C-COR.net FlexNet E629, Руководство по эксплуатации оборудования

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4-12 FlexNet ® 700 Series Line Extender Rev F
4
Return Balancing
For signals on the return path to arrive at the headend at the correct level and with as little distortion
as possible, the return path must be properly balanced. In a network that is properly return balanced,
the return signals on each leg arrive at each succeeding amplifier at the same level and tilt; this is called
unity gain. A cascade with unity gain keeps signal distortions to the lowest levels possible. In most
systems, the return band will have a tilt of 0 dB between the low and high return bandages. The
following sections cover the single person and the two person return balancing procedures.
These procedures assume the forward balancing requirements of Forward Balancing Requirements on
page 4-8 are met. When balancing the return path keep in mind the following:
✔
Balance the forward path first and ensure that it is trouble free.
✔
The network must be free of ingress.
✔
You are trying to achieve constant inputs at the
return input port
of each amplifier. To do this
you must adjust signal level and tilt in the return path through the use of return port pads,
equalizers, and distribution accessories.
✔
With the single person method, turn off the ALC, if present, in the return rackmount receiver
at the headend.
✔
The first amplifier or node must be balanced correctly. If balanced incorrectly, all amplifiers
after it will be affected.