Chapter 8
Measure Mode – Basic Tab
Hum Analysis
190
DSAM Help User Guide
Rev. 001
Reset
– Manually resets the QAM Ingress function. (Only enabled
if Peak Hold is enabled.)
Single Channel
– Displays measurements one channel at a time.
First, use the arrow keys to move the marker to the preferred
channel then highlight this option from the View menu.
MiniScan
– Displays the MiniScan screen.
Constellation
– Displays the Constellation screen.
Pause
(
Shift, 8
) – Suspends measurement updates.
Marker A
– Sets Marker A as the active marker. Using the arrow
keys, move the marker on the grid.
Marker B
– Sets Marker B as the active marker. Using the arrow
keys, move the marker on the grid.
3
Press
ENTER
.
Hum Analysis
Hum is the undesirable modulation of the television video carrier by
power line frequencies and harmonics, or other low frequency distur-
bances (FCC Limit: < 1 kHz) The Hum mode displays the total amount
of hum for an analog channel over a 1 kHz span. An evenly spaced
breakdown of hum percentages is displayed in a graph with bars at
either a 50 or 60 Hz spacing.
Hum measurements are displayed on a graph and as a numeric value
for each carrier within the channel.
1
To tune directly to a specific channel, use the
alphanumeric
keys
.
2
Press
ENTER
.
Hum measurements are continuously updated on the screen.
Performing Hum
Analysis
To perform hum analysis
1
Press
Measure
.
2
Press the
Basic
softkey.
21128026 R001 DSAM Help User Guide.book Page 190 Thursday, February 5, 2009 2:02 PM
