Gigahertz Solutions HFW59D Manual page 27

approximation 9 . In practice, different radio services often occur in par-
allel. The audio analysis allows an estimation which part of the dis-
played total signal is due to such "crest signals".
Depending on the proportion to the total signal, please apply the fol-
lowing "rules of thumb" for corrections:
o Slightly audible portion of "high crest factor signals":
multiply display reading by 2
o ~"Fifty-fifty"-ratio:
multiply display reading by 5
o Dominating "high crest factor signals":
multiply display reading by 10.
This adjusted measurement value can now be recorded or compared
directly to the building biology recommendations. Taking into account
the multiple external factors of measurement uncertainty, this ap-
proach is perfectly adequate for an assessment of the total pollution.
The use of a frequency filter and service specific correction factors will
allow an increased accuracy.
Please note: In the combination of the settings "VBW Maximum",
"Range: min" and "Peak hold" the the background noise level can sum
up to a value of 1.00 or more on the display
levels you can use the preamplifier HV10.
For obvious reasons the use of a correction factor only makes sense
for readings above the noise level!
Radar
For air and sea navigation, a radar antenna slowly rotates around its
own axis, thereby emitting a tightly bundled "radar ray". This ray can
only be detected every couple of seconds, for a few milliseconds. This
requires special measurement technology.
We recommend the following procedure for the acoustic identification
of a radar signal (a short "beep" which may only recur every 12s):
Switch meter settings to "VBW Maximum" and "Peak hold" and take
several measurements of the radar signal from varying measurement
points in order to be able to identify the main direction of emission and
to record the quantitatively correct measurement value.
If the location of the radar base is not known, the quasi isotropic UBB
antenna is particularly useful, as the exact location of the source of
radiation is very difficult due to the long breaks between the individual
radar pulses.
9
Although the standards of these radio services allow even higher crest factors, the
industry aims to minimize them for cost reasons, so that the resulting correction fac-
tors do not exceed ten.
10
For TETRA a factor of 2, and for WLAN ("standby-rattling") a factor of 4 will be
enough.
11 Inherent to the system: The higher the video bandwidth, the higher the displayed
noise level.
© Gigahertz Solutions GmbH
10
. In order to reach lower
11
M a d e in G e r m a n y
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