9-6 Amplitude Menu Chapter 9 — Interference Analyzer, Option 25
9-12 MS20xxA VNA Master UG 10580-00166 Rev. C
Reference Level
The reference level is the top graticule line on the display, and can be set from +30 dBm
to -150 dBm. A negative value may be entered from the key pad, using the ± key as the
minus sign. After entering the value press the
dBm soft key or the Enter key. The
Up/Down arrow keys change the reference level in 10 dB steps, and the Left/Right
arrow keys change the value by 1 dB. The rotary knob changes the value by 0.1 dB per
detent.
The reference level value may be modified by the reference level offset value to
compensate for an external attenuator, as discussed later in this chapter.
Scale
The scale can be set in 1 dB steps from 1 dB per division to 15 dB per division. The
value can be changed using the keypad, the rotary knob or the Up/Down arrow keys.
Auto Atten On/Off
Input attenuation can be either tied to the reference level (On) or manually selected
(Off). When input attenuation is tied to the reference level, attenuation is increased as
higher reference levels are selected to make sure the instrument input circuits are not
saturated by large signals that are likely to be present when high reference levels are
required.
Atten Lvl
Input attenuation can be set from 0 dB to 65 dB, in 5 dB steps. Select this soft key and
use the keypad, the rotary knob or the Up/Down arrow keys to change the attenuation
value. When the Preamplifier is turned on, the allowed attenuation settings are 0 dB
and 10 dB.
RL Offset
Reference Level Offset compensates for the presence of input attenuation or gain
external to the instrument. Enter a positive value to compensate for an external
amplifier or a negative value to compensate for an external attenuator. Use the
±key to
enter the negative sign when a negative attenuation value is being entered.
Units
The
Units soft key is available only in the Spectrum view. Select the display units from
this soft key menu:
dBm
dBV
dBmV
dBµV
Volt
Watt
Back
Press the
Back soft key to return to the Amplitude menu.
Pre Amp On/Off
This soft key turns the low-noise front-end preamplifier on or off. The preamplifier
lowers the noise floor by approximately 25 dB. To assure accurate measurement
results, the largest signal into the instrument input when the preamplifier is turned on
should be less than -50 dBm.
10580-00166C.book Page 12 Thursday, February 21, 2008 12:52 PM
To Next Page