Thought that I had better respond to Laurie's e-mail, now a few days ago.
This is because the matter of the power level is to an extent under review by
Ofcom. If you recall we, RSGB, asked back in 2004 for a 1W ERP limit as that
was consistent with experience at 136kHz. A ERP limit also gives Ofcom a real
view as to what the likely coverage would be at any particular bandwidth. That
we were offered -10dBW ERP reflects both a bold step by Ofcom and also some
caution, given that they have to an extent taken an interesting view of ITU
Radio Regulation 5.58 to our benefit. RR 5.58 defines 500kHz as an
international distress and calling frequency for Morse radiotelegraphy. Ofcom
may have taken the decision as they may expect to be withdrawn at WRC07, and on
knowledge that in this part of the world 500kHz is no longer used as an
international distress calling frequency. Other authorities have not been so
minded, as Dick, PA0SE, recently discovered; they prefer to wait until such
time as RR 5.58 has been deleted.
Whilst we are currently limited to -10dBW RSGB/Ofcom are keeping the matter
under review and it may be timely, now that we have a good body of experience
to request that the limit be reconsidered. As far as I am aware no
interference complaints, or even local RFI problems have been received, and our
operating and conformance to licencing conditions have been exemplary. From
comments on this group it may be better to request say a 10 or 20W power limit
at the aerial feed-point, for reasons mentioned by Laurie. Whatever change to
the limit is agreed, if indeed any in the near term, it will have to be a
cautious change until such time as the Radio Regulations are more helpful in
allowing administrations to consider proper secondary allocation to the Amateur
service. This may or may not happen for a while, as we are only really working
at present to get the matter firmly on the WRC2011 agenda, such is the speed of
the ITU. There is good practical reason for making a request of this nature as
one of the reasons why the ITU process seems so slow is that for normal
protocol to be followed one needs to have had technical studies completed that
relate to the new proposals for the part of the spectrum in question. Our
activity between 502 and 504kHz, along with that by the US, Germany and Sweden
may qualify as such a study, so continuing the experiments at a higher power,
with the added challenge of maximising ERP from a fixed feed-point power limit
would add some breadth to our work.
Of course, the unexpected could always happen, and we get something sooner in
the margins of Agenda Item 1.14 at this year's WRC. However, as Agenda Item
1.14 is to review the operational procedures and requirements for GMDSS and
other related provisions our chances are slim, as the Maritime service is
likely to want to reuse the frequency around 500kHz. However, it is an agenda
item concerning this part of the spectrum so the possibility, however distant,
must be there.
I'd be interested in any further views to Laurie's proposal; I'am open to
suggestions as to the power level, but it will be important to hit a target
that is both challenging to the experimenter, helpful for continued propagation
research and also one that will not provide too much risk for Ofcom in terms of
coordination with the primary user service.
73 John, G3WKL
RSGB HF Manager
IARU Region 1 LF Coordinator
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