Symbol Rate (S/R) Calculation - Alcad 912-TQ Serie Manual De Instalación Y Programación

MHz 122
BW 7.0
4.

SYMBOL RATE (S/R) CALCULATION

When programming QAM digital receivers, it may be necessary to tell
the receiver the symbol rate (S/R) of the QAM signals. This symbol rate
should not be mistaken for the QPSK signal rate (shown in the channel
lists published in magazines). It is also necessary to know the QAM signal
symbol rate in order to determine the bandwidth to be occupied by the
QAM signal.
The QAM signal symbol rate is derived from the following equation:
n
QAM
And the QAM signal bandwidth will be:
Serie 912 - TQ
130 136
7.9 2.0
8 MHz 6 MHz 4 MHz
Fig. 6 - Adjusted frequency plan
S/R = S/R
QAM
S/R symbol rate QAM
QAM
S/R tsymbol rate QPSK
QPSK
n number of bits per QPSK symbol
QPSK
n number of bits per QAM symbol
QAM
FEC forward error correction QPSK
QPSK
n = 2
QPSK
2 4 QAM
4 16 QAM
5 32 QAM
=
6 64 QAM
7 128 QAM
8 256 QAM
140 146
4.3 7.0
6 MHz 8 MHz
n
QPSK
. . FEC
QPSK
n
QAM
FEC
QPSK
ENG - 25
154 161
6.4 6.4
7 MHz
QPSK
1/2
2/3
=
3/4
5/6
7/8