Impairment or other conditions (e.g., signal to noise ratio or noise floor)
in a data-over--cable system are represented graphically in an easy to use
and comprehensible manner, enabling quick identification and isolation of
the source of the impairment. The graphical representation of the
condition, referred to herein as an "impairment circle", is in the form of
a circular template with a line segment superimposed thereon representing
the impairment. One end of the line segment is placed on the perimeter of
the circle at a location associated with a particular cable modem or
channel. The other end of the line segment either terminates in the
interior of the circle or terminates on another portion of the perimeter.
The perimeter of the circle can be divided into multiple sections, each
section representing a channel in a transmission path. The sections can be
further divided into multiple divisions, each division corresponding to a
particular cable modem in the path or number of occurrences. In one type
of the impairment circle, the location in which the line segment
terminates within the interior of the circle indicates the magnitude of
the impairment or other measurement. A single impairment circle can be
used to represent impairments or other measurements of multiple channels
and multiple cable modems. In another type of impairment circle, the line
segment goes from one division of one section to another division of
another section, indicating a condition of impairment of other channels
when a particular cable modem in one channel is active. Different colors
for the line segments and different widths of the line segments can convey
additional information, such as the number of occurrences of the
condition, or the magnitude of the impairment.
