User manual
8
Subject to change without notice
Does a spectrum analyzer’s response
to pulsed interference inuence the
measurement result?
CISPR 16 contains a curve that denes how quasi-
peak detectors respond to a pulsed signal. The
curve is based upon the signal’s pulse repetition
frequency (PRF). For a 0MHz to 1000MHz radiated
emissions measurement, the measured value of
the input signal can potentially be reduced by a -
gure up to about 0dB. This number is also known
as the overload factor. The design of a compliance
receiver ensures this response. However, pulsed
signals can overload a spectrum analyzer’s input
circuitry, particularly on signals with a very low
PRF. In practice, few signals have such a low PRF
and therefore errors occur infrequently.
What are the results if I surround
the entire equipment under test in a
shielded housing?
This question is often asked if a CE-Mark EMC test
is failed. Unfortunately, this question can not be
answered in general because a metallic housing
is not always a good shield. No one wants to wait
until the next full-scale EMC test for the results.
What if the EUT fails again? What is needed is a
simple measurement procedure to determine the
relative improvement of the radiated RFI. For this
purpose the highly sensitive E-Field probe is used,
which is used as broad bandwidth measurement
antenna to help answer the above questions.
Does the E-Field-Monopole of the
HZ540/550 have sufcient sensitivity for
pre-compliance testing?
First, before the E-eld probe is used, determi-
nation must be made if the probe has sufcient
sensitivity and bandwidth. In general, all passive
probes are not usable since they have insufcient
sensitivity. The E-Field-Monopole is sensitive
enough to be used as an antenna for radio or TV
reception. With this probe the entire radiation
from a circuit or an equipment can be measured
Co m m o nly a s ked Q u est i o n s