The System

The System: Three’s the Challenge

August 1, 2010By

A small variance in the L5 signal, which remains well within signal specifications and will not affect pseudorange measurements, may show some impact on triple-frequency combinations of the signal’s carrier phase in high-precision applications. Observations suggest a temperature-dependent line bias in one or more carriers as a likely cause of the observed variation in the tri-carrier combination of L1, L2, and L5. read more

This article is tagged with , and posted in GNSS Opinions, GPS Modernization, The System

The System: An L5 Surprise

August 1, 2010By

Researchers at the German Aerospace Center say they have found a small variance in the L5 signal on IIF-1. The signal variation results in no more than a 5-centimeter error with a predictable periodicity of about six hours. The GPS Wing is studying the issue and expects to resolve it before setting the satellite healthy, in another month or so according to the schedule. read more

This article is tagged with , , , , and posted in Aviation & Space, GNSS Opinions, GPS Modernization, The System

The System: GPS L5, the Real Stuff

July 1, 2010By
Fig.1 Carrier-to-noise-density ratio of GPS (left) and GIOVE-A/B signals measured at the Wettzell station on June 17, 2010. Red curves refer to signals in the L5/E5a band and include data from the PRN1 test satellite and the new PRN25 satellite.

The L5 signal of the new Block IIF satellite shows a very favorable signal strength (Fig. 1), which is somewhere in between the L1 and L2C signal strength for the employed antenna and slightly higher than that of the GIOVE-A/B satellites. While the L5 test signal of the second-last Block IIR-M satellite (PRN1/SVN49) is transmitted through a narrow beam antenna and shows a steep variation with elevation angle, the new satellite exhibits an almost constant flux irrespective of the boresight angle. read more

This article is tagged with and posted in The System

The System: First IIF Satellite Speeds into Orbit

June 1, 2010By

  At press time, GPS spacecraft IIF-1 was set to be launched May 27 from Cape Canaveral Air Force Station in Florida. This first of a new generation of satellites will travel quickly — instead of taking several days to reach its orbital slot, the new satellite should make the journey in three-and-a-half hours. The new IIFs will broadcast the... read more

This article is tagged with and posted in Galileo, GLONASS, GNSS, GPS Modernization, The System

The System: Galileo ICD, Free at Last

May 1, 2010By

Galileo ICD, Free at Last The European Commission (EC) has published an updated Galileo Open Service Signal-In-Space Interface Control Document (OS SIS ICD) giving technical specifications and performance expectations for the future system. As reported by GPS World in October 2009, the EC will not charge for manufacturing licenses. No fees will be required for manufacturers to design, develop, make,... read more

This article is tagged with , and posted in Augmentation & Assistance, Galileo, GNSS, The System

The System: Vistas from the Summit

April 1, 2010By

“This is an event where one gets one’s goals for the next year.” Paul Verhoef, program director for satellite navigation programs of the European Commission, may have exaggerated for effect, and for the benefit of his audience and hosts at the Munich Satellite Navigation Summit in March. But not by much. The conference, now in its eighth year, has assumed... read more

The System: New Kid on the Block: IIF Readied

March 1, 2010By
It takes four hefty guys to wheel the new satellite along the tarmac, but it will only take one Delta IV rocket to lift it 20,171 kilometers into space on May 13.

The first Block IIF satellite destined for orbit arrived at the Navstar Processing Facility at Cape Canaveral, Florida, aboard an Air Force C-17 cargo aircraft on February 12. It is now undergoing preparations for its launch this spring on a Delta IV rocket. Block IIF will enhance GPS performance by reportedly providing twice the navigational accuracy of heritage satellites, more robust signals for commercial aviation and search-and-rescue, and greater resistance to jamming in hostile environments. Plus: GLONASS, Beidou, Galileo, 24+3 FAQ, and AEP 5.5C software update. read more

This article is tagged with , and posted in The System

The System: New Math for GPS

February 1, 2010By

The U.S. Air Force GPS Wing and 50th Space Wing have begun repositioning GPS satellites in space to fly what they call the 24+3 or Expandable 24 constellation plan. The initiative will take up to 24 months to fully implement. Benefits to users will be slowly realized during that time, as the number of GPS satellites in view will increase, potentially increasing GPS receiver accuracy. Plus: Penny-Wise, Pound-Foolish U.S. Coast Guard to Pull Loran Plug; Galileo Satellites Awarded to OHB; Compass at Three read more

This article is tagged with and posted in The System, Uncategorized