Kathrein UFO 331/TP Manual Del Usuario página 21

1.9 Selecting the COFDM mode
The COFDM mode of the output signal is selected using the "<" and ">" buttons.
A 1236
27.500 MS/s
Outp. S21
8 MHz
Use the "+" or "-" keys to set the modulation type of the COFDM carriers to the values QPSK, QAM16, or QAM64 defi ned in the
DVB-T specifi cation.
Note: Since the possible output data rate for COFDM-modulated signals is normally lower than the input data rate,
it is recommended to use the highest QAM stage (QAM64) if possible. The lower QAM stages QAM16 and
QPSK offer a higher resistance to interference but a lower data rate can be transmitted. The exclamation
mark beside the selected QAM stage indicates that the maximum possible output data rate is lower
than the input data rate. In this case the channel fi lter must be used and the number of channels limited
in the output data stream (see Chapter 1.12).
For the relationship between modulation type, code rate, guard interval and possible maximum data rate,
see Table 1 in Chapter 3.1.
1.10 Selecting the operating mode for the COFDM
modulator
In the sub-menu of the COFDM mode you can select the operating mode (source signal) for the COFDM modulator.
Press the "Sub-menu" button
The modes are selected using the "<" and ">" buttons and adjusted using the "+" and "-" buttons.
A 1236
27.500 MS/s
Outp. S21
8 MHz
The following settings are available:
Mode SAT Sig
PRBS
CW
Outp. S21
MHz
8
Main menu (display in PRBS mode)
MHz
3/4
306.00
QAM64
Main menu
to activate the sub-menu; press the "Sub-menu" button
MHz
3/4
306.00
QAM64
Main menu
Normal mode,
the SAT input signal is transmodulated, in the case of input signal interference only full bytes (0xFF)
are modulated
Test mode: the COFDM signal is modulated with a PRBS-23 sequence, normal mode is not available
in this setting
Test mode: sine wave signal for levelling using simple measurement devices, normal mode is not
available in this setting
306.00
QAM64
TP
QPSK
MHz
!
TP ***
QPSK Mode
MHz Guard
! Code rate
PRBS ***
Mode
MHz Guard
! Code rate
"COFDM mode" sub-menu (for setting the PRBS)
7 / 14
again to deactivate it.
UFO331TP
SAT Sig
1/32
5/6
"COFDM modes" sub-menu
UFO331TP
PRBS
1/32
5/6
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