EMFields AM-10 User Manual

Acoustimeter User Manual

Table of Contents

Introduction.............................................................................. 2

Safety Instructions ................................................................. 3

Specifications .......................................................................... 3

Instrument guide..................................................................... 4

Operation ................................................................................. 5

Peak & Average -what are the differences ...................... 6-7

Peak & Average LED guide ................................................. 8

Troubleshooting ..................................................................... 9-10

Guarantee ................................................................................ 10

Appendix A: Some international guideline levels .......... 11

Appendix B: Conversion table between V/m and µW/m

for c ontinuous wave signals ......................................... 12

Disposal & Disclaimer ......................................................... 12

2

Introduction

The Acoustimeter has been designed to enable you to make a quick and
informed judgement regarding the level and nature of microwave signals

in your environment. It is a broadband instrument that accurately
measures the totality of the radiation in the range 200 MHz to over 8000

MHz (8 GHz), which covers the frequencies used by most modern
communication systems encountered in our everyday environment. The
Acoustimeter was designed using the experience gained from many years

of practical RF and microwave measurements using a wide variety of
professionalinstruments.

Readings are shown on both an LCD display and two series of graduated
LED lights. The LEDs update rapidly, and allow you to quickly gauge the

levels in an area and find any hot-spots. The Acoustimeter also has a
loudspeaker (and audio output socket for headphones or an audio

recorder), allowing you to determine, with a small amount of practice,
what type of device is creating the signals. Sound samples are available

on http://www.emfields.org/detectors/acoustimeter.asp to help you
identify different signals.

2

Safety instructions

Please read through these instructions carefully before operating the
instrument. It contains important information regarding usage, safety and
maintenance.

The instrument is not waterproof and should not come into direct contact
with water, nor should it be used outdoors in the rain. If it is raining and

you want to take measurements outside, please cover the instrument in a
plastic bag that does not have holes in it. Clean the case using a damp

cloth,and do not use detergents.
This instrument is sensitive to heat and impact. Exposing the instrument to

high temperatures or dropping the instrument may cause it to stop
functioning properly. It may not display properly below freezing (0°C).

This instrument is not intended to be serviced by the user and it needs no
special maintenance from the user. Unscrewing the case will void the

guarantee.

Specifications

Typical overall frequencyresponseusing the internal antenna:
200 MHz –8000 MHz ±3dB; 150-200 MHz and 8000-10000 MHz ± 6dB

Measurement sensitivity:0.02 to 6.00 volts per metre [ V/m ]
1 to 100 000 microwatts per square metre [ µW/m2]

The detector can respond tolevels below 0.02 V/m - audio from signal
demodulationmay be heard at RF levels below 0.02 V/m

LED Scale Points: (peak LEDsupdated approximatelyevery 0.1 seconds)
Peak: 0.02,0.03,0.05, 0.07, 0.1, 0.2,0.3,0.5,0.7,1, 1.5,2, 3, 4.5, 6 V/m

Average: (calculated as the average 1024 samplesmeasuredeveryc. 0.35 seconds)
1, 5, 10, 25, 50, 100, 250, 500, 1 000, 2 500, 5 000, 10 000, 25 000,50 000,100 000

2

µW/m
Power Draw: 105 mA at 3 volts (2 x AA AlkalineorRechargeable cells @ 1.2 - 1.5V)
BatteryLife: Up to 20 hours. ‘Lowbattery’ detectionisindicated.
Typically15 hourson two new 1500 mAhrAAalkaline cells and

Typically25 hoursontwocharged 2700mAhr NIMH rechargeable cells
Size:190mm x 102mmx33mm (LxWxD)
Weight: 280g, excludingbatteries

3

Instrument guide

Key

1. Display 4. Audio, mono2.5mm 7. Internal antenna

2. Peak signal LEDs 5. Volume control 8. Loudspeaker

3. Average power LEDs 6. On - Off switch 9. Battery compartment

4

Operation

Ensure that you have correctly inserted appropriate batteries (2 x AA
cells). Move the power switch into the “On” position. The LCD display
should briefly display “Acoustimeter, © EMFields 2009”, changing to

readings aftera short time.
Hold the bottom of the instrument in one hand at least 30cm from your

body as close proximity to your body will affect the readings. Keep your
hands away from the top of the instrument as this contains the antenna

which is located inside the case at the rear towards the top. The
Acoustimeter can be placed upon a stable surface, but movements nearby
can still affect the RF/microwave levels.

