Message-ID: <F0FEBB6345B7401D9B88BAB39FB9F646@AGB>
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
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Date: Tue, 23 Dec 2008 21:13:41 -0000
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Subject: Re: LF: Extension of the UK's 500kHz NoVs
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John,

This is my own observations on the proposal detailed, based on my use and 
expectations of the experimental licence.

Increase to +10 dBW

>From my own point of view I would find such power levels unnecessary, 
firstly from the safety point of view, Initially  the estate boundary field 
levels are calculated  at 100mW erp the  increase to 1 watt erp may of taken 
up any slack in the calculations but compliance at  10dBw within a 'normal' 
location  may prevent  successful licence applications in the future and if 
applicable  retrospectively may result in the loss of the facility ?

Operating from a normal installation the power levels required to  establish 
such a level of radiation are prohibitive and would greatly increase the 
possibility of generating localised BC interference, acknowledging advancing 
technology even achieving a 30 db signal to  noise ratio would result in a 1 
or 2 watt spurious emission at power levels required to  achieve 10dBW . 
>From observation, 2 watts in ground wave range is a substantial signal at 30 
miles ..


Tx bandwidth


If such a increase is  to  be at the loss of  transmitter bandwidth, this 
would effectively prevent the investigation of existing and the future 
deployment of developing digital modes. I am aware that there are stations 
involved in the construction of linear drive translation systems and the 
provision of complimentary amplification.  such developments are also noted