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It is generally accepted to use the highest reading in the room for comparison with limit or recommended values.
To be on the safe side in this comparison you may multiply the measurement by 4 and use the result as base value for the comparison. This is often done to make safe recommendations even in case of readings on the low side despite still being within the tolerance band. One has to consider, however, that this may also lead to higher values than actually existent.
Special case: Radar for aviation and navigation. Radar beams are emitted by slowly rotating antennas. Therefore they are only measurable and “audio-analysed” every few seconds for milliseconds. This necessitates a special approach:
Set ”Signal“ to ”peak“. After a couple of radar beam passes read out the highest number displayed. Because of the slow repetition rate of the display necessary for all other measurements, the numbers will vary considerably and will only be displayed for a very short period of time.
In most cases the measurement will be at the lower tolerance band or in the extreme case even up to a factor of 10 too low.
Limiting values, recommendations and precautions
The ”Standard der baubiologischen Messtechnik“ (Standard for
Building Biology Measurements), SBM 2008, classifies measurements (per radio communication service), with a note of caution
”pulsed signals to be taken more seriously than continuous ones“, as follows:
Building Biology Recommendations as per SBM-2015
Peak measurements
µW/m²
un-
conspicuous
< 0.1
moderately
conspicuous
0.1 - 10
very
conspicuous
10 - 1000
extremely
conspicuous
> 1000
© Baubiologie Maes / IBN
In fall 2008 the "Bund für Umwelt und Naturschutz Deutschland e.V." ( BUND) (environmental NGO) recommended a limiting value of 1 µW/m² even for outdoor situations.
The Landessanitätsdirektion Salzburg (Austrian health authority) proposed already in 2002 to lower the present
”Salzburger
Vorsorgewert“ (precautionary value) to 1 µW/m² for indoor situ-
ations.
Limiting values imposed by governments are mostly considerably higher. There are indications of rethinking, though. The Internet provides large collections of recommendations and data.
Identification of the sources of pollution
After determination of the total exposure the next step is to find out where the radiation enters the examined room. As a first step eliminate sources from within the same room (e.g. wireless rout-
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Made in Germany ers, etc.) Once this is completed, the remaining radiation will originate from outside. For remedial shielding it is important to identify those areas of all walls (including doors, windows and window frames!), of ceiling and floor, which are penetrated by the radiation. To do this one should not stand in the centre of the room, measuring in all directions from there, but monitor the permeable areas with the antenna (LogPer) directed and positioned close to
the wall/ceiling/floor 4 . The reason for this is that the antenna lobe
widens with increasing frequency. In addition reflections and cancellations inside rooms make it impossible to locate the “leaks” accurately. See the illustrating sketch below!
Wand
Wall
Mur
Pared
no!
Potentiell durchlässiger Bereich
Potentially permeable Area potentiell durchlässiger
Bereich antenna antenna
For the definition and installation of shielding measures as well as surveying their effect, professional advice is recommendable. Anyway, the area covered by shielding material should be much larger than the leak itself.
Audio Frequency Analysis
Many different frequencies within the frequency band between 2. to 6.0 GHz, are being used by many different services. The audio analysis of the modulated portion of the HF signal helps to
identi-
fy the source of a given HF radiation signal.
Sounds and signals are very difficult to describe in writing. The best way to learn the signals is to approach known HF sources very closely and listen to their specific signal patterns.
On our home page you will find a link to some typical samples of audio analyses as MP3-files. Furthermore, the audio analysis can be significantly simplified by the filters we offer.
Permanently low display values?
Fortunately, exposures in the frequency range of the HFW35C are not yet widespread. Therefore, we have often been asked whether the device does in fact work, as it rarely ever shows any values. In the following please find answers to frequently asked questions:
“The HFW35C only indicates very low measuring values”
Answer:
Naturally, the radar and directional radio frequencies within the frequency range of the HFW35C will only be found regionally. At present, the components for the upper WLAN band (from 5 to 6
4
Please note: In this position the readings on the LCD only indicate relative highs and lows that cannot be interpreted in absolute terms.
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GHz) are still difficult to obtain, so you will only encounter selective exposures in this frequency range. The WiMAX network (from
3 to 5 GHz) is only active in some testing locations, its extension all over the country is, however, expected to be accomplished within the coming two years. Therefore, for the time being, the
HFW35C can be considered as a device enabling to exclude potential stronger exposures caused by these sources at the respective site. This already is an important information.
