Scan Settings And Resolution Bandwidth
The Start and End frequencies define the boundaries of the RF spectrum trace when the analyzer is scanning and measuring RF energy across a frequency range. The frequency settings are always specified in units of megahertz (MHz). When scanning the 2.4x GHz ISM band the frequency range is fixed at 2401 MHz to 2495 MHz. When scanning the 5.x GHz ISM band the frequency range is fixed at 5100 MHz to 6100 MHz.
The Resolution Bandwidth feature allows some control over the detail of each spectrum trace measured when scanning. The resolution bandwidth determines the smallest distance between adjacent peaks that can be resolved. The smaller the RBW, the finer the resolution. Finer resolutions result in longer scans, since more data points need to be acquired.
The Vertical Scale slider controls the height of the Y-axis in the Spectrum Trace view. By default it is set to -30 dBm (the maximum value). If the signal strengths are low then decreasing the Vertical Scale has the effect of “zooming” the trace views. This has no effect on the data acquisition but, rather, simply how the data is displayed.
The Waterfall Scale slider control applies only to the Waterfall History view. This control can be used to rescale and remap the signal strengths to better spread them across the range of colors that are used (see legend to the right of the Waterfall History view). This is useful when all the signal strengths are large and the Waterfall view appears mostly red or when all the signal strengths are low and the Waterfall view appears mostly blue. For the best visual effect, ideally you’d like the peaks (strong signals) to appear red and the valleys (weak signals) to appear blue. But sometimes even the valleys have large signal strength values or the peaks have low signal strength values. This control is useful in remapping the color legend to better make use of the colors and how they are spread across the peaks and valleys of the signal strength values.
Threshold Trace Setting
This setting is where you specify a threshold value that is applied to the Threshold Trace diagnostic chart. Frequencies whose signal strength exceeds this threshold will be highlighted with a yellow box.
This feature makes it easy to create a PDF report. Select Create Report from the main menu and you will be prompted for a folder and filename. An Adobe PDF-formatted file will be created that includes all charts. Selecting Open Report allows you to open and view Adobe PDF-formatted reports you’ve previously created (or any other PDF file).
This feature allows you to save a spectrum trace to a file, in XML or CSV format, for use by another program. Several options are available. The first three allow you to select the format (CSV or XML) of the exported file. The fourth option, ‘Apply Frequency Boundaries’, allows you to specify whether the frequencies (and signal strengths) recorded in the trace should be calculated for 25, 50, or 100 KHz intervals, or whether to not round the data at all. Applying frequency boundaries could be of value if you plan to import this data to another application that assumes wireless devices are assigned channels that fall on 25, 50 and 100 KHz boundaries. The fifth option, ‘Set amplitudes above’, allows you to emphasize those frequencies whose signal strength exceeds a threshold. In the resultant file the signal amplitudes will have a value of either -30 (dBm) or -105 (dBm) depending whether the original signal exceeds the threshold you’ve specified. That is, if the original signal exceeds the threshold then it will be recorded as -30 (dBm) in the resultant file and if it does not exceed the threshold then it will be recorded as -105 (dBm). To use this option, select the check box and use the slider control to set a threshold value (in dBm). When you press the ‘Export’ button you will then be prompted for a folder and filename to save the exported spectrum trace data.
This feature allows the user to import a saved trace that appears as a ‘reference trace’ on the Spectrum Trace chart when scanning is active. This is useful when it is desirable to compare current traces with a trace that was collected at a prior time and/or different location. To load a reference trace select Add Reference Trace from the main menu, and you will then be prompted to select a file to import as the Reference Trace.
IMPORTANT: The file used as a reference trace must have previously been saved using the ‘Export Last Trace’ feature (see above).
When scanning is active then the reference trace appears in blue and is static — that is, it does not change.
This feature allows you to compare two traces captured at different times. Use the ‘Load #1’ and ‘Load #2’ buttons to select the two spectrum traces to be compared. Trace #1 is plotted in yellow, and Trace #2 is plotted in green.
IMPORTANT: The trace files to be compared must have previously been saved using the ‘Export Last Trace’ feature (see above).
WiFi Surveyor — Other Features
Threshold Trace Setting