ecen5553 telecom systems dr. george scheets week #14 [33] "huge growth for video telephony?...
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ECEN5553 Telecom SystemsDr. George ScheetsWeek #14[33] "Huge Growth for Video Telephony? Skeptics Wary of
Predicted Data Crunch"[34] "The Picturephone is Here. Really."[35] "Perspective in Next-Generation Home
Networks: Toward Optical Solutions?"Final Exam
Friday, 11 December, 1400 – 1550 (Live)< 18 December (Distance Learning)
Exam #2 (90 points) final resultsHi = 88.1, Low = 50.4, Ave = 78.84, σ = 8.46A > 81, B > 70, C > 61, D > 52
ECEN5553 Telecom SystemsDr. George ScheetsWeek #14[33] "Huge Growth for Video Telephony? Skeptics Wary of
Predicted Data Crunch"[34] "The Picturephone is Here. Really."[35] "Perspective in Next-Generation Home
Networks: Toward Optical Solutions?"Final Exam
Friday, 11 December, 1400 – 1550 (Live)< 18 December (Distance Learning)
Exam #2 (90 points) final resultsHi = 88.1, Low = 50.4, Ave = 78.84, σ = 8.46A > 81, B > 70, C > 61, D > 52
INMARSAT PhonesINMARSAT Phones
Recently smallerphones have become
available for usewith latest satellites.
Parabolic AntennasParabolic Antennas
Geosynchronous Satellite vs Sun, Mid-day, Northern Hemisphere
Geosynchronous Satellite vs Sun, Mid-day, Northern Hemisphere
x
WinterSun is belowsatelliteorbital plane.
x
Fall Sun → sameplane assatellite.
x
Spring Sun→ sameplane asSatellite.
x
SummerSun is abovesatelliteorbital plane.
2013 Fall Sun Outage, Microspace's AMC-12013 Fall Sun Outage, Microspace's AMC-1
Source: www.ses.com/4551568/sun-outage-data
x
Market Split for Backhaul GearMarket Split for Backhaul Gear
Source: "High-Capacity Ethernet Backhaul Radio Systems for Advanced Mobile Data Networks", IEEE Microwave Magazine, August 2009.
Cell Towerwith
Point-to-Point RF link
Cell Towerwith
Point-to-Point RF link
ProtocolsProtocols ProprietaryProprietary 802.16802.16 802.11802.11
Free Space LasersFree Space Lasers
Sources: www.fsona.comwww.engadget.com/media/2006/02/gigabeam.jpg
Comparison: Optical vs RF BackhaulComparison: Optical vs RF Backhaul
Source:"The Next Challenge for Cellular Networks: Backhaul", IEEE Microwave Magazine, August 2009 .
194,000 GHz XX GHz
5.3 minutes downtime/year
8.8 hours downtime/year
Hughes Net (2013)Hughes Net (2013)
IridiumIridium
6 Low Earth orbits, 11 satellites per polar orbit
Not-so-miniature phone.image sources: Wikipedia& www.iridium.com
Iridium in AntarcticaIridium in Antarctica
Source: wikipedia
1
2 34
5
7
6
8
GlobalstarGlobalstar
image source: www.globalstar.com
The TCom Systems final is in three weeks Chief. I need some time off to study. Dick
TracywithWristRadio
DickTracywithWristRadio
Image Source:Wikipedia
You too could have had a Wrist RadioYou too could have had a Wrist Radio
Touchscreen GSM Cell Phone/
PDA/ Wristwatch
formerlyavailable at
www.thinkgeek.com
Stick-on Smart PhoneStick-on Smart Phone
NTSC TVNTSC TV Analog video Analog video
Obsolete as of June 2009Obsolete as of June 2009 30 frames/second30 frames/second 525 Scan Lines in a Frame, 525 Scan Lines in a Frame, ≈ ≈ 485 Active485 Active Resolution ≈ 640 x 480 pixelsResolution ≈ 640 x 480 pixels Video Bandwidth 4.2 MHzVideo Bandwidth 4.2 MHz RF Bandwidth 6.0 MHzRF Bandwidth 6.0 MHz
AM modulated VideoAM modulated VideoFM Modulated VoiceFM Modulated VoiceGuard BandGuard Band
Red, Green, & Blue used on MonitorsRed, Green, & Blue used on Monitors
Color VideoColor Video
Ele
ctro
nic
s
3 Pick-Up Elements
CCD’s
R
G
B
Camera
Ele
ctro
nic
s R
G
B
3 drivesignals
Monitor
Receiver electronics generate 3 signals withstrength proportional to light falling on the 3 camera pick-up elements.
