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Sunday, December 16, 2012

Multi Frequency and multi sources - the real world of RF

Multi frequency - a state in which a RF signal is compose of several RF small signal, or a case in which in the AIR there are several RF signals.

Multi sources - a state in which in a surrounding there are several RF emitting devices which each and every one of them transmit different, or same, one, or many RF signals.

Please note -the problem shown in this clip is not unique to the CORNET meters. Most meters have the some issue. The only way to measure RF radiation correctly is using a spectrum analyzer (a good, fast one cost a lot!), finding every signal and analyzing it one by one. The CORNET meters are great for their price. 
I made this video so activist and people will know that when they measure RF with the CORNET or other DETECTORS, or when a government official or a professional tester measure RF with his meter, it is never the full picture. 

In the real world, in most cases when we measure RF radiation, we have more than one RF signal that is originated from more then one source. Sources like mobile phone antennas, WIFI router or a 3G mobile phone emits multi frequency signals. Measuring the radiation from these sources with a simple RF meter (professional or home use) which is not a spectrum analyzer will show only part of the picture. Simple meters can also detect the radiation emitted from the sources, show when it is ON of OFF, and show if there is more or less radiation in one point of time or between different locations.
It is not that I think we should not use simple RF meters. on the contrary, simple RF meters is the only effortable way we can see the radiation before it makes us sick. But when official bodies try to show how low the RF radiation is by using an RF detector (simple meter that show only accumulated calculated number) against a WIFI router or a cell phone antenna, this is wrong.

The way to analyze the RF radiation before assessing it's health risks, from most of today sources, is to use a fast spectrum analyzer and count the number of signals, their frequency (different frequency does different damage to different people), their MAX, MIN, AVARAGE amplitude (over long time, not just 6 minutes) and the type of signal (Digital, analog, GSM, UMTS, Spectrum speed, frequency hoping and more).

In most countries today the official bodies that are responsible on the regulation of RF radiation, not only use the high non protective ICNIRP guide lines, but also uses simple RF meters.

In every country in the world when analyzing RF radiation from the electronic perspective, they use very fast spectrum analyzer and even very low RF single are considered as a disturbance that needs to be shielded.

Why electronic equipment is treated better than real people?

Video experiments
In the following video, I use the excellent CORNET ED85 RF meter  to measure RF radiation from 2 identical DECT cordless phones. The phones transmit in different channels, which means different frequency (very close to one another). After it is power up the DECT phone scan the 2.4 frequency span that is used by DECT standard and select an unoccupied channel. The ED85 show this when soon after the second DECT phone is powered up the levels goes up from ~60 to ~90 for a brief second (when both phone transmits in the same channel for a second) and then goes down again to ~60 mW/m2.
If I would have a spectrum analyzer, we would have seen that there are 2 different signals right next to each other. The human body is effected by both, while the meter shows the same level as if only one was present.

WIFI radiation
In the next video (Hebrew audio with English Subtitles) I show the same thing, this time with several laptops and a WIFI router. In this video I use both CORNET ED75 RF meter and the CORNET ED15 a simple WIFI analyzer. When all the RF sources are transmitting you can see on the ED15 that all the WIFI span is busy, while the levels on the RF meter remains very low.


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