Researchers at the Politecnico di Torino university detected spikes in the L1 signal spectrum. The origin of the spikes was identified as the transmission of a non-standard code from a non-operational GPS satellite. This story reports on signal observations performed to identify the source of the interference and the impact it could have on GNSS signal processing.
User equipment incorrectly interpreting data from a satellite set “unhealthy” led to an apparent constellation outage for roughly […]
News courtesy of CANSPACE Listserv. It appears that GPS SVN49, the Block IIR-M satellite with the problematic L5 […]
The GPS Block IIR-M satellite, SVN49, resumed transmissions as PRN24 at about 18:35 UTC on August 9, 2012. The signals are marked unhealthy and the satellite is not included in broadcast almanacs. SVN49 was launched on March 24, 2009 but remains out of service until an L1/L2 satellite multipath issue is resolved.
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.
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.
I had a great visit at the ESRI User Conference earlier this month. If you recall last year, I wrote:
“As much as surveyors, engineers, and constructors may not appreciate geographic information systems (GIS) technology, at some point everyone should attend at least the ESRI Survey/Engineering Summit and the first couple of days of the ESRI User Conference held every summer in San Diego, California. This is not a GIS sales pitch. It’s a networking sales pitch. When other conferences are struggling to maintain attendance levels, the ESRI conferences seemingly never fail to grow in attendance. This year, it attracted some 15,000 people from 120 countries. That means gobs of GIS people, and also gobs of surveyors and engineers.”
The statement rang true this year too. Even in today’s economy where conferences are severely impacted or even cancelled due to travel budget cuts, the ESRI User conference still attracted ~11,000 people this month.
The GPS Wing and its contractors have traced the cause of pseudorange errors on L1 and L2 broadcast by the newest GPS satellite, SVN-49, to the manner in which the L5 signal demonstration payload was added to the satellite. Signal leakage between the two input ports of the antenna coupler network for the satellite’s array of 12 helical antenna elements, reflected from the L5 filter and then transmitted, creates a second signal with a delay of approximately 30 nanoseconds, and the appearance of a multipath component. While testing an adjustment to the signal-in-space to minimize the effect of the problem on receiver navigation solutions on Earth, the GPS Wing is interested in hearing from manufacturers and the user community concerning the different impacts of SVN-49 signals on the wide range products and applications in operation, before reaching a final decision on what to do with the satellite prior to setting it healthy.
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