GPS Week Number Rollover Timestamp Complement.

Majdi K Qabalin,Saja Abu-Zaideh,Wafa M Hawajreh,Muawya Naser

doi:10.3390/s21237826

Majdi K Qabalin, Saja Abu-Zaideh + Show 2 more

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https://doi.org/10.3390/s21237826

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Abstract

Global Positioning System (GPS) is a global navigation satellite system and the most common satellite system used in navigation and tracking devices. The phenomenon of week number rollover happened recently—a year ago—due to a design limitation in the week number variable that counting weeks which causes vast losses. As many fleet management systems depend on GPS raw data, such systems stopped working due to inaccurate data provided by GPS receivers. In this paper, we propose a technical and mathematical analysis for the GPS week number rollover phenomenon and suggest a solution to avoid the resulting damage to other subsystems that depend on the GPS device’s raw data. In addition, this paper seeks to provide precautionary measures to deal with the problem proactively. The Open Systems Interconnection model (OSI) and transport layer level solution that has been suggested depends on a TCP packet reforming tool that re-formats the value of the week number according to a mathematical model based on a timestamp complement. At the level of the database, a solution is also suggested which uses triggers. A hardware-level solution is suggested by applying a timestamp complement over the GPS internal controller. Complete testing is applied for all suggested solutions using actual data provided by Traklink—a leading company in navigation and fleet management solutions. After testing, it is evident that the transport layer level solution was the most effective in terms of speed, efficiency, accuracy, cost, and complexity. Applying a transport layer level complement mathematical model can fix the consequences of GPS week number rollover and provide stability to all subsystems that used GPS data from infected devices.

Highlights

Time data that is transmitted by operational satellites and used by the Global Navigation System (GPS) is mathematically referenced as the Global Positioning System (GPS) until 1990 and GPS Time (GPST), based on the U.S Naval Observatory (USNO) Atomic time scale
Few microseconds can be accepted as a difference between the GPS and global time standard or the so-called Universal Time Coordinated (UTC), which is calculated by the International
Leap-seconds added to UTC have affected GPS relational difference, as GPS time is always ahead of UTC by a few nanoseconds, and this value varies from day to day [4]

Summary

Introduction

Time data that is transmitted by operational satellites and used by the Global Navigation System (GPS) is mathematically referenced as the GPS until 1990 and GPS Time (GPST), based on the U.S Naval Observatory (USNO) Atomic time scale. USNO is based on both International Atomic Time (TAI) and UTC, using periodic corrections. Few microseconds can be accepted as a difference between the GPS and global time standard or the so-called Universal Time Coordinated (UTC), which is calculated by the International. BIPM achieves ultimate precision, by a few nanoseconds, using comparison processes. For this reason, leap seconds are added in calculations for UTC every specific period in order to maintain ultimate synchronization with the Earth’s rotational period concerning the sun. Leap seconds are added in calculations for UTC every specific period in order to maintain ultimate synchronization with the Earth’s rotational period concerning the sun Such a process is necessary to obtain the proper correction for the time [2]. While the Standard Positioning Service (SPS), a positioning and timing service, provides almost

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