Atec Acterna-DSAM-6000 - Manual (Page 8)

Forward Sweep Option
During a forward sweep, existing video carriers (analog, digital, or scrambled) are
continuously referenced, eliminating any possibility of interference to the sub-
scriber services.
The DSAM-6000 offers fast forward sweep capabilities, especially in systems with
numerous digital channels. By referencing 64, 128 and 256 QAM signal types, the
DSAM-6000 removes any worries about subscriber interference and prevents
sweep carriers from being injected into the guard bands. Referencing active
carriers, instead of transmitting sweep signals over active carriers, allows the
DSAM-6000 to sweep without degrading service quality.
Where there are absent carriers the SDA-5500 headend transceiver inserts a sweep
point to fill vacant spectrum frequencies. To remove effects of headend level drift,
this instrument monitors the levels and transmits new reference information with
every sweep. If the signal levels change in the headend, they won't effect the sweep
response measurement.
Reverse Sweep Option
The return path can be problematic for two-way communications. It should be
tended to as often or more than the forward path and any impairments should
promptly be fixed. One of the best procedures to preserving a clean return path is
with an active reverse sweep maintenance plan. The DSAM-6000 has a built-in
reverse sweep transmitter, removing the need for externally generated carriers.
A reverse sweep can uncover mismatch problems, revealed as standing waves, or
diplex filter roll-offs that can severely hamper the quality of services in the reverse
band.
Headend Sweep Equipment
With the DSAM-6000, one person can perform forward (downstream) and
reverse (upstream) path alignment simultaneously. For reverse testing with more
than one field technician, the rack mounted Model SDA-5510 Headend Reverse
Sweep Manager can perform reverse sweep on the same cluster of nodes for up to
ten different technicians. The SDA-5500 transceiver used in conjunction with the
model SDA-5510 receiver provides a full forward and reverse sweep alignment
solution. The SDA-5510 can also stand alone in remote hub sites for dedicated
reverse alignment applications.
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DSAM-6000 DIGITAL SERVICE ANALYSIS METER
Tight reverse sweep points are setup in the sweep
plan to view better resolution of the entire return
path. Helping to find mismatches or other problems
heading back to the headend or hubsite.
Forward sweep on the DSAM-6000 uses a unique ref-
erencing method to accurately reveal any problems in
the system without interfering with any of the analog
or digital carriers.