Atec Agilent-8568b-8566b - Manual (Page 2)

2
EMI Testing According
to CSPR Publication 16
Recommendations
Combining the 85685A RF preselector
with the 8566B or 8568B spectrum ana-
lyzer and the 85650A quasi-peak adapter
produces an EMI receiver with the char-
acteristics recommended in CISPR pub-
lication 161. The RF preselector provides
the measurement sensitivity and over-
load protection needed for FCC and VDE
radiated emission testing at open sites.
For commercial and MIL-STD conducted
EMI tests, the low-frequency input toler-
ates large impulses and line impedance
stabilization network (LISN) transients. A
built-in calibrator ensures ±2.0 dB abso-
lute-amplitude accuracy as required by
the FCC and VDE. For measurement con-
fidence, a linearity check tests for system
overload and distortion.
The sample display shows results for
VDE 0871 emission testing at an open
site. To prevent overload from the high-
level ambient signals, a spectrum analyz-
er needs input attenuation. This however,
increases displayed noise, which can
mask the low-level emissions. Using the
RF preselector in this test eliminates the
need for adding attenuation. The noise
of the spectrum analyzer, as shown,
exceeds the VDE limit, but the spectrum
analyzer/test receiver noise is more than
10 dB below the lowest limit.
1. Comite International Special Des Perturbations
Radio-Electriques (CISPR) publication 16 is the
"CISPR specification for radio interference measur-
ing apparatus and measurement methods."
Signal Monitoring in the
Presence of High-Level
Interference
The RF preselector gives the 8566B
or the 8568B spectrum analyzer the
sensitivity and selectivity of a receiver.
The spectrum analyzer/test receiver
measures signals within the preselec-
tor filter passband and rejects out-
of-band interference by 40 dB. Even
in the presence of interference with
a total input power of +10 dBm, your
test receiver can monitor signals down
to -150 dBm.
The RF preselector improves signal
reception for the broadband signal
environment of a mobile test station.
In the 150 – 170 MHz business band,
the RF preselector reduces interfer-
ence from radio and TV broadcast
stations and from amateur radios. For
the 800 – 900 MHz cellular radio band,
the spectrum analyzer/test receiver
makes field strength measurements
on cellular base-station transmitters
while rejecting interference from cel-
lular mobile transmitters.
Transmitter Spurious
Testing with Fast Wideband
Measurements
Reduce transmitter-spurious test time
by adding the RF preselector to your
8566B or 8568B spectrum analyzer. The
preselector decreases input overload
from the out-of-band carrier and thereby
increases the range for measuring low-
level signals. Compared to the spectrum
analyzer alone, the spectrum analyzer/
test receiver uses a wider resolution
bandwidth for the same measurement
range, resulting in a faster sweep time.
For example, to measure spurious sig-
nals over a 1 GHz frequency range at
–100 dB relative to the transmitter car-
rier, a spectrum analyzer by itself takes
3000 seconds, but when configured as a
test receiver it requires only 3 seconds.