EMFields AM-10 Manuale utente

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/m2

for continuous wave signals ......................................... 12

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

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

professional instruments.

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.

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 heatand 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 frequency response using the internal antenna:

200 MHz – 8000 MHz ±3dB; 150-200 MHzand 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

demodulation may be heardat RF levelsbelow 0.02 V/m

LED Scale Points: (peak LEDs updated 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 samples measured everyc. 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

µW/m2

Power Draw: 105 mA at 3 volts (2x AA Alkaline or Rechargeable cells @ 1.2 - 1.5V)

Battery Life: Up to 20 hours. ‘Low battery’ detection is indicated.

Typically 15 hours on two new 1500 mAhr AA alkaline cells and

Typically 25 hours on two charged 2700 mAhr NIMH rechargeable cells

Size: 190mm x 102mm x 33mm (LxWxD)

Weight: 280g, excluding batteries

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

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 after a 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 (usually somewhere about mid-

volume is best; only use maximum whenmonitoring 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 facing you atan 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 anynoise 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.

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 & 3G/UMTS), WiFi, Cordless phones

(DECT), Digital TV & Digital (DAB) Radio. Many modern digital systems

(such as GSM, DECT and WiFi) turn the signal on and off at high speeds to

represent data, often with long gaps between data bursts. This produces a

non-continuous signal, which we describe as “pulsing”. It is these

amplitude changes that the Acoustimeter allowsyou 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 inthe diagrams below.

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 averaged power 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, signals in a meaningful manner. Signal

strength is measured in volts per metre (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 theseare

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

report experiencing some adverse health effects, sothese are red.

The average power density scale LEDs areall orange in colour.

1 W/m2= 1,000,000 µW/m2= 100 µW/cm2=0.1 mW/cm2

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 comparison to the average power scale.

The LED scales are shown on the next page.

Troubleshooting

Problem Possible Solutions

The instrumentis not

showing any reading

The Acoustimeter doesn’t

seem to be working

Check that the power switch is in the“on” position

Check that the batteries are correctly inserted into

the instrument.

The batteries may be flat. Try changing them.

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

and working.

The instrumentis not

picking up signals very well Make sureyour fingers are not covering thearea

where the internal aerial islocated (seediagram).

Rotate theinstrument in all directions. The aerial

will pick up signals bestwhenitis mostaligned

with them. This is usually between horizontal and

vertical, but can be inany position.

When aligned with the signals, the instrument will pick

up and indicatelevelsof 0.02V/m or above.

The instrumentisgiving

varying readings Makesureyour 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 thesevariations.

Make sure you hold the instrument still, or place it

on something to hold it steady. Fieldlevels canvary

substantially even over small distances.

Regular high“blips” every few seconds may be due

to a rotating radar transmitter or a WiFi signal

The instrumentisgiving

readings that surpriseme.

Are they correct?

Our extensive tests have shown that the

Acoustimeter readings give a good indication of the

microwave levels being measured.

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 pounds have 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 whatisbeing measured.

Problem Possible Solutions

It still makes a noisewhen

inside a headnet/behind

my screening

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

microwave signals.

Your screening material may have deteriorated over

time.

The levels are very low, but

I can just hear a slow,

regular, ticking (a bit like a

very faint heartbeat)

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 signals are present.

The peak signal is high, but

the average signal islow. This is normal and to be expected from modern

digital microwave frequency signals.

The instrumentis on, but

the LCD screenis blank or

shows a row of black

squares

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.

The instrumentmakes

three loud beeps from time

to time

This is an indication that the batteries need

replacing. Check for a “Low battery” screen message

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 such as from dropping it.

It has a degree of overload protection built-in, but it should not be used next to

high-powered RF transmitters that are likely to grossly overload it. Approach these

with caution and watch thedisplays toavoid gross overload.

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