Agilent Technologies X Series Manual page 357

More Information
When the Electronic Attenuator is enabled, the Mechanical Attenuator transitions to a state in which it
has no Auto function. Here are the rules for transitioning the Mechanical Attenuator:
When the Electronic Attenuation is enabled:
• In the dual attenuator configuration, 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 line on the (Mech) Atten key disappears and the auto rules are disabled
• In the dual attenuator configuration, 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:
• In the dual attenuator configuration, the Elec Atten key is grayed out (it never displays in the single
attenuator configuration)
• 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
analyzer 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.
AMPTD Y Scale
357