Survey Scene

GPS 24+3 Configuration: A Closer Look

February 3, 2010By

In the few years I’ve been writing this column, very few subjects have warranted back-to-back newsletter coverage. The new GPS 24+3 configuration is one of them. The reason I’ve continued with this discussion is because it will significantly affect your GPS operations, especially if you’re using RTK or DGPS. read more

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The New GPS 24+3 Constellation: What Does it Mean to the Surveying and GIS User?

January 19, 2010By

Last week, the U.S. Air Force announced it is reconfiguring the GPS constellation. The Air Force is changing the constellation from a 21+3 configuration to a 24+3 configuration. The result will be more satellites in view, on average. This is great news for the GPS surveying and GIS mapping user. In my opinion, it was the only achievable short/medium-term solution to the GPS "brownout" problem that has plagued GPS surveying and mapping users for years, and has worsened in recent months. read more

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The Federal Radionavigation Plan

January 5, 2010By

I’ve intended to write about the 2008 Federal Radionavigation Plan (FRP) for quite some time. It is an important document because it is the official policy document that drives the United States’ radio navigation (including GPS) program planning. According to the FRP, it includes the introductions, policies, radionavigation system user requirements, system descriptions, and operating plans of various radionavigation systems. read more

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Directions 2010: It’s the Economy, Stupid

December 15, 2009By

At the end of every year, I devote this column to Directions 2010 in which I discuss significant developments, trends, technologies, and companies in the GNSS industry. Two years ago, I wrote about the Year of the Who. Not GNSS technology; rather, the people and companies they run. Last year, I highlighted 2009 as being the Year of the Other GNSS. The little brother of GPS…GLONASS. read more

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As Loran Fades, Attention Shifts to DGPS and SBAS

November 30, 2009By

Few precise-positioning users have employed Loran in a professional sense, although maybe you have in your personal life if you’re a airplane pilot or a mariner. Then again, if you've flown as an airline passenger or cruised onboard a ship, you've benefited from the back-up to GPS that Loran provides. That back-up is about to go away. As attention and resources shift away from Loran, they focuses more intensely on GPS augmentations, specifically differential GPS (DGPS) and satellite-based augmentation systems (SBAS) such as WAAS and EGNOS. read more

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A Little Q&A Follow-up and Feedback on My Last Column

November 19, 2009By

I received some feedback on my last column entitled "What’s the Difference Between a Used Car Salesman and a GPS Salesman?" Most of the comments were positive in that the technical content was reasonably deep and thorough. However, I did receive a couple of e-mails from folks who were offended by the comparison. read more

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What’s the Difference between a Used Car Salesman and a GPS Salesman?

November 3, 2009By

I didn’t attend the Minnesota GIS/LIS Annual Conference last week, but I received a report from someone who attended a session in which the presenter seemed to fit the maxim quite well. One of the presenter’s messages was that people should stop using WAAS immediately as a GPS correction source due to the inability of data collection software to handle the ITRF00 > NAD83/CORS96 datum shift. Following is a statement from one of his slides… read more

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GPS Constellation Management: Playing Not to Lose

October 22, 2009By

In sports, there is a phenomenon that sometimes occurs when a team is leading towards the end of a game. It’s called “playing not to lose.” The reason you are seeing high HDOP warnings from the NAVCEN and GPS “brownouts” during the day when RTK (GPS-only) isn’t working is because the GPS satellite constellation is sub-optimal. The current design of the GPS constellation is not focused on “playing to win”, but rather “playing not to lose.” read more

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