[time-nuts] LORAN C shutdown

Robert Atkinson robert8rpi at yahoo.co.uk
Tue Nov 10 20:58:57 UTC 2009


Hi Bjorn,
This depends on what you call high performance. The normal definition of "high performance" in relation to IN is low drift with time. Even "cheap" fibre optic gyro based IN platforms can perform as well as the early airline standard mecanical units. GPS does not provide attitude or heading information (I'm ignoring specialist multi antenna differential set ups, these are not normal or mature systems). This information is needed in real time to fly the aircraft in IMC (low visibility) or on autopilot. Either attitude and directional gyros or an IN platform are still needed and IN is becoming the norm. There are also MEMS units that are making inroads in the light aviation market, especially in the USA. GPS (or to be more accurate GNSS) is only part of the system, all be it a very important one.
 
 
Robert G8RPI.


--- On Tue, 10/11/09, bg at lysator.liu.se <bg at lysator.liu.se> wrote:


From: bg at lysator.liu.se <bg at lysator.liu.se>
Subject: Re: [time-nuts] LORAN C shutdown
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Date: Tuesday, 10 November, 2009, 19:29


On the other hand... With GPS-aiding its argued that high performance
INS-systems are not needed. The same performance will be reached with a
low cost GPS and a mid to low performance inertial system. So I doubt we
will have low cost high performance intertial sensors anytime soon.

--

   Björn

> Don't overlook that laser/fiber "ring-gyros" will drop in price the
> patents expire and the predatory pricing ends:
>
>     http://www.es.northropgrumman.com/solutions/mk39/assets/mk39.pdf
>
> As much as I have enjoyed playing with Loran-C, I would far rather
> have a shoebox-sized, totally autonomous dead-reckoning backup, with
> no lightning-prone antenna, than a Loran-C receiver.
>
> Doesn't help us timing guys, but we have Cesiums if we are really
> serious.
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by
> incompetence.
>
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