7 / 14
1.10
Selecting the COFDM mode
The COFDM mode of the output signal is selected using the “<” and “>” buttons.
Main Menu
E1
1236
MHz
TP
27.500
MS/s
3/4
QPSK
Outp.
S21
306.00
MHz
8
MHz
QAM64
Use the “+” or “-” keys to set the modulation type of the COFDM carriers to the values QPSK, QAM16, or QAM64 de
fi
ned in the
DVB-T speci
fi
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 interference resistance but a lower transmissible data rate. Table 1 in the appendix shows
the connection between modulation type, code rate, guard interval and the possible maximum data rate.
1.11
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
to activate the sub-menu; press the “Sub-menu” button
again to deactivate it.
The modes are selected using the “<” and “>” buttons and adjusted using the “+” and “-” buttons.
Main Menu
E1
1236
MHz
TP
27.500
MS/s
3/4
QPSK
Outp.
S21
306.00
MHz
8
MHz
QAM64
Sub-menu for “COFDM modes”
***
UFO333MX
***
Mode
SAT Sig
Guard
1/32
Code rate
5/6
The following settings are available:
Mode
SAT-Sig
Normal mode,
the SAT input signal is transmodulated, in the case of input signal interferences only full
bytes
(0xFF)
are
modulated
PRBS
Test mode: the COFDM signal is modulated with a PRBS-23 sequence, normal mode is not
available
in
this
setting
CW
Test mode: sine wave signal for levelling using simple measurement devices, normal mode is not
available
in
this
setting
Main menu (display in PRBS mode)
PRBS
Outp.
S21
306.00
MHz
8
MHz
QAM64
“COFDM mode” sub-menu (for setting the PRBS)
***
UFO333MX
***
Mode
PRBS
Guard
1/32
Code rate
5/6
Summary of Contents for UFO 333/MX
Page 71: ......
