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Chapter 2 81
Instrument Functions: A - L
Auto Couple
Instrument Functions: A - L
Factory Preset: Autorange
Remote Command:
[:SENSe]:ADC:RANGe AUTO|NONE
[:SENSe]:ADC:RANGe?
Example:
ADC:RANG NONE
2.1.7.1 Autorange
Turns the ADC ranging to automatic which provides the best signal to noise ratio. Auto
Couple All sets the ADC ranging to Autorange. Autorange is usually preferred over
Bypass.
Key Path:
Auto Couple
State Saved: Saved in Instrument State
Remote Command:
Example: ADC:RANG AUTO
2.1.7.2 Bypass
Turning the ADC ranging to bypass mode allows higher throughput for FFT
measurements. (It can improve FFT measurement speed by 10% to 50%.) Bypass also
provides better phase noise, though the effect is negligible when using swept analysis or
for offsets below 300 kHz. The £(f) improvement is a few dB in FFT mode at 800 kHz offset.
Bypass allows triggered FFT measurements to occur at the trigger time instead of following
an autoranging time. Therefore, whenever the trigger selected is anything other than Free
Run
,andtheManual:FFT sweep selection is made, the ADC hardware is set to Bypass
regardless of the setting of ADC Ranging. See “Making Gated FFT Measurements With Your
PSA” on page 74
. Another advantage of Bypass is lower IF harmonic distortion, which may
be visible with very high signal levels at the input mixer.
Key Path:
Auto Couple
State Saved: Saved in Instrument State
Remote Command:
Example: ADC:RANG NONE