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
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