Gigahertz Solutions HF59B Instruction Manual page 9

Digital High Frequency Analyser HF59B
minutes to run out of tolerance, but in order
to get an accurate reading the display should
be checked frequently. If very short signal
peaks occur then the holding capacity of the
function needs some recurrences to load
fully.
Setting:
LF-Processing - Video Bandwidth
The video bandwidth defines the minimum
duration of short pulses that still can be
measured by the meter without being dis-
torted.
For measurement of exceptionally short
pulses (e.g. Radar) or specific signals like
UMTS/3G an extremely high video band-
width is needed for accurate readings. The
HF59B allows for 2 MHz video bandwidth, an
unparalleled high value which guarantees the
best accuracy available on this sector.
Use the setting "TPmax" only for measur-
ing radar and UMTS/3G signals, as along
with the high video bandwidth comes a
higher noise level as illustrated in the picture
below.
low Noise
Video-
UMTS (3G) and
"low" "high"
(e.g. 30 kHz) (e.g. 2 MHz)
Radar readings
bandwidth
displayed too small
The standard setting therefore is "TP30kHz".
Only if a Radar signal or UMTS (G3) signal is
detected, by means of the audio analysis,
the "Tpmax" setting is used.
Some technical background
The circuits processing the incoming high
frequencies are only a small fraction of the
total circuitry. Their output is a signal propor-
© Gigahertz Solutions GmbH, 90579 Langenzenn, Germany
tionate to the power density in the frequency
of the modulations or the pulses of the in-
coming HF signal, i.e. an LF signal in the
broadest sense.
The video bandwidth is important for the po-
tential as well as the limitations of an instru-
ment. Your HF analyzer allows you to select
between two settings of bandwidth, depend-
ing on the objective of the measurement:
- TPmax (Radar): With this setting the full 2
MHz bandwidth is at your disposal. Select
this when you have identified Radar or a
UMTS/3G signal by audio analysis. Please
note that with this setting not only the
UMTS/3G and the Radar signals are
measured, also any signals from other
sources in this frequency range. With this
setting TPmax and the range selector
"fine" the noise can be up to a value be-
tween 30 and 120 digits. The tolerance
level of bandwidth and associated noise is
wide, but the bandwidth is beyond 2 MHz
minimum. A high noise level indicates an
even higher bandwidth of the instrument
Please note: In view of the unavoidable
higher noise associated with the high video
bandwidth one should not use TPmax as
higher noise
standard setting.
ideal for Radar
- TP30kHz (Standard): This should be the
and UMTS (3G)
standard default setting for general pur-
pose use of the instrument. The video
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When the setting "Tpmax" and "Peak Hold – slow" is
chosen the reading on the display will at first rise for a
few second or even minutes, as also minute stochastic
peaks will be picked up and retained, which in normal
processing would be just "averaged out". After some
time some slightly varying state of equilibrium will be
established.
Revision 4.5 (December 2006)
bandwidth is about 30 kHz, which will rep-
resent the shortest continuously pulsed
signals (e.g. DECT) without distortion. At
the same time, even with the range switch
on "Fine" the noise is significantly less than
with TPmax.
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