TEST ECRIT du 2 avril 2015 sur les lectures préparées
(8 points sur 40 total année)
Le test comportera :
- une partie audio (quelques extraits des fichiers étudiés, dont vous restituerez le contenu dans vos propres mots); SANS documents
- une quinzaine d’expressions à traduire d’anglais en français; SANS documents
- questions en anglais, réponses à donner en français en consultant les textes dépourvus de toute annotation de vocabulaire (+ dictionnaires explicatifs monolingues si nécessaire)
Partie de N. Baertsoen : NETWORKS
TEXTES
- Networking basics (1p. recto/verso, compilation de plusieurs sources) – schémas : voir billet du 5 mars (à consulter pour info, inutile de les imprimer)
- Introduction to How Wi-Fi works (HowStuffWorks)
- Choosing a wireless router (Computer Shopper 324, Feb 2015)
- Wireless routers (Computer Shopper 323, Jan 2015) p.97 + p. 99 non lue au cours (une question du test consistera à y rechercher des informations en rapport avec la p. 97)
- The layered approach to Internet software (Brookshear, Computer science : an overview, p. 167-170)
- Why homes could soon be wire-free (BBC Click, Apr 3rd 2013) : transcript of the video
- Gigabit Wi-Fi (The Economist, Apr 22nd 2013)
AUDITION (partie audio du test)
- Why homes could soon be wire-free (BBC Click, Apr 3rd 2013)
Partie de M. Casier : voir ses indications
màj 26/3/15 : Transcription de la vidéo (minutageYouTube)
0:32 What would you do to boost your signal ?
This week on Click we ask if the trusted Wi-Fi in our homes is up to the job anymore
and we showcase the new tech promising a lightning-fast connection.
0:43 (…)
1:12 Welcome to Click. I’m Spencer Kelly.
If you think about it, we really are living in a world of magic, aren’t we ?
Our phones, our tablets and our laptops
just talk to each other and the rest of the world
without any wires whatsoever.
And it all does seem to work quite well – up to a point.
1:30 Because the files that we want to send are getting larger
and if for example you’ve ever tried to stream a high-def movie over Wi-Fi,
well, things may have got a touch sticky.
Dan Simmons has been looking at some of the new wireless technologies in the pipeline
that may be better at handling those huge files and high data rates.
__________________
1:49 The future looks great, doesn’t it ?
Except when it does this.
(buffering circles on screen)
And if we were to travel to the time we expect to see these technologies,
about five years from now,
then this video would be in super high definition
Maybe if we were streaming this over our home Wi-Fi
we’d be watching… these buffering circles a little bit too often.
2:21 And that can happen today in the home,
even with high definition or standard definition video streaming,
regardless of how fast the connected broadband speeed into the home is.
And that’s because we are starting to ask too much of our home Wi-Fi router.
Wherever we’ve placed it in the house,
we expect it to service all of our devices at once.
2:46 Wi-Fi is no longer used just to browse the net.
We’re using it for gaming
and to stream content we’ve already downloaded to larger screens,
using technologies like HP’s TV Connect or Apple’s AirPLay,
to throw content from our phones, tablets or laptops to the big screen.
The magic all relies on Wi-Fi.
3:11 And Wi-Fi has another problem to deal with.
It uses a similar frequency to send and receive data
as many other things that we use around the home,
like all of our Bluetooth devices
or these wireless telephone handsets
– and of course our neighbours’ Wi-Fi, Bluetooth and wireless handsets.
So there’s quite a bit of interference.
3:36 So it seems that if we want to hang on to our wireless world,
we’ll need to upgrade our home Wi-Fi to something else.
No – something else.
The good news is that in recent years some of our tech has switched
from using the old 2.4GHz frequency
to jointly being able to use he less congested 5GHz frequency,
and that’s like moving up a gear
from trundling along a country road
to cruising on a motorway.
Higher frequencies make for faster data transfers,
and a new upgrade to the 5GHz service, called 802.11ac
(a name that sounds a bit like a number plate)
is starting to make its way to a range of products,
including mobile phones from HTC and Samsung.
4:28 And to reliably stream this super high definition video
(« HEVC 4K x 2K @ 3.7 Mbps »)
which has four times as many pixels as full HD,
the Wi-Fi people are about to push things even higher up the scale,
to 60 GHz.
(« 60GHZ WirelessHD » – « UltraGig » labels on gear)
This system is called WirelessHD
and as the name suggests
it’s been specifically designed for video and gaming content.
4:53 Jim Chase (Silicon Image WirelessHD) :
– It supports full HD uncompressed video transmission
with up to 4 Gbps of data rate.
(« Designed to work in high-density environments »)
While WirelessHD is geared to streaming,
another emerging standard, WiGig, allows you to use that speed
to transfer any file – important for our future movie downloads
that are going to be huge.
5:20 But there’s a catch with using faster, higher frequencies for wireless devices :
the higher the frequency, the shorter the distance our data can travel through the air,
and our superfast highway simply runs out.
WiGig can transfer files (at) an amazing four and a half (4.5) Gbps.
Now that’s about as fast as this latest USB 3 cable.
But expect a big dropoff in that rate depending on how far the signal has to travel.
In fact it won’t go further than a few metres
when the first products come out later this year.
6:01 Well, that could still be useful within the confines of one room.
We could crack open two or three devices
and start streaming super high definition.
But come upstairs to the bedroom
and you get absolutely no signal at all.
Worse than the current Wi-Fi situation.
(« – Sorry about that. »)
6:29 So, just like the Washington bridge, our wireless devices will double up,
running two or more frequencies at the same time.
Dr Henry Samueli, Co-founder, Broadcom :
– If you look at Wi-Fi today,
it operates at 2.4GHz and 5GHz,
same dual-band solutions that we’re selling to the market today.
But I can see in the future, you’ll have tri-band solutions,
you’ll have 2.4GHz, 5GHz and 60GHz,
all sitting underneath the Wi-Fi protocol umbrella
and giving you the choices of speed versus distance in communication.
7:00 The limit on distance for the superfast Wi-Fi
means it’s likely to be used to replace cables.
This WiGig docking station is one of the first to use the tech.
Simply pop your laptop close by,
and it backs up all your files in seconds.
The direct link means there’s no need for a router,
so this setup could be used anywhere in the house.
7:25 So, might this be the end of cables altogether ?
Mazar Nekoveey, Communications Expert :
– Ultimately wireless goes through the air, so there’s no medium,
and it might not get always as stable as… with cables.
But then there’s no wire(s), and people that… like that,
and it’s magic, that’s what I think.
It’s even more interesting making everything as wireless as possible.
7:47 By this time next year
we should know whether that magic will allow our cables to finally disappear.
7:55