Paints are SubtractivePaints are Subtractive
24 bit color 224 = 16.78 M colors24 bit color 224 = 16.78 M colors
256 Colors256 Colors
16 Colors16 Colors
MPEG Employs...MPEG Employs... Motion Estimation Algorithms
Tracks groups of NxN pixels... ...imperfectly if small and fast moving
Discrete Cosine Transforms Maps NxN pixel block spatial characteristics to
frequency domain Values Quantized
Some high frequency components zero'd out Gets rid of very fine detail Other values rounded off Causes some distortion (smearing)
Example of High Frequency FilteringExample of High Frequency Filtering
0 20 40 60 80 100 120 140
0
22
1
1270 i
Scan Line (Time Domain)
Monitor Image
FilteringFiltering
0 10 20 30 40 50 60 700
2
44
Xj
640 j
Scan Line (Frequency Domain)
Scan Line (Frequency Domain after zeroing)
0 10 20 30 40 50 60 700
2
44
0
Yj
640 j
1/2 the points thrown out (values < .1)
FilteringFilteringReconstructed Scan Lines (Time Domain after filtering)
0 20 40 60 80 100 120 1401
0
1
22
0.086
yi
1270 i
y
Monitor Image
Using NxNpixel blockslocalizesdistortion to NxN area,unlike thisexample.
Note Edges Aren't As SharpNote Edges Aren't As Sharp
y
Compare
Dick Tracy with Wrist RadioDick Tracy with Wrist RadioThis is a small JPEG imagethat's been enlarged.
With a good contrast monitor, you should be able to see evidence of theblocks, and should alsonote that the distortion tends to be localized to areas where the picture is changing.
JPEG DistortionJPEG Distortion
Note the fuzzygray 'cloud'.
MPEG Employs...MPEG Employs... Huffman Coding
Used to map DCT results to a bit streamUses unequal length code wordsHigh probability outputs get shorter words G.711: equal length code words (8 bits/sample) Morse Code: unequal length
Morse Code:An UnequalLength Code
Average bit rate is < fixed length code= 5 bits/character for the alphabet,
or 6 bits/characterfor alphabet &
numbers 0-9
Morse Code:An UnequalLength Code
Average bit rate is < fixed length code= 5 bits/character for the alphabet,
or 6 bits/characterfor alphabet &
numbers 0-9
Image Source: Wikipedia
Huffman CoderUnequal Length Code Words
High Probability? Assign Small Word.
Huffman CoderUnequal Length Code Words
High Probability? Assign Small Word. Suppose have 4 voltages to move:Suppose have 4 voltages to move:
-3 v-3 v 25%25%-1 v-1 v 5% 5%+1 v+1 v 40%40%+3 v+3 v 30%30%
2 bit code word11100001
Huffman Code111110
010
1,000,000 voltages/sec → 2,000,000 bps (2 bit code)1,000,000 voltages/sec → 1,900,000 bps (Huffman)
.25(3) +.05(3) + .40(1) + .30(2) = 1.9 bits/word on averageUniquely Decodable: 1110010110 = ?
MPEG Video Frame SequenceMPEG Video Frame Sequence1/30th second
Intrapictures (JPEG Still)
Bi-directional PicturesMostly
Motion EstimationTechniques
Predicted PicturesMostly changesince previousI or P frame