Adjust the volume to an appropriate level (usuallysomewhere about mid­volume is best; only use maximum when monitoring weak signals).

The instrument will display the peak signal strength and the average
power on both the LEDs and the LCD. Slowly turn the instrument around
in all directions. Stop moving the instrument and hold it still to take a

reading.
Bear in mind that even moving the meter small distances can result in

detecting very different levels of microwave energy. Microwaves are
reflected off the ground and other surfaces so it is important to check all
angles. The highest readings will often be found when holding the

instrument facingyou at an angle between horizontal and vertical.
We recommend taking the highest reading found in any one spot,as this is

when the antenna is most closely aligned with the directionality of the
signal. The “Peak-hold” function will display the highest peak reading

measured until the instrument is turned off and on again.
If there is hardly any noise with the volume turned up then the instrument

is not detecting any amplitude modulated (i.e. “pulsing”) signals. Other
sounds represent the amplitude modulation and digital pulsing of RF

signals detected by the instrument. It is sometimes possible to hear voices
and music when very close to powerful medium and short-wave AM
transmitters, which are outside of the normal RF frequency detection

range of the meter. When no LEDs are illuminated any quiet ticking
sounds heard should be ignored.

5

Why are there two different readings?

The Acoustimeter is unique in the way it displays information about its
measurements. There are two different displayed results showing both
Peak and Average measurements. At first, this may seem confusing. We
believe that it is important to know both when assessing your exposure to

modern telecommunication signals.

Digital and Analogue: What is the difference?

Many modern wireless devices use a digital system of communicating.
This includes Mobile Phones (GSM & 3 G/UMTS), WiFi, Cordless phones
(DECT), Digital TV & Digital (DAB) Radio. Many modern digital systems

(such as GSM, DECT and WiFi) turnthe signal on and off at high speedsto
represent data, often w ith long gaps between data bursts. This produces a
non-continuous signal, which we describe as “pulsing”. It is these

amplitude changes that the Acoustimeter allows you to hear.
An analogue signal is a system of communication that is not digital. The

old TV system, most radios, walkie-talkies and hearing aids are examples
of analogue signals. They use a continuous carrier, and instead of turning

“on and off” to represent data, will vary the frequency (FM) or strength
(AM). Analogue TV & VHF FM Radio stations are being phased out over

time.

Typical differences between Peak and Average

With an analogue system, the peak and average levels should be similar,
as the signal is continuously on while it is being used. However, because
most digital systems spend a large proportion of their time not

transmitting, the average level does not represent the actual waveform
even though it is technically accurate as shown in the diagrams below.

6

Why does this matter?

Since wireless communications were first developed on a large scale, the
scientific community held the opinion that “if it does not heat you it will not
hurt you”, as 30 years ago these were the only effects that were

acknowledged... The obvious thing to measure was the average heating
effect. The metric typically used now for measuring the averagedpower of
microwave frequency EMFs is microwatts of power arriving per square

metre (µW/m2), and we have used this for the Acoustimeter’s average
power measurement.

There have now been hundreds of studies finding non-thermal effects
from modern wireless communication signals, which means that the
measurement system needs to be re-addressed to suit much lower signal

levels and very different characteristics. We believe that peak signal
strength is the most appropriate way to measure complex digitally

modulated, often non-continuous, signa ls in a meaningful manner. Signal
strength is m easured in volts per m etre (V/m). Many electrosensitive

individuals report adverse health effects in areas that have quite high peak
levels but have average field strengths below the more precautionary

average power guidelines.
You can mathematically convert between V/m and µW/m2, but this is

only accurate if you have a continuous waveform (CW) carrier signal. See
Appendix C for further details.

