GSS HDM 660 T, Руководство по сборке

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- 28 - HDM 660 T
t
r ansmission par a meters
In this menu you can set the transmission modes, the code rate (" C … ") and
the guard interval (" G … ").
Bx 1A
2k C7/8 COFDM-MODE
G1/32
t
r ansmission mode
In this menu item you set the quantity of carriers:
2k mode: 1512 carriers for user data (total 1705 carriers)
4k mode: 3024 carriers for user data (total 3410 carriers)
8k mode: 6048 carriers for user data (total 6817 carriers)
—> The standard modes for DVB-T are 2k and 8k.
• Using the buttons set the transmission mode required (" 2k " … " 8k ").
C
ode r ate
During a transmission data can be lost or changed. To recover this data redun-
dancy is added to the signal to be transmitted (forward error correction). 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 lowest re-
dundancy.
• Use the buttons to place the cursor under " C… ".
• Set the code rate required using the buttons (" C1/2 ", " C2/3 ",
" C3/4 ", " C5/6 ", " C7/8 ").
g
uard interval
In this menu item you set the relation of the duration of the user symbols to the
duration of the guard intervals to be transmitted. A high guard interval, e.g.
"
G1/4 " causes a low output data rate. For cable networks the setting " G1/32 "
is adequate.
• Use the buttons to place the cursor under " G… ".
• Set the guard interval required using the buttons (" G1/4 ", " G1/8 ",
" G1/16 ", " G1/32 ").