R&S ESU Series Operating Manual page 298

R&S ESU
• With the preselection active, the start frequency is set to 150 kHz in the FULL
SPAN setting to avoid permanent switching of the relay at the band limit of 150
kHz.
• Due to the limited tuning speed of the tracking passband filters, the maximum
sweep rate (3.6 GHz / 5 ms) can no longer be attained with the preselection
switched on. The minimum settable sweep time is obtained from the sum of the
minimum possible sweep times in the associated filter bands.
Preamplification
Switching on the preamplifier diminishes the total noise figure of the R&S ESU, thus
increasing the sensitivity. The preamplifier follows the preselection filters so that the
risk of overdriving by strong out-of-band signals is reduced to a minimum. The signal
level of the subsequent mixer is 20 dB higher so that the maximum input level is
reduced by the gain of the preamplifier. The total noise figure of R&S ESU is
reduced from approx. 18 dB to approx. 11 dB with the preamplifier switched on. The
use of the preamplifier is recommended when measurements with a maximum sen-
sitivity are to be performed. If the measurement should be performed at maximum
dynamic range, the preamplifier should be switched off.
The gain of the preamplifier is automatically considered in the level display. In ana-
lyzer mode, on switching on the preamplifier the RF attenuation or the reference
level is adapted depending on the settings of the R&S ESU.
The base unit already provides a built-in preamplifier of 20 dB gain in the frequency
range from 9 kHz to 3.6 GHz. An additional low noise preamplifier that covers the
frequency range from 100 kHz to the upper frequency limit of the R&S ESU is avail-
able as option R&S ESU-B24. Due to its inherent noise figure, the optional low noise
amplifier provides a higher noise reduction and better sensitivity than the standard
preamplifer.
As of firmware version 4.43, it is possible to activate the low noise preamplifier in
combination with an active preselector. Only one preamplifier can be active at a
time.
Operating Manual 1302.6163.12 - 03
Filter band
9 kHz to 150 kHz
150 kHz to 2 MHz
2 to 8 MHz
8 to 30 MHz
30 to 70 MHz
70 to 150 MHz
150 to 300 MHz
300 to 600 MHz
600 to 1000 MHz
1000 to 2000 MHz
2000 to 3000 MHz
3000 to 3600 MHz
Min. sweep time for filter band
-
-
500 ms
50 ms
50 ms
50 ms
50 ms
50 ms
50 ms
50 ms
-
-
Instrument Functions
Basic Settings
4.267