Week Number Rollover in the Global Positioning System (GPS)

EN
On April 6, 2019, one era of global positioning system ended and another began, an event that affected some old equipment or systems, which are based on GPS for time and location.

When American GPS was first implemented, the time and date function was defined as a 10-bit number (210 = 1024). Unlike the Gregorian calendar (currently used), which uses the date format year, month and day, GPS data is a “week number” or WN (week number). WN is transmitted as a 10-bit field and reverts, or resets to zero, every 1024 weeks (19.7 years = 19 years, 7 months, 2 weeks).

The GPS week started on January 6, 1980 and from that moment the counter was incremented by one each week and transmitted as part of the GPS message. It returned to zero for the first time at midnight on August 21-22, 1999. The second reset took place on the night of April 6-7, 2019, when GPS week 2047, represented as 1023 in the counter, advanced and moved again to 0.

The next rollover should take place on November 25, 2038, but efforts have been made to avoid this problem – or at least send it back :mrgreen: – and the modernized GPS navigation message uses a field on 13 bits that are repeated every 8,192 weeks – 157 years (157 years, one month, one week ­čśÄ ).
This phenomenon is specific only to the American GPS and affects only the interpretation of the date (day, month, year). The time continues to operate with unaltered accuracy.
Other satellite navigation systems developed after GPS, such as Russian GLONASS, European Galileo or Chinese BeiDou, are not affected by this problem.

However, tests of GPS devices have revealed that not all manufacturers implementations correctly address the WN resumption of April 6, 2019. In addition, some programs interpret the WN parameter as compared to a date other than the (initial) January 5, 1980. These devices should not be affected by the WN reset on April 6, 2019, but may have similar issues at a later date. If you own a newer commercial device with updated software, you’re probably fine.

GPS is not only used for positioning, but also for precise time control. Extremely accurate time is required to precisely synchronize records, payment operations, mobile telephony, space and aviation activities and more.
One nanosecond time (10-9 seconds = 0.000000001 s) equals one foot (0.3048 m) distance at speed of light.
Due to the reduced use of GPS and the relatively limited consumption at that time, during the 1999 rollover, the interruption was minor. Among the products known to have been affected by the 2019 reset, we include Honeywell’s flight management and navigation software, which has caused delays for a KLM flight and cancellations for numerous flights from China, as technicians have not managed to apply updates on time, the New York City Wireless Network (NYCWiN) that stopped, mobile phones that were sold in 2013 or earlier, weather balloons from the Australian Bureau of Meteorology, weather beacons from the National Oceanic and Atmospheric Administration (NOAA), many scientific tools and GPS navigation devices for consumers.

 

 

A ticket machine from Prague showing August 23 (instead of April 8) after the  GPS weeks rollover in 2019.

 

 

 

A USB GPS clock receiver for computer.

And the GPS time message received and decoded with a simple leisure software.

RO
La 6 aprilie 2019 s-a ├«ncheiat o epoc─â a sistemului de pozi╚Ťionare global─â ╚Öi a ├«nceput alta, un eveniment care a afectat unele echipamente sau sisteme vechi, ce se bazeaz─â pe GPS pentru timp ╚Öi loca╚Ťie.

C├ónd a fost implementat pentru prima dat─â GPS american, func╚Ťia de timp ╚Öi dat─â a fost definit─â ca num─âr pe 10 bi╚Ťi (210=1024). Spre deosebire de calendarul gregorian (utilizat ├«n prezent), care folose╚Öte formatul de dat─â tip an, lun─â ╚Öi zi, data GPS este un ÔÇ×num─âr de s─âpt─âm├ón─âÔÇŁ sau WN (week number). WN este transmis ca un c├ómp de 10 bi╚Ťi ╚Öi se reia, sau se reseteaz─â la zero, la fiecare 1024 de s─âpt─âm├óni (19,7 ani = 19 ani, 7 luni, 2 s─âpt─âm├óni, 5 zile, 22 ore, 6 minute ╚Öi 40 de secunde ­čśÄ ) .
S─âpt─âm├óna GPS a ├«nceput pe 6 ianuarie 1980 ╚Öi din acel moment contorul a fost majorat cu unu ├«n fiecare s─âpt─âm├ón─â ╚Öi transmis ca parte a mesajului GPS. A revenit la zero pentru prima dat─â la miezul nop╚Ťii de 21-22 august 1999. Cel de-al doilea reset a avut loc ├«n noaptea de 6-7 aprilie 2019, c├ónd s─âpt─âm├óna GPS 2047, reprezentat─â ca 1023 ├«n contor, a avansat ╚Öi a trecut iar la 0.

