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Ethernet Interface Operation
CDM-760 Advanced High-Speed Trunking Modem
When the presence of the optional K4 GZip Compression is detected, this page provides a live
graphical representation of the trending characteristics that are available while using this feature.
Once you open or refresh this graph page, allow some time for the modem to
compile and graph the performance statistics. If you resize the browser window,
allow approximately 5 to 10 seconds for the graph set to regenerate, then re-center
in the browser window.
This page provides three performance graphs and four configuration status graphs:
Tx Percent Compression Graph
The Tx Percent Compression graph represents the LAN to WAN compression statistic as
described in Chapter 6. FRONT PANEL OPERATION Sect. 6.2.3.6.3 (Monitor: Stats)
Compression LanToWan or WantoLan. Tx Percent Compression (% Comp) is calculated using
the following formula:
Tx WAN Capacity Graph
The Tx WAN Capacity graph logs the following information:
•
Avail means "Available Capacity" or what the satellite link is capable of transmitting at
any given moment. Available Capacity is calculated using the following formula:
Spectral Efficiency is a function of ModCod, Pilots On or Off, and Normal or Short Block
being used.
•
Used means "Capacity Used" or the data rate of all traffic sent over the satellite after
compression (if enabled), and including any overhead the modem asserts due to
encapsulation or overhead due to compression. The Capacity Used is taken directly from
the "Bytes to WAN" Monitor Statistics, as averaged over the graphed time period. When
compression is enabled, the capacity used may be substantially less than the terrestrial
rate of the user traffic due to the effect of the compression card.
Tx ModCod and Remote Es/No Graph
The Tx ModCod and Remote Es/No graph is particularly useful when the modem is running is
ACM mode, as it maps the remote Es/No of the far end modem synchronously along with the
near side (local) Tx ModCod used. Two pieces of data are graphed in time synchronous manner:
•
The left side of the graph has a vertical key of Tx ModCod (blue).
•
The right side of the graph has a vertical key of Remote Es/No (red).
In this format, the graph depicts changes in ModCod that occur when the reported Remote
Es/No meets the Es/No trigger points to switch up or down.
Note that the Remote Es/No is the "reported" Es/No of the far end modem as seen by the local
modem. This reported Remote Es/No data can be 250ms to 400ms old as this is the amount of
time it can take for this data to traverse the satellite link for processing by the local modem.
100 * (1-(Bytes Out/Bytes In))
(Tx Symbol Rate)(Tx Spectral Efficiency)
See Appendix B. Es/No MEASUREMENT for detailed information about and
reference tables pertaining to Spectral Efficiency.
7–71
Revision 4
MN-CDM760
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