Cisco Cisco 2504 Wireless Controller Guia De Resolução De Problemas
Heat map that displays the noise floor for all 'in−scope' areas with the target noise floor set and a
noise floor legend.
noise floor legend.
•
Spectrum Analysis screenshots and recordings of possible sources of interference. Define what is
desired in the analysis − Fast Fourier Transform (FFT), spectrograms, duty cycle, max hold, and so
on.
desired in the analysis − Fast Fourier Transform (FFT), spectrograms, duty cycle, max hold, and so
on.
•
Identify and list possible sources of interference. A walkthrough should be performed through the
facility. Ask about and look for possible sources of interference, such as microwave ovens, cordless
phones, and so on.
facility. Ask about and look for possible sources of interference, such as microwave ovens, cordless
phones, and so on.
•
The AP hardware to be used. For example, the heat maps may look different for Aironet 3500 Series
Access Points verses Aireonet 3600 Series Access Points. The AP should be selected to match the AP
that is planned to be purchased and deployed.
Access Points verses Aireonet 3600 Series Access Points. The AP should be selected to match the AP
that is planned to be purchased and deployed.
•
If a passive survey is performed, define how many AP's at a time are planned to be used, one or three.
Three is quicker than one, but the AP placements might be sub−optimal.
Three is quicker than one, but the AP placements might be sub−optimal.
•
Identify the type of survey to be conducted: voice, location, or data only.
•
Mistakes That Make a Survey Poor
Mistakes can be made with the use of survey tools that are able to make a site survey report look good. These
mistakes can make an entire floor or building appear to have sufficient coverage when, in reality, client
devices in certain areas might have very weak coverage.
mistakes can make an entire floor or building appear to have sufficient coverage when, in reality, client
devices in certain areas might have very weak coverage.
You should always request the actual survey data files with the survey report so the actual data can be
re−examined for mistakes and issues that are not shown in the survey report.
re−examined for mistakes and issues that are not shown in the survey report.
Calibration
The map calibration in a survey tool allows you to define the correct distance between two points on the map.
For example, you can draw a line across a 40−foot wall on the map and specify that the distance of the line
represents 40 feet. The rest of the map can be rescaled based on this defined distance.
For example, you can draw a line across a 40−foot wall on the map and specify that the distance of the line
represents 40 feet. The rest of the map can be rescaled based on this defined distance.
If the map is not properly calibrated, the heat maps generated from the AP do not represent the correct
distance. Data gathered from a map that is not properly calibrated results in a completely inaccurate survey
report. It is recommended to verify the map calibration in survey reports where the heat maps do not look
correct. Most cases you see a single data point or AP radio provides much larger coverage in the survey map
when compared to actual coverage. It is a good practice to view AP heat maps one at a time and verify
whether the coverage looks too big or too small. For example, you might see an AP heat map cover an entire
floor; this could be an indicator that the calibration is not properly configured.
distance. Data gathered from a map that is not properly calibrated results in a completely inaccurate survey
report. It is recommended to verify the map calibration in survey reports where the heat maps do not look
correct. Most cases you see a single data point or AP radio provides much larger coverage in the survey map
when compared to actual coverage. It is a good practice to view AP heat maps one at a time and verify
whether the coverage looks too big or too small. For example, you might see an AP heat map cover an entire
floor; this could be an indicator that the calibration is not properly configured.
You might also notice maps that do not look accurate where the image looks stretched or skewed. This can be
an indication of an invalid map that is not properly scaled. Best practice to always use a long distance on the
map when you measure a distance that is used for calibration as this results in better accuracy. Discrepancies
by even a millimeter with the use of a small doorway has a more harmful result when compared to
discrepancy by a millimeter when an entire hallway is used. The default dimensions after a drawing is
imported is 120 feet by 120 feet. If you see a map still calibrated at 120 feet by 120 feet, it is an indication that
the map is not calibrated.
an indication of an invalid map that is not properly scaled. Best practice to always use a long distance on the
map when you measure a distance that is used for calibration as this results in better accuracy. Discrepancies
by even a millimeter with the use of a small doorway has a more harmful result when compared to
discrepancy by a millimeter when an entire hallway is used. The default dimensions after a drawing is
imported is 120 feet by 120 feet. If you see a map still calibrated at 120 feet by 120 feet, it is an indication that
the map is not calibrated.
Note: You cannot recalibrate the map after the survey is performed to repair survey data that was taken when
the map calibration was not properly scaled. You must correct the map calibration and perform a new survey.
the map calibration was not properly scaled. You must correct the map calibration and perform a new survey.
Figure 1: Improperly−scaled Map with default dimensions of 120 feet by 120 feet