5.6.- DVB Channels Identifier: DCI function
This function permits to identify DVB channels with no need to have a digital signal decoder which permits to see transmitted TV
channels.
The DVB group recommends to digital TV service operators the codification on the Transport Stream of some particular fields containing
data information. The Transport Stream is a sequence of packets, of constant length, which carry video or audio information or data.
Data packets can be grouped to constitute TABLES, some of these tables content information defined by the network operator and which
show the type of service that is being supplied to the users. Among the different data defined in these tables, the most frequently used data
for channel identification purposes are:
Network
It contents the name given to the set of all the Transport Stream managed inside the same communication channel.
Bouquet
It contents the name given to the set of all the services commercialized as one entity.
Service
It contents the names of services that, under the control of one operator, can be shown at each moment on the
Transport Stream, as a function of current programming.
In case the operator includes this information, the three fields are not transmitted at the same time but they appear alternatively in
different packets. Besides, the cadence of presentation of each one of these packets may vary from one operator to another.
When tuning a DVB compatible transponder, the DCI function (DVB Channels Identifier) detects those data packets including service
information relative to these three fields and shows on the lower line on the screen the information contained in them automatically.
Figure 33.- DCI function. In this example the information coded by the operator on the
Service and Network fields is the same.
The information that appears in the Network, Bouquet and Service fields is responsibility of the Operator in charge
of the tuned transponder. The MTD 120 only decodes this information, if it is present, and shows it on the screen.
QPSK
1.0E-7
BER before FEC:
1.0E-3
-6 -5 -4 -3 -2 -1
BER after Viterbi:
1.0E-7
-8 -7 -6 -5 QEF -3 -2
Freq: 1224.0 - 0,8 MHz
W.P. 0 in 00:22:59
MPEG-2 DVB-S
QPSK
1.0E-7
BER before FEC:
1.0E-3
-6 -5 -4 -3 -2 -1
BER after Viterbi:
1.0E-7
-8 -7 -6 -5 QEF -3 -2
Freq: 1224.0 - 0,8 MHz
W.P. 0 in 00:23:22
Bouquet: News Bouquet
QPSK
1.0E-7
BER before FEC:
1.0E-3
-6 -5 -4 -3 -2 -1
BER after Viterbi:
1.0E-7
-8 -7 -6 -5 QEF -3 -2
Freq: 1224.0 - 0,8 MHz
W.P. 0 in 00:23:15
Network: NetMed
QPSK
1.0E-7
BER before FEC:
1.0E-3
-6 -5 -4 -3 -2 -1
BER after Viterbi:
1.0E-7
-8 -7 -6 -5 QEF -3 -2
Freq: 1224.0 - 0,8 MHz
W.P. 0 in 00:23:48
Service: NetMed
148
TV & SAT Level Meter MTD 120
User Manual
