3 Short-Range Comms & IoT Mode
3.7 ACP Measurement
You can select a shorter sweep time to improve the measurement throughput (with
some potential unspecified accuracy reduction), but the Meas Uncal indicator will
appear if the sweep time you set is less than the calculated Auto Sweep time.
You can also select a longer sweep time, which can be useful (for example) for
obtaining accurate insertion loss measurements on very narrowband filters.
NOTE
Significantly faster sweep times are available with Option FS1.
NOTE
The Meas Uncal (measurement uncalibrated) warning is displayed in the Status
Bar at the bottom of the screen when the manual Sweep time entered is faster
than the time computed by the instrument’s Sweep time equations, that is, the
Auto Sweep Time. The instrument’s computed Sweep time will provide accurate
measurements; if you sweep faster than this your measurements may be
inaccurate. A Meas Uncal condition may be corrected by returning the Sweep
Time to Auto; by entering a longer Sweep Time; or by choosing a wider RBW
and/or VBW.
NOTE
On non-sweeping hardware, this control is grayed-out. The value shown on this
control is an estimate. It is the measurement’s turnaround time, which is the sum
of signal acquisition time, FFT time, and other overhead time, to complete the
entire span of the measurement. If you need to specify the same “Sweep Time”
as you would for sweeping hardware, send [:SENSe]:<meas>:SWEep:TIME
<time>. The measurement emulates the “Sweep Time” effect, but this emulation
is not straightforward, and therefore the behavior is not specified. Instead, we
recommend using Minimum Acquisition Time, which provides better control.
Remote Command
[:SENSe]:<meas>:SWEep:TIME <time>
[:SENSe]:<meas>:SWEep:TIME?
Example Channel Power measurement:
:CHP:SWE:TIME 25ms
:CHP:SWE:TIME?
Notes In the ACP measurement in WCDMA Mode, this parameter is preset by Meas Method selection. Preset
values are as follows:
–
IBW: 29 ms
–
IBWR: 108 ms
–
FAST 7.5 ms
Dependencies On non-sweeping hardware, this control is grayed out, and the Auto/Man toggle disappears. The
read-only control shows estimated sweep time
In those instruments, "Minimum Acquisition Time" on page 1721 is available
Couplings Coupled to Span, RBW, VBW, and Sweep Time Rules when Sweep Time is set to Auto; Sweep Time
976 Short Range Comms & IoT Mode User's &Programmer's Reference
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