Posted by admin | Posted in Uncategorized | Posted on 30-10-2007
Tags: photography, science, sea, under, under sea pictures, under seal, under seat dvd player, under seat luggage, under seat subwoofer, under seat truck storage, underwater
Under Sea
Why do we have communication cables under the sea?
we have many satellites for communication purposes , but why do we lay cables under the sea for communication...Is there something which a satellite system cant do for us..?I want the details about the purpose of satellite and cable communication system.
Satellite communications have much greater latency (delay) than a earth bound cable because the communication paths are much longer. For example, a trans-atlantic cable from New York to The South Western tip of England is about 5000km long.
Since communication satellites are about 36,000km above sea level, transmissions from the same two points using a slightly oversimplified right isosceles triangle with a base 5000km long and a height of 36,000km yields a path of 72,000 km from ground to satellite to ground.
Assuming that the signals move at the speed of light (or close to it) the cable will take about 0.0017 seconds to carry the signal but the satellite will take 0.24 seconds,
All figures are approximate, but the general idea holds: it is much faster to send a signal across the much shorter oceanic cable than via communications satellite.
Also before satellites we could lay trans-atlantic telegraph and then telephone cables. The first transatlantic telegraph cable was laid in 1858, the first trans-atlantic communications satellite was launched in 1964.
 |
 KIDSLINE ZANZIBAR NURSERY LOT RUG LAMP WALL HANGINGS EX  US $20.50
|
 Boutique All Star Sports Boy 13PCS CRIB BEDDING SET US $49.99
|
 Boutique Brown Pink Star Moon 13 PCS CRIB BEDDING SET US $49.99
|
 Boutique Brown Blue Star Moon 13 PCS CRIB BEDDING SET US $49.99
|
 Boutique Baby Boy Fire Truck 13PCS CRIB BEDDING SET US $49.99
|
 Boutique Designer Blossom Quilt 13PCS CRIB BEDDING SET US $49.99
|
| Powered by phpBay Pro |
 |
Colgate Classica I Foam Crib Mattress, White List Price: $179.99 Sale Price: $137.00 Average Rating:   |
|
HC515237F The most recognized and popular foam crib mattress by name in America. The Colgate Classica I extra firm foam mattress crib mattress was rated #1 of all crib mattresses tested by one of the nation's leading consumer products magazines and has been a recommended buy for over fourteen years by another popular baby products publication... |
 |
Naturepedic Waterproof Fitted Crib Pad, 28x52 List Price: $59.00 Sale Price: $58.95 Average Rating: |
|
The Naturpedic Organic Cotton No-Compromise Waterproof Fitted Crib Pad is soft and breathable providing a non-sweaty and comfortable barrier that blocks dust-mites and other allergens. The top and bottom layers are 100% cotton fabric... |
 |
Stops Crying: Heartbeat Lullabies Original, Vol. 1 List Price: $14.99 Sale Price: $11.87 Used From: $2.90 Average Rating: |
|
Having trouble with a Crying Newborn Baby? Stressed - nerves on edge - due to your crying baby? It's the #1 Problem Facing New Parents Today: How do I Put my Baby to Sleep and get my Baby to Stop Crying? Millions of People have heard these baby lullabies with Heartbeat Rhythm You heard these baby lullabies when you were young, you have seen them calm infants, Now you can own it yourself - BUY NOW or BUY FOR NEW PARENTS It works We GUARANTEE it... |
 |
NoJo Jungle Babies Switch Plate Cover List Price: $9.99 Sale Price: $9.95 Average Rating: |
|
3544987 -Standard size light switch plate. -Green with jungle theme. -Coordinates with the NoJo Jungle Babies Crib Bedding Collection. ***Please note that these products cannot be shipped to Alaska, Hawaii, or Puerto Rico... |
 |
Kids Line Animal Acres Nightlight, Green/Brown List Price: $14.99 Sale Price: $12.95 |
 |
Kids Line Jungle 123 Night Light, Brown List Price: $14.99 Sale Price: $13.95 |
|
The Jungle 123 Nursery Night Light features a jungle animal design theme in a neutral color scheme. |
 |
Summer Infant Ultra Plush Change Pad Cover - White List Price: $15.00 Sale Price: $14.99 Average Rating:  |
|
These plush covers from Summer Infant are a perfect accent to any nursery. The Ultra Plush⢠covers are so soft to the touch and fit over most standard sized changing pads. The velboa material is stain resistant and colorfast for long lasting use... |
 |
Naturepedic Contoured Changing Pad Cover List Price: $29.00 Sale Price: Too low to display Average Rating: |
|
The optional Changing Pad Covers for Naturepedic Changing Pads feature a fitted design that secures to changing pad. Made from 100% organic cotton flannel. Provides a soft absorptive surface for added comfort... |
 |
Colgate Mattress 3 Sided Contour Changing Pad, White List Price: $41.99 Sale Price: $33.95 |
|
CR300-041 Features: -Changing pad. -Cover material: Quilted vinyl. -Color: White. -3-Sided contour changing pad turns any flat surface into a changing station. -3-Sided pad provides a secure cocoon for baby while being changed... |
