Black Box LWN600CM-1 Guide de l'utilisateur télécharger pdf (Page 26)

724-746-5500 | blackbox.com

Page 26

724-746-5500 | blackbox.com

Chapter 2: Preparing for a WAN Deployment

Each of the representations can be enlarged to fill the entire analysis pane to provide more detail or to increase its visibility, or be

deleted from the array to simplify the display. To change the display in this manner, use the buttons in the upper right corner of

each of the representations.

Pause/Resume: You can suspend a trace by clicking the Pause button. When you click “Pause,” the button becomes a Resume

button (right-pointing triangle). To resume the trace, click “Resume.”

NOTE: Pausing one of the displays does not affect any of the other displays and does not stop the collection of data. When you

resume a display, it returns to displaying data as if there were no interruption.

Maximize: Click the Maximize button (four outward-pointing arrows). This causes the small display to enlarge to fill the entire

content pane of the page. This is distinct from the Maximize button on the status bar, which maximizes the content pane to fill

the browser. To return to the smaller view, click the Restore Down button. This causes the display to return to the previous

arrangement.

Close: When you click the Close [ x ] button, the affected display disappears and the neighboring display expands to fill the

vacated area. To recover a closed display, navigate away from the spectrum analysis page and then return to it. When you return,

SmartPath EMS VMA again organizes the display in its default arrangement.

A description of each of the four graphical representations of the RF environment follows:

Real-time FFT: The real-time FFT is a trace that indicates the power of a signal (vertical axis) along a domain of frequencies

(horizontal axis). The term FFT (fast Fourier transform) refers to the mathematical algorithm used to decompose received signals

into their component’s frequencies. Within this display, there are two traces: the red trace indicates the real-time power levels,

whereas the gray trace indicates the maximum power level reached during the current data collection session.

On maximizing this display, you gain access to the following additional display parameters:

Band: You can choose which band you want to monitor in this display: 2.400-2.500 GHz, 5.150-5.350 GHz, 5.470-5.725 GHz, or

5.725-5.850 GHz.

Channels: Choose one of the channel combinations in the drop-down list to display channel boundaries within the graph.

Center: Use this control to scroll the graph right or left. You can use the Center control in combination with the Span control to

zoom in on a specific area of the frequency domain.

Span: This control establishes the width of the viewable area, effectively zooming in on the center frequency. Use this control

with the Center control to zoom in on a specific area of the frequency domain.

Reference Level: By default, the reference level of the graph (the top line) is 0 dBm. When used with the Vertical Scale control,

you can zoom in on a specific portion of the actual trace.

By changing the reference level using this control, you can also view very low power levels near the noise floor. In a very quiet

environment, the noise floor is generally between -130 dBm and -90 dBm; in very noisy or busy environments, it is much higher.

Vertical Scale: The vertical scale of a graph indicates how much vertical distance on the graph corresponds to power. By default,

the vertical scale is set to 10 dB, which means that a power change of 10 dB corresponds to a specific, physical vertical distance

on the graphic display. Changing that setting to 5 dB doubles the vertical resolution of the graph. Because there are many

different sizes of monitors, the actual scale that you see in your browser is relative.

Max Hold: By default, this check box is selected and SmartPath EMS VMA displays the gray trace that indicates the maximum

power level reached during the current data collection session. To turn off the gray trace, clear the check box.

FFT Duty Cycle: The FFT duty cycle is the amount of time as a percent of total time that the SmartPath AP receives a signal

above 20 dB above the noise floor. FFT duty cycle is often referred to as channel utilization because it indicates to what extent a

channel is actually in use in terms of the relative amount of time the signal is present (vertical axis). Within this display, there are

two traces: the red trace indicates the real-time duty cycle, whereas the gray trace indicates the maximum duty cycle reached

during this data collection session.

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Black Box LWN600CM-1 Guide de l'utilisateur Page 26

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