UNI-T UTS3000B/A Series User Manual page 44

Attenuation （Auto/Man） : Set RF front-end attenuator so that signal can pass through the mixer with low
distortion (small signals with low noise). Input attenuation can be switched between automatic and
manual. When auto is selected, the input attenuation value is linked to the reference level. When manual
is selected, the user can change the input attenuation value via the numeric key, rotary knobs, direction
key or touch panel menu.
Note

When the maximum mixer level and reference level are determined, the minimum of input
attenuation of the spectrum analyzer should meet the formula: Reference Level ≤ Input Attenuation-
Pre-amplification -10dBm.
Preamplifier: The switch that controls the internal preamplifier of the instrument. Turn on to produce a
gain to compensate for the preamplifier, so that the amplitude value read out is the actual value of the
input signal. When the pre-preamplifier is turned on, the measurement bar area of the screen displays
Preamp: on.
Scale/Div: Sets the logarithmic value corresponding to a grid in the vertical direction of the screen. The
scale function is only available when the scale type is logarithmic. User can change the scale value by
using the numeric key, rotary knobs, direction key or touch panel menu.
Scale: When the scale type is set to logarithmic, the logarithmic value corresponding to a grid in the
vertical direction of the screen can be used. When linear is selected, the vertical grid becomes a linear
scale with the default amplitude in volts V. The grid line at the top of the screen is the set reference level,
while the grid line at the bottom is the zero level. Each grid is a tenth of the reference level in volts V.
Y Axis Unit: Change the amplitude unit which can be both used in logarithmic and linear mode. Optional
unit: dBm, dBmV, dBμV, V and W. The default is dBm.
Ref Level Offset: When there is gain or loss between the device under test and the import of spectrum
analyzer, an offset value is added to the reference level to compensate for the resulting gain or loss. This
value does not change the position of the trace and modifies the reference level and the amplitude
reading of the cursor.
Impedance: Set the input impedance when converting voltage to power. The default input impedance is
50Ω. If the input impedance of the DUT to the spectrum analyzer is 75Ω, then need to use a 75Ω to 50Ω
adapter to connect the DUT to the spectrum analyzer and set the input impedance to 75Ω.
Correction: Enter the amplitude correction to set the compensation of the gain or loss of external
devices, such as antennas and cables. When the correction is turned on, the trace and the
corresponding measurements are corrected.
1. Select: Spectrum analyzer provides 10 correction factors and each factor can edit independent.
2. Correction（On/Off）: The switch of correction, the default is off.
3. Close all: Close all the correction has been turned on.
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