[time-nuts] Satellite Glitch Rekindles GPS Concerns
brooke at pacific.net
Thu Jun 18 12:55:46 EDT 2009
The current issue of Inside GNSS has two articles about this and their web page
has a new article dated 17 June 2009.
Also on line is a story that directly relates to GPS:
"eLoran: The Never-Ending Story?"
June 15, 2009
To say that enhanced Loran (eLoran) has been an on-again off-again program
would give short shrift to multiple generations of official ambivalence about
the proposed backup for GPS.
The latest chapter began on June 4 when Senator Maria Cantwell (D-Washington)
introduced S. 1194, the Coast Guard Authorization Act for Fiscal Years 2010 and
Among other details, the measure directs the Secretary of Transportation to
continue the Loran system until a plan has been drawn up and implemented to
transition the program to eLoran.
In effect, this would reverse the course set by President Obama, whose FY10
budget proposal calls for termination of Loran in the coming year. At a May 7
press conference the president described Loran as a system that’s been eclipsed
by the rise of GPS.
“Year after year, this obsolete technology has continued to be funded even
though it serves no government function and very few people are left who still
actually use it,” Obama said.
The president’s proposal had overruled plans set in motion last year for the
Department of Homeland Security (DHS) to complete the upgrade to eLoran as a
backup to GPS.
Now, S. 1194 would authorize the appropriation of $37 million for each of
fiscal years 2010 and 2011 and direct the U.S. Coast Guard (USCG) to modernize
and upgrade the Loran infrastructure to provide eLoran services. Under the
legislation, the Department of Transportation (DoT) could transfer funds from
the Federal Aviation Administration (FAA) or other DoT agencies to reimburse
the USCG for costs of the modernization.
The activity comes at the same time that a Government Accountability Office
(GAO) report warns about the possibility that the GPS constellation may decline
substantially in the coming years.
Prospects for passage of S. 1194 appear promising. Cantwell is chairwoman of
the Oceans, Atmosphere, Fisheries, and Coast Guard subcommittee of the Senate
Committee on Commerce, Science, and Transportation to which S. 1194 has been
Three senators join her as cosponsors of the measure: Sen. Olympia Snowe
(R-Maine), the ranking Republican member of the subcommittee; John D.
Rockefeller IV (D-West Virginia), chairman of the Commerce, Science, and
Transportation Committee itself, and Kay Hutchison (R-Texas), the committee’s
The legislation implicitly confirms the findings of an Independent Assessment
Team (IAT) on eLoran, funded by the office of the under secretary of
transportation policy and chaired by Brad Parkinson, the first program manager
DoT contracted with the Institute for Defense Analysis (IDA), which organized
the IAT with IDA staff member Jim Doherty serving as the IAT’s executive director.
If offset by an estimated $146 million decommissioning cost of existing Loran
infrastructure, the IAT concluded that eLoran could be established effectively
Going forward, eLoran would require only the current $37 million per year in
USCG operations and management base funds for Loran plus $20 million a year in
new funds for five to eight years to complete all upgrades, new transmitters,
and “jump start” deferred maintenance.
After that time, savings from substantially reduced staffing at the modernized
facilities would offset eLoran operational and sustainment costs.
In December 2006 the IAT unanimously recommended that for, at least the next 20
years, eLoran “be completed and retained as the national backup system for
critical safety of life, national and economic security, and quality of life
applications currently reliant on position, time, and/or frequency from GPS.”
Among the IAT’s key findings: “eLoran is the only cost-effective backup for
national needs; it is completely interoperable with and independent of GPS,
with different propagation and failure mechanisms, plus significantly superior
robustness to radio frequency interference and jamming.”
Despite the report’s acceptance by the Bush administration, which relied on it
for the DHS decision to move forward with eLoran, a summary of the IAT findings
and supporting charts was only released in May. Parkinson told Inside GNSS that
he estimates the probability of Congress approving eLoran at 75 to 80 percent.
Currently, the Radio Technical Commission for Maritime Services (RTCM) is
developing performance standards for eLoran in the maritime environment. eLoran
also has strong support from the General Lighthouse Authorities (GLA) of the UK
and Ireland (equivalent to USCG for maritime safety, which have committed to
e-Navigation for maritime safety, using GPS/DGPS as primary input, eLoran as
secondary or backup, and electronic charting.
Mike Monett wrote:
> An article in NetWork World discusses performance degredation in the
> new Lockheed-built GPS IIR-2 satellite. Apparently. the new L5
> transmissions are interfering with other signals from the satellite.
> This reduces the accuracy an order of magnitude, from 2 feet to 20
> feet. It should have a corresponding effect on the accuracy of the
> decoded time signals.
> The Air Force said it has identified several parameters in the GPS
> IIR-20 (M)'s navigation message that can be corrected and is
> studying the impact these may have on military and civil GPS users.
> Presumably, the problem will be corrected in the 12 Boeing GPS
> satellites currently being built that also feature the L5 signal.
> The article discusses issues such as delays due to techical
> problems, cost overruns, and aging of the fleet. These could affect
> system performance in the future.
> However, Col. Dave Buckman stated
> "The issue is under control. We are working hard to get out the
> word. The issue is not whether GPS will stop working. There's only a
> small risk we will not continue to exceed our performance standard,"
> he said.
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