Atec Rohde-Schwarz-ESPI_Series_DatasheetsЙ - Manual (Page 4)

4 Test Receiver ¸ESPI
¸ESPI-B2: preamplifier and preselection filters up to 3 GHz
The input stages of precompliance test equipment, which often feature
a rather poor overload capability, would be hopelessly overdriven
without a preselection unit. This is different with the ¸ESPI where,
in combination with preselection filter units, a low-noise preamplifier
comes after the filter module but before the mixer stage. It must be
possible to switch the preamplifier on/off as required, since in the case
of high signal levels, the dynamic range would be reduced by an amount
numerically equal to the gain. Where low signal levels are to be
expected, it is best to switch in the preamplifier. Since the Test
Receivers ¸ESPI operate both in the spectrum analyzer mode and in
the test receiver mode, both modes offer the choice of switching the
preamplifier on or off. In the receiver mode, the preselection filter
setting is fixed, whereas in the analyzer mode it can be selected.
Spectrum analyzer mode with selectable preselection filters and preamplifier switched on
Accuracy and reproducibility are also key
parameters for all applications of the
¸ESPI test receiver family.
The combination of test receiver and
spectrum analyzer provides an optimum
concept for precompliance measure-
ments in development environments.
Standard-conforming EMI
measurements
Fitted with the optional preselector/pre-
amplifier (¸ESPI-B2), all ¸ESPI
models feature an excellent dynamic
range compared with other precompli-
ance solutions and are, therefore, able to
perform precise interference measure-
ments with pulse repetition frequencies
(PRF) from 10 Hz in line with
CISPR 16-1-1.
Measurements to commercial EMI stan-
dards such as CISPR, EN 550xx, ETS, FCC,
ANSI C63.4, VCCI or VDE can be carried
out directly by comparing the EMI spec-
trum with the associated limit lines and
switching on the appropriate detectors
(PK, QP, CAV, AV, RMS-AV, RMS).
The detectors
Depending on the operating mode of the
¸ESPI 3 and ¸ESPI 7, i.e. spec-
trum analyzer or test receiver, the follow-
ing detectors are available:
◆ Analyzer mode: MaxPeak, MinPeak,
AutoPeak, Sample, Quasi-Peak,
Average, CISPR Average, RMS,
RMS Average
◆ Receiver mode: MaxPeak, MinPeak,
Quasi-Peak, Average, CISPR Average,
RMS, RMS Average
Up to 3 detectors can be activated simul-
taneously and the results displayed.
The bargraph display, with current detec-
tor value and MaxHold display, clearly
shows the results of manual circuit
adjustment when the DUT cabling is
arranged for maximum emissions and
when the antenna is aligned relative to
the DUT for a maximum reading.
In the receiver mode, the QP detector is
coupled with the time constants, pre-
scribed by the standard, as a function of
the frequency range. This ensures that
the correct time constants and IF band-
width are used for signal weighting in the
CISPR bands. This means much greater
ease of operation for the user.