Equipped To Survive Equipped To Survive® Presents
The Survival Forum
Where do you want to go on ETS?

Page 2 of 2 < 1 2
Topic Options
#50529 - 09/27/05 11:42 PM Re: New improved GPS satellites going up
groo Offline
Old Hand

Registered: 11/02/03
Posts: 740
Loc: Florida
I know you're kidding, but check this out:

1 nanosecond is 1/1000000000 of a second, or 1.0 x 10^-9.

2 nanoseconds per day, cumulative error, 2.0E-9 * 365, is 7.3E-7.

Still doesn't sound like much? Light moves at 186,282 miles per second. In 7.37 x 10^-7 seconds, light moves 0.136 miles. Or 718 feet. Going from 11 to 8 nanoseconds improves positional accuracy a noticable amount.




Top
#50530 - 09/28/05 12:39 AM Re: New improved GPS satellites going up
scout Offline
Stranger

Registered: 11/30/04
Posts: 23
Loc: Eagle, Idaho
Now I have never tried to substantiate this, but I've read that the typical eye blink is in the neighborhood of 40 milliseconds. Well . . . you asked. Let's see . . . one thousand one. . . Nope. One thou . . . Nope. One t . . . Nope. On . . . Nope. It's dang fast, that's for sure.

Top
#50531 - 09/28/05 06:36 AM Re: New improved GPS satellites going up
benjammin Offline
Rapscallion
Carpal Tunnel

Registered: 02/06/04
Posts: 4020
Loc: Anchorage AK
Only if your travelling near the speed of light <img src="/images/graemlins/smirk.gif" alt="" />

If you are stationary or moving relatively slowly (less than say 700 mph), the propogational delay shouldn't be much of a factor. My GPS doesn't update fast enough to be accurate if I am moving much more than 100 mph anyways, certainly at the highest resolution, where by the time it updates I am already several hundred feet beyond the marker and off the screen already.
_________________________
The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)

Top
#50532 - 09/28/05 06:38 AM Re: New improved GPS satellites going up
benjammin Offline
Rapscallion
Carpal Tunnel

Registered: 02/06/04
Posts: 4020
Loc: Anchorage AK
Hmm, that sounds about right. Fractionally, I think the range for most eye blinks was between 1/20 and 1 60 of a second (50 milliseconds to 15 milliseconds).
_________________________
The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)

Top
#50533 - 09/28/05 01:30 PM Re: New improved GPS satellites going up
harrkev Offline
Enthusiast

Registered: 09/05/01
Posts: 384
Loc: Colorado Springs, CO
Groo...
The time as recorded by the sattelites is periodically updated from the ground. So those errors never have a chance to accumulate. The ground stations have enough room for a really good atomic clock.
_________________________
--
Darwin was wrong -- I'm still alive

Top
#50534 - 09/28/05 04:02 PM Re: New improved GPS satellites going up
groo Offline
Old Hand

Registered: 11/02/03
Posts: 740
Loc: Florida
True. It's a contrived example. But people easily forget just how fast light travels. 1 nanosecond is just about 1 foot.

I figured the on board clocks received updates from the ground... I'm guessing the ephemeris is updated from the ground too. But the onboard clock accuracy improvement is still important. I wonder if the improved accuracy allows for either fewer updates, or better accuracy if ground based updates are... interrupted... for some reason. <img src="/images/graemlins/frown.gif" alt="" />


Top
Page 2 of 2 < 1 2



Moderator:  Alan_Romania, Blast, cliff, Hikin_Jim 
November
Su M Tu W Th F Sa
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
Who's Online
0 registered (), 831 Guests and 23 Spiders online.
Key: Admin, Global Mod, Mod
Newest Members
Aaron_Guinn, israfaceVity, Explorer9, GallenR, Jeebo
5370 Registered Users
Newest Posts
Leather Work Gloves
by dougwalkabout
11/16/24 05:28 PM
Satellite texting via iPhone, 911 via Pixel
by Ren
11/05/24 03:30 PM
Emergency Toilets for Obese People
by adam2
11/04/24 06:59 PM
For your Halloween enjoyment
by brandtb
10/31/24 01:29 PM
Chronic Wasting Disease, How are people dealing?
by clearwater
10/30/24 05:41 PM
Things I Have Learned About Generators
by roberttheiii
10/29/24 07:32 PM
Gift ideas for a fire station?
by brandtb
10/27/24 12:35 AM
Newest Images
Tiny knife / wrench
Handmade knives
2"x2" Glass Signal Mirror, Retroreflective Mesh
Trade School Tool Kit
My Pocket Kit
Glossary
Test

WARNING & DISCLAIMER: SELECT AND USE OUTDOORS AND SURVIVAL EQUIPMENT, SUPPLIES AND TECHNIQUES AT YOUR OWN RISK. Information posted on this forum is not reviewed for accuracy and may not be reliable, use at your own risk. Please review the full WARNING & DISCLAIMER about information on this site.