[Forbes] SpaceX Launches First Starlink Satellites In Space Internet Battle - Page 3 - Overclock.net - An Overclocking Community

Forum Jump: 

[Forbes] SpaceX Launches First Starlink Satellites In Space Internet Battle

Reply
 
Thread Tools
post #21 of 47 (permalink) Old 05-29-2019, 10:03 PM
Otherworlder
 
epic1337's Avatar
 
Join Date: Feb 2011
Posts: 7,355
Rep: 217 (Unique: 125)
Quote: Originally Posted by UltraMega View Post
Just want to add, I did a little more reading up on fiber speeds. Apparently there are some research projects that put fiber at 97% the speed of light. There is also some variation in the claims about how fast fiber is vs a vacuum. Some claim 50% slower in fiber, some claim only 30% slower.


But here is the real question that I have not found an answer to yet:

Even if light travels at 100% speed in fiber, it still has to travel quite a bit further. Not only because fiber cables would be obviously longer than a direct line of sight link but also because the light has to bounce around in the glass.



So my next questions would be; how much further does light really have to travel to send a signal in fiber, and how will this really impact latency.

looniam already answered that.

Quote: Originally Posted by looniam View Post
How-fast-does-light-travel-through-a-fibre-optic-cable
We can make a 1st-order approximation by assuming the following:

L=3 m is the length of the fibre optic cable
d=3⋅10−6 m is the diameter of the cable
the cable is perfectly straight
θ=0.785 rad (~45∘) is the angle of reflection inside the cable
photons are classical balls
reflection is perfectly elastic
photons still travel at c
Simple geometry shows that the particle travels h=dsinθ=4.24×10−6 m over a linear distance of x=3⋅10−6 m. Do this a million times, you find that the photon traveled 4.24 meters instead of 3 meters!

Given speed of light in vacuum, it would take 14.1 nanoseconds for the photon to travel the reflected path, whereas it would take 10.0 nanoseconds to travel 3 meters linearly. Both the distance & duration are about 40% increases!

Since L=3 m and t=14.1⋅10−9 s, then the "linear" photon speed in the fibre optic cable is vγ,fo=2.13⋅108 m/s, a reduction of about 30%.

What is precisely the speed of light in fiber optics?


Researchers create fiber network that operates at 99.7% speed of light, smashes speed and latency records
March 25, 2013

trolling an adult is very dangerous, don't try it at home nor at work. you don't want to play tag with a rabid man.
epic1337 is offline  
Sponsored Links
Advertisement
 
post #22 of 47 (permalink) Old 05-29-2019, 10:08 PM
New to Overclock.net
 
DNMock's Avatar
 
Join Date: Jul 2014
Location: Dallas
Posts: 3,461
Rep: 171 (Unique: 125)
In Europe at least, there are fiber connections that yield a ping in line with the packets moving around 50% the speed of light.


DNMock is offline  
post #23 of 47 (permalink) Old 05-29-2019, 11:23 PM - Thread Starter
Graphics Junkie
 
UltraMega's Avatar
 
Join Date: Feb 2017
Location: USA
Posts: 1,283
Rep: 30 (Unique: 26)
Quote: Originally Posted by epic1337 View Post
looniam already answered that.
Quite a good answer. Thanks for pointing that out. It was so mathematically worded that my brain skipped over it knowing it would take a long time to process. I think the picture I included also helps a lot to visualize the delay.

i7 7700kK @4.2ghz
16GB DDR4 3200mhz
GeForce 1080 Ti
UltraMega is offline  
Sponsored Links
Advertisement
 
post #24 of 47 (permalink) Old 05-29-2019, 11:57 PM
professional curmudgeon
 
looniam's Avatar
 
Join Date: Apr 2009
Posts: 9,678
Rep: 791 (Unique: 451)
Quote: Originally Posted by UltraMega View Post
So sorry, I misheard the video in the OP. Light only travels 47% faster in space vs fiber. I misheard it as 47 times faster. MY BAD.
it happens. to be fair i didn't watch the vid, just that stat caught my attention.

glad its sorted.
Quote: Originally Posted by epic1337 View Post
looniam already copy/pasta that.
FTFY.

