In Broadcast - July 2013 - 54


I N T E R N A T I O N A L

WWW.INBROADCAST.COM | ISSUE 21 - JULY 2013

N E W S

InTECH

ABonAir Part II – Wireless Video Links
Continuing our review of microwave video links, we take a closer look at the issues surrounding
uni-directional / bi-directional technologies and transmission range...

By Eran Igler
CEO, ABonAir

I

54

n our previous ar ticle we
reviewed different wireless video
transmission technologies that
allow camera teams to transmit
video content from cameras back
to outside broadcasting vans
(OB-vans) or central stations.
Broadcasters increasingly
appreciate the value of wireless
links to create attractive, compelling
content along with easy video
shooting. For this reason the use of
wireless link solutions is on the rise.
In our last issue’s overview,
we discussed the way different
technologies suit different broadcast
uses, and indicated a set of buyingdecision parameters: transmission
stability, picture quality, compression,
licensed / un-licensed frequencies,
delay, uni-directional / bi-directional
technologies and transmission range.
The last two parameters will be
elaborated in this article.

Uni / Bi-Directional
Technologies
Most microwave broadcast
systems today are based on unidirectional (or half-duplex) RF links,
where the transmitter sends video
content to the receiver and does
not receive any feedback about the
transmission quality. Uni-directional
systems have no acknowledgement
confirmation or error notification
from the receiver.
With no content confirmation or

acknowledgment mechanism, unidirectional links cannot identify
errors while they occur, and so they
need to allocate large amount of the
bandwidth for redundant information
transmission. The redundancy
enables the receiver to correct some
of the errors in the received data and
improve the overall error rate to an
acceptable level.
In bi-directional links, however,
both transmitter and receiver can
send and receive data and control
information. The technology enables
the receiver to acknowledge each
pixel transmitted over the air
and thus guarantees zero errors
in transmission. The packet
acknowledgment mechanism
identifies errors and quickly fixes
them (by re-transmitting the
corrupted data) before the frame
is presented.
By acknowledging the correct
acceptance of each packet of
pixels, full-duplex systems enable
continuous and reliable content
transmission and allow broadcast
professionals to rely on stable and
accurate transmission.
In addition, bi-directional links
double the system efficiency and
provide higher net throughput
since there is no need to constantly
transmit redundant data, with only
error information being re-sent.
For example: let’s assume we
have a bandwidth of 20Mbps and

Outdoor applications require large transmission range. ABonAir exclusively
enabled a live coverage of the Israeli Parliament ceremony

a typical 1% PER (Packet Error
Rate). A uni-directional transmitter
would need approximately half of
the bandwidth for redundancy, or:
FEC = ½ (FEC is the technical term
used for redundancy – Forward Error
Correction) as the system cannot
identify when in time errors occur
and is forced to send the redundant
information of all the data.
So with 20Mbps available
bandwidth, the actual bit rate
decreases to only 10Mbps
because the system wastes 50%
on redundancy (FEC = ½), even
though there is only 1% error rate!
In bi-directional solutions the
numbers are totally different.
Since we know that errors occur
only 1% of the time, and we
know exactly when they occur
(due to the acknowledgment

mechanism), we then need to save
only 1% of the original bandwidth
for re-transmission of the wrong
information. It means that from
20Mbps, as much as 19.8Mbps
can be utilised to transfer the data
and only 0.2Mbps is dedicated to
error correction.
This high efficiency provides
two valuable advantages: higher
picture quality – since the available
bandwidth for compressed video is
almost double – and superior link
robustness, as simpler and more
robust modulation can be used due
to the relatively smaller bandwidth
requirement.
Bi-directional technology also
enables fully automated system
configuration based on changing
conditions to ensure robust link
performance - for example, since
there is full communication between
the transmitter and receiver, both
can identify new interference in the
frequency they use and decide to
move to a clearer frequency.
In conclusion, bi-directional
solutions assure that all the data
is well received without errors, and
increase efficiency, picture quality,
stability and robustness.

Transmission Range
The range between receiver and
transmitter may vary from 10 meters
to 2.5 Km. A few meters range may
satisfy in-studio applications like
video-assist or monitoring, or indoor
sport coverage (basketball, billiard
or ping-pong games) while outdoor
applications like live news broadcast,
open-air sports coverage or
Bi-directional technology enables robust and reliable video links

CONTINUED ON PAGE 56


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Table of Contents for the Digital Edition of In Broadcast - July 2013

