Audio Frequency Analysis - Gigahertz Solutions HF W 35C Instruction Manual

Digital High Frequency Analyser HF W 35C
- The limit should be applicable to the maxi-
mum possible emission of the transmitting
stations. As the emission measured de-
pends on the constantly varying actual
load, this restricts the normal exposure
much further.
- A single station should not contribute more
than one third to this total.
- The extensive experience and findings of
medical and building biology specialists
could not be considered for the proposed
limits, as their results are not sufficiently
documented. The authors state, that "sci-
entific scrutiny of their recommendations is
needed urgently".
- Not all effects on and in cells found in their
research could be considered for the pro-
posed limits, as their damaging potential
could not be established with sufficient cer-
tainty.
In summary it confirms the justification of
precautionary limits well below the pre-
sent legal limits.
© Gigahertz Solutions GmbH, 90579 Langenzenn, Germany

Audio Frequency Analysis

Many different frequencies within the fre-
quency band between 2.4 and 6 GHz, are
being used by many different services. The
audio analysis of the modulated portion of
the HF signal, help to identify the source of
a given HF radiation signal.
How to proceed:
Set the On/OFF switch at .
For audio analysis, simply turn the volume
knob of the speaker at the top of the case all
the way to the left ("-"). If you are switching
to audio analysis while high field strength
levels prevail, high volumes can be generated
quite suddenly. The knob is not fastened with
glue to prevent over winding. However, if by
accident you should turn the knob too far,
simply turn it back again. No damage will be
caused.
Sounds and signals are very difficult to de-
scribe in writing. The best way to learn the
signals is to approach known HF sources
very closely and listen to their specific signal
patterns. Without detailed knowledge, the
characteristic signal patterns of the follow-
ing HF sources can be easily identified: 2.4-
GHz telephones (base station and handset)
as well as cellular phones, the signal patterns
of which can be divided into "a live con-
nected phone call", "stand-by mode" and
especially the "establishing of a connection".
The typical signal patterns of a cellular phone
base station can also be identified this way.
For comparison reasons you are well advised
to take measurements during high-traffic
times, as well as some times during the
night, in order to familiarize yourself with the
different noises.
Revision 4.7 (October 2007)
The volume can be controlled with the "vol-
ume" (speaker) knob. Note: The power con-
sumption of the speaker is directly propor-
tional to the volume.
On our home page (www.gigahertz-
solutions.de) there is a link to some typical
samples of audio analyses as MP3-files.
Marking of unpulsed signals
Un-pulsed signals (more precisely: not ampli-
tude-modulated signals) by their very nature
are not audible in the audio analysis and
therefore easily missed. For that reason they
are marked by a uniform "rattling" tone, with
its volume proportional to its contents of the
total signal. This "marking" has a frequency
of 16 Hz, and an audio sample can also be
downloaded as a MP3 file from our website.
If pre-amplifiers are applied with this device,
the setting of the signal switch must be
"Pulse", as the "marking" feature will "inter-
pret" the white noise as an unpulsed signal
and thus be heard all the time. All relevant
field sources in this range are pulsed anyway
so there is no problem related to switch to
"Pulse".
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