After conducting all the preparation work necessary to perform a site
survey, it is time to actually begin the survey. Prior to arriving on site,
ensure that all of the equipment is operational, configured, and ready to
survey. Figure
illustrates the
basic steps to perform in preparing for a site survey.
In-building
Survey
Call ahead to find out if a scissor lift will be needed to reach
the ceiling. If so, find out if the customer will provide the lift or not. If
necessary, make sure that the proper equipment and a licensed operator have
been obtained.
Site-to-site Survey
If the survey is for a
site-to-site WLAN for a distance of several kilometers, or miles, roof access
will probably be necessary. Also, make sure that a spectrum analyzer is
available. Building-mounted antennas are much more costly than in-building
installations. Building or roof mounts, power, hardware, lightening arrestors,
coax cable, fittings, and lightening rod systems are expensive. Electrical and
grounding installation should only be done by a licensed professional, which
will add to the cost. In many areas, a building permit is also required to
install the antenna. The legal protection and coverage provided by a reputable
contractor is even more important than following building codes, regulations,
and licensing requirements. Any attempts to reduce costs during this process
may result in ultimately losing a lot of money and credibility in a lawsuit.
By testing the line-of-sight (LOS) path, both visually and with an RF
spectrum analyzer, the costly mistake of having to relocate the antenna is
initially avoided. Remember that WLANs use the unlicensed 2.4-GHz band and
there are no guarantees that interference will not become a problem in the
future. Be sure to explain and document this for legal protection as well as
customer knowledge. The spectrum analysis should be documented for current
conditions. If possible, perform this test over several days at different times
during the day. If the customer depends on a reliable link during the middle of
the night, then a survey should be performed at that time, if possible.
If more than a few kilometers, or miles, separate sites, then a tower may be
necessary at one or both ends of the path. A crane equipped with a basket to
simulate a tower may be necessary to check the LOS for obstacles and RF
interference. This can become quite expensive and time consuming, even if the
equipment is rented. Remember to rent a crane that reaches the desired height
and always plan ahead to reserve the equipment. At this point, a team will
probably be necessary so that team members several kilometers, or miles, away
can work together to establish and test link quality. It is also important to
have cell phones or communication devices available to coordinate efforts.
Few mistakes could be more costly than erecting a 45.7-m (150-ft) tower to
later discover that RF interference has partially or completely destroyed the
link quality. The tower could easily have been relocated several meters, or
feet, to avoid the problem.
Charge all batteries and battery packs the
night before the scheduled survey. This includes the scissor lift if it is
battery operated. Plan ahead to ensure all survey equipment will be functional
for the day of the survey.