Comtech EF Data SLM-5650A - Manual (Page 48)

SLM-5650A Satellite Modem Revision 8
Introduction MN-SLM5650AMN-SLM5650A
1–20
1.4.1.3.9 BER Performance with Asymmetrical Adjacent Carriers
Operating in the presence of two adjacent asymmetrical carriers, one lower in frequency and one
higher in frequency, and each adjacent carrier symbol rate (R"
s
) = 2.0 R'
s
, the modem performance
is not degraded more than indicated in Table 1-10 Column 4, and a) and b) in this section.
Performance is measured with the adjacent carriers center frequencies offset (X/2) times (R'
s
+ R"
s
)
Hz from the test carrier center frequency, where X is the spacing factor and R'
s
is the modulation
symbol rate in Hz of the test carrier, and R"
s
is the modulation symbol rate in Hz of each adjacent
carrier. For modulation symbol rates below 38.4 ksps, this paragraph does not apply.
a) For X (spacing factor) = 1.2, and R"
s
= 2.0 R'
s
, the asymmetric degradation shall be IAW
one of the values in Table 1-10 Column 4, and the corresponding test carrier E
s
/N
0
in
Column 1. Select a test carrier E
s
/N
0
that will yield timely results based on modulation
and coding used in the test configuration. The adjacent carriers E
s
/N
0
are set to the
corresponding value in Column 2.
b) For the case of (1.4/2)(R'
s
+ R"
s
) Hz carrier spacing, the degradation is < 0.2 dB.
Table 1-10. Acceptable ACI Degradation with Spacing Factor of 1.2
Test Carrier
E
s
/N
0
(dB)
Adjacent Carriers
E
s
/N
0
(dB)
E
b
/N
0
Degradation (dB)
Symmetric Case
E
b
/N
0
Degradation (dB)
Asymmetric Case
5.5 18.5 < 0.36 < 0.41
6.0 19.0 < 0.38 < 0.43
8.0 21.0 < 0.48 < 0.56
8.4 21.4 < 0.51 < 0.60
10.0 23.0 < 0.64 < 0.77
12.0 25.0 < 0.88 < 1.10
12.7 25.7 < 0.99 < 1.21
1.4.1.3.10 LDPC ULL Decoding
Table 1-11. LDPC ULL Decoder BER Performance
Eb/N0 (dB) Specification
BER
BPSK QPSK
1/2 1/2 2/3 3/4
10 -5 3.1 3.1 3.6 4.1
10 -8 3.7 3.7 4.2 4.7