5 Measuring with the NBM-550 and HF probes
46 NBM-550 Narda
5.2 Measuring in Normal display mode
The latest measurement results are displayed in Normal
mode. You can also display maximum and average values.
Selecting the result type
You can select the following result displays on the NBM-550:
Result type Description
Actual The latest measured value of field strength is shown numerically and as a bar
graph.
Max Hold The maximum field strength measured during the course of the measurement is
frozen and displayed numerically and as a separate line on the bar graph. The bar
graph continues to display the latest value.
Press the ESC (Clear) key to reset the display value to 0.
Average The average of the current measurement values is determined and displayed.
The progress in forming the average value is shown as a bar graph until the first
valid average value has been determined. The remaining measurement time in
seconds is shown in the window on the right. You can set the averaging time in the
MEASUREMENT SETTINGS/Averaging Time menu (see “Setting the
averaging time” on page 49).
The bar graph disappears once the first average value has been determined. The
average result is then valid. As the measurement continues, the average is formed
continuously using the results obtained during the time window (averaging time).
Press the ESC (Clear) key to reset the display value to 0.
Max Avg The maximum value of the measured average values is displayed.
The average values are determined as described for the Average result type. Only
the highest average value determined during the course of the measurement is
displayed.
Press the ESC (Clear) key to reset the display value to 0.
The following averages are determined for result types Average or Max Average:
• Linear average of power values (e.g. W/m
2
or mW/cm
2
)
• Root mean square (RMS) of field strength values (e.g. V/m or A/m)
Both types of average give the same result. The averaging process conforms to current safety
standards for high frequency fields and normally takes place over a period of 6 minutes. The units
of the measured value can be switched at any time without affecting the results already averaged.
154 s
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