Real-Time Kinematic and High Accuracy Navigation With Low-Cost GPS Receivers

Christian Altmayer

Abstract:	Today's high accuracy applications demand the most accurate ranging information obtainable with satellite navigation systems, the carrier beat phase observable. Common practice is to utilize high-performance (dual-frequency) geodetic-type GPS receivers for these applications costing about US$10,000 each. Instead, the mass-market and the private user segemnt demand low-cost (< US$100), low weight and volume GPS receivers. Furthermore, there are many GPS-related scientific applications where GPS receivers have to be modified and which also require high ranging accuracies. Most often the only possible way is to use receiver experimental kits based on low-cost chipsets allowing broad control over the receiver’s control loops and digital signal processing. Therefore, the important question arises whether low-cost receivers are capable of fulfilling the stringent requirements of high accuracy applications (typically < 10 cm) and how they distinguish from high-end receivers. The Institute of Flight Guidance and Control (IFF) has studied a typical GPS receiver kit based on the PLESSEY (now: MITEL Corp.) chipset due to its research activities on the fields of low-cost pseudolite systems and high precision integrated GPS/IMU systems intended for automated vehicle guidance. When starting with the single-frequency receiver kit only poor pseudorange accuracies were available and any real carrier beat phase was missing. Thus a high precision carrier beat phase had to be developed. Additionally, a high precision pseudorange was implemented by carrier smoothing technique which tremendously reduces the effects of large code noise and multipath. Two low-cost GPS receivers with the developed software were operated in a differential mode and compared with a pair of high-end dual-frequency receivers. The tests show that low-cost GPS receivers are even suitable for real-time kinematic (RTK) high accuracy positioning.
Published in:	Proceedings of the 2001 National Technical Meeting of The Institute of Navigation January 22 - 24, 2001 Westin Long Beach Hotel Long Beach, CA
Pages:	604 - 613
Cite this article:	Altmayer, Christian, "Real-Time Kinematic and High Accuracy Navigation With Low-Cost GPS Receivers," Proceedings of the 2001 National Technical Meeting of The Institute of Navigation, Long Beach, CA, January 2001, pp. 604-613.
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