In Broadcast - July 2013
Contents
InNews: Fiji TV Playout Facility Opts for Harris Broadcast Gear
InNews: Avalon Studios Goes for Xytech
InFocus: Panasonic Pro-Camera Equipment in Antartica
InSound: European Soccer Covered With Lawo Technology
InGear: Egripment Launch Universal Dolly
InTech: Abonair Part II – Wireless Video Links
InMedia: Vector 3: The Playout People
In Broadcast - July 2013 - Intro
In Broadcast - July 2013 - In Broadcast - July 2013
In Broadcast - July 2013 - Cover2
In Broadcast - July 2013 - Contents
In Broadcast - July 2013 - InNews: Fiji TV Playout Facility Opts for Harris Broadcast Gear
In Broadcast - July 2013 - 5
In Broadcast - July 2013 - InNews: Avalon Studios Goes for Xytech
In Broadcast - July 2013 - 7
In Broadcast - July 2013 - 8
In Broadcast - July 2013 - 9
In Broadcast - July 2013 - 10
In Broadcast - July 2013 - 11
In Broadcast - July 2013 - 12
In Broadcast - July 2013 - 13
In Broadcast - July 2013 - 14
In Broadcast - July 2013 - 15
In Broadcast - July 2013 - 16
In Broadcast - July 2013 - 17
In Broadcast - July 2013 - 18
In Broadcast - July 2013 - 19
In Broadcast - July 2013 - 20
In Broadcast - July 2013 - 21
In Broadcast - July 2013 - 22
In Broadcast - July 2013 - 23
In Broadcast - July 2013 - InFocus: Panasonic Pro-Camera Equipment in Antartica
In Broadcast - July 2013 - 25
In Broadcast - July 2013 - 26
In Broadcast - July 2013 - 27
In Broadcast - July 2013 - 28
In Broadcast - July 2013 - 29
In Broadcast - July 2013 - 30
In Broadcast - July 2013 - 31
In Broadcast - July 2013 - 32
In Broadcast - July 2013 - 33
In Broadcast - July 2013 - 34
In Broadcast - July 2013 - 35
In Broadcast - July 2013 - 36
In Broadcast - July 2013 - 37
In Broadcast - July 2013 - 38
In Broadcast - July 2013 - 39
In Broadcast - July 2013 - InSound: European Soccer Covered With Lawo Technology
In Broadcast - July 2013 - 41
In Broadcast - July 2013 - 42
In Broadcast - July 2013 - 43
In Broadcast - July 2013 - 44
In Broadcast - July 2013 - 45
In Broadcast - July 2013 - 46
In Broadcast - July 2013 - InGear: Egripment Launch Universal Dolly
In Broadcast - July 2013 - 48
In Broadcast - July 2013 - 49
In Broadcast - July 2013 - 50
In Broadcast - July 2013 - 51
In Broadcast - July 2013 - 52
In Broadcast - July 2013 - 53
In Broadcast - July 2013 - InTech: Abonair Part II – Wireless Video Links
In Broadcast - July 2013 - 55
In Broadcast - July 2013 - 56
In Broadcast - July 2013 - 57
In Broadcast - July 2013 - 58
In Broadcast - July 2013 - 59
In Broadcast - July 2013 - 60
In Broadcast - July 2013 - InMedia: Vector 3: The Playout People
In Broadcast - July 2013 - 62
In Broadcast - July 2013 - 63
In Broadcast - July 2013 - 64
In Broadcast - July 2013 - 65
In Broadcast - July 2013 - 66
In Broadcast - July 2013 - 67
In Broadcast - July 2013 - 68
In Broadcast - July 2013 - 69
In Broadcast - July 2013 - 70
In Broadcast - July 2013 - 71
In Broadcast - July 2013 - 72
In Broadcast - July 2013 - 73
In Broadcast - July 2013 - Cover3
In Broadcast - July 2013 - Cover4
In Broadcast - July 2013 - S1
In Broadcast - July 2013 - S2
In Broadcast - July 2013 - S3
In Broadcast - July 2013 - S4
In Broadcast - July 2013 - S5
In Broadcast - July 2013 - S6
In Broadcast - July 2013 - S7
In Broadcast - July 2013 - S8
In Broadcast - July 2013 - S9
In Broadcast - July 2013 - S10
In Broadcast - July 2013 - S11
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http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_NewYork2018
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http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201803
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http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_cabsat2018
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201801
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201712
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201711
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http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201708
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http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201705
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_NABSHOW2017
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201704
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_cabsat2017
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201703
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201702
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201701
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_INREVIEW2016
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201612
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201611
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_NABSHOWNYexpo
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_20110708_DEMO
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201610
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_inshowguide2016
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201609
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201608
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201607
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201606
http://europe.nxtbook.com/nxtbooks/lesommet/inbroadcast_APAC03
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201605
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_NABSHOW2016
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201604
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201603
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_cabsat2016
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201602
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201601
http://www.nxtbook.com/nxtbooks/lesommet/inbroadcast_APAC02
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201512
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201511
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_CCW15expo
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201510
http://www.nxtbook.com/nxtbooks/lesommet/inbroadcast_APAC01
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201509
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_IBC2015
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201508
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201507
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201506
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_BROADCASTASIA2015
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201505
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201504
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_NABSHOW2015
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201503
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_cabsat2015
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201502
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201501
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201412
http://www.nxtbook.com/nxteu/lesommet/inbroadcast_201411
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201410
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201409
http://europe.nxtbook.com/nxteu/lesommet/inbroadcastIBCPRINTEDGUIDE_201409
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201408
http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201407
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http://europe.nxtbook.com/nxteu/lesommet/inbroadcast_201401
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