- 27 -
STI 1932 CT
155
For exceptional cases and "older" digital cable receivers, in column
Spectrum
the spectral position of the user signal can be inverted (
invers
).
Factory default is "
normal
".
156
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
.
158
Only if the RF output is set to COFDM (page 44):
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.
159
Only if the RF output is set to COFDM (page 44):
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.
160
Only if the RF output is set to COFDM (page 44):
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.
161
Balance here the
master output level of the station
to the level of the ca-
ble network (0…-31dB; off).
0dB = unchanged level; -31dB = 31dB attenuation
off = Level 0 (no output signal)
—> Changes must be transmitted to the head-end station!
Therefore click on button
.
