docsPnmCmtsUsHistTable

The purpose of the upstream histogram is to provide a measurement of
nonlinear effects in the channel such as amplifier compression and
laser clipping. For example, laser clipping causes one tail of the
histogram to be truncated and replaced with a spike. When the
UpstreamHistogram Enable attribute is set to 'true', the CMTS will begin
capturing the histogram of time domain samples at the wideband front
end of the receiver (full upstream band). The histogram is two-sided;
that is, it encompasses values from far-negative to far-positive values
of the samples. The histogram will have 256 equally spaced bins. These
bins typically correspond to the 8 MSBs of the wideband analog-to-digital
converter (ADC). The histogram dwell count, a 32-bit unsigned integer,
is the number of samples observed while counting hits for a given bin,
and may have the same value for all bins. The histogram hit count, a
32-bit unsigned integer, is the number of samples falling in a given bin.
The CMTS will report the dwell count per bin and the hit count per bin.
When enabled, the CMTS will compute a histogram with a dwell of at least
10 million samples at each bin in 30 seconds or less. The CMTS will
continue accumulating histogram samples until it is restarted, disabled
or times out. If the highest dwell count approaches its 32-bit overflow
value, the CMTS will save the current set of histogram values and reset
the histogram, so that in a steady-state condition a complete measurement
is always available. The CMTS will be capable of reporting the start and
end time of the histogram measurement using bits 21-52 of the extended
timestamp, which provides a 32-bit timestamp value with resolution of
0.4 ms and range of 20 days.

MIB

DOCS-PNM-MIB

OID

.1.3.6.1.4.1.4491.2.1.27.1.3.5

Type

table

Status

current

Parent

docsPnmCmtsObjects

Siblings

7

Children

1