Comtech EF Data SLM-5650A - Manual (Page 47)

SLM-5650A Satellite Modem Revision 8
Introduction MN-SLM5650AMN-SLM5650A
1–19
1.4.1.3.7 Sequential Decoding with / without Reed-Solomon
Table 1-9. Sequential Decoding with / without Reed-Solomon BER Performance
E
b
/N
o
(dB) Specifications
Sequential Decoder with / without Reed-Solomon
DESCRIPTION BER
BPSK QPSK/OQPSK
1/2 1/2 3/4 7/8
Sequential – 64 kbps
10 -5 4.8 4.8 5.8 7.0
10 -6 5.2 5.2 6.4 7.5
10 -7 5.6 5.6 6.9 8.0
Sequential – 1544 kbps
10 -5 5.2 5.2 5.9 7.2
10 -6 5.7 5.7 6.5 7.7
10 -7 6.1 6.1 7.0 8.3
Sequential+RS (225,205)
10 -6 4.4 4.4 5.0 5.6
10 -7 4.6 4.6 5.3 6.0
10 -8 4.8 4.8 5.6 6.4
1.4.1.3.8 BER Performance with Symmetrical Adjacent Carriers
Operating in the presence of two adjacent symmetrical carriers (one lower in frequency and one
higher in frequency with same modulation, data rate, and coding), the modem performance is not
degraded more than as indicated in Table 1-10 Column 3, and a) and b) in this section. This
performance is measured with the adjacent carrier’s center frequencies offset XR
s
Hz from the center
frequency of the carrier under test, where X is the spacing factor and R
s
is the modulation symbol rate
in Hz of the symmetrical carriers.
The BER of the test carrier is measured at the specified carrier Ratio of Energy per Symbol to Noise
Power Density in a 1 Hz Bandwidth (E
s
/N
0
) Carrier to Noise Ratio (C/N) without the adjacent carriers.
The adjacent carriers are applied at the specified center frequencies and E
s
/N
0
and the BER of the test
carrier is measured. The change in BER is equal to the change in E
b
/N
0
based on the characterization
curve of the test carrier and the amount of Adjacent Channel Interference (ACI) degradation. For
modulation symbol rates below 38.4 ksps, this paragraph does not apply.
a) For X (spacing factor) = 1.2, the symmetric degradation shall be IAW one of the values in
Table 1-10 Column 3, and 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
shall be set to corresponding value in Column 2.
b) For the case of X (spacing factor) = 1.4, the degradation is less than 0.2 dB.