Keysight Technologies N774 C Series, Руководство пользователя

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64 Keysight N774xC Series Multiport Power Meter User’s Guide
4 User Interface Reference
How to Set the Range
The range setting determines the power levels that can be measured. The
setting should be high enough for the applied power, but lower settings
will provide a lower noise level for weak signals.
If you choose auto-ranging mode, this parameter can not be set. The
Range parameter returns the automatically-determined range.
If the measured power is more than 3 dB greater than the range setting,
the power cannot be measured and an overflow is indicated by the
returned power value. This means that the measured power is greater than
the Upper Power Limit . You must increase the Range value.
For more details, see the following table.
Upper Power Limit
The following table shows the upper power limit at the available power
ranges. The lowest measurable power in each range is determined by the
noise level, which depends on the range setting and the averaging time.
How to Set the Averaging Time
This is the length of time over which a signal is averaged to produce a
measured value. Longer averaging times increase the accuracy and
improve the noise rejection.
The averaging time of the N7744C and N7745C can be set over a wide
range from 1 μ s to 10s. Up to 2 ms, the setting can be varied with a typical
resolution of 2 μ s, and for higher averaging times the setting resolution is
about 0.1%. This flexible setting time supports optimal synchronization
with the time scale of the signals. The high sampling rate with short
averaging times is supported by the high cutoff frequency, as shown in the
Range Upper Power Limit
10 dBm 10.000 mW 10.000 dBm
0 dBm 1.9999 mW 3.000 dBm
-10 dBm 199.99 μ W -7.000 dBm
-20 dBm 19.999 μ W -17.000 dBm
-30 dBm 1.9999 μ W -27.000 dBm