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Satellite Status / Space Weather Update 16 July 2008, GPSWeek 1488 NOTE: A positive leap second update is scheduled for December 31 2008-January 01 2009. After the update the GPS/UTC offset will be 15 seconds. The last leap second update was in 2006. More leap second information at: http://tycho.usno.navy.mil/leapsec.html The sequence of dates of the UTC second markers will be:
This update will impact both GPS and Glonass systems and user equipment. GPS user equipment applies an offset to its published UTC internal time via the IONO/UTC message in the almanac broadcast, while Glonass intrinsically operates in UTC time and must account for this change in all of its segments; ground, space and user equipment (Glonass ephemeris uses UTC time as its reference). 31 healthy GPS Satellites: (GPS/UTC offset is 14 seconds) Mission planning is strongly encouraged for your GPS operations as even with 31 satellites there remain some periods of high DOP and reduced availability in some regions when using an elevation mask of 10 degrees or higher. You can have high DOP even with 6 satellites if the geometry is poor. Right now there is an area of DOP weakness in the South Eastern and West Coast US during part of the day which impacts kinematic users.
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ftp://ftp.trimble.com/pub/eph/almanac.alm (Latest combined GPS/GLONASS Almanac) http://www.navcen.uscg.gov/gps/almanacs.htm(YUMA GPS only Almanac from USCG NAVCEN) http://www.trimble.com/planningsoftware_ts.asp (Free Trimble GPS/GLONASS planning software) |
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Note: Always download and use the latest almanac for mission planning. Otherwise you
must explicitly set satellites unhealthy/healthy as necessary to evaluate your
specific constellation scenario. Always verify age of downloaded Almanac to be
sure it is current.
GPS Launch Update: Next launch has been set to TBD (IIRM 20, SVN49 – with demo L5 payload) followed by 11 September (IIRM 21, SVN 50). In any event, 2SOPS intends to try to launch the remaining 2RM GPS satellites by the end of FY 2008, replacing older, high maintenance satellites.
Specific times/dates are listed at: WAAS GEO (correction source) Satellite Status GLONASS Status 12 (of 16) Satellites healthy Launch Update: Expect two launches of 3 satellites each, in September and December 2008. Galileo vs Glonass… The European Commission has decided to start buying satellites and ground-based equipment for its Galileo satellite navigation project. By 2010(???rab), the system should comprise 30 satellites and a ramified ground infrastructure. Europe's independence from the U.S. Global Positioning System (GPS) will cost it 3.4 billion euros by 2013. But the European Commission thinks it is worth it. Galileo, an initiative launched by the European Union and the European Space Agency, will provide information concerning the positioning of users in many sectors such as transport (vehicle location, route searching, speed control, guidance systems, etc.), social services (aid for the disabled or elderly), the justice system and customs services (location of suspects, border control), public projects (geographical information systems), search and rescue systems, or leisure (direction finding at sea or in the mountains, etc.). Good for Europe, but what about Russia's Glonass? In the mid-2000s it was declared a priority national project and a successful commercial undertaking capable of rivaling Europe's Galileo and America's Navstar (NAVigation Satellites providing Time And Range) GPS. In the past few years, though, we have seen that it cannot rival either. Moreover, it is not clear why Glonass is not progressing as fast as it should. The success of any undertaking in space or on the Earth depends on the goals and conditions for attaining them, as well as allocations and deadlines. The more uncertain and vague they are, the fewer chances a project has. We know from Soviet and Russian history that when a project is described as "global" and "a national priority," and the more special programs are approved and special commissions established, the fewer the project's chances. Glonass was first proposed in 1982 and took off quite well as a military project. But the demise of the Soviet Union in 1991 brought down the system of satellite navigation. In 2001, Glonass was declared a priority national project for the space sector and the national economy as a whole. A special federal targeted program was approved for its implementation. It was also given a new goal - to compete with the U.S. and European programs in attracting commercial users. In other words, we have been trying to turn a purely scientific and technical project into yet another symbol of Russia's greatness, without clearly formulating tasks for the navigation satellites. Lack of funds for the program has forced us to review it twice, in 2006, when the task was set to increase the number of the group's satellites, and in late May 2008, when the government approved the goal of increasing the production of Glonass sets to create a vast market of users. We are again presenting the program as a commercial project, a lucrative business, which it cannot be. So far, there have been no more than 16 of the planned 18 Glonass satellites in orbit to cover the entire Russian territory, although '18' is also something of an arbitrary figure. Russian research institutes have conducted mathematical modeling studies that prove that 18 satellites can ensure only 70% reliability of positioning. I'm not sure we will have the 30 satellites required for a truly reliable system in the foreseeable future. As for Glonass receivers, the questionable achievements of Russian producers of household radio electronics make me wonder. And then, who will use Glonass' services, and where? Are we doing anything to develop a market for navigation satellites' data? There is no reliable information about any of these elements, although it has been reported that Russian and foreign cargo transportation companies working in Russia have been supplied with Glonass sets. But this is not a market, and not a commercial business. And lastly, Galileo, which was announced as a commercial project in 1999, has been marking time until 2007 because of haggling between the EU countries over investment and revenues. Some of them have questioned the very possibility of profiting from satellite navigation. Eventually, a thorough business analysis put an end to disputes and commercial considerations, and the program became a purely budget project with net expenses estimated at 3.4 billion euros. Maybe Russia should do the same with its Glonass system? But where will it find the money? You say everything is cheaper in Russia? Don't make me laugh. The only solution is to reassign the task of developing satellite navigation to those who really need it, the army. http://www.gpsdaily.com/reports/Galileo_Leads_The_Race_Against_Russia_Glonass_999.html Iono Status and Geomagnetic Forecast: Current Space weather Conditions: Solar Cycle Update Stop the presses! The sun is behaving normally. So says NASA solar physicist David Hathaway. "There have been some reports lately that Solar Minimum is lasting longer than it should. That's not true. The ongoing lull in sunspot number is well within historic norms for the solar cycle." This report, that there's nothing to report, is newsworthy because of a growing buzz in lay and academic circles that something is wrong with the sun. Sun Goes Longer Than Normal Without Producing Sunspots declared one recent press release. A careful look at the data, however, suggests otherwise. But first, a status report: "The sun is now near the low point of its 11-year activity cycle," says Hathaway. "We call this 'Solar Minimum.' It is the period of quiet that separates one Solar Max from another." During Solar Max, huge sunspots and intense solar flares are a daily occurance. Auroras appear in Florida. Radiation storms knock out satellites. Radio blackouts frustrate hams. The last such episode took place in the years around 2000-2001. During Solar Minimum, the opposite occurs. Solar flares are almost non-existant while whole weeks go by without a single, tiny sunspot to break the monotony of the blank sun. This is what we are experiencing now. Although minima are a normal aspect of the solar cycle, some observers are questioning the length of the ongoing minimum, now slogging through its 3rd year. "It does seem like it's taking a long time," allows Hathaway, "but I think we're just forgetting how long a solar minimum can last." In the early 20th century there were periods of quiet lasting almost twice as long as the current spell. Most researchers weren't even born then. Hathaway has studied international sunspot counts stretching all the way back to 1749 and he offers these statistics: "The average period of a solar cycle is 131 months with a standard deviation of 14 months. Decaying solar cycle 23 (the one we are experiencing now) has so far lasted 142 months--well within the first standard deviation and thus not at all abnormal. The last available 13-month smoothed sunspot number was 5.70. This is bigger than 12 of the last 23 solar minimum values." In summary, "the current minimum is not abnormally low or long." The longest minimum on record, the Maunder Minimum of 1645-1715, lasted an incredible 70 years. Sunspots were rarely observed and the solar cycle seemed to have broken down completely. The period of quiet coincided with the Little Ice Age, a series of extraordinarily bitter winters in Earth's northern hemisphere. Many researchers are convinced that low solar activity, acting in concert with increased volcanism and possible changes in ocean current patterns, played a role in that 17th century cooling. For reasons no one understands, the sunspot cycle revived itself in the early 18th century and has carried on since with the familiar 11-year period. Because solar physicists do not understand what triggered the Maunder Minimum or exactly how it influenced Earth's climate, they are always on the look-out for signs that it might be happening again. The quiet of 2008 is not the second coming of the Maunder Minimum, believes Hathaway. "We have already observed a few sunspots from the next solar cycle," he says. "This suggests the solar cycle is progressing normally." What's next? Hathaway anticipates more spotless days, maybe even hundreds, followed by a return to Solar Max conditions in the years around 2012. The following link has a nice plot comparing the differing solar cycle predictions:
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