Urm─âtoarea reluare ar trebui s─â aib─â loc pe 25 noiembrie 2038, dar s-au depus eforturi pentru a evita acest tip de problem─â – sau cel pu╚Ťin s─â o trimit─â mai la spate :mrgreen: – ╚Öi mesajul de navigare GPS modernizat utilizeaz─â un c├ómp pe 13 bi╚Ťi care se repet─â la fiecare 8.192 s─âpt─âm├óni – 157 de ani (157 ani, o lun─â, o s─âpt─âm├ón─â, o zi, 13 ore, 26 minute ╚Öi 40 secunde).
Acest fenomen este specific doar GPS-ului american ╚Öi afecteaz─â numai interpretarea datei (zi, lun─â, an). Ora func╚Ťioneaz─â┬á ├«n continuare cu precizie nealterat─â.
Alte sisteme de naviga╚Ťie prin satelit dezvoltate dup─â GPS, precum GLONASS rusesc, Galileo european sau BeiDou chinezesc, nu sunt afectate de aceast─â problem─â.

Cu toate acestea, testele unor dispozitive GPS au relevat faptul c─â nu toate implement─ârile produc─âtorilor se ocup─â corect de reluarea WN din 6 aprilie 2019. ├Än plus, unele programe interpreteaz─â parametrul WN ├«n compara╚Ťie cu o alt─â dat─â dec├ót cea (ini╚Ťial─â) de 5 ianuarie 1980. Aceste dispozitive nu ar trebui s─â fie afectate de resetul WN la 6 aprilie 2019, dar pot avea probleme similare la o dat─â viitoare. Dac─â de╚Ťii un dispozitiv comercial mai nou cu software actualizat, cel mai probabil stai bine.

GPS-ul nu este folosit doar pentru pozi╚Ťionare, ci ╚Öi pentru reglarea precis─â a timpului. Precizia extrem─â a timpului este necesar─â pentru a sincroniza cu exactitate ├«nregistr─âri, opera╚Ťii de plat─â, telefonie mobil─â, activit─â╚Ťi spa╚Ťiale ╚Öi de avia╚Ťie ╚Öi altele.
O nanosecund─â (10-9 secunde = 0,000000001 s) echivaleaz─â cu un picior (feet) = 0.3048 m.
Datorit─â utiliz─ârii reduse a GPS-ului ╚Öi a consumului relativ limitat la data respectiv─â, ├«n timpul resetului din 1999 ├«ntreruperea a fost minor─â. Printre produsele despre care se ╚Ötie c─â au fost afectate de revizuirea din 2019, num─âr─âm software-ul de gestionare a zborurilor ╚Öi de naviga╚Ťie de la Honeywell, care a provocat ├«nt├órzieri pentru un zbor KLM ╚Öi anul─âri pentru numeroase zboruri din China, deoarece tehnicienii nu au reu╚Öit s─â aplice la timp actualiz─ârile, re╚Ťeaua wireless a ora╚Öului New York (NYCWiN) care s-a oprit, telefoanele mobile care au fost v├óndute ├«n 2013 sau mai devreme,┬á baloane meteorologice ale Biroului Australian de Meteorologie, balize meteorologice ale Administra╚Ťiei Na╚Ťionale Oceanice ╚Öi Atmosferice (NOAA), multe instrumente ╚Ötiin╚Ťifice ╚Öi dispozitive de navigare GPS pentru consumatori.

 

Leave a Reply

Your email address will not be published. Required fields are marked *