5-4
Figure 2. Single Cable - Split Band Network Reverse Sweep
Configuration With Directional Test Points.
Another common architecture, which is only slightly different from
those described above, prescribes the use of fiber optics to "nodes".
In these architectures the installation of the transmitter in the
headend is slightly modified, as shown in figure 3. Notice that a
diplex filter is used on the input of the 3ST/3HRV. This provides
optimal isolation between forward paths and minimal insertion loss.
The connection at the node may be as shown in figure 4. Notice that
in this configuration the forward and reverse test points are separated,
and two directional couplers must be used. In all of these connection
scenarios, either a summing network or two directional couplers are
used to interface with the system test points. Care should be taken to
use the same interface at each test point to ensure that the normaliza-
tion process is cancelling out any response variation caused by the
interface.
It is also important to remember not to make absolute level measure-
ments through the summing network due to the insertion loss and
frequency response characteristics of the interface.
Summary of Contents for 3SR
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