By: Eugene Brusin
Why would Loran-C be expanding worldwide as a utility system when the GPS
system is here? This is the question that the U.S. Government is debating
within the various agencies, user groups and the press.
A brief explanation of how the U.S. Government selects a navigation system
or policy: The system in question is studied by responsible government
agencies such as the U.S.C.G. and FAA and by experts in the navigation
field, with various inputs from industry and the various user communities.
After a decision is made, the system specifications are published in the
Federal Radionavigation Plan (FRP). This document states the policy for the
U.S. Government in terms of "How good will it be" and "How long will it be
in operation". Other countries use this document to coordinate their
navigation plan with the USA. Companies like airlines use this information
to install navigation equipment and plan for its replacement in the future.
User meetings were scheduled at airports, fishing ports and cities large and
small so that people could be heard, pro and con.
Every two years this process was repeated from 1984 to 1992 when the FRP
document was produced which was widely acclaimed for its vision and clear
policy statements. Then the 1994 and 1996 FRP presented radical changes in
policies, schedules and the projected mix of systems. Why? It seems that a
major shift in navigation policy was starting. The new Department of
Defense Global Positioning System (GPS) was looked at as a savior by the
politicians÷this system could do everything for everyone. There was no
reason to keep all those expensive ground-based systems, Omega, Loran-C,
DME, VOR, TACAN and Transit. With a well planned public press release, a
new age was about to dawn upon the United States and the World. A funny
thing happened at the user's meetings (down to two from hundreds), the
navigation community protested the change in shut-off dates: Omega from
2005 to 1997, Transit from 1994 to 1996 (due to delays in the GPS system),
and Loran-C 2015 to 2000. Of these three systems, Transit and Omega are
both gone, but the Loran-C system seems to be fighting back.
Why would anyone want Loran-C? Several reasons, it is inexpensive to
operate, at $17 million per year and user equipment is low-cost and of
proven capabilities. GPS requires in excess of $500 million per year.
Loran's signal format has an integrity check built in, the GPS does not.
Loran is easy to service÷just drive to the transmitting station, GPS
replacement requires a new satellite launch schedule. On-air time for
Loran-C is about 99.99%, GPS about 99.6% These features have convinced over
25,000 users to sign petitions to keep Loran-C online to its original date,
2015. Various editorials have stated that Loran-C is a proven and valuable
complement to GPS. Foreign nations have purchased new solid-state Loran-C
transmitters to form new Loran-C chains in Europe, China, Japan and Russia.
This land-based navigation system is viewed as a desireable, stable
complement to the future GNSS of the world civilian community. And Loran is
totally unclassified and is operated by host country authorities÷not the
Some new thoughts for people who say "GPS can do it all". . .
Why does the military, who designed the GPS system, not rely on it totally?
The ease of which GPS can be jammed either on purpose or by unexpected
interferences is certainly a major reason. The on-purpose jamming is well
documented by the U.S. military, the International Association of
Lighthouses and the Civil Aviation Authority (UK). A one watt jammer about
2"x2"x4" with a 4 inch antenna can block out a 35 mile diameter circle.
Picture that near your local airport÷such a unit costs about $100.USD. If
you want a jammer for GPS and Glonass, (the Russian equivalent to the GPS),
such units were offered for sale by the Aviaconversia Company, Russia,
which displayed them at a recent Moscow Air Show. Their jamming range was
said to be 120 miles. What was the reaction by the FAA? "Nothing new"
because there are "hundreds of these devices on the market". Besides, it is
a federal offense to jam navigation signals; you could go to jail. I am
sure that will stop a terrorist dead in his tracks! Isn't it illegal to try
and blow up buildings like the World Trade Towers?
The next issue, "Will there be GPS signals?" are dependent upon the solar
weather effects and will be examined carefully at the upcoming "World
Radio Conference 1997" (October 27 November 21). How can the sun affect
GPS? As the solar sun spot cycle approaches its peak at year 2000, the
atmosphere of the earth will be altered resulting in signal outages which
could be widespread. This conference also will address a proposal to share
the GPS frequency band with the Mobile Satellite Service community. The end
result if this notion passes (each country gets one vote), is that the GPS
performance will be seriously degraded and its use denied in certain
situations÷so says the USAF GPS Joint Program Office.
A quick look at the "Information Superhighway" promoted by Vice President,
Al Gore, shows that its infrastructure is timed and synchronized by GPS and
Loran-C signals. Every line of data/voice communication is time signal
critical. For example, during a recent GPS signal disturbance, the industry
giant Motorola was able to fall back on Loran-C units and kept its network
online. Not so for some competitors who lost business while Motorola gained
about a $50 million dollars in new sales.
With the President's Commission on Critical Infrastructure Protection report
out, the main conclusion is that the USA is vulnerable to "Single System
Failures". Would not a total dependence on GPS for everything sound like a
good bet to be included. The DoT seems to be single minded in its focus for
a "One System" approach to our navigation, position fixing and precise
timing needs. Doesn't a backup make sense? Loran-C is the most appropriate
candidate. After all, doesn't your car and airplane have different type
backups to primary systems?
The FAA has decided to augment the GPS system with the Wide Area
Augumentation System (WAAS) program, which carries a life cycle cost
estimate of $2.8 Billion. The current contracts only covers the
ground-based segment, not the geostationary satellites or system integrator
needed to provide the accuracy and integrity requirements of the users for
whom the WAAS program was intended. The major airlines aren't even
enthusiastic about WAAS. They are promoting LAAS, local area systems. Each
system has its champions for acceptance into the National Airspace Plan and
What can Loran-C do for the United States? The most important is that it
provides coast-to-coast, border-to-border signal coverage for navigation and
timing users' a proven complement and backup to the GPS. When the whole
system GPS, WAAS, LAAS and U.S.C.G. DGPS have some operational history,
then, one can discuss shutting off the backup Loran-C, because by then 2015,
a new system will be in the testing phase, a global owned and controlled
system, the GNSS.
In closing, a quote from the former FAA administrator, Mr. Langhorne Bond.
"GPS POLICY is a train wreck". He does not believe in a total dependence on
a "ONE SYSTEM ATC". The current system of Air Traffic Control has layers of
backup, which cannot be matched by GPS alone.
As a further enhancement of GPS by Loran-C, it has been demonstrated in
Europe that the GPS differential correction information can be broadcast by
using the Loran-C signal format. Typical achieved accuracies are in the
2-4 meter range and include assuring the integrity of the GPS signal. To
convert the Loran transmitter stations to this format is low cost÷several
million dollars total. This would provide a DGPS network in the USA without
a national building program and operating budget.
In conclusion, Loran-C makes sense to backup GPS until the GPS system
including its augmentations prove themselves in real operations over time.
After all, a backup is cheap insurance and failure will be unthinkable.
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