GPS-kellonajan outo hyppäys huomattiin Metsähovissa

Tiistaina 26. tammikuuta 2016 hieman puolenpäivän jälkeen Aalto-yliopiston Metsähovin radiotutkimusaseman suunnittelema ja toteuttama vetymaser-atomikellon automaattinen valvontajärjestelmä hälytti GPS-satelliittipaikannuksen välittämän kellonajan hypänneen äkillisesti väärään aikaan. Ilmoitettuamme tästä muille radioastronomisille tutkimuslaitoksille he vahvistivat ilmiön omista valvontatiedoistaan. Ilmiön taustalla oleva alkusyy ei ole vielä selvillä, mutta vikaantunut GPS-satelliitti tai sellaiseen sijoitettu atomikello ovat hyvin mahdollisia selityksiä. Auringon hiukkaspurkauksen aiheuttamasta satelliittivauriosta on tällä kertaa tuskin kyse, sillä Metsähovin aurinkovalvonnassa ei ole havaittu tavanomaista merkittävämpää aktiivisuutta.

Vaikka tämänkertainen kellonajan virhe oli suuruudeltaan ainoastaan 13.7  mikrosekuntia, mikään ei sulje pois suurempien tai yllättävämpien kellovirheiden mahdollisuutta. GPS-kellonaikaa käytetään yhä enemmän järjestelmien automaattiseen tahdistamiseen ja mitä laajempaa käyttö on, sitä riippuvaisempia ollaan GPS-ajan ja paikannustarkkuuden virheettömyydestä.

Posted by Merja

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7 Responses to GPS-kellonajan outo hyppäys huomattiin Metsähovissa

  1. Jeff says:

    I see the leap at different times for different places. Is it because one satellite showed wrong time, and it is used by different observatories at different time? Such as CNS at 1:00 and Symm at 7:00.

  2. Sorry! Must have gotten my input flux too high when arriving. Just hrer to change a few things. Expect a negative time dilatation in a few days upon my return.

  3. Sardar khan says:

    Two crew recording seismic data in Saudi Arabia for Saudi Aramco suddenly notice a bulk time shift in time with there GPS tome synchronization on 26th January 2016 for almost 12 hours from 3PM to 3AM.

  4. Pedro Pintor says:

    Thank you for the graph. It is very interesting. One doubt comes up, there are four timediff (HP, CNS, Symm, Lantime) calculated but it seems the 13microseconds appears once per timediff (at 00.00h for the green line/receiver, at 07.00h for the magenta line/receiver).

    How is this explained? Are all the receivers in the same location? Are all fed by the same antena?

    Thank you!!

  5. Pingback: 卫星退役触发软件问题导致GPS时间异常 | 陈丹的博客

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  7. RRChief says:

    I worked for ten years as an engineer officer. I know that the time clocks on the satellite are synchronized, and atomic decay rate of the same isotope on each satellite is the method that achieves that. The ship transceives signals from a number of Inmarsat sattelites and it is the differing time (distance) that signals take that is used to position the vessel. We used DGPS, an upgraded system as we required greater accuracy for laying fibre optic cable systems. So had a need for both extreme accuracy, as well as recording via charts where the cable and its repeaters, actually were. From memory we needed 5 SATs.
    So the GPS clocks jumped, the important question is did the clock time act as one, or were GPS satellites erroneous by differing amounts, for this is potentially more dangerous. I used to work on a vessel, CS Cable installer. Every now and again, while on DP (GPS input to Konigsberg simrad dynamic positioning system utilising bow and stern thrusters in conjunction with main propulsion, to maintain position or maneuver according to the GPS and the ships actual position. Occasionally, the vessel used to, as far as the GPS/DP interface would suddenly indicate the vessel was 150M away, from where, (perhaps when? After looking at article) we actually were. The engines would take on load from the generators as they struggled to geive the multiple thrusters power. The kfully, we had Toby, the DP officer who usually was quick enough to correct the offset. Just as well, for if the thrusters call for more power than the engines could supply the breakers would trip, that usually caused at least one generator/engine then to overspeed trip.

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