Types of Broadcasting Networks Broadcasting Networks
Radio Broadcasting
Kithsiri Samarasinghe
Senior Lecturer Dept. of Electronic & Telecommunication Eng. University of Moratuwa
Data Broadcasting
Television Broadcasting
According to Delivery Medium
Combinations
Terrestrial
Radio
Terrestrial Satellite
Data Television
Satellite Cable
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Cable
Development
Television Broadcasting
TV TV on Cable and Satellite,
DTTB/ HDTV IPTV Mobile TV
(T-DMB, DVB-H,
DAB
1960 1970 1980 1990
2000 6
Analogue Television Broadcasting
Commenced in June 1979 in Sri Lanka
A Television Transmitter
System B/G PAL
A Television transmitter has to deliver two signals to the viewer simultaneouly
Vision (Video) signal Sound (Audio) signal Common Amplification Separate Amplification
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Band
I III IV/V
Frequency Range
47 MHz 68 MHz 174 MHz 230 MHz 470MHz 806 MHz
Channel
24 5 12 21 62
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Two ways for implementing it;
Common Amplification
Exciter
RF Divider
RF Amp
RF Combiner
Filter
RF divider and combiner are required if the RF amplifier consists of SSPA modules.
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A Simple Test Transmitter
Separate Amplification
RF Divider Video RF Amp RF Combiner Audio Video Diplexer Audio RF Amp 11 12
Exciter Stages
Main Processes
A CIN Diplexer
Vision/sound exciter stages carry out the modulation on IF carriers Then IF is upconverted to RF using crystal stabilized local oscilllators RF vision & sound carriers are separately amplified. Amplified RF carriers are combined using a TV diplexer
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CIN = Constant Impedance Notch 14
SSPA Modules for Power Amplification
Increasing Reliability
Multiple SSPAs and 1+1 Redundancy for exciter
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Multiple SSPAs allow for graceful degradation of the output level 15
Dual Transmitters in Parallel Operation
Exciters operate in passive reserve mode with automatic switching
Standard Configurations
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Power Amplifiers
Power Amplifying Devices
Klystron Tetrode Diacrode Klystrode, further developed to IOT SSPA, using LDMOS
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Tetrodes
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IOT Common Amplifiers Diacrodes
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TV signal
Interlaced Scanning
Resolution
Level Range of CVS
CVS Format
Vestigial Side Band Modulation
NICAM Digital Audio
Terrestrial Broadcast Coverage
Audio Sampling rate - 32 kHz Resolution -14 bits/sample Bit rate - 728 kbps Type of Modulation DQPSK NICAM IF Carrier is at [fv + 5.85] MHz
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Achieved through a terrestrial transmission network Consists of STL, Transmitter stations and Transposer stations Transmission plan consists of;
Frequency plan Coverage predication ERP
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Antenna Radiation Patterns should Match Coverage Requirements;
Antenna Arrays
Horizontal Plane Radiation Pattern
Vertical Plane Radiation Pattern 31 32
Important Aspects
Limiting factors of Analogue TV
Beam Tilt
Signal degradation
Tilting the beam downwards to minimize power wastage Calculate it according to coverage area An array produces peaks and nulls Null filing should be done in both horizontal & vertical planes by phasing the antennas.
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Noise & Interference
Ghosting Effect Spectrum Congestion No Mobile Reception
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Null Filling
Content Creation from Analog to Digital
Emerging Technologies
DTTB
(Digital Terrestrial TV Broadcasting)
Using digital technology to provide - more channels (SDTV) and/ or - better picture (HDTV) and sound (surround) .over the terrestrial TV broadcast.
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Three DTTB Systems
PAL (studio quality)
DVB-T ATSC ISDB-T
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HDTV
Emerging Technologies
HDTV
(High Definition TV)
16 x 9 aspect ratio. Studio Standard: 1080/50i in 50Hz countries. Transmission standard: country-dependent. Picture information about 5 times that of conventional TV Needs critical camera focusing and attention to the wide aspect ratio. OB can use fewer cameras. Compatibility with 4x3 SDTV
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Emerging Technologies
Emerging Technologies
Mobile TV
Broadcast to hand-sets (mobile phones, PDAs), notebook PCs, etc. Interactive and audio services. T-DMB (Terrestrial-DMB) Evolved from DAB. Allows video, audio and data to be transmitted to mobile devices. More efficient audio coding. Backward compatible with DAB audio (MUSICAM). DVB-H (Digital Video Broadcasting Handheld) Tailored for transmitting multiple TV channels to mobile devices. Time-slicing technology conserves battery power of mobile devices.
IPTV
(Internet Protocol TV)
Use of Internet Protocol (IP) for home TV transmission, can be over phone lines, via optical fibre trunks. Flexibility of including interactive services and HDTV. Offers many TV channels, viewer-targeting. For HDTV, application of MPEG4 AVC (H.264)/ VC-1 (WMV) coding, VDSL2/ ADSL2+ technologies or Fibre to the Home/ Building (FTTH/ FTTB).
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Status of Digital Broadcast Technologies
Technologies
DAB HDTV IPTV-SD Mobile TV Internet Users Broadband Users
A Beam produces a Footprint
Sets (in M), world-wide
>5 > 30 >5 > 2.5 > 1,100 > 200
Main Areas
United Kingdom USA, Japan Hong Kong, France S. Korea (T-DMB) USA, China, Japan USA, Japan, S. Korea
Sources : wilkipedia, internetworldstat.com, etc. (2009)
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Satellite Broadcasting
Transponder
Satellite Transponder
More Power-limited than Bandwidthlimited 36 MHz and 72 MHz Bandwidth 50 W typical
C Earth Station A B Receivers in the Footprint
Contribution Distribution Feeds
Satellite DVB-S
Broadcasters ? Internet services
DVB-C
ARD linear IPTV and IP Radio DSLhead end Multicast WWW + IPTV IP Radio
Broadbandcablehead end
Broadcast delivery
IPTV
Internet ?
DSL-Access DSLAM
Distribution
Broadband-Internet Voice-phone Unicast
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