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Time Varying Kalman Filter Processing to Predict the Future Errors of a GPS Receiver Receiver and the Data Collection To collect the position data, a low cost GPS engine manufactured by Rockwell Company, MicroTracker Low Power (MLP), was used. It is a single-board, five parallel-channel GPS engine suitable for integration into a wide variety of Original Equipment Manufacturer (OEM) products. The receiver tracks up to nine satellites, providing accurate satellite positioning data, with power requirements suitable for integrating handheld products. At power-up or after a reset, the MLP operates in a default mode unless commanded to do otherwise. After a brief start-up period from two to four seconds, the receiver provides a binary message containing some useful information about time, position, velocity, and receiver status. In order to setup the receiver, we designed and implemented a hardware system containing a microcontroller and its peripherals. As shown in Figure-1, the microcontroller is connected to the GPS engine through its serial port and can receive and save the data produced by the receiver. A keyboard and LCD panel is used to command the system and display the result respectively. To collect and process the data, the system was installed in a fixed and known position and the collected data was saved in a PC, through an external RS232 port, for several times [5, 6].  Figure-1: Hardware Structure. |