User's Manual

Table 3-2: Upstream Frequency Plan
5
Modem US &
Cable System
US Channel
Upper Carrier
CPE air Tx &
Access Point
Rx
Lower Carrier
CPE air Tx &
Access Point
Rx
center (MHz) center (MHz) center (MHz)
f
ch
5300+ f
ch
5300- f
ch
6.4 5306.4 5293.6
9.6 5309.6 5290.4
12.8 5312.8 5287.2
16.0 5316.0 5284.0
19.2 5319.2 5280.8
22.4 5322.4 5277.6
25.6 5325.6 5274.4
28.8 5328.8 5271.2
32.0 5332.0 5268.0
35.2 5335.2 5264.8
38.4 5338.4 5261.6
41.6 5341.6 5258.4
This mapping of the modem upstream channel to the over-the-air 5.3 GHz channels
(double sideband modulation) is fixed. Should interference or other factors force the
choice of a specific 5.3 GHz channel, the Access Point Receive Frequency should
be flipped to the alternate frequency. This is done through the Access Point control
interface.
3.5 Example of Frequency Plan
The system in Figure 3-4 is an example of a frequency plan at one Access Point.
The CMTS Downstream is EIA Channel 93 (639 MHz) for wired and wireless
modems.
The ARCXtend Access Point is programmed to convert this into a Downstream air
frequency of 5777 MHz (the programming is covered in a later Section).
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A spectrum analyzer looking at the subscriber’s transmitted RF will see two frequencies. The two
carriers are 5300 MHz +- the upstream IF frequency. The Hub receiver is tuned to only one of these
two frequencies.
ARCXtend manual, August 2003 3-9