Check out the bookstore at IRBS.com
| Home | Mailing Lists | Bookstore | Weather | Tide Predictions | Bowditch |

Re: GPS Timing

Subject: Re: GPS Timing
From: Steven Wepster (wepster@XXX.XXX)
Date: Mon Jul 29 2002 - 08:37:14 EDT

Hi Vic,

While doing astron navigation, an error of one second in time will give you
a longitude error of 15 seconds of arc, since the earth is spinning through
360 degrees in almost 24 hours. A good astro fix might have an error of 1
or 2 minutes of arc. I think missing one or two seconds is tolerable;
remember the old books that tought you to take a shot and then count out
loud while stumbling back into the cabin on your way to the precious
chronometer that hasn't been checked for three weeks.

But, if you practice astronav for in case GPS fails, then you better buy
yourself a wrist watch. I think it's preferable to keep systems separate;
if you trust on GPS for your time signal then the breakdown of GPS implies
the breakdown of your astro. That's bad.

Hope this helps,

Steven.

-----------------------------------------------------------
Steven Wepster wepster@XXX.XXX
                                        tel +31 30 253 1531
Mathematisch Instituut
Universiteit Utrecht
PO Box 80.010
3508 TA Utrecht
The Netherlands
===========================================================



| Home | Mailing Lists | Bookstore | Weather | Tide Predictions | Bowditch | Trawlerworld |