Your behavior appears to be a little unusual. Please verify that you are not a bot.


Archives

3D Geospatial Data

November 1, 2009 - By

The usage of three dimensional data in the geospatial industry is in its infancy. It makes sense to me. Sometimes, it’s hard enough for folks to obtain and maintain accurate two dimensional data, not to mention elevation! However, as geospatial technology continues to evolve, the availability of 3D geospatial data will evolve. I’m pretty sure that in ten years we... read more

This article is tagged with and posted in GSS Monthly, Lidar

The System: Galileo Slips, EGNOS Operates

November 1, 2009 - By

Four Galileo in-orbit validation (IOV) satellites scheduled to launch next year have already missed their first pad date.The European version of Russia’s Soyuz rocket is now scheduled to carry the four IOV satellites into orbit in two launches in November 2010 and early 2011, as announced by European Space Agency (ESA) Director-General Jean-Jacques Dordain on October 9. Both launches had... read more

This article is tagged with , , , , , , and posted in GNSS

On the Edge: Multipath Measures Snow Depth

November 1, 2009 - By

The September “Innovation” column in this magazine, “It’s Not All Bad: Understanding and Using GNSS Multipath,” by Andria Bilich and Kristine Larson (see www.gpsworld.com/multipath), mentions the use of multipath in studying soil moisture, ocean altimetry and winds, and snow sensing. An experiment the authors conducted, designed to study soil moisture, yielded a surprise bonus: a new methodology for measuring snow depth via GPS multipath. It has important implications for weather and flood forecasting, and could also bring new insight to bear on GPS antenna design. read more

The True Story of the Origins of GPS

November 1, 2009 - By

Photos from the GPS World Leadership Dinner 2009, September 24 ION GNSS 2009 Conference, Savannah, Georgia read more

Expert Advice: GPS Constellation Maxed Out at 30

November 1, 2009 - By

It appears that the GPS satellite constellation has a glass ceiling, so to speak. GPS was designed as a 24-satellite constellation, with four satellites in six orbital planes arranged to provide maximum observability around the globe. According to the government’s Space-Based Positioning, Navigation, and Timing website, “The U.S. government is committed to provide a minimum of 24 operational GPS satellites on orbit, 95 percent of the time. The U.S. Air Force launches additional satellites that function as active spares to accommodate periodic satellite maintenance downtime and assure the availability of at least 24 operating satellites. As of August 28, 2009, there were 35 satellites in the GPS constellation, with 30 set ‘healthy’ to users.” read more

This article is tagged with , and posted in From the Magazine, Opinions

Out in Front: An SVN up for Grabs

November 1, 2009 - By

Wednesday evening, September 23, Savannah, Georgia, 5:30 to 7:00 p.m., Session P2b — a date that will live in GPS history. The 400 to 600 of us who were there to witness it will never forget it. The SVN49 Review Panel. Unprecedented puts it mildly. read more

This article is tagged with , , and posted in From the Magazine, Opinions

Higher Timing Accuracy, Lower Cost

November 1, 2009 - By

Inside a typical GNSS receiver, the estimate of the error in the local oscillator is formed as a component of the navigation solution, which is in turn based on the output of each satellite-tracking channel propagating its estimate of carrier and code measurements to a common future point. But this method limits the resolution with which the noise of the local oscillator can be quantified. To bypass this shortcoming requires a method of coherently gathering information about the phase change in the local oscillator across all available satellite signals: to use the same samples simultaneously for all satellites in view to estimate the center-point phase error common across the visible constellation. We explore how. read more

This article is tagged with , , , and posted in OEM

Innovation: Improving Dilution of Precision

November 1, 2009 - By

A Companion Measure of Systematic Effects
GPS receivers must deal with measurements and models that have some degree of error, which gets propagated into the position solution. If the errors are systematically different for the different simultaneous pseudoranges, as is typically the case when trying to correct for ionospheric and tropospheric effects, these errors propagate into the receiver solution in a way that is fundamentally different from the way that random errors propagate. So in addition to dilution of precision, we need a companion measure of systematic effects. In this month’s column, we introduce just such a measure. read more

This article is tagged with and posted in Innovation, OEM