CATV Measurements
2715 User Manual
5–3
For this reason, the maximum signal input level for the digital tests (except for
ACL) is depicted as +37 dBmV for the multichannel environment. In specific
cases, the safe limit may be higher, but it is your responsibility to correctly make
that determination based on your specific circumstances (number of analog
channels on the system and how far down the digital signal is from the general
level of the analog channels).
Note that even when the preselector is used, the maximum signal level input for
most of the digital tests is depicted as being below the +70 dBmV burnout limit.
This is because of specific measurement-dependent hardware limits of the
instrument. Violating the depicted limit can result in inaccurate measurement
results.
CAUTION.
To avoid overloading the 2715 and possibly damaging it, do not place
AC or DC power supply voltages on the input of the 2715.
At power-up, the 2715 comes up in the CATV mode tuned to the default
power-up channel. The power-up channel is the last active channel when power
was turned off or channel T–7 (labeled 907 in STD Table 5–4) if NVRAM was
erased before the last power-down.
Upon entering the CATV MEASUREMENT MODE, the instrument software
searches for the visual carrier signal associated with the default power-up
channel and places a marker at the visual carrier peak. The instrument then
configures itself as follows.
Frequency
Center of default power-up
Channel Band
1
Reference Level
+68.8 dBmV
Span/Div
Channel Band — 10
RF Attenuation
50 dB
Resolution Bandwidth
300 kHz
Sync & Video Polarity
From current channel table
Vertical Mode
Log
Vertical Scale
10 dB/div
Sweep
Auto
Trigger
Free Run
Marker
On
Marker Frequency
Apparent Visual Carrier Position
1
Channel Band = Channel limits defined in the current channel table. If the last
selected channel does not exist, such as when NVRAM has been erased, the default
channel becomes Channel T–7 (labeled 907 on the display) — the first channel in the
first channel table.
Initial Setup
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Страница 25: ...Getting Started ...
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