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Ofcom confuses again, wrt EMF exposure risks

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Ofcom confuses again, wrt EMF exposure risks

Old 16th Aug 2021, 08:54
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Ofcom confuses again, wrt EMF exposure risks

I have just received an email, apparently from Ofcom (I can't see any benefit for a scammer - it seems genuine) about the 'new conditions they are imposing to cater for EMF exposure concerns.

This effort is almost as impenetrable as their previous and in my view every bit as pointless and absurd.
It tells me about different dates by which I have to demonstrate compliance for equipments transmitting on various frequencies (why make that bit complicated chaps?), provides a website link to their 'Final Decision' which does not work, promises a compliance flowchart which also appears to be unavailable and also promises that at some indeterminate point in the future they will provide an 'updated online calculator', no doubt to allow me to find out, again, that this is a load of needless hooey.

Has anyone else been sent this? Does it make sense to you? Can you access any of it? I ask because although I can't see a scam in this, it seems rather too absurd even for our impressively useless mob of official numpties.
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Old 16th Aug 2021, 10:03
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Got that one as well. If I understand correctly, it will have no practical impact on onboard transmitters, it's mostly the ground stations that may be affected, and then only the powerful ones.
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Old 16th Aug 2021, 10:23
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I think that is correct ultranomad, judging by information eventually gleaned from the last strange communication - thanks for your response, nice to know it is not some strange scam or spoof.

Once their website responds again, no doubt that will confirm tat only high power systems need a detailed look-see.
And why could they not have said that in this? Sigh - 'officaldom' and simple language seldom go together.
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Old 16th Aug 2021, 12:40
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Yes, this is going out to all licensees of transmitting equipment. Basically it seems to be a large scale ass covering. It's known that exposure to non-ionising radiation can cause damage and they seem to be making the operators aware that they could be liable for any injury if they haven't made the calculation and taken the necessary steps to mitigate the risk.

It seems, to me, that they are trying to ensure that nobody can come back to OFCOM and say you never told us about this, and perhaps hold them liable.
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Old 16th Aug 2021, 15:49
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Originally Posted by topradio View Post
It's known that exposure to non-ionising radiation can cause damage.
It's not quite as clear-cut as that. High field strengths at high frequencies can cause localised heating (as with a microwave oven) but a great many studies at various frequencies and power levels have produced rather inconclusive results in other respects.
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Old 16th Aug 2021, 16:35
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This page might help.

AOPA UK Ofcom guidance
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Old 17th Aug 2021, 09:39
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The OFCOM calculator refers to EIRP (Effective Isotropic Radiated Power) i.e. when using an isotropic antennae. I tried to buy an isotropic antenna - but apparently they are theoretically impossible for radio waves.
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Old 17th Aug 2021, 13:56
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It's just just OFCOM and it's not just UK. - https://docs.fcc.gov/public/attachments/DA-21-363A1.pdf

ARRL has been alerting US radio amateurs to the change and I would expect that RSGB has been doing the same in UK.
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Old 18th Aug 2021, 07:06
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Useful from LAA

Communications regulator Ofcom has issued revised guidance prepared in conjunction with the LAA, on electromagnetic field (EMF) license conditions that will apply to radio equipment in light aircraft.

Following receipt of communications from Ofcom in April, the LAA made representations that the proposed requirements, while well intentioned, were overly onerous and hard to interpret. As a result LAA engineers Jon Viner and Joe Hadley worked with the regulator to better define the risks from aircraft equipage. Their work, carried out on behalf of other member organisations within the GA Alliance, has resulted in the revised guidance.

In summary:

If you only use handheld radio equipment, you do not need to comply and do not need to take any further action in relation to your VHF radio.

If you use fixed equipment with an external antenna and a radiated power of 25 Watts, and you transmit for less than 25% of the time in any six minute period (i.e. less than 1 minute and 30 seconds), you do not need to comply and do not need to take any further action in relation to your VHF radio. (There should be very few situations where operators would need to transmit for more than 25% of the time).

Aircraft transponders generally have a nominal output power of up to 260 Watts, with a typical antenna gain of 3dB. However, they transmit very short pulsed signals for 0.55% of the time. This means that the average radiated power of this equipment is in the region of 4-5 Watts.



Ofcom has calculated that, in the absence of a ground plane, the compliance distance for this equipment would be in the region of 26cm. However, the presence of an antenna ground plane will mean that compliance distances will be very small (typically much less than 10 cm).

In most cases therefore, no further action will be required, unless an antenna ground plane is not installed AND the transponder antenna is located less than 26cm from a passenger who is a member of the general public. In such cases a compliance check will be required as outlined in the Ofcom advice.
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Old 18th Aug 2021, 20:05
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" If you use fixed equipment with an external antenna and a radiated power of 25 Watts, and you transmit for less than 25% of the time in any six minute period (i.e. less than 1 minute and 30 seconds), you do not need to comply "
Thank Ofcom. A safety reason to not make long transmissions.

Last edited by Maoraigh1; 18th Aug 2021 at 20:06. Reason: Spelling.
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Old 21st Aug 2021, 15:51
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Another email today. 4 page attachment. It's contradictory as to whether a copy must be kept in the cockpit of my 630Kg AUW aircraft. I can see why I must carry the licence, but not this document.

"A copy of the EMF Conditions is attached, please keep this with your existing licence document." Not mandatory. But later:

" Until then, you must retain the attached copy of the terms and conditions relating to EMF wherever you keep your current radio licence."
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Old 21st Aug 2021, 18:11
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A common King digital radio, cuts you off if the transmit is pushed more than 30 seconds.
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Old 21st Aug 2021, 22:46
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Originally Posted by BigEndBob View Post
A common King digital radio, cuts you off if the transmit is pushed more than 30 seconds.
That's so you don't clutter the frequency if you sit on it.
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