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CGT 660
tps
module
funCtions
When converting COFDM-modulated signals to QAM-modulated cable sig-
nals, the demodulated data stream can be accessed via the integrated TPS
module. This data stream, also called transport stream, contains several sta-
tions in all their components (video, audio, data and service information),
which can be changed using the TPS module.
s
tation
filter
Individual stations can be deleted. This reduces the data rate. As a result, a
lower output symbol rate can be selected.
s
tuffing
The transport stream is padded using what is known as zero data. This in-
creases the data rate and, consequently, the output symbol rate. Changing
the output symbol rate suitably alters the bandwidth used (halving the output
symbol rate roughly halves the bandwidth at the output).
C
hanging
serviCe
infor m ation
The transport stream contains data in the form of tables which the receiv-
ers evaluate and require for convenient use. The TPS module can adjust the
"Network Information Table" (NIT) to accommodate the new station data. The
"NIT" contains data which is required by the set-top box for the automatic
search feature.
C
hanging
the
oper ator
id (Cat)
Some network operators transmit an operator ID in the data stream (e.g.
visAvision). By changing the CAT the operator ID can be adjusted to the de-
mands.
