3 Spectrum Analyzer Mode
3.2 Swept SA Measurement
best signal to noise ratio. You can specify the range for the best FFT speed, and
optimize for noise or for large signals.
When the sweep type is FFT and this function is in Autorange, the IF Gain is set ON
initially for each chunk of data. The data is then acquired. If the IF overloads, then
the IF Gain is set OFF and the data is re-acquired. Because of this operation, the
Auto setting uses more measurement time as the instrument checks/resets its
range. You can get faster measurement speed by forcing the range to either the high
or low gain setting. But you must know that your measurement conditions will not
overload the IF (in the high gain range) and that your signals are well above the
noise floor (for the low gain range), and that the signals are not changing.
Option SCPI Details
Auto AUTO = ON "Auto" on page 443
Autorange
AUTOrange
"Autorange (Slower: Follows Signals)" on page 443
Low
LOW
"Low Gain (Best for Large Signals)" on page 443
High
HIGH
"High Gain (Best Noise Level)" on page 443
Remote Command
[:SENSe]:IF:GAIN:FFT[:STATe] AUTOrange | LOW | HIGH
[:SENSe]:IF:GAIN:FFT[:STATe]?
Example
:IF:GAIN:FFT ON
Dependencies The IF Gain keys (FFT IF Gain and Swept IF Gain) have no effect when the U7227A USB Preamplifier is
connected. This is not annotated or reflected on any control; there are no keys grayed-out nor any
SCPI locked out. The instrument simply behaves as though both FFT IF Gain and Swept IF Gain are set
to Low regardless of the setting on the keys
Couplings As with most parameters with an AUTO state, "Auto Couple" on page 2017 sets it to Auto, which then
picks AUTOrange, and setting any specific value (AUTOrange, LOW or HIGH) will set the AUTO
state to false
Preset
AUTOrange
State Saved Saved in instrument state
Range
AUTOrange|LOW|HIGH
Annunciation Autorange | Low | High
Found in the Meas Bar under IF Gain when in FFT sweep type
When not in Auto, label changes to #IF Gain
Backwards
Compatibility SCPI
:DISPlay:WINDow[1]:TRACe:Y[:SCALe]:LOG:RANGe:AUTO
[:SENSe]:ADC:RANGe AUTO | NONE
Backwards
Compatibility
Notes
The first form is included for ESA compatibility
The second form is included for PSA compatibility. The command and query are accepted without
error but ignored
Auto Function
Remote Command
[:SENSe]:IF:GAIN:FFT:AUTO[:STATe] OFF | ON | 0 | 1
[:SENSe]:IF:GAIN:FFT:AUTO[:STATe]?
442 Spectrum Analyzer Mode User's &Programmer's Reference
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