What do the different LED colours mean?

Our peak signal strength scale is based on personal experience of what
electrosensitive individuals have reported as adversely affecting their

health.
Below 0.05 volts per metre(V/m),few people report ill-effects, so these are

green. Between 0.05 and 0.5 V/m, some individuals report ill-effects, so
these are yellow. Above 0.5 V/m, nearly all electrosensitive individuals

reportexperiencing some adverse health effects, so these are red.
The average power density scaleLEDs are all orange in colour.

1 W/m2= 1,000,000 µW/m2= 100 µW/cm2=0.1 mW/cm
The LED points on each of the scales approximately match for continuous

wave (CW) signals. The more pulsatile the signal is the higher the peak
scale will read in comparisontotheaverage power scale.

The LED scales are shown onthe next page.

7

2

8

Troubleshooting

Problem Possible Solutions

The instrumentis not
showing anyreading

The Acoustimeterdoesn’t
seem to be working

The instrumentis not
picking up signalsvery well

The instrumentisgiving
varying readings

Check that the power switchisin the “on” position
Check that the batteries are correctly inserted into

the instrument.
The batteriesmay be flat.Trychanging them.

If the LCD is displaying a reading, then it is turned on
and working.

Make sureyour fingers are not coveringthearea
where the internal aerial is located (seediagram).

Rotate the instrumentin all directions. The aerial
will pick up signalsbestwhenit is mostaligned
with them.Thisis usuallybetweenhorizontal and
vertical,butcanbeinany position.

When aligned with the signals,the instrument will pick

up and indicatelevels of 0.02 V/m orabove.

Make sureyour fingers are clear of the aerial.
Digital signals pulse,which means that peak signals

are not consistent. The instrument is very sensitive
and picks up these variations.
Make sure you hold the instrument still, or place it
on something to hold it steady. Fieldlevels can vary

substantially even over small distances.
Regular high “blips” every few seconds may be due
to a rotating radar transmitter ora WiFi signal

The instrumentisgiving
readings that surprise me.

Are they correct?

Our extensive tests have shown that the
Acoustimeterreadingsgive a good indicationofthe

microwavelevelsbeingmeasured.
The Specifications are given on page 3. Receiving

and measuring pulsing RF signals over a wide
frequency range is extremely difficult to do. Even
professional instruments costing many thousands
of poundshave quite large error margins. How you

should add all the various frequencies and
waveforms is a large debate on its own. Different
meters may well give different readings depending
on what is being measured.

9

Problem Possible Solutions

It still makes a noise when
inside a headnet/behind
my screening

The levels areverylow,but
I can just hear a slow,
regular, ticking (a bi t like a
very faint heartbeat)

The peak signal is high, but
the average signal is low.

The instrumentis on, but
the LCD screenis blank or
shows a row of black
squares

The audio produced by the Acoustimeter is
logarithmic in volume, so even quiet signals can
seem quite loud. Check the figures that the

Acoustimeter is displaying for an accurate measure
of how effective your screening is. Close to
transmitting sources it is likely that you will still
hear something.

You may have a gap in your screening. Even small
gaps (including above and below you) will let in

microwavesignals.
Your screening material may have deteriorated over

time.

This is the instrument picking up the noise of its
own internal meter circuitry and not external
microwave signals. This will only happen if the
external field levels are well below 0.02 V/m.. The
displays will not show that any signalsarepresent.

This is normal and to be expected from modern
digital microwave frequencysignals.

The instrument is stuck because it was turned off
then on too quickly. Make sure that you leave 1
second between turning it off and turning it on
again.

Theinstrumentmakes
three loud beeps from time
to time

This is an indication that the batteries need
replacing. Check for a “Lowbattery” screenmessage
next the time it beeps.

