Digital Equipment ChannelWorks DECTV-AA, Руководство по установке, Страница: 44 / 106

3-10 ChannelWorks Cable TV Installer’s Guide
Verifying The Cable TV Network’s Return Outlet To Outlet Variation
The Return Outlet to Outlet Variation is a target variation between signals transmitted
at the network outlets as measured at the input to the TransMaster. This is a network-
wide specification based on data taken at individual sites.
To measure the cable TV network’s Return Outlet to Outlet Variation, use the system
analysis meter and signal generator at the selected cable TV Drop’s outlet in conjunc-
tion with another system analysis meter or RF Combination Meter located at the head-
end and perform the following procedure. Refer to Figure 3-5. Perform the following
to:
1. Record the Maximum Return Path Loss.
2. Record the Minimum Return Path Loss.
3. Calculate the Return Outlet to Outlet Variation:
Max Return Path Loss - Min Return Path Loss
4. Check the calculated Return Outlet to Outlet Variation against the specifications.
Refer to the Cable TV Network Requirements in Chapter 1. If the Return Outlet to
Outlet Variation is not within specification (
≤
6 dB), take corrective action. You may
have to attach external attenuators to the ChannelWorks Bridge if the situation cannot
be corrected by adjustments to the cable plant.