Carrier-In-Carrier And Adaptive Coding And Modulation; Carrier-In-Carrier Link Design; Symmetric Data Rate Link - Comtech EF Data CDM-425 Installation And Operation Manual

Advanced satellite modem (18 kbps – 25 mbps)
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F.2.3 Carrier-in-Carrier Latency
Carrier-in-Carrier has no measurable impact on circuit latency.
F.2.4

Carrier-in-Carrier and Adaptive Coding and Modulation

Carrier-in-Carrier is fully compatible with VersaFEC Adaptive Coding and Modulation (ACM)
mode of operation in the CDM-425 Advanced Satellite Modem.
Carrier-in-Carrier combined with VersaFEC ACM can provide 100-200% increase in average
throughput.
F.2.5

Carrier-in-Carrier Link Design

Carrier-in-Carrier link design involves finding the FEC and modulation combination that provides
optimal bandwidth utilization. Just like conventional link design, it is an iterative process that
involves trying different FEC and modulation combinations with Carrier-in-Carrier until an optimal
combination is found.
For optimal Carrier-in-Carrier performance, it is recommended that the two carriers have similar
symbol rate and power. This can be achieved by selecting appropriate ModCods as shown in
following sections.
F.2.5.1

Symmetric Data Rate Link

Consider the example shown in Table F-3.
Satellite & Transponder
Appendix F
Table F-3. Symmetrical Data Rate Link Example
Earth Station 1
Earth Station 2
Data Rate
CDM-425 Advanced Satellite Modem
Galaxy 18 @ 123º W, 13K/13K
Phoenix, AZ – 4.6 m
Phoenix, AZ – 2.4 m
512 kbps / 512 kbps
F–10
Revision 0
MN-CDM-425

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