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This note describes how ATDI software can be used across current
Analogue and Digital Broadcast Technologies in both TV and
radio to optimise and roll out networks. Tools are included within
ATDI planning tools for future technologies such as T-DAB and DTTV.
The methods and sub-tools within tools such as ICS Telecom have
come from our work with various broadcast customers including several
national broadcast organisations as well as systems integrators
supplying turnkey broadcast solutions. These customers have either
used our tools or have contracted ATDI to carry out work on their
behalf to furthers their development of their broadcast networks.
General Broadcast
Planning Methods
The following general modelling methods have
application in broadcast networks and are included in ATDI planning
tools. Please refer to the technologies section on microwave links
for details of tools for transmission bearer planning.
- The ability to compute the coverage
of ground area from a given transmitter type and specification
to a given receiver type and specification considering both directional
and omni-directional antennas.
- The ability to design and model all
types of sectored broadcast antennas including those with
down tilt. Antennas may be theoretical, mirroring administration
masks or real, emulating reality and comparisons may be done between
the two.
- The ability to compute the degree of interference
suffered by subscribers from all sources on the same or adjacent
channels. This includes the ability to view interference limited
coverage across all combinations of culprit and victim networks.
Interference includes considering varying protection ratios taken
from ITU recommendations.
- The counting of subscriber population
covered under a transmitter footprint with the addition of
an irregular polygon limit. Includes the graphing subscribers
by social category.
- The counting of area under a transmitter
footprint but showing results over a variety of different urbanisation
categories including roads, urban and suburban areas with the
addition of an irregular polygon limit.
- The ability to link the planning tools
via an Open DataBase Connectivity protocol to external
databases such as Oracle or MS Access allowing the sharing of
engineering data across a multi-discipline project team.
Specific Broadcast
Planning Methods
The design and subsequently the roll our
of broadcast networks to cover both analogue and new digital services
is a well established process. There is however great scope for
automation in the methods and for optimisation of the engineering
design to critically engineer the network to meet the customer requirements
with the minimum transmitter and antenna system resources both initially
and as the network develops. The specific methods noted below are
some of the many tools employable to ensure that the planning team
produce the most cost effective system.
The coverage calculated can be filtered to
only display on specified ground use types such as suburban areas
or roads. This then allows the planner to focus on the desired target
user for the service. Similarly interference calculations over rural
or open areas away from that target user can be ignored or reduced
in consideration during automatic frequency planning.
Several views are possible once a coverage
computation from a given sites or radio base station has been made.
The best server view shows where on the ground mobiles would
vote or register on the basis of signal strength. The simultaneous
communications view shows which areas on the ground benefit
from signal from several sites.
Once coverage has been assessed the operating
frequency of the transmitter can be assigned automatically from
a frequency list. Frequency planning can be set to consider
either omni-directional or directional subscriber antennas.
With new digital services in both television
and radio ICS Telecom incorporates methods of assessing the effects
of both amplitude and phase of multiple arrivals at the subscriber
antenna. At the overlap if the incident signals are within capture
of the receiver and if the differential delay between the various
signals is within various guard intervals the effect may be constructive
or destructive interference. This effect typical of the Single
Frequency Network can be modelled.
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