GPS (Global Positioning System) will be "zero" on April 6 this year, ushering in a new cycle. Recently, at the RSA us information security conference held in San Francisco, some experts predicted that the old GPS system would make a mistake similar to the computer millennium bug on April 6. Netizens are eager to pay attention to the global positioning system zeroing? What is the impact of GPS zeroing? Let's have a look.
GPs' zeroing 'is actually a popular term for' GPS week reversal '. The CGSIC recently issued a notice that the GPS whole week count will change from 1023 to 0 at 24:00 on April 6, 2019, which is called GPS week reversal.
The emergence of this phenomenon is related to the interface design of the GPS system at that time. It is learned that as a global navigation, positioning and time service system, the GPS system established a set of time system at the beginning of the design, which is called 'GPS time', and this starting point corresponds to 0:00 UTC time on January 6, 1980. In order to achieve the purpose of time service, the GPS system continuously broadcasts the GPS time corresponding to the current time to the user through the navigation signal, and the system designers jointly represent the time difference between the current time and the initial GPS time through the week count (WN) and the intra week second (tow), so as to obtain the current UTC time by combining the leap second and complete the time service.
For many reasons, at the beginning of GPS design, the designer only used 10bit to represent the WN, resulting in the WN can only cycle between 0-1023. When the WN changes from 1023 to 0, the GPS cycle number will be reversed, and it is said to welcome the new week. The time from 1024 weeks to the year is about 19.7 years. From the starting time of GPS system, the last GPS week reversal occurred on August 21, 1999, this time on April 6, 2019, and the next GPS week reversal will occur on November 20, 2038.
Possible impacts:
Without GPS cycle reversal preprocessing, the output time of GPS receiver will return to about 19 years ago. This may affect any system and application relying on GPS timing. It is reported that in the field of civil aviation, time service is basically completed by satellite navigation system, and all automatic equipment is based on this time.
Therefore, the cycle reversal may lead to the confusion of ATC radar signal data, the interruption of data and the uncorrelation of target track and plan.
At the same time, the information exchange between meteorological equipment can not automatically complete the alignment of meteorological information due to time hopping, resulting in difficulties in weather forecast, which may affect flight scheduling and bring unnecessary losses.
In addition, the reversal of GPS receiver will also have an impact on the operation of the infrastructure in the fields of power service and financial automation. If bits system only refers to GPS timing signal, it may cause system paralysis.
Solution:
In order to avoid the impact, all industries should contact the supplier of GPS receiver in advance to inquire whether there is a problem of timing error caused by GPS week turnover, and make a good plan and simulation test.
As for China's Beidou system, there is also the problem of BD cycle number reversal. However, in the design, the cycle number is expressed as 13bit, and the reversal cycle is 8192 weeks, about 160 years, thus effectively avoiding this problem. However, as long as the satellite navigation system has the problem of cycle reversal, the cycle time is different.