3 Short-Range Comms & IoT Mode
3.3 LoRa (CSS) Demodulation Measurement
Note that for N9042B+V3050A, in the Swept SA measurement, Software
Preselection works even if the measurement is using an FFT Sweep Type. In
measurements other than Swept SA, Software Preselection is not used if the
measurement is using an FFT Sweep Type.
VXT models M9410A/11A/15A/16A
Software Preselection is used to provide the preselection function, as there is no
hardware preselector in these models. Two background traces are taken and
compared point by point, and the point with the lowest amplitude from the two
traces is used. This provides a method to reduce spurs that are internally generated
within the VXT, but you should note the following when using Software Preselection:
–
There is some speed cost due to the need to take multiple captures
–
Taking the point with the lowest amplitude in each trace will make the average
noise level lower at all points that do not have a spur. This can reduce the
accuracy of the measurement of noise and noise-like signals
Because of the difficulty in identifying spurs manually, you are recommended to
leave Software Preselection ON at all times in VXT models M9410A/11A. If you turn it
off in order to speed up your measurement or improve noise accuracy, be aware of
unwanted onscreen spurs.
Remote Command
[:SENSe]:POWer[:RF]:SWPResel:STATe 0 | 1 | ON | OFF
[:SENSe]:POWer[:RF]:SWPresel:STAT?
Example
:POW:SWPR:STAT 1
:POW:SWPR:STAT?
Dependencies Only appears in N9041B, N9042B+V2050A, VXT models M9410A/11A and M9410E/11E. Does not
appear in all measurements
Couplings Affects Sweep Time
Auto Tune supports Software Preselection, so Auto Tune should be performed after setting the
Software Preselection state
Preset
N9041B
OFF
N9042B+V3050A
ON
M9410A/11A
ON
State Saved Saved in instrument state
SW Preselection Type
Specifies the algorithm used for software preselection.
364 Short Range Comms & IoT Mode User's &Programmer's Reference
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