Comtech EF Data SDM-650B - Manual (Page 31)

SDM-650B Satellite Modem Introduction
Rev. 5 1–7
The specifications for the Bit Energy-to-Noise Ratio (E
b
/N
0
) required to achieve 10
-5
and
10 -7 BER for different coding configurations is listed in Table 1-2. All values are for
operation in QPSK mode.
Table 1-2. BER Performance Specifications
Data Rate Sequential Viterbi K=7
1/2 Rate 3/4 rate 7/8 Rate 1/2 Rate
100 kbit/s
BER 10 -5 4.8 dB 5.8 dB 6.7 dB 5.5 dB
BER 10 -7 5.8 dB 6.6 dB 8.0 dB 6.7 dB
1544 kbit/s
BER 10 -5 5.8 dB 6.3 dB 6.9 dB 5.5 dB
BER 10 -7 6.6 dB 7.1 dB 8.0 dB 6.7 dB
Without coding, the modem provides operation within 0.5 dB of theoretical for BPSK,
and within 0.8 dB for QPSK.
Performance measurements are with transmit, and receive IF connected back-to-back
through an additive white Gaussian noise channel.
BER performances of the modem are shown in Figures 1-4 through 1-7.
A typical output spectrum of the modem is shown in Figure 1-8.