technical aspects in channel planning for digital terrestrial television broadcasting in nigeria n.
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TECHNICAL ASPECTS IN CHANNEL PLANNING FOR DIGITAL TERRESTRIAL TELEVISION BROADCASTING IN NIGERIA. GBENGA-ILORI, A.O. DEPARTMENT OF ELECTRICAL AND ELECTRONIC ENGINEERING FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE, ONDO-STATE, NIGERIA. biodun732000@yahoo.com. WHY DIGITAL BROADCASTING?.

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technical aspects in channel planning for digital terrestrial television broadcasting in nigeria

TECHNICAL ASPECTS IN CHANNEL PLANNING FOR DIGITAL TERRESTRIAL TELEVISION BROADCASTING IN NIGERIA

GBENGA-ILORI, A.O.

DEPARTMENT OF ELECTRICAL AND ELECTRONIC ENGINEERING

FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE,

ONDO-STATE, NIGERIA.

biodun732000@yahoo.com

why digital broadcasting
WHY DIGITAL BROADCASTING?
  • Consistent service quality with improved immunity to noise
  • Near error-free picture and sound propagation within the range of performance
  • Lower operating costs through the use of compression technology
  • Efficient use of the spectrum; small re-use distance
  • Lower transmitter power required compared with analogue counterpart
key objectives in channel planning
KEY OBJECTIVES IN CHANNEL PLANNING
  • To minimize or avoid interference and disruption to analogue television reception.
  • To identify a number of channels that can be used for digital services at sufficient e.r.p. levels to achieve the same level of coverage from the same transmitting sites as analogue services
constraints
CONSTRAINTS
  • The suitability of existing transmission facilities; and
  • The population of existing receive antennas
types of interference
TYPES OF INTERFERENCE
  • Digital-to-analogue Interference
  • Digital-to-digital interference
digital toanalogue interference
DIGITAL-TOANALOGUE INTERFERENCE
  • Degree of degradation on analogue services from digital services
  • Digital spectrum characteristic is similar to Gaussian noise
  • Effect of CCI is to raise the noise thresholds of analogue receivers
  • Overall effect is reduction in picture grade
digital to digital interference
DIGITAL-TO-DIGITAL INTERFERENCE
  • Degree of degradation to digital service from a digital service
  • The effect is to increase the system’s susceptibility as the modulation levels are increase.
  • However, higher modulation levels allows very sophisticated error-management schemes
digital channel planning methodology
DIGITAL CHANNEL PLANNING METHODOLOGY
  • Propagation prediction methods
  • Station Information
  • Establishment of the size of analogue coverage areas
  • Establishment of the size of digital coverage areas
  • Protection ratio
station information
STATION INFORMATION
  • Name
  • Channel Number
  • Frequency of operation
  • Location
  • ERP
  • Antenna Height
  • Polarisation
size of analogue coverage areas
SIZE OF ANALOGUE COVERAGE AREAS
  • Need for analogue coverage area to estimate digital service e.r.p.
  • Impact of co-channel interference on analogue services
  • Impact of adjacent channel interference on analogue services
co channel interference
CO-CHANNEL INTERFERENCE

Ta

Tb

Ra

Rb

Dm

Dt

Figure1: Protection Ratio Parameters

protection ratio parameters
PROTECTION RATIO PARAMETERS

Rp = Dt - (Ra + Rb)

Dm

Rp - Protection ratio

Dt - Line of sight distance between two co-channel transmitter

Dm - Limiting Distance between them

Ra - Service range of transmitter A

Rb - Service range of transmitter B

levels of protection
LEVELS OF PROTECTION

Dt - (Ra + Rb) = 1

Dm

Dt - (Ra + Rb) > 1

Dm

Dt - (Ra + Rb) < 1

Dm

size of digital coverage areas more complicated why
SIZE OF DIGITAL COVERAGE AREASMORE COMPLICATED; WHY?
  • Maximum e.r.p. can be largest value which does not cause unacceptable interference
  • Polarization may be the same with existing analogue service or orthogonal
  • Planning to choose required standard
required protection ratio
REQUIRED PROTECTION RATIO
  • UNWANTED ANALOG UNWANTED DIGITAL

LOWER ADJACENT

CHANNEL

-37dB

-30dB

CO-CHANNEL

+20dB

+3dB

Wanted

Digital

UPPER ADJACENT

CHANNEL

-38dB

-30dB

-30dB

-46dB

IMAGE CHANNEL

FIGURE 2: DIGITAL PROTECTION RATIO

the situation in nigeria
THE SITUATION IN NIGERIA
  • 42 CO-CHANNEL VHF STATIONS
  • 22 CO-CHANNEL UHF STATIONS
  • NUMBER INCLUDE PROPOSED ANALOGUE TELEVISION STATIONS
preferential television channel for digital television in nigeria
PREFERENTIAL TELEVISION CHANNEL FOR DIGITAL TELEVISION IN NIGERIA

Not preferred for digital television

because of co-channel interference

CH 5 - 12

VHF BAND III

Not preferred for digital television

because of co-channel interference

CH 28 - 35

UHF BAND IV

Preferred for digital transmission

since it is relatively free from CCI

CH 36 - 69

UHF BAND V