The System

The System: Galileo PRS Delivery in Question

November 1, 2010By

Once envisioned to orbit 30 satellites, Galileo’s constellation has over time been reduced to a planned, though still not space-borne, four initial satellites plus 14 operational satellites for a total of 18. The European Space Agency (ESA), under direction of the European Commission (EC), confirmed at the October 19–21 European Navigation Conference (ENC) in Germany that it plans to declare... read more

This article is tagged with and posted in BeiDou/Compass, Galileo, GNSS, The System

The System: GLONASS Forecast Bright and Plentiful

October 1, 2010By

At the Civil GPS Service Interface Committee meeting in Portland, Oregon, on September 20, Sergey Revnivykh, Deputy Director General of Roscosmos’s Central Research Institute of Machine Building, reported on the status and future of GLONASS. He provided a number of details on the present constellation and how it will be augmented in the future, stressing that GLONASS is doing well... read more

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

The System: Michibiki Takes Up Station and Other GNSS Constellation Updates

September 1, 2010By
QZSS-orbits

As this issue goes to press in late August, the first Japan Aerospace Exploration Agency Quasi-Zenith Satellite System (QZSS) space vehicle, nicknamed Michibiki, holds steady for a September 11 launch. QZSS will use multiple satellites in inclined orbits, placed so that one satellite always appears near zenith above Japan, well known for its high-rise cities. The design provides high-accuracy satellite... read more

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

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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

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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

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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