CHAPTER 3: FIELD APPLICATIONS
DigiVu
®
Series Multichannel MPEG-2/H.264 Encoder/Multiplexer with QAM &/or IP Output - Installation & Operation Manual
3-3
3.4 QAM Insertion Without Decoding
3.4.1 Insertion Into Empty Channel
DigiVu series products can be used to insert local programming into the cable system where there is empty spectrum (no QAM
or analog channel). This can be spectrum in the middle of other channels or above the HFC plant end frequency (at the “band
edge”). In these scenarios, a channel is allocated on the system where no carrier is sent from the headend and every property
in the system where the DigiVu is installed may insert a QAM without the use of a channel deletion filter. When RF spectrum
is available for this application and/or there are a large number of insertion systems installed, the cost of a channel deletion
filter may be saved at every property.
3.4.2 Insertion Into Channel at Band Edge
There are two main scenarios for this deployment:
•
Regular 870 MHz plant has some empty channels remaining unused just below 870 MHz. The new QAM channel is
inserted on one of these empty channels.
•
Plant is built to 750 so at least 100 MHz of plant is available with empty channels. The new QAM is inserted in this
upper band above the 750 plant.
In each case, some extra loss may be incurred through passives that are near or past their usable bandwidth but in such
a case, only a very few passives are affecting the new QAM channel and the DigiVu output may be increased slightly to
compensate if required.
Figure 3-2:
Insertion Into Channel at Band Edge
