Keysight x-series Programmer's Reference

3 VMA Mode
3.5 Channel Power Measurement
–
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)
Using the Electronic Attenuator: Pros and Cons
The electronic attenuator offers finer steps than the mechanical attenuator, has no
acoustical noise, is faster, and is less subject to wear.
The “finer steps” advantage of the electronic attenuator is beneficial in optimizing
the alignment of the instrument dynamic range to the signal power in the front
panel as well as remote use. Thus, you can achieve improved relative signal
measurement accuracy. Compared to a mechanical attenuator with 2dB steps, the
1dB resolution of the electronic attenuator only gives better resolution when the
odd-decibel steps are used. Those odd-decibel steps are less accurately calibrated
than the even-decibel steps, so one tradeoff for this superior relative accuracy is
reduced absolute amplitude accuracy.
Another disadvantage of the electronic attenuator is that the spectrum analyzer
loses its “Auto” setting, making operation less convenient.
Also, the relationship between the dynamic range specifications (TOI, SHI,
compression, and noise) and instrument performance are less well-known with the
Vector Modulation Analyzer Mode User's &Programmer's Reference 816

Keysight x-series Specifications

General

Analysis Bandwidth	Up to 1 GHz (depending on model)
Real-Time Bandwidth	Up to 1 GHz (depending on model)
Form Factor	Benchtop
Connectivity	LAN, USB, GPIB
Resolution Bandwidth	1 Hz to 10 MHz (depending on model)