Atec Acterna-JDSU-SDA-5000 - Manual (Page 3)

Normalized sweep
To ensure that network specifications
are maintained, starting from the
headend to the subscriber, each
section of the network has its own set
of specifications. A normalized sweep
divides the network into easily man-
aged sections. Each of these network
sections can be designated to an
individual team or contractor and
tested to its own specifications and
quality standards.
The SDA Series uses a variation of
Acterna original market-leading Stealth
Sweep technology. Existing video
carriers (analog, digital, or scrambled)
are referenced when possible, elimi-
nating any possibility of interference to
the subscriber services. Where carriers
are absent, the SDA-5500 transceiver
at the headend transmits a sweep to
fill vacant spectrum areas. To remove
effects of headend level drift, the
SDA-5500 transceiver monitors the
levels and transmits new reference
information with every sweep. This
means that if the signal levels are
changing in the headend, they will not
affect the sweep response measure-
ment. The SDA-5500 transceiver has
all of the measurement capability of
the SDA-5000 receiver enabling the
technician to check headend levels.
The SDA Series also offers significantly
faster forward sweep speed than earlier
instruments, especially in systems that
include many digital signals. They can
reference 64/256 QAM signal types,
removing the need to worry about
subscriber interference, or injecting
sweep carriers in the guard bands.
Reverse sweep
The SDA-5000 (with option 1 installed)
enables simple and practical testing
of the reverse path frequency response,
regardless of the frequency (5 to
1000 MHz). It has a built-in reverse
sweep transmitter, which means
externally generated carriers are not
required. Furthermore, the SDA-5500
transmitter and field receivers have
frequency agile telemetry, enabling
them to communicate on both the
forward and reverse paths.
SDA Series instruments enable one
person to perform forward and reverse
path alignment simultaneously.
The operator simply indicates which
screen should be displayed – either
the response from the headend to the
testpoint, or the response from the
testpoint to the headend. A reverse
sweep can uncover mismatch prob-
lems, which reveal themselves as
standing waves, or diplex filter roll-offs
that can severely hamper the quality
of services in the reverse band.
3
Reverse ingress spectrum display Constellation display with MER and
pre/post FEC BER
Multiple-user reverse testing
For intense reverse testing require-
ments, the rack mounted model
SDA-5510 Headend Reverse Sweep
Manager handles the reverse sweep
job for up to 10 different technicians
on the same cluster of nodes. Using
the SDA-5510 in conjunction with the
model SDA-5500 transceiver 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.
Seeing headend/hub site accumulated
ingress in the field
The reverse noise feature of the
SDA-5000 enables easy reverse path
noise testing. The operator simply
presses the “noise” softkey while
reverse sweeping, and the display
changes to a noise/ingress response
indicating the noise level over
the entire reverse path spectrum
measured at the headend or hub site.
All SDA transmitters provide feedback
to the field regarding the current
condition of noise and ingress in the
headend, even when noise or ingress
is swamping the telemetry (Broadcast
mode). A picture of the headend noise/
ingress is sent out to the SDA receiver
via a special forward telemetry carrier.
Reverse Alignment mode prepares network for
cable modem deployment