Receiver Mode
R&S
®
ESR
148
User Manual 1175.7068.02 ─ 12
Auto Rang-
ing
= Turns automatic selection of the input attenuation on and off, see
RF Attenua-
tion
= Attenuation level at the RF input.
Preamplifier = Turns the preamplifier on and off. If you select "Auto", the preamplifier is also considered in
the auto ranging process.
RF Input
= Selects the RF input.
5.1.3.4
Scan on a Fixed Frequency
Fixed frequency scans are scans in the time domain, i.e. at a fixed frequency. Time
domain analysis is generally used to examine the time characteristics of interferences.
Evaluating the detected voltage with an oscilloscope is useful in order to correctly set
the receiver measurement time. By doing so, you can determine whether and how
strongly a narrowband interference fluctuates and whether it is amplitude-modulated or
pulsed. You can also determine the pulse rate of a broadband interference. You can
set the measurement time to a value that is greater than or equal to the reciprocal of
the pulse rate.
Click rate analysis
A special application for fixed frequency scans is click rate analysis. Clicks are short
and occasional interferences or pulses that usually occur in thermostat-controlled, soft-
ware-controlled or other electrically controlled devices like washing machines or air
conditioning devices.
The click characteristics of such a device are subject to the occurrence of successive
pulses whose individual pulse heights cannot be assigned exactly by using the time
constants of quasipeak weighting. This can be critical for these measurements,
because it can lead to limits being exceeded. Using time domain analysis, you are able
to determine the length, repetition rate and level of the clicks.
Because of their irregularity, different limits have to be applied than for periodic interfer-
ences. These limits are defined by the CISPR
14-1 and EN
55014-1 standards. Both
standards define limits for RFI voltage with click rate weighting in the range from
150
kHz to 30
MHz.
You can perform this task according to the standards with the R&S
ESR. It meets the
requirements of the standards regarding the accuracy of pulse length measurements
with pulse lengths of 10
ms or more. With a memory capacity of 2 million values per
trace, it also has a large enough memory to completely record maximum peak and
quasipeak data for at least 2 hours with a measurement time of 5
ms for each value
that has been measured.
5.1.4
Peak List and Data Reduction
Peak List
The Peak Search function of the R&S
ESR can be used to create a peak list containing
only the measurement values of high interferers. In a fast prescan the signal is mea-
Measurements and Result Displays