Remember the golden rule of statistics: A personal sample size of one is a sufficient basis upon which to draw universal conclusions.
Upload the computer to Dropbox and provide a link to it so others may download it to examine and give advice for repairs.
loon 3.2
(18 items)
CPU
i7-3770K
Motherboard
Asus P8Z77-V Pro
GPU
EVGA 980TI SC+
RAM
16Gb PNY ddr3 1866
Hard Drive
PNY 1311 240Gb
Hard Drive
1 TB Seagate
Hard Drive
3 TB WD Blue
Optical Drive
DVD DVDRW+/-
Power Supply
EVGA SuperNova 750 G2
Cooling
EKWB P280 kit
Cooling
EK-VGA supremacy
Case
Stryker M [hammered and drilled]
Operating System
Win X
Monitor
LG 24MC57HQ-P
Keyboard
Ducky Zero [blues]
Mouse
corsair M65
Audio
SB Recon3D
Audio
Klipsch ProMedia 2.1
▲ hide details ▲


looniam is offline  
post #25 of 47 (permalink) Old 05-30-2019, 12:21 AM
mfw
 
ToTheSun!'s Avatar
 
Join Date: Jul 2011
Location: Terra
Posts: 6,967
Rep: 389 (Unique: 203)
Quote: Originally Posted by UltraMega View Post
Ground to satellite communication is very good, be it via ground based lasers or otherwise there is really no meaningful atmospheric issues to interfere with communication. Keep in mind the atmosphere is only like 30 miles high, and only thick for maybe half that, so it's not a long distance to send signals through. Assuming idea satellite operation, I think this will basically bring international/overseas latency down quite a bit, probably close to normal gaming standards, but probably won't impact continental communication for quite a while. Once it's fully operational you would probably have to be pretty close to a server to beat satellite communication latency.
Yeah. I guess time will tell. According to Wikipedia, the final orbital shell deployed (and the closest to sea level) will be at 340 Km, which is pretty close. The damned thing might even beat fiber in the same continent if the connection is a few countries apart; hypothetically, anyway. It's really a guess for a layman like me how the entire chain will handle data transmission.

CPU
Intel 6700K
Motherboard
Asus Z170i
GPU
MSI 2080 Sea Hawk X
RAM
G.skill Trident Z 3200CL14 8+8
Hard Drive
Samsung 850 EVO 1TB
Hard Drive
Crucial M4 256GB
Power Supply
Corsair SF600
Cooling
Noctua NH C14S
Case
Fractal Design Core 500
Operating System
Windows 10 Education
Monitor
ViewSonic XG2703-GS
Keyboard
Ducky One 2 Mini
Mouse
Glorious Odin
Mousepad
Asus Scabbard
Audio
Fiio E17K v1.0 + Beyerdynamic DT 1990 PRO (B pads)
▲ hide details ▲

Last edited by ToTheSun!; 05-30-2019 at 01:44 AM.
ToTheSun! is offline  
post #26 of 47 (permalink) Old 05-30-2019, 01:38 AM - Thread Starter
Graphics Junkie
 
UltraMega's Avatar
 
Join Date: Feb 2017
Location: USA
Posts: 1,283
Rep: 30 (Unique: 26)
Quote: Originally Posted by ToTheSun! View Post
Yeah. I guess time will tell. According to Wikipedia, the final orbital shell deployed (and the closest to sea level) will be at 340 Km, which is pretty close. The damned thing might even beat fiber in the same continent if the connection if a few countries apart; hypothetically, anyway. It's really a guess for a layman like me how the entire chain will handle data transmission.
Once fully operational, unless the satellites themselves are a latency issue more so than ground bases server (which is unlikely), the latency from Los Angeles to San Francisco should be better over satellite than fiber. This assumes ideal-full operational capabilities.

i7 7700kK @4.2ghz
16GB DDR4 3200mhz
GeForce 1080 Ti
UltraMega is offline  
post #27 of 47 (permalink) Old 05-30-2019, 01:53 AM
Robotic Chemist
 
Asmodian's Avatar
 
Join Date: Aug 2009
Location: San Jose, California
Posts: 2,576
Rep: 189 (Unique: 127)
Quote: Originally Posted by UltraMega View Post
Quite a good answer. Thanks for pointing that out. It was so mathematically worded that my brain skipped over it knowing it would take a long time to process. I think the picture I included also helps a lot to visualize the delay.
That picture is not why there is a delay, the angles are much lower so geometry does not add much delay. You shoot the laser straight down the fiber and the fiber diameter is very low. That is one of those explanations that gets the right answer, looks nice, and makes sense, but is a total lie.