The presently most frequently measured appliances are Bluetooth appliances found at the lowest end of the involved frequency range… Questions related to this field:
“Even when transmitting data with my notebook, only low values are shown on the display”
Answer:
Thanks to the integrated transmitting power control, the notebook won’t draw more power than needed for its communication with the remote station. However, if you measure within splitting distance to a notebook just transmitting data wireless, you will obtain values, at least in the finer measuring range.
“No measurement values obtained, even directly next to my
WLAN/Bluetooth-compatible notebook…”
“…although the display indicates: ‘searching wireless connections’”
Answer:
While searching a network, the notebook is basically not transmitting itself, so obviously no measurements can be obtained.
“…although my notebook shows various networks with good
reception”
Answer:
A notebook has no problems with the reception, even if the signal strength is a factor 1000 or more below the lowest display value of the measuring device or below the building biology recommendations.
“In the finer measuring range, the HFW never shows values lower than 0.3 to 0.5 µW/m² (with or without antenna)”
Answer:
This is the residual noise of the device. It would be easy to wire the display in such a way that it would approach zero as soon as only little values are shown, thus suggesting higher precision (paradoxically, the producer himself even recommends to do so!).
However, we do not consider this useful, and prefer to indicate the residual noise the way it is. Yet, if measurements without antenna reach values beyond 0.9 µW/m² within the fine measurement range (or 9 within the coarse measurement range), you should return the device for investigation, as this does no longer correspond to the specifications.
Simple testing method:
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Take measurements only few meters away from an active point of access (e.g. “DSL-WLAN-router). Its “heartbeat”, the well known
“tac-tac-tac…”, will be clearly audible, and the corresponding pulsed radiation measurable. If this works out, errors can be (almost) excluded, even for the highest frequency range. At least we have not yet had a frequency selected defect of this kind in all the years of producing HF devices.
THE solution: a pre-amplifier!
Based on the statements in the chapter “Limiting values, recommendations and precautions” about the extreme effects of WLAN signals on the human biology, an increased range appears to make sense. There is a pre-amplifier available for the amplification by a factor of 100 (HV20_2400G10). Please note:
Always meas-
ure in the “Pulse”-mode when applying the pre-amplilfier.
For more in-depth analyses
Gigahertz Solutions offers:
A Preamplifier (see above).
Attenuators for expanding the designed range of the analysers upwards for strong sources of pollution.
Instruments for other HF-ranges
Instruments for low frequencies: Electrosmog is not limited to the High (Radio) Frequency range! Also for the low frequency range such as power (distribution and domestic installations) and railways including their higher harmonics we offer a broad range of affordably priced instruments with high professional standards.
Please refer to our homepage for comprehensive coverage.
Power Supply
Changing the Battery
The battery compartment is at the back of the analyzer. To remove the lid, press on the grooved arrow and pull the cap off. The foam pad inserted pushes the battery against the lid preventing the heavy battery from rattling. This is the reason for the lid’s resistance during opening.
Auto-Power-Off:
This feature conserves energy and extends the operating time.
1. In case you have forgotten to turn OFF the HF analyzer or it has been turned ON accidentally during transport, it will shut off automatically after 40 minutes of continuous use.
2. If “LOW BATT” appears vertically between the digits in the centre of the display, the HF analyzer will turn OFF after 2 to 3 min in order to avoid unreliable measurements. It reminds you to change the battery as soon as possible.
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Shielding done by an expert is a dependable remedy
The effectiveness of shielding done by an experienced craftsman can be verified by measurement. He has quite a number of options at his disposal. There is no “best method”, however, befitting for all problems – shielding always has to be adapted to the specific situation.
Shielding, too, is covered comprehensively on our homepage which also contains further links on this issue
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© Gigahertz Solutions GmbH
Made in Germany
© Gigahertz Solutions GmbH
Made in Germany
Hersteller / Manufacturer:
Gigahertz Solutions GmbH
Am Galgenberg 12
90579 Langenzenn
Germany
Tel : +49 (9101) 9093-0
Fax : +49 (9101) 9093-23 www.gigahertz-solutions.de
Ihr Partner vor Ort / Your local partner :
DRU00192
© Gigahertz Solutions GmbH, D-90579 Langenzenn