Chapter 9 Measure Mode – Service Tab
DOCSIS
222 DSAM Help User Guide Rev. 001
To view VoIPCheck results
1 Press the View softkey.
2 Using the arrow keys, select VoIPCheck.
3 Press ENTER.
The CMTS Loop screen displays Packet and Quality measure-
ment data. Packet loss, delay and jitter are factors that affect voice
quality on a VoIP network. The data is captured and continuously
updated.
Measurement
Information Area
The Measurement Information area (area above the graph) displays
information about the limit plan, channel number, channel type, and
channel label.
Packet Loss
Significant packet loss degrades voice quality. Packet loss occurs
when packets are lost on a network, when packets are delayed too
long, or when packets arrive out of order. Packet loss can cause
reconstructed speech to sound choppy and distorted.
Jitter
Jitter occurs when packets are sent at equal intervals, but received at
uneven time intervals, this can cause audible pops, clicks and a
greater delay of audio communications. Gateways compensate for
this by accumulating the received packets into an internal buffer and
“playing them out” at the proper time intervals and in packet order. The
more jitter buffer available, the more the network can reduce the
effects of jitter.
Figure 198 Measure Mode – DOCSIS CMTS Loop
Measurement
Information Area
Packet Loss
Jitter
Delay
MOS
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21128026 R001 DSAM Help User Guide.book Page 222 Thursday, February 5, 2009 2:02 PM
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