Why light is slower in glass is a complicated topic involving both the wave nature of light and its interactions with the electrons in the material it is passing through:

Quote: Originally Posted by UltraMega View Post
Just want to add, I did a little more reading up on fiber speeds. Apparently there are some research projects that put fiber at 97% the speed of light.
That is by making it a hollow fiber, so still doing all the bouncing but not interacting with many electrons.

Last edited by Asmodian; 05-30-2019 at 02:03 AM.
Asmodian is offline  
post #28 of 47 (permalink) Old 05-30-2019, 03:17 AM - Thread Starter
Graphics Junkie
 
UltraMega's Avatar
 
Join Date: Feb 2017
Location: USA
Posts: 1,283
Rep: 30 (Unique: 26)
Quote: Originally Posted by Asmodian View Post
That picture is not why there is a delay, the angles are much lower so geometry does not add much delay. You shoot the laser straight down the fiber and the fiber diameter is very low. That is one of those explanations that gets the right answer, looks nice, and makes sense, but is a total lie.

Why light is slower in glass is a complicated topic involving both the wave nature of light and its interactions with the electrons in the material it is passing through:
https://www.youtube.com/watch?v=CUjt36SD3h8



That is by making it a hollow fiber, so still doing all the bouncing but not interacting with many electrons.
OK, so light doing its wave thing and not its photon thing in fiber. Damned if don't get those mixed up (and really if I were smart enough to in the first place).

Thank you for clarifying. I watched that video and it was definitely helpful.

If it's a wave wouldn't that mean it gets a lot weaker a lot faster? Sorry if thats a dumb question here but I'm picturing a wave traveling though the fiber now and it seems like that would be fast but heavy degradation? IDK this is def over my head at this point but love to learn more about it.

i7 7700kK @4.2ghz
16GB DDR4 3200mhz
GeForce 1080 Ti

Last edited by UltraMega; 05-30-2019 at 03:24 AM.
UltraMega is offline  
post #29 of 47 (permalink) Old 05-30-2019, 04:20 AM
I dunno what I'm doing.
 
Blze001's Avatar
 
Join Date: Mar 2013
Posts: 1,453
Rep: 63 (Unique: 45)
My little brother is studying astronomy. They're livid about this, it's gonna severely inhibit ground-based observations.

It is what it is.
Waterworld
(21 items)
CPU
i7-8700k
Motherboard
ASRock Fatal1ty Z370 Gaming-ITX/ac
GPU
GTX-1080ti Founder's Edition
RAM
Kingston HyperX
Hard Drive
Samsung M.2 950 PRO
Hard Drive
SanDisk Ultra II
Power Supply
Corsair RM650x
Cooling
Optimus V1 LGA-1151 Waterblock
Cooling
Nemesis GTS240
Cooling
Nemesis 120GTS
Cooling
EK D5 Revo
Cooling
Singularity Protium Pump Top/Case
Cooling
EKWB 10x0 Waterblock
Cooling
SavantPCs 240mm Reservoir
Cooling
Noctua NF-A12x25
Case
Fractal Nano S
Operating System
Windows 10 Pro
Monitor
Alienware AW3418DW
Keyboard
GMMK TKL
Mouse
Logitech G602
Audio
Creative X7
▲ hide details ▲
Blze001 is offline  
post #30 of 47 (permalink) Old 05-30-2019, 07:26 AM
Otherworlder
 
epic1337's Avatar
 
Join Date: Feb 2011
Posts: 7,355
Rep: 217 (Unique: 125)
uhhh, maybe within the span of a few minutes per hour, these satellites aren't stationary.

trolling an adult is very dangerous, don't try it at home nor at work. you don't want to play tag with a rabid man.
epic1337 is offline  
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Overclock.net - An Overclocking Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off