Comments on: Mixed signals over Loran-C

By: Tom Lusch

Tom Lusch — Wed, 17 Feb 2010 18:56:55 +0000

An engineer passed along the following link to me. I feel it is important to share, as it informs us as to just how utterly vulerable GPS is to being jammed. In this Radio Frequency Interference (RFI) case, GPS signals within a harbor were jammed by, of all things, a simple VHF/UHF television antenna with built-in preamplifier!!!…

http://www.gpsworld.com/gnss-system/signal-processing/the-hunt-rfi-776

Imagine what havoc a terrorist could wreak with a simple transmitter attached to a weather ballon!

We should NOT put all our eggs in one basket. We should have a seamless backup system, designed such that we would have GPS boxes with eLORAN capable backup receivers within.

In my opinion, the decision to abandon LORAN/eLORAN, is a decision that we will one day regret.

By: eastriver

eastriver — Sat, 06 Feb 2010 10:54:11 +0000

Good post. “Illogical” is, to me, a kind characterization of the decision CG’s certification of existing alternatives to GPS does not lead me to think of Galileo or Glonass, but sextants and lighthouses.

Some in our company had been looking at the advent of eLoran and the promise of a combined receiver, able to provide system check and backup in one unit. Now, this startling development.

One may find interesting the blog post by Eagle 1, repeated in the US Naval Institute blog:
http://www.eaglespeak.us/2010/02/war-in-future-satellite-alternatives.html

By: Capt Ken E. Beck

Capt Ken E. Beck — Tue, 26 Jan 2010 22:50:57 +0000

I have to disagree with Velu on this one. I feel somewhat uneasy approaching the coast using only gps. We are all supposed to be checking and verifying etc but how many do? eLoran could be made convenient enough to be a reliable backup.

By: Neville

Neville — Sat, 23 Jan 2010 18:57:54 +0000

Thanks for your comment – my view is that Loran-C is not the issue it’s that GNSS is far from being a magic bullet. Having talked for so long about the need for a back-up, it seems perverse to suddenly decide we don’t need one. Do you feel you would have sufficient back-up if GPS signals were unavailable?
Neville

By: velu

velu — Thu, 21 Jan 2010 07:24:25 +0000

Sorry but the above was getting to long, so I put it up as a blog post of my own where I tried to put up the arguments in a more coherent manner. Please do drop by.

Cheers,
Velu

By: velu

velu — Thu, 21 Jan 2010 04:42:06 +0000

I do believe that the USCG is right in closing down the LORAN. I speak this personally, but I have not used the LORAN in more then 11 years. It is of course good to have all systems running for perpetuity, but there is no use. You have to let systems go. The same manner of debate arose when Australia decide to stop transmitting Weather faxes. No one was reading them.

As per Wiki, the new GPS satellites that will be launched from 2010, will not be able to implement SA even if the US government wants to. So even though it is an option, the US govt is resigned to never using it.

Lastly, even if the GPS shut down tomorrow, you need ask hos many of the Marine ships actually have an LORAN unit to navigate. I have honestly not seen one on my ship since 1997.

Let it go.

Cheers,
Velu