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HDTV 1000 ASI LAN / HDTV 1001 C
Changing the operator 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.
2.7 Explanation of the term “symbol rate”
Modulation schemes such as QPSK and QAM transmit multiple bits simultane-
ously. These are referred to as symbols. In addition to the user data flow which
ÌÀ>ÃÌÃÊÛ`iÊ>`Ê>Õ`ÊvÀ>Ì]ÊiÀÀÀÊVÀÀiVÌÊLÌÃÊ>ÀiÊÌÀ>ÃviÀÀi`°Ê
The FEC number states the ratio of user bits to the complete transmitted bits.
The output symbol rate is calculated as follows:
256-QAM:
SR (A)
= FEC x
1
/
4
x SR (E)
128-QAM:
SR (A)
= FEC x
2
/
7
x SR (E)
64-QAM:
SR (A)
= FEC x
1
/
3
x SR (E)
32-QAM:
SR (A)
= FEC x
2
/
5
x SR (E)
16-QAM:
SR (A)
= FEC x
1
/
2
x SR (E)
4-QAM:
SR (A)
= FEC x
1
/
1
x SR (E)
Example:
Ê
"ÕÌ«ÕÌÊÃÞLÊÀ>ÌiÊÈ{+]
FEC=
3
/
4
]
Ê
«ÕÌÊÃÞLÊÀ>ÌiÊ-,Ê®ÊrÊÓÇ]xääÊ
kSymb/s
SR (A)
=
3
/
4
x
1
/
3
ÊÝÊÓÇ]xääÊ
kSymb/s =
6,875 kSymb/s
Note:
Ê
vÊʺ»ÊÃÊÃÌ>Ìi`ÊÊÌ iÊÃÌ>ÌÊÃÌÃ]ÊÌÊV>ÊLiÊ>ÃÃÕi`ÊÌÊLiʺÊrÊ
3
/
4
”.
Reception from a transponder with a very low symbol rate (SCPC station)
The extremely low data rate means that the output symbol rate is very low. If
Ì iÀiÊ>ÀiÊÀiVi«ÌÊ«ÀLiÃÊÜÌ Ê`vviÀiÌÊ`}Ì>ÊÀiViÛiÀÃ]ÊÃiÌÊÕÌ«ÕÌÊÃÞLÊ
rate to a higher value.
Defined symbol rates
Ê
-iÊV>LiÊ«iÀ>ÌÀÃÊëiVvÞÊ>ÊvÝi`ÊÃÞLÊÀ>ÌiÊi°}°ÊÈ]ääÊ-ÞLÉî°Ê
