Once
the project configuration has been completed, you are ready to
perform the actual survey by walking the site with a laptop that
runs TamoGraph (unless you perform
predictive
modeling,
where no on-site data collection is necessary). To facilitate the
data collection process, TamoGraph offers three survey modes that
can be selected by pressing the corresponding buttons on the tool
bar:
Continuous
(the left button on the illustration),
Point-by-Point
(the middle button on the illustration), and
GPS
(the right button on the illustration) for GPS-assisted outdoor
surveys.
In the default
continuous mode,
after you mark your initial location on the map by clicking on it,
the application scanner continuously scans the air by sweeping
through the Wi-Fi channels. When you mark the next location on the
map, the data that has been collected between the two clicks on the
map is spread evenly along the path between the two data points.
This means that your path should consist of straight lines and that
you should walk steadily, clicking on the map every time you change
direction.
In the
point-by-point mode,
TamoGraph collects data only when you click on the map. In that
mode, you should stay where you are after marking your location on
the map, until the scanner completes the cycle. Then the scanner
stops, until you mark your next location, where the scanner makes
another full cycle. This means that your path can have any shape,
but less data will be collected, as compared to the continuous
mode, and a smaller area will be covered.
In the
GPS mode,
the data collection process is similar to the one in
continuous mode,
but the location is automatically determined by the GPS receiver
connected to the computer.
Continuous
and
Point-by-Point
surveys can be conducted both indoors and outdoors;
GPS
surveys can be conducted outdoors only, as GPS receivers cannot
receive location data when indoors.
Before you begin, spend some time thinking through your walkabout
path. Decide which areas you need to survey and how you are going
to do that. Remember that it is quite all right to mix the three
data collection modes—that is, you can survey some areas where
walking steadily in a straight line is not a problem in continuous
mode; you can then survey other areas in point-by-point mode, and
then survey the area outside the building in GPS mode. You can also
stop the survey at any moment and continue after a break, as you
can select several survey segments for data analysis. Once you have
thought through your walkabout path, begin the actual
survey.
TamoGraph allows you to perform two types of surveys:
active
and
passive
(or both at the same time). Every time you start data collection,
you will be prompted to select the type of survey, as shown
below.
It is extremely important to understand the difference between the
two survey types, as they focus on different WLAN characteristics.
Please refer to
Understanding Survey Types: Passive, Active, and
Predictive
for more information. When performing an active survey, an
additional configuration dialog is displayed before you can start
data collection. This dialog is explained in the
Active
Survey Configuration
chapter.
Additionally, when a compatible
spectrum analysis
device
is connected to the computer, you will be able to collect spectrum
data either in parallel with a passive survey (the first dialog
option will be titled
Passive Survey + Spectrum Survey)
or in spectrum-only mode (another option titled
Spectrum Survey
will be added to the dialog).
Continuous Mode:
To start data collection, click on the
Start
button (illustrated on the  left)
and then mark your initial location on the map by clicking on the
corresponding spot. Walk along the planned path at a steady pace in
a straight line. You should walk a bit slower than you normally do.
Every time you reach the end of the straight line on your path
(i.e., every time you need to change direction), click on the map
again to mark your current location. Data collection stops when you
click on the
Stop
button (illustrated on the right.)
If you want to suspend data collection temporarily without stopping
your current survey (e.g. when you want to answer
a phone call and then continue), click on the
Pause
button (illustrated on the left) to pause the survey and then click
it again to resume. Important: if you paused the survey, you can
move freely, but
you must return to the exact location where you paused the
survey
before you resume it, otherwise your survey data will be
invalid.
Point-by-Point Mode:
To start data collection, click on the
Start
button. Mark your location on the map by clicking on the
corresponding spot. TamoGraph will collect data by scanning the
channels twice and display a notification at the bottom of the
window when all the data has been collected. Proceed to the next
point on your path and mark your location again. Repeat until you
have surveyed all the planned points. Data collection stops when
you click on the
Stop
button.
GPS Mode:
To start data collection, turn on your GPS receiver, connect it to
your computer, and then click on the
Start
button. Your current location will be displayed on the map with a
circle. Make sure that the displayed location matches your actual
location. If it does not, you made a mistake while calibrating the
map with reference points, and you need to re-calibrate the map.
Walk or drive slowly along the planned
path. The slower you drive, the more Wi-Fi data will be collected,
and the more accurate the data analysis will be. GPS surveys can be
conducted outdoors only, in open areas where a GPS receiver can see
many satellites. Location data accuracy is directly related to the
number of satellites in view. As you move along the path, location
data accuracy is indicated on the application status bar, as shown
on the illustration. If location data accuracy becomes poor, you
may want to stop the survey until more satellites become visible to
the receiver (you can click on the data accuracy indicator to
display the GPS receiver configuration dialog that displays
accuracy level and visible satellites). Data collection stops
when you click on the
Stop
button.
When you are through with the survey, you can proceed to the data
analysis of a
passive
and/or
active
survey. However, before you do, it is recommended that you read the
next three chapters, especially if you are new to Wi-Fi site
surveys. They provide important information about the available
types of surveys, their purpose, as well as some valuable tips and
tricks to make your site surveying more efficient.
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