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Data tables in digital transmissions


Digital broadcasting of TV channels require special care at the time of configuration.
There are parameters that, if not properly defined, can cause the lack of channels and services on TV sets.
For this reason, you must configure of NIT (Network Information Table). By means of NIT will be possible ID settings (Network Identifier) and ONID (Original Network Identifier).
These two identifiers must be consistent with the country in which the facility is located, because there are already specific values of these fields for each country, meaning that all units in the system must have the same values.
Each unit will have a parameter value TSID (Transport Stream Identifier), unique and different. Otherwise, if a facility has two multiplex with equal TSID, one of the services will not be tuned, since when making a search the TV set, or the receiver, they will identify the two different services as being the same.
Therefore, each Transport Stream (TS) comprises several services identified by a unique SID (Service Identifier) each one of them, and can be repeated in different TS.
You can also assign a name to the network, either to set the


  hierarchy information, or to define the LCN of each service.
In the T.0X transmodulators with COFDM output, the NIT can be configured from two modes:
Auto: values for NID,TSID and ONID are the same as those of the input signal.
Manual: the values of the parameters can be edited.This option is required for installations where more than one module has to be configured to receive all programs of a transponder. In this case, you would need to change at least the TSID of one of them in order to be able to tune the services of the two modules by either the TV set or the receiver of the end user.
You can also define the LCN of each service module. Be aware that there can not be identical values between units.
In the COFDM Encoders and Modulators there is the possibility of editing the program name and the SID. In the NIT can be assigned a name to the network, and configure the NID, TSID and ONID.
In any of these devices can be configured both the hierarchy and the LCN for each service. Thus it is possible, through an automatic search on the TV set or DTT receiver, a classification of programs according to the desired order, regardless of multiplex to

which they belong. This feature is  for any facility with a large number of services and televisions such as hotels, hospitals and CATV networks. 

Hélder Martins
International Technical Assistance

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