Guarantee

The Acoustimeter comes with a 2 year return-to-base Manufacturer’s Guarantee.
Please contact us (see page 12) for details and to arrange a return if required. It is
guaranteed to be free of manufacturing defects, but not against wear from normal
use, nor damage caused by water or by physical impacts suchas from dropping it.
It has a degree of overload protection built-in, but it should not be used next to
high-poweredRF transmitters that are likely to grosslyoverload it. Approach these

with cautionandwatchthedisplays to avoidgrossoverload.

10

Appendix A : a comparison of some international guidance levels

General Public Levels

ICNIRP, 1998

(recognised by WHO, EU & UK )

Frequency

MHz

400

900
1800
2100

Russia 2003(general publi c), PRChina 300-300000 6 0.1 100000

Italy, Decree381 (1999) 30 - 30000 6 0.1 100000
Swiss OrdinanceORNI, rms values ,

(forbasestations) 1st.Feb.2000
EU & UK EMC Regulations

suscept testlevel (domestic& comm.)

Belgium -Wallonia

900
1800

30-2000 3

900, 1800,2100

E field

V/m

28
41
58
61

any signal

Power

2

W/m

2

4.5
9

10

4
6

not

specified

not

specified

3 0.024 24 000

Power

µW/m

2000 000
4500 000
9000 000

10000000

not

specified

not

specified

2

Typicalmaxin public areas near base
stationmasts (can be higher)

USA CityDweller max (FCC 1999)

900 & 1800

Aprx.30 - 300000

2 0.01 10 000

< 2

< 0.01

< 10 000
Wien (Vienna) Sum of GSM 1.9 0.01 10 000
Italy (2003) each base station (aim);

Lichtenstein lawfrom2013

900, 1800,2100

0.6 0.001 1000

Salzburg -1998&2000 Sum of GSM 0.6 0.001 1000
BioInitiative,2007 30- 300000 0.6 0.001 1000
EU-Parliament,GD Wissenschaft,

STOA GSM (2001)
TypicalUS(EPA1980, mainly FM& TV)

Salzburg -2002,outsidehouses aim

BioInitiative, 2012 (guidance)

Salzburg -2002,inside houses
Bürgerforum-BRD 1999

Mobile phones willworkatlevels 900 -2100 0.00001
Broadband ‘natural’ background 300 -3000

900, 1800,

2100

Aprx.30 - 300000

GSM UMTS 3G

< 0.13

30- 300000 0.03

GSM UMTS 3G

GSM UMTS 3G

< 0.00003 < 1 e-13 <0.0000001

0.2 0.0001 100

0.06

0.02

0.02

< 0.00005

0.00001

0.000005

0.000001

0.000001
< 3 e-11 < 0.00003

< 50

10

5
1
1

11

Appendix B

Conversion between V/m and µW/m2for continuous wave (CW) signals

There is an approximate equivalence between the columns of LEDs for
CW signals. It is not possible to calculate the average power in a digitally

modulated communication signal without detailed analysis of the signal
waveform. This is what the Acoustimeter does for you and it presents the

result on the average power LED and LCD displays.

The EMFields websitehas a calculator for CW signals:

http://www.emfields.org/detectors/acoustimeter.asp

A pulsed digital signal strength in V/m will often be significantly higher
than the listed equivalent CW average power µW/m2. This is due to the

waveform of the signal.

European Approvals: CE, ROHSand WEEE

The Acoustimeter meets EN61000-6-3:2001+A11:2004 & EN61000-6-1:2001
Electromagnetic compatibility (EMC) standards and also meets the ROHS
(2002/95/EC)and WEEE (2002/96/EC) requirements.

The Waste Electrical and Electronic Equipment (WEEE) Directive requires that

unwanted electronic equipment must be disposed of using specialist recycling.
Your Acoustimeter canbereturned to us for recycling.
UK local waste recycling centres also providefree collection points for WEEE.

Disclaimer

While EMFields considers that the information and opinions given here are
sound, you must rely upon your own skill and judgement when interpreting or

making use of theinformation contained in this manual. [v4.1 2013-04-02 ]

http://www.emfields.org

EMFields,2 Tower Road, Sutton, Ely, Cambs, CB6 2QA, UK

Tel:(+44) (0)1353 778814 Email: [email protected]