How To Set The Averaging Time; How To Set Automatic Gain For Averaging Modulated Signals - Keysight N7744A User Manual

2
Power Measurement

How to Set the Averaging Time

How to Set Automatic Gain for Averaging Modulated Signals

54
Table 3 Upper Power Limits for Various Power Ranges
[RANGE]
-40 dBm
-50 dBm
-60 dBm
-70 dBm
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 N7744A and N7745A can be set over a wide
range from 1 µs to 10s. Up to 2 ms, the setting can be varied with a typical
resolution of 2 µs, 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 specifications. These bandwidths are
reduced in steps, when longer averaging times are used to improve the
noise performance while maintaining signal fidelity.
For the N7747A and N7748A, the averaging time can be set from 25 µs
to 10 s. Up to 2 ms, the setting can be varied with a typical resolution
of 2 µs, and for higher averaging times the setting resolution is about
0.1%. The bandwidth is fixed with the chosen power range, as listed in
the specifications and independent of the selected averaging time.
Individual values for live readings and for the MinMax mode, are
generated with a minimum resolution of 1 ms. This limit does not apply
to the Logging and Stability functions.
A fast Auto Gain switching is used to achieve the high dynamic range
in the N7744A and N7745A. In some applications, like determining the
average power of signals modulated with periods shorter than the
averaging time, this switching produces irregular readings. In such
Upper Power Limit
199.99 nW
199.99 nW
199.99 nW
199.99 pW
-37.000 dBm
-47.000 dBm
-57.000 dBm
-67.000 dBm
Keysight N774x Series