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EMFields AM-11, Руководство пользователя

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20 

Digital and Analogue signals 

Most modern wireless devices, such as mobile 

phones, Wi-Fi devices and cordless phones, use a 

digital system of communicating. 

This means they turn the signal on and off at high 

speeds to represent data, often with wide gaps 

between data bursts. This produces a non-

continuous signal, which we describe as ‘pulsing’. 

This means that when taking measurements in most 

environments, you are likely to find that the left 

peak (V/m) LEDs are higher up the scale than the 

right PFD (µW/m

2

) LEDs.  

A simple digital signal 

 

The pulsing is almost always faster and more 

complex than shown in the diagram, but the 

principle is similar. 

Содержание AM-11

Страница 1: ...add front high res photo here Acoustimeter User Manual ...

Страница 2: ... a hard surface may cause it to stop functioning properly The meter is sensitive and is intended to measure typical modern environmental exposures Do not take it close to high power radiofrequency transmitters or put it inside a microwave oven Clean the case using a damp cloth if necessary and do not use chemicals This instrument is not intended to be serviced by the user nor does it need any spec...

Страница 3: ... Setting up for first use 7 Taking measurements 7 Audio 9 EMFs What to measure 10 What are EMFs 10 Electromagnetic spectrum guide 11 Guidance levels 12 Various exposures and effects 14 Why are there two different readings 17 Digital and Analogue signals 20 Typical real life exposures 22 Troubleshooting 26 Warranty 28 ...

Страница 4: ... to 6 V m Updated 5 times per second Average readings 1 100 000 µW m2 LED Scale 15 levels from 1 to 100 000 µW m2 Updated 3 times per second Note 100 000 µW m2 equals 10 µW cm2 The audio can be heard at levels below 0 02 V m Power Current 100 to 150 mA at 3 volts 2xAA 1 5V Alkaline or NiMH 1 2V rechargeable cells Battery Life is typically 15 hours alkaline and up to 25 hours NiMH 2000 mAh cells Lo...

Страница 5: ...be exposed to This includes mobile phone networks 2G 3G 4G 5G local wireless networks such as WiFi 2 4 and 5 GHz digital cordless phones DECT and many other sources that will expose you to RF energy Readings are shown on both a 2 line OLED display and two series of graduated LED lights The LEDs update rapidly allowing you to quickly gauge the levels in an area and find any hot spots The Acoustimet...

Страница 6: ...er Key 1 OLED Display 2 Peak signal LEDs 3 Average power LEDs 4 Volume controls 5 levels lower higher 5 Clear peak hold button 6 Power button 7 Internal Antenna location 8 Loudspeaker 9 Battery compartment for 2x AA cells ...

Страница 7: ...h and the average power flux density PFD on both the LEDs and LCD We discuss what these mean in the Why are there two different readings part of the next EMFs what to measure section It is important to remember that RF EMFs create hot spots due to reflections so both the position and orientation of the instrument is very important Moving the instrument small distances can result in noticeable real...

Страница 8: ...e recommend taking the highest reading found in any one spot as this is when the antenna is optimally aligned with the incoming signals The Peak hold function will display the highest peak reading measured until the instrument is turned off and on again or until the CLEAR PEAK button is pressed When you have finished taking measurements press the POWER button again to turn the AM11 off The AM11 wi...

Страница 9: ...ever some sources are not amplitude modulated including analogue sources and these will not produce much sound even with the volume turned up We explain more about this in the Digital and Analogue signals section It is sometimes possible to hear voices and music when close to powerful broadcast AM radio transmitters These are outside of the normal RF frequency detection range of the meter but they...

Страница 10: ...level and health effects though there is a great deal of peer reviewed published evidence of real effects at both high and low exposure levels Further research into each part of the spectrum and different modulation types is still required It is almost certain that sensitivity to EMF exposure varies from person to person Some electric and magnetic fields are part of the natural environment that li...

Страница 11: ...11 Electromagnetic spectrum guide ...

Страница 12: ...countries have set more restrictive guidance for environmental exposures based on their interpretation of the published scientific evidence The most comprehensive current overview of the science came from an experienced group of 15 leading European health scientists and medics EUROPAEM 2016 They state these are for the prevention diagnosis and treatment of EMF related health problems and illnesses...

Страница 13: ...13 ...

Страница 14: ...studies the solid red part of the bar indicates exposure levels were statistically significant effects were found The cross hatched area is based on the assumption that these higher levels will continue to exhibit the effects but were not directly examined and tested as part of the research For further information about the interaction of EMF and RF with life people and animals a good source is th...

