Keysight N9010B - Page 239

3 VMA Mode
3.1 Digital Demod Measurement
Mechanical Attenuator Transition Rules
When the Electronic Attenuator is enabled, the Mechanical Attenuator transitions to
a state that has no Auto function. Below are the rules for transitioning the
Mechanical Attenuator. Note that the information below only applies to the Dual-
Attenuator configurations, and only when the Electronic Attenuator is installed:
When the Electronic Attenuation is enabled from a disabled state:
–
The Mechanical Attenuator is initialized to 10dB (this is its optimal performance
setting). You can then set it as desired with SCPI, numeric keypad, step keys, or
knob, and it behaves as it normally would in manual mode
–
The Auto/Man state of (Mech) Atten is saved
–
The Auto/Man toggle on the (Mech) Atten control disappears, and the auto rules
are disabled
–
The Electronic Attenuator is set to 10dB less than the previous value of the
Mechanical Attenuator, within the limitation that it must stay within the range of
0 to 24dB of attenuation
Examples in the Dual-Attenuator configuration:
–
Mech Atten at 20dB. Elec Atten enabled, Mech Atten set to 10dB, and Elec
Atten set to 10dB. New total attenuation equals the value before Elec Atten
enabled
–
Mech Atten at 0dB. Elec Atten enabled, Mech Atten set to 10dB, and Elec Atten
set to 0dB. New total attenuation does not equal the value before Elec Atten
enabled
–
Mech Atten at 40dB. Elec Atten enabled, Mech Atten set to 10dB, and Elec
Atten set to 24dB. New total attenuation does not equal the value before Elec
Atten enabled
When the Electronic Attenuation is disabled from an enabled state:
–
The Elec Atten control is grayed out
–
The Auto/Man state of (Mech) Atten is restored
–
If now in Auto, (Mech) Atten recouples
–
If now in Man, (Mech) Atten is set to the value of total attenuation that existed
before the Elec Atten was disabled. The resulting value is rounded up to the
smallest value possible given the (Mech) Atten Step setting - (That is, 57dB
changes to 58dB when (Mech) Atten Step is 2dB)
239 Vector Modulation Analyzer Mode User's &Programmer's Reference