Agilent Technologies Signal Analyzer N9030a - Manual (Page 520)

6 RLC Swept SA Measurement Front-Panel & SCPI Reference
AMPTD Y Scale
[:SENSe]:POWer[:RF]:ATTenuation?
[:SENSe]:POWer[:RF]:ATTenuation:AUTO OFF|ON|0|1
[:SENSe]:POWer[:RF]:ATTenuation:AUTO?
Example POW:ATT 20
Dual attenuator configuration: sets the mechanical attenuator to 20 dB
Single attenuator mode: sets the main attenuation to 20 dB (see below for definition of “main”
attenuation).
If the attenuator was in Auto, it sets it to Manual.
Dependencies Some measurements do not support the Auto setting of (Mech) Atten. In these measurements,
the Auto/Man selection is not available, and the Auto/Man line on the key disappears.
In dual attenuator configurations, when the electronic attenuator is enabled, the mechanical
attenuator has no auto setting and the Auto/Man line on the key disappears. The state of
Auto/Man is remembered and restored when the electronic attenuator is once again disabled.
This is described in more detail in the
"Enable Elec Atten" on page 521 key description.
See "Attenuator Configurations and Auto/Man" on page 521 for more information on the
Auto/Man functionality of Attenuation.
Couplings
When (Mech) Atten is in Auto, it uses the following algorithm to determine a value:
Atten = ReferenceLevel + PreAmpGain + ExternalGain – RefLevelOffset - MaxMixerLevel + IF
Gain.
Limit this value to be between 6 dB and the Max value. No value below 6 dB can ever be chosen
by Auto.
The resulting value is rounded up to the largest value possible given the attenuation step setting.
That is, 50.01 dB would change to 60 dB (for a 10 dB attenuation step).
The “IF Gain” term in the equation above is either 0 dB or +10 dB, depending on the settings of
FFT IF Gain, Swept IF Gain, max Ref Level and the Auto/Man setting of Mech Atten.
In External Mixing and BBIQ,where the Attenuator is not in the signal path, the Attenuator
setting changes as described above when (Mech) Atten is in Auto, but no changes are made to
the actual attenuator hardware setting until the input is changed back to the RF Input.
Preset The preset for Mech Attenuation is “Auto.”
The Auto value of attenuation is:
CXA, EXA, MXA and PXA: 10 dB
State Saved Saved in instrument state
Min 0 dB
The attenuation set by this key cannot be decreased below 6 dB with the knob or step keys. To
get to a value below 6 dB it has to be directly entered from the keypad or via SCPI. This protects
from adjusting the attenuation to a dangerously small value which can put the instrument at risk
of damage to input circuitry. However, if the current mechanical attenuation is below 6 dB it can
520 Remote Language Compatibility Measurement Application Reference