Rohde & Schwarz EMI Test ReceiverESCI Operating Manual page 221

R&S ESCI
MAIN PLL
BANDWIDTH
VBW MODE
LIN LOG
1166.6004.12
The MAIN PLL BANDWIDTH softkey defines the bandwidth of the main PLL of
the analyzer synthesizer and thus influences the phase noise of the analyzer.
Three bandwidth settings are possible (High / Medium / Low); if AUTO is
selected, the bandwidth is set automatically (default).
IEC/IEEE-bus command:
The VBW MODE LIN/LOG softkey determines the position of the video filter in
the signal path for resolution bandwidths ≤ 100 kHz:
! If LINear is selected, the video filter will be in front of the logarithmic
amplifier (default).
! If LOGarithmic is selected, the video filter will be behind the logarithmic
amplifier.
The essential difference between the two operating modes relates to the
settling in the case of falling signal edges:
With LINear, the falling signal edge will be "flatter" than with LOGarithmic.
This is due to the conversion from linear power to logarithmic level units: a
reduction of the linear power by 50% reduces the logarithmic signal level by
only 3 dB.
IEC/IEEE-bus-command:
Analyzer - Bandwidths and Sweep Time
BAND:PLL AUTO
BAND:VID:TYPE LIN
4.89 E-1