Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]

Re: LF: RE: 500kHz Distance

To: [email protected]
Subject: Re: LF: RE: 500kHz Distance
From: Alan Ibbetson <[email protected]>
Date: Wed, 23 May 2007 23:14:43 +0100
Cc: [email protected]
Delivered-to: [email protected]
In-reply-to: <[email protected]>
References: <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
User-agent: Turnpike/6.04-S (<7srEZhc6E9URia1sWEYXKv9liU>)
John,

I think your group has done a fantastic job getting UK amateurs the first general operating permits for 500K in Europe.

I'm interested in aerial experiments but, to make this offer some returns on the effort, I would favour a power limit at the aerial input, as we have on the higher bands. That way I will be motivated to make my electrically small aerial as efficient as possible within its domestic setting.

I don't really mind what that power limit is. Although 20W or more might be nice for DXing, it doesn't seem necessary for inter-UK contacts. I would be happy with 4 or 5W, which is what most people seem to be running. Once other countries gain access to the band I think there will be stronger case for higher power.

I'm a newcomer to the band, so treat these comments as "from a novice".

73,

Alan G3XAQ

In message <[email protected]>, John W Gould <[email protected]> writes
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 Ofcom may have taken the decision as they may expect to be withdrawn at WRC07, and on knowledge that in this part of the world 500kHz is no longer used as an international distress calling frequency.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







--

Cheers,

Alan G3XAQ
[email protected]



<Prev in Thread] Current Thread [Next in Thread>