GARMIN GPS15L (OEMmodule) and SUMSUNG S3C44B0 (32 bit ARM SCM), in term of international standardNMEA-0183, a small GPS fixing data information acquisition system was developed. In thisdesign, ARM embedded system by way of hardware platform, real-time operation systemμC/OS-II was programmed for OEM system's stability and expansibility. Because μC/OS-IIcan realize resource management and program flow control, depress hardness of systemsoftware design and debugging, and increasing system reliability. In addition, when otherfunctions or system integration to be added again, for example, GPRS instead of broadcastingstation in DGPS mode, primary software should be programmed again even if they were able todebug successfully, most time lost and much new matter comes up. So joining operation systemUC/OS-II to SCM as system running platform is very essential to avoid those disadvantages.There are two parts in this system software: embedded real-time operation system and user'sprograms on it. In the design, the former used as running platform and applications implementOEM system's functions. They cooperate and supply with each other harmoniously.After debugging successfully, OEM System was packed and tested at certain place of theplayground. Four types of experiments: OEM system testing and DGPS testing mode (bothdynamic and static), recording experimental data and analyzing differences with practice. Inconclusion, this developed OEM system's fixing value: Single Orientation Precision: <6m,DGPS Orientation Precision: <3m .During the testing course, OEM system showed that it hasgood reliability, precision, repeatability and automatic level, so it can be installed onagricultural implements or vehicles to show its position as demands with the value: single<6m,DGPS<3m.Because of its small, automatic, integrated and low-cost character, this system hasdefinite application value.
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