Main differences between DVB-S and DVB-S2

    

 DVB-S                                                                          DVB-S2
                                                                    • Fully transparent to all data
  Meant for broadcast only

                                                                     • Baseband in 16 or 64 kb/s
  Fixed 188 byte/packets

                                                                     • CCM/MultiStream-VCM-ACM
  One TS / carrier

                                                                     • LDPC and BCH coding
  RS and Viterbi coding

                                                                      • Can work within noise floor
  Need of high Rx margin

                                                                       • QPSK-8PSK-16APSK-32APSK
  QPSK /QPSK-8PSK-16QAM

                                                                        • 20% Roll-off carrier
  35% 25% Roll-off carrier

                                                                        • Pilot tones for extra synch in  Consumer LNB’s work in QPSK only

                                                                                                     8PSK

Data Rate Calculations for TV Broadcasting(DVB-S and DVB-S2)

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

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

The formula for DVB-S2 is:
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