Страница 15: ...15 ...

Страница 16: ...n incredible amount over recent years and where most of the reported health related concerns exist Modern wireless communication frequencies in the range from about 100 MHz to over 10 GHz virtually did not exist on Earth just 100 years ago Our typical daily exposures are now 1 000 000 000 000 000 000 times greater than they were at these frequencies ...

Страница 17: ...tom line of the OLED display The traditional scientific viewpoint is that the only relevant measurement of high frequency RF fields is the total amount of absorbed energy from exposure which causes body tissue heating measured as PFD This is the basis of most official international guidelines and so most legal guidelines and limits are specified as a time averaged PFD limit However there is now a ...

Страница 18: ...ome just display the peak level directly converted and they give incorrectly high readings The direct conversion only works correctly for continuous non pulsing CW signals The Acoustimeter displays both the peak signal strength in V m as well as the power in µW m2 correctly integrated over some 25 000 readings every second The EMFields website has an RF unit converter for continuous RF CW signals ...

Страница 19: ...19 ...

Страница 20: ...present data often with wide gaps between data bursts This produces a non continuous signal which we describe as pulsing This means that when taking measurements in most environments you are likely to find that the left peak V m LEDs are higher up the scale than the right PFD µW m2 LEDs A simple digital signal The pulsing is almost always faster and more complex than shown in the diagram but the p...

Страница 21: ...ht to make it more bioactive and it also brings the PFD level more in line with the V m on the LED displays A simple analogue signal In contrast an analogue non digital signal uses a more continuous signal and instead of turning on and off to represent data will vary the frequency FM or strength AM at audio frequencies Nowadays there are relatively few analogue signals that you are likely to encou...

Страница 22: ...ng smartphones and laptops but also fixed smart devices Readings of 3 to 6 V m are normal at 25cm from WiFi devices decreasing with distance WiFi is usually always on 3 Mobile phones When in use these devices can easily produce 6 V m at 25cm Many apps send data in the background so storing the phone in a pocket or purse can lead to high exposures 4 Mobile Phone Masts and other external sources inc...

Страница 23: ...continuous readings of 1 3 V m are often found In rural environments with no near base station readings are usually below 0 2 V m At 100m from a mast you will typically find readings of 1 5 V m falling to 0 5 V m at 300m Base stations have a main beam which directs the energy sideways but there are also various side lobes which can give high readings close to the mast Cars Modern cars are increasi...

Страница 24: ...te buildings so that devices can work reliably indoors Mid band 2 5 to 5 GHz offers greater capacity and speed It has a shorter range and is more easily blocked by solid structures so more base stations are needed Massive MIMO multiple carriers and targeted beams can start to be used High band 24 29 37 42 64 71 GHz will slowly be rolled out from 2020 It offers extreme capacity and speed and will n...

Страница 25: ...DGE GPRS HSPA 4G LTE Low and Mid band 5G TETRA Wi Fi bands 802 11A B G N at 2 4 and 5 6 GHz Wireless enabled laptops tablets and PCs WI MAX Bluetooth BLE UHF RFID readers Zigbee Z wave and other IoT device protocols Internet of Things IOT devices fitness trackers Wireless burglar fire and security alarms Extremely strong signals below 200 MHz The AM11 does not measure the following This is because...

Страница 26: ...ct off many types of surfaces This results in many small hotspots so movement of the Acoustimeter show up these real hot RF exposure spots The peak signal is high but the average is low This is to be expected from many sources as most wireless technology uses pulsed digital signals The instrument readings are varying a lot even when the Acoustimeter stays still Regular high blips every few seconds...

Страница 27: ...orking and not external signals This only happens if the field levels are below 0 02 V m and no LEDs are lit It still makes a noise when shielded behind screening materials The screening material may have degraded Also even small gaps including above and below you will let in some RF signals Even a 30 dB 99 9 reduction of 10000 µW m2 to 10 µW m2 a 2 V m signal reduced to 0 06 V m will still be sho...

Страница 28: ...y water or by physical impacts such as from dropping it Please contact us to arrange a return if required EMFields Solutions Ltd 12 Mepal Road Sutton Ely Cambridgeshire CB6 2PZ UK Email info emfields solutions com Web www emfields solutions com The European WEEE Directive requires recycling of unwanted electronic equipment Your AM11 can be returned to us for recycling if necessary V0813 1 ...

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