As Loran Fades, Attention Shifts to DGPS and SBAS

As Loran Fades, Attention Shifts to DGPS and SBAS
http://www.gpsworld.com/survey/as-loran-fades-attention-shifts-dgps-an=
d-sbas-9181?print=3D1
December 2, 2009
By: Eric Gakstatter

Few precise-positioning users have employed Loran in a professional sense=
, although maybe=20
you have in your personal life if you=E2=80=99re a airplane pilot or a ma=
riner. Then again, if=20
you've flown as an airline passenger or cruised onboard a ship, you've be=
nefited from the=20
back-up to GPS that Loran provides. Similarly, if you've used a mobile ph=
one recently; you=20
don't see it, but the wireless carriers all use Loran as a back-up. That =
back-up is about=20
to go away.

Loran was developed initially for marine navigation and then adopted for =
aviation=20
navigation. I used Loran-C for aviation navigation in the early 90=E2=80=99=
s after I earned my=20
private pilot=E2=80=99s license. It was much easier than triangulating of=
f of VORs and NDBs. Yes,=20
GPS receivers for aviation were starting to emerge at that time but flyin=
g is expensive so=20
a hand-held GPS was an out-of-reach luxury for a newlywed who just bought=
his first house=20
and was preparing to start a family.

Loran is a terrestrial (ground-based) system of broadcasting towers, some=
what synonymous=20
with NDGPS. You can read details about the system in the link I provided,=
but essentially=20
it=E2=80=99s a line-of-sight system in which the Loran receiver antenna n=
eeds a direct path to the=20
tower to utilize the signal. Coverage depends on the density of the broad=
casting towers.=20
Some regions are covered better than others and when I was using it, ther=
e were many areas=20
that were not covered. Accuracy is always an ambiguous subject with respe=
ct to navigation=20
technologies, so I=E2=80=99ll go out on a limb and say that Loran-C accur=
acy is repeatable to=20
about 20 meters. A proposal was floated to upgrade Loran to a system call=
ed e-Loran which=20
is reportedly accurate to about 9 meters.

Anyway, over the past several years there=E2=80=99s been a discussion abo=
ut what to do with the=20
Loran system because it=E2=80=99s clear that GPS has supplanted Loran as =
the primary navigation=20
system for marine and aviation. Several articles have been published in G=
PS World by=20
industry experts with most being in favor of maintaining Loran. The prima=
ry argument is=20
that we need a back-up system for GPS, not only for navigation, but for t=
he many invisible=20
ways that GPS supports the national infrastructure (financial networks, w=
ireless=20
communications, transportation).

s-a...
, although maybe
Then again, if
nefited from the
one recently; you
back-up is about
aviation
ter I earned my
ORs and NDBs. Yes,
g is expensive so
his first house
what synonymous
but essentially
direct path to the
casting towers.
e were many areas
ct to navigation
repeatable to
ed e-Loran which
t to do with the
imary navigation
PS World by
ry argument is
he many invisible
ireless

'Loran is a terrestrial (ground-based) system of broadcasting towers,
somewhat synonymous
with NDGPS. You can read details about the system in the link I
provided, but essentially
it=92s a line-of-sight system in which the Loran receiver antenna needs
a direct path to the
tower to utilize the signal. Coverage depends on the density of the
broadcasting towers.'

???

--- CHAS

HIPAR wrote:
What was your question?

I'm questioning the veracity of the the segment of the article I
quoted. Let's start:

a) 'Loran is a terrestrial (ground-based) system of broadcasting
towers' -- True

b) 'somewhat synonymous with NDGPS' -- Not even close LORAN is a
hyperbolic radio navigation system

c) 'but essentially it=92s a line-of-sight system in which the Loran
receiver antenna needs a direct path to the
tower to utilize the signal' -- LORAN is not a line of sight
system. It's signal operates at 100 kHz and propagates by ground wave
and ducting modes. There is often a sky-wave signal component.

d) 'Coverage depends on the density of the broadcasting towers.' --
Not really; more like the location of a (relatively) small number of
towers.

--- CHAS

It is not like Loran is going to provide the microsecond clock
synchronization that cell towers need.

The government seems to be really bad at closing down anything, no
matter now antiquated and expensive it is to run. I was just reading
about how the post office was losing billions per year but they can't
lay off unneeded labor and they can't close underutilized post office
locations. It would cost political brownie points. It is easier to just
keep underutilized services going forever.

-wolfgang
--
Wolfgang S. Rupprecht
If the airwaves belong to the public why does the public only get 3
non-overlapping WIFI channels?