EXAMPLE1:DVB-S
Calculations for Bandwidth = 36 MHz, DVB-S, QPSK-7/8, Roll off Factor:
0.20
Symbol rate= BW/ (1+Roll Off)= 36/1.20= 30
Msps
Datarate= Sym. Rate X Modulation
Index X FEC X 188/204
=48.38 Mbps
Note:-
modulation Index – for QPSK is 2 and for 8PSK – 3 and for 16PSK -4
modulation Index – for QPSK is 2 and for 8PSK – 3 and for 16PSK -4
EXAMPLE2: DVB-S2
Calculations for 36 MHz, DVB-S2, 8PSK-7/8, Roll off Factor:
0.20
Symbol rate= BW/ (1+Roll Off)= 36/1.20= 30
Msps
Data rate, Mbps = Symbol rate X LDPC X BCH *modulation index because it uses BCH and LDPC (low-density parity check) for error correction.
roll-off factor – usually for DVB-S2 is 0.2
modulation Index – for QPSK is 2 and for 8PSK – 3
LDPC – the available LDPC values are: 1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 8/9
BCH -- The value is approximately=0.98
Data Rate=30 X 7/8 X 0.98 X 3 = 77.175 Mbps
