Channel Measurements
Making Channel Measurements
Step
2.
Connect
the
signal
to
the
analyzer
CAUTION
To prevent the analyzer input from being damaged, the total power at the
analyzer input must be less than
+72
dBmV.
To prevent the analyzer input mixer from being overloaded, the total power
at the analyzer input mixer must be less than
+37
dBmV
except for CSO or
CTB for which +27
dBmv
is the maximum total power input to the mixer.
For systems with unequal carrier levels (system tilt), the total power must be
calculated by summing the individual carriers. The TOTL PWR
Q
INPUT
softkey function accounts for system tilt.
You can measure the input power by pressing Setup , Analyzer Input ,
TOTL PWR
Q
INPUT The total power is displayed at the bottom of the
screen.
Total power at the input mixer can be reduced by increasing input
attenuation. Press
C-1
ATTEN
, and make the adjustment. The
analyzer retains a manually selected attenuation until you either select a
new value or reset the analyzer power-on default conditions. For all tests
provided by the HP 85721A personality, the analyzer automatically selects the
attenuator setting to meet the above requirements.
1. Use the necessary adapters to connect the cable TV signal to the analyzer.
See Figure 2-4.
2. If your analyzer has Option 107 installed, you must use the coupler
(provided) and connect the cable TV signal to the TV IN and analyzer
input connectors as shown in Figure 2-5. Figure 2-5 shows the
connections for RF and video measurements.
3. If your analyzer has Option 107 installed, ensure that the rear-panel TV
TRIG OUT is connected to GATE IN as shown in Chapter 1, “Step 4.
Connect cables for non-interfering measurements.
’
2-9
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