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Measuring System Performance: Measuring Signal Levels
110
6
You measure signal levels in the Level, Tilt, and Scan modes. In Level and
Scan, the process measures the difference between video and audio for a
channel and displays the difference in dB. In Tilt mode, the difference, or tilt,
refers to the difference in dB between the upper and lower pilot channels.
Keep in mind that measurement configuration parameters for Level,
Frequency, and Tilt interact, and are important factors in all three
measurements.
Level Measurements
With Level mode selected, you can tune by channel or frequency.
Tune by channel: When you press the CHAN key on the keypad, the
channel number and label appear at the top of the display (see Fig.
6-1). Use the left and right diamond keys to decrement and increment
the channel number. You can also enter the channel number by using the
numeric keys, followed by CHAN.
If you were in the Frequency screen, CHAN tunes to the nearest channel
in the channel plan.
Tune by frequency: To tune by frequency, use the numeric keys to
enter a frequency, followed by the FREQ key (see Fig. 6-2). Use the left
and right diamond keys to decrement and increment the frequency. The
step size for these frequency changes is programmed during setup.
See Also
½ The "Measurements Configuration" section in Chapter 2
covers setting the frequency tuning step size (page 25).
If you are tuning by channel, the FREQ key tunes to the video frequency
of the current channel or to the of a digital channel. (For digital channels
set up in the channel plan, the measurement algorithm is used.)
In Level, Chan mode, you can measure the difference in video and audio
level (dBmV) for a specific channel, expressed as dB. If one of the readings
is off scale (low or high), use the up and down diamond keys to see both
readings on the screen, or press the Function and Enter keys to Autoscale
the readings. Use the left and right diamond keys to scroll through the
channels one at a time.
MEASURING SIGNAL LEVELS
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