Radyne OM20 User Manual download pdf (Page 44)

Figure 4.16 [EN 302 307] shows the required C/N (Carrier-to-Noise power ratio measured in

a bandwidth equal to the symbol rate R

) versus the spectrum efficiency (useful bit rate R per

unit symbol rate R

) of the different DVB-S flavours:

• DVB-S

o QPSK / code rates: 1/2, 2/3, 3/4, 5/6, 7/8

• DVB-DSNG

o QPSK: same curve as DVB-S

o 8PSK / code rates: 2/3, 5/6, 8/9

o 16QAM / code rates: 3/4, 7/8

• DVB-S2

o QPSK / code rates: 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 8/9, 9/10

o 8PSK / code rates: 3/5, 2/3, 3/4, 5/6, 8/9, 9/10

o 16APSK / code rates: 2/3, 3/4, 4/5, 5/6, 8/9, 9/10

o 32APSK / code rates: 3/4, 4/5, 5/6, 8/9, 9/10

in contrast to the modulation-constrained, but just theoretically reachable, Shannon limits.

Fig. 4.16: DVB, spectrum efficiency versus required C/N on AWGN channel [EN 302 307]

These idealised reference curves were obtained by computer simulations on AWGN channel

(ideal demodulator, no phase noise). The performance refers to the quality target PER = 10

-7

C/N refers to average power [EN 302 307].

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Radyne OM20 User Manual Page 44