User's Manual

ARCXTEND USER MANUAL – R1.4, ISSUE 4

VM-90 provides maximum coverage and maximum range but requires access to a building or tower

for mounting. Locations on building or towers are availably but generally involve a lease agreement

with the owner and the site must be within a thousand feet of the cable plant.

Once you have identified possible sites for the Hub, drive out to these locations and determine

which, if any of them, provide a line of site path to the customer site(s) to be served. The simplest

way to do this is, using a spotting scope, find the other end of the path and determine if it meets the

Fresnel zone criteria. A more accurate approach would be to use a range finder to measure the

height of the highest obstruction in the path and GPS to measure the distance. If you find that none

of the Hub sites will work then you need to go back to the map and try and locate alternative

locations.

Checking for Interference

ARCXtend maps the upstream DOCSIS channel to a high frequency and a low frequency pair in the

5.250 to 5.350 GHz band. This mapping is fixed and based solely on the frequency of the upstream

DOCSIS channel. Determine the corresponding wireless channels the upstream frequency used in

your cable plant. Check for interference at both frequencies and note which of these channels are

free of interference, as it will be used for the deployment. If you can’t find free spectrum for the

downstream and upstream signals then you will need to find another location.

Handheld wireless LAN spectrum analyzers covering the 5.250 to 5.350 range and capable of

identifying signals regardless of origin, like the BANTAM INSTRUMENTS Model 425A, are ideal for

locating potential interference.

CPE Site Selection

Height and Location

A suitable location for the CPE is one that provides an acceptable line of sight (LOS) wireless link,

as previously defined, to the Hub. This requires the CPE to be placed high enough on the rooftop to

provide the required Fresnel zone clearance. Using the setup shown in Figure 3-2 monitoring, the

optimal height and location can be determined by monitoring the Signal Level reading on the AR100

Signal Strength Meter. Monitoring the Signal Level meter on the AR100, the optimal CPE height

and location will be indicated by maximum signal level readings.

The CPE are that it should be located to the edge of the building closet to the Hub. If the CPE were

to be mounted towards the middle or back of the building, the incoming wireless signal can be

reflected by the rooftop impairing the performance of the link. It is also advisable to select a location

near to the rooftop grounding system to have a short, low resistance path and within 300 feet of an

AC power source. The routing path for the coaxial cable that connects the CPE to the cable modem

is also worked following your normal guidelines.