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Guru

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Pulsed Radio Emission Harmful? It Would Appear So

09/18/2010 3:54 AM

I know this subject has been approached before.

But i recently came across this site, which has information about TETRA a public utility radio system used in the UK by the police etc, Which replaced the old 446 MHz system.

The problem is

1 the power from the base sites ie 25 watts continuous

2 the nature of the output ie pulsed

3 and the frequency of the pulses.

do you lot have any information about such problems

The key question here is whether TETRA masts or handsets present a risk to health and well-being. Since TETRA has been used, and especially during the construction of the Airwave network, people have reported consistent reactions to the mast emissions, and to handset use. Much of this is described as electro-hypersensitivity (EHS), or microwave sickness. Some is much more serious. Such is the amount of this, that campaign groups all over the UK have sought official investigation: medical, environmental, and technical. The health effects are nothing to do with signal strengths, since these are well below the international guidelines (ICNIRP) on protection from acute thermal effects from radiation. The concern is with non-thermal biological effects, probably related to the coherent (regular, consistent) signal frequencies used by TETRA. These effects are not unique to TETRA: other mobile phone masts can do the same. What is different is the number of people affected, and how quickly they are affected.

the full link

http://www.tetrawatch.net/tetra/pulse.php

other items on CR4 relating to this issue though most are about Cell Phones which work in a different way

http://cr4.globalspec.com/search/sitesearch?do=show&sort=textmatchrank&srch=cell%20phones&order=asc

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Guru

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#1

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 12:15 AM

I recognize the pattern: di-di-dah-di-di-dah. It is Morse code for uu. I suspect that tinfoil hats are definitely called for in this case.

Sorry to be flippant but it is hard to imagine that there should be an effect since we are already awash in an unimaginable sea of electromagnetic energy. Also, much of the conclusions and assertions on the site are seem to be more a function of fear induced hysteria than any technically astute development. Of course that doesn't disprove anything any more than saying something is so makes it so. Sadly if there is anything to this it may only be brought to light as a result of long term health records.

For a long as there have been fearful assertions of the electromagnetic phenomenon, if there were any clear smoking gun we would have found it by now. If there are in fact actual effects we may have to wait still until we evolve the tools to observe what surely must be a very slight impact on a very few people in terms of the population at large.

Until then, foil hats may be the best protection.

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Guru

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#2

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 5:44 AM

Cars immobalised by police radio base stations

http://www.timesonline.co.uk/tol/news/uk/article425256.ece

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Power-User

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#3

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 10:48 AM

The first thing that occured to me is that the referenced links are rather dated. Has the 'problem' gone away?

In the first link (TETRA) it was said that the problems were more significant during the construction period (before it was even turned on?). Sounds like a case of hyperanxiety resulting in a fear factor of the unknown. A ton of conjecture and misused/non-applicable verbage in attempt to put forth something the author knew nothing or very little about.

But, for what it's worth, a comment: 30 years ago and for some years I was servicing VHF and UHF handhelds. Somehow, I could sense (in my cabeza?) if a unit was transmitting RF or not, 100% of the time. Same with mobile radios. Not with servicing "mast" or tower sites, as the antenna was then above radiated level was very low at that point. And yes, still alive and typing this today and no brain cancer or whatever.

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Guru

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#4
In reply to #3

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 11:22 AM

Yes i too can sense radios and overhead power lines.

Its the pulsed radio bit i was wondering about, although wireless routers used pulsed radio, and so does DECT phones though in very low power.

the TETRA system has been up and running for some time here in the UK one of the main reasons it was introduced was the security aspect as even the old VHF scrambled raidios could be listened into with cheap software.

just wondering if anyone had any upto date TETRA info

How it works its very clever

http://www.radio-electronics.com/info/cellulartelecomms/private-mobile-radio/tetra/what-is-tetra-radios-communications.php

http://www.google.co.uk/search?q=tetra+radio+communication+system&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&rlz=1I7GGLT_en&redir_esc=&ei=3CqWTMy0Co7KjAfdr5DJBQ

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Guru

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#7
In reply to #3

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 3:28 PM

When you transmit it loads the power supply components of the system and many parts are microphonic. Whether you realize it or not, there are almost always audible clues that can be detected with our amazing 110+ dB dynamic range hearing mechanism. I can tell when one of my computers is processing more intensively because the extra load on the power supply slows the fan, which runs of the DC output of the supply, ever so slightly.

This is a common problem with bad science. No one takes the time to discover all the subtitles of what's going on that may mess with their perception or projection of what they think is happening.

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Power-User

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#8
In reply to #7

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 3:50 PM

rcapp: I opt to not go with off topic. I do know what you are speaking of, but not quite what we were making reference to.

Only to add to the confusion: I can also tell when my cat is hungry!

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Guru

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#9
In reply to #8

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 6:44 PM

Good for you. Sorry if you don't see the relevance.

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#12
In reply to #9

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 8:35 PM

After some debate with myself: obviously you have not had the experience with RF sources, and as peter cites. Further, there is nothing in this technology that hums nor any other audible indicators to queue a user as to it's state.

You are quite correct. I do not see the relevance.

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Guru

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#10
In reply to #7

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 7:03 PM

Thanks but the load on a computers power supply is hardly in the same frequency as 300 MHz or cell phones 800 + MHz

I too can hear the changing sounds of computer drives fan etc, but as i say at this frequency ie 50 hertz 60 hertz

As for the components being micro-phonic this is not the case on sophisticated circuits like TETRA and Mobile Phones, as the components are designed to stop and harmonics, as any undue stray circuit harmonics would cause chaos with the control circuits, And any undue harmonics would cause the system to shut down, as the harmonics would take the radio output outside the prescribed licence regulations.

So again thanks but your comments are as someone else has already stated outside the scope of the question

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Power-User

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#5

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 12:40 PM

The important thing firstly to understand about the technology is even though transmitters are turning on and off (at a relatively low repetition rate) it is of no consequence to the user. Any time when turning on and off an RF carrier, noise is created in the spectrum, but is disbursed broadly and where any component is many tens of decibels below the original. This means that this factor is harmless to human 'beans' (sorry, I enjoy the intentional misspelling). The digital modulation is not carrier on-off.

Truly, we the repetition rate is increased dramatically, the adjacent sideband noise intensifies and of greater magnitude; but that is not what we are talking about here.

So, the bottom line simply is that this technology exhibits nothing different than the cellular infrastructure; the same as, in so far as concern of EM radiation and any effect upon the human 'bean'.

BTW: Think the original article implied that 400 MHz was microwave. Not, never seen any such reference; generally microwave is above 1000 MHz. Also wrong was any impact on human tissue more-so at 400 MHz than above. Believe that the inverse is true, the higher the frequency the more heating of any internal tissue would be. I suppose there have been studies to prove that there is a turnaround point where at some extremely high frequency (that we so far do not use yet) that only the peripheral is affected (like UV).

There may be ramifications to our using cell phones and handhelds that may be one day be proven.

Related, and with your comment peter: I've never ran into anyone before that remarked they had the same sensation. What I worked with were 1-6 watt handhelds. I believe they had to be quite close to the cabeza by perhaps a foot or two; if much over that: nada. I also used to work with "wires/bugs" that would be about 500 mW, but no sensation. Cellphones (100 mW max) neither. So, I guess my threshold is about 1 watt. I doubt that there is not enough energy to 'cook' anything in the cabeza oven. We also have to understand that the energy is not focused. To backtrack, even those cell mast antennae are designed to be directional (degrees varied by spec). The pic depicted (redundant?) in the article told me that the TETRA antennae are omnidirectional. So what that means is simply the RF energy is more so widely dispersed 360 degrees and much less of any issue for the human 'beans'; and where they might want to backstep and continue onward with any bitching about cellphone.

On your other: You were probably referring to a low tier of DES scrambling. In the US there were several, first developed by Motorola I think for the military (don't think anyone has been able to break it yet), down to other gov't and to commercial application algorithms.

I spent some hours today digesting and sorting with this. Hope you deem as a resolve to your question and concern.

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#6
In reply to #5

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 1:07 PM

hi thanks for the reply icant remember the exact out put but its around 2 watts this depends on the location of the handset from the base, the further the handset is from the base the greater the output

Radiation absorption

http://en.wikipedia.org/wiki/Mobile_phone_radiation_and_health

Part of the radio waves emitted by a mobile telephone handset are absorbed by the human head. The radio waves emitted by a GSM handset can have a peak power of 2 watts, and a US analogue phone had a maximum transmit power of 3.6 watts. Other digital mobile technologies, such as CDMA2000 and D-AMPS, use lower output power, typically below 1 watt, UVA. The maximum power output from a mobile phone is regulated by the mobile phone standard and by the regulatory agencies in each country.[citation needed] In most systems the cellphone and the base station check reception quality and signal strength and the power level is increased or decreased automatically, within a certain span, to accommodate for different situations such as inside or outside of buildings and vehicles. The rate at which radiation is absorbed by the human body is measured by the Specific Absorption Rate (SAR), and its maximum levels for modern handsets have been set by governmental regulating agencies in many countries. In the USA, the Federal Communications Commission (FCC) has set a SAR limit of 1.6 W/kg, averaged over a volume of 1 gram of tissue, for the head. In Europe, the limit is 2 W/kg, averaged over a volume of 10 grams of tissue. SAR values are heavily dependent on the size of the averaging volume. Without information about the averaging volume used, comparisons between different measurements cannot be made. Thus, the European 10-gram ratings should be compared among themselves, and the American 1-gram ratings should only be compared among themselves. SAR data for specific mobile phones, along with other useful information, can be found directly on manufacturers' websites, as well as on third party web sites.[7]

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#11

Re: Pulsed Radio Emission Harmful? It Would Appear So

09/19/2010 8:20 PM

Had to do some homework, hence the lull.

The straight skinny is this: In the US the cell mobile is limited to 100 mW maximum. Not a function of distance from tower/mast/base antenna but where the output power is inversely proportional to the received signal level. Probably the same in the UK.

Not a clue about the TETRA handhelds, but would suspect that they are also low power, probably not to exceed 1 Watt anyway, based upon should the cited 25 W from the base/mast antennae.

Even though there are at least several formats today for cellular, and growing, the RF outputs of the base and handhelds remain the same. The formats are merely methods of modulation and has nothing to do with the RF power. I do find that G4 does task the base/tower/mast infrastructure with effective ERP on any given channel when busy toward it's maximum; and remains an issue for the gov't applicable. In any event, it does have any impact upon the handheld.

My opinion would be: even if the TETRA mast transmitters were to go to perhaps 50 Watts, there would be no biological/human 'bean' issues.

How's that in a nutshell?

As Elmer Fudd would say: "I yam impwessed with me self".

Where's Del? I've got a deal he can't refuse!

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