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Geoinformatics-8-2008
article solar cycle and beyond gnss update the next solar cycle is coming. the older surveyors amongst us will remember the last cycle with its peak in 2001. the younger generation however has been pampered with stand-alone gps accuracies of 2-3 meters and sub-meter dgps results. one can however reasonably expect that this will not last. by huibert-jan lekkerkerk that it will operate for long. for that reason it has been set unhealthy initially and is not included in the broadcast almanacs. meanwhile, the launch of the block iir-20 satellite with its l5 demonstration payload has been delayed again, with an expected new launch date sometime in 2009. either this satellite or the first block iif satellite must be launched before august 26, 2009 in order to keep the l5 frequency allocation. the delay is the result of problems with the delta ii launcher provided by boeing while the first iif satellite is still in development and build at boeing. boeing has been awarded a $153.5 million contract to demonstrate high integrity gps technical concepts. the objective is to combine signals from the iridium satellites as well as the gps satellites to enhance availability, integrity, accuracy and the jam-resistant capabilities for warfighters. iridium is a satellite communication system with worldwide coverage. russian proton-k rocket on the launch platform. russian proton-k rocket with glonass satellites en-route to the launch platform. un spots cause heightened amounts of charged particles in the ionosphere. during normal circumstances a single frequency gps receiver uses a model to determine the delay of the signal through the ionosphere. but during a solar storm the amount of particles will deviate from that in the model, resulting in a position degradation of meters. users of multiple frequency receivers are less affected but will probably show a reduction in baseline lengths. the solution: new signals, but whether they will be available on time remains to be seen. s gps gps satellite svn37, which was retired just under a year ago, was reactivated in october and is once again transmitting as prn01. the satellite has only a single healthy clock and as such there is no guarantee december 2008 30
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