4-21 Amplitude Chapter 4 — Spectrum Analyzer
4-24 MS20xxA VNA Master UG 10580-00166 Rev. C
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, 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.
Pre Amp On/Off
This soft key turns the low-noise front-end preamplifier on or off. The preamplifier in
the MS203xA 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.
Detection
Several detection methods tailor the performance of the instrument to meet specific
measurement requirements. In general, there are more measurement points across the
screen than display points. The various detection methods are different ways of dealing
with selecting which measurement point will be shown at each display point.
10580-00166C.book Page 24 Thursday, February 21, 2008 12:52 PM
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