Which sounds like moderately bad news, on occasion, for GPS users. Remember to carry that map and compass, he nags.
While I'm on this subject, does anyone know if the European Space Agency Galileo and the Chinese satellites will transmit on frequencies which existing GPS units will pick up, or are we off out the the shop again in a few years time?
This isn’t a new topic by any means. The space weather forecast, if you will, has been available for a long time. As far as I see it there are two sources of disruption and the article only really speaks of one. The first – as described – is the loss of path-length accuracy due to the modified ionospheric environment. If the claims in the article are true – sporadic degradation of the order of 10m – this really isn’t a big issue for most users most of the time.
What the article doesn’t mention, however, is the impact of solar activity on the GPS / Glonass constellation of satellites. Now this is speculation on my part, but I’m in home territory given my day-job. I would anticipate that there will be a higher rate of equipment failure on the spacecraft during the solar maxima. The GPS satellites, being military in origin, will be hardened against certain forms of radiation and therefore fairly robust to this problem. But there could be degradation in service due to failing equipment on the satellites. As far as I know, Glonass doesn’t have the kind of replacement budget and infrastructure that GPS does. If a GPS satellite is rendered unusable, the DoD won’t hang around before launching a replacement. Not necessarily true of Glonass. Also potentially worrying for the LEO/MEO satellite phone systems like Iridium.
Galileo frequencies have been chosen to be very similar to GPS ones for interoperability reasons. That means that future devices will be likely to handle both systems but older GPS units won’t be able to benefit from Galileo signal. Being able to handle both systems could also improve positioning accuracy as well as availability especially if the systems use augmentation techniques such as EGNOS. I know nothing of the Chinese proposal.
