Comtech EF Data SLM-5650A - Manual (Page 301)

SLM5650A_CDM625 Satellite Modem Revision 8
DoubleTalk Carrier-in-Carrier Option MN-SLM5650A
15–3
component due to movement of the satellite. The CnC module tracks and compensates
for this variation.
2) Frequency offset and drift: Common sources are satellite Doppler shift, up and down
converter frequency uncertainties, and other drift associated with the electronics in the
SLM-5650A itself. The CnC module tracks and compensates for this frequency offset
and drift.
3) Atmospheric effects: Fading and scintillation can affect amplitude, phase, and spectral
composition of the signal and the degree to which it correlates with the original signal.
The CnC module tracks and compensates for these atmospheric related impairments.
4) Link Asymmetries: Various asymmetries in the forward and return link can produce
differences in the relative power of the two received signal components. These can be
both deterministic (static) or random (and time varying). An example of the former would
be the differences resulting from antenna size/gain variations between the two ends of the
link. An example of the latter would be transient power differences due to different levels
of atmospheric fading in the uplinks. CnC compensates for the asymmetries, up to a
certain extent.
Figure 155-1. Conceptual Block Diagram