- 21 -
STI 1916 CT
62
In column
Modulation
, select the desired kind of modulation of the indi-
vidual lines:
For QAM: QAM 16, 32, 64, 128, 256
For COFDM:
QPSK, 16 QAM, 64 QAM
—> The background colour
in column
Line
indicates an output data
overflow. In this case change the output settings or remove stations
from the data stream using the station filter.
—> COFDM: SAT transponders can transmit higher data rates than
DVB-T transponders. If complete SAT transponders are present as
MPTS data streams at the input, you must remove services from the
data stream via the "Filter" menu!
63
Only if the RF output is set to COFDM (page 37):
Setting of the
Code rate
- column
CR
During a transmission data can be lost or changed. To recover this data
redundancy is added to the signal to be transmitted (forward error cor-
rection). The factor of the quantity of redundancy contained in the bits
transmitted is called code rate.
Using the setting "C7/8" you can get the highest output data rate at low-
est redundancy.
64
Only if the RF output is set to COFDM (page 37):
Setting of the
Guard interval
- column
GI
In this column you set the relation of the duration of the user symbols to
the duration of the guard intervals to be transmitted. A high guard inter-
val, e.g. "G1/4" causes a low output data rate. For cable networks the
setting "G1/32" is adequate.
65
Only if the RF output is set to COFDM (page 37):
Setting of the
Bandwidth
- column
BW
To transmit the output signal in the channel range of S21 to C69 a band-
width of 8 MHz can be used.
In the channel range of C5 to C12 a bandwidth of ≤ 7 MHz must be set.
66
In column
Level [dB]
, balance the output levels of the different lines
(0…-10dB). Therefore measure and note down the output level of each
modulator. Adjust the higher output levels to the output level of the modu-
lator with the lowest output level incrementally.
—> Changes must be transmitted to the head-end station!
Therefore click on button
.
