Wavetek 3ST Manuel d'utilisateur télécharger pdf (Page 3)

A “scan limits” feature enables

a quick Go/No-Go test based on

user-defined limits for minimum

video carrier levels, maximum and

minimum difference between

video and audio carrier levels,

maximum level difference be-

tween adjacent video carriers, and

maximum level difference over

the entire band. This allows the

operator to quickly check to make

sure the subscriber drop is within

FCC specifications before initiat-

ing the 24 hour test.

Sweep Display

The Stealth sweep method is fast,

accurate, and non-interfering. The

levels are measured and stored at a

reference point (headend, hub site,

or first amplifier) and then com-

pared on a sweep display at subse-

quent test points.

Dynamic nonvolatile memory

enables the storage of at least 50

sweep traces for later viewing and

at least 16 references may be

stored, enabling the operator to test

the response from any specific

point in the system (bridger, fiber

node, splitter, etc.).

A tilt compensation feature

enables consistent measurement

accuracy when specified tilt

changes in the system, eliminating

the need to store a new reference.

In-Service C/N Measurement

To receive a C/N measurement

simply press the “C/N” key. The

C/N ratio of the last tuned channel

will be displayed, along with the

noise measurement frequency and

bandwidth. The C/N measure-

ment bandwidth and the frequency

offset for the noise measurement

may be controlled from the mea-

surement screen.

The Stealth System Sweep

automatically searches for a quiet

line in the vertical interval and

acquires the noise measurement

during that line. Preselection is not

required for up to 78 channels at a

+10 dBmV input level.

In-Service Hum Measurement

For a hum measurement simply

press the “hum” key. The hum

modulation of the last tuned channel

will be displayed in either % or dB,

as selected by the operator. Soft

keys allow the selection of 60, 120

(50 or 100 for PAL systems) or

<1,000 Hz filters for help in

troubleshooting. Stealth’s hum

measurement tech-nique permits

testing modulated carriers.

Video Depth of Modulation

The video depth of modulation

screen provides percent modulation

in both graphical and precise

numeric format. This feature on

the model 3ST makes it easy for

the headend technician to do a

quick check-up on modulation

depth without having to set up

special equipment.

Spectrum Analyzer Display

Stealth’s spectrum analyzer display

provides a view of the system

spectrum with variable spans from

3 MHz to 50 MHz and a dynamic

range of better that 60 dB. The

“max hold” function ensures that

the highest signal over multiple

sweeps is displayed. The spectrum

analyzer display can even make

FCC in-channel response measure-

ments. Composite second order

and composite third order inter-

modulation distortion tests are

simplified with user prompted

automated measurement processes.

Preselection is required for accu-

racy in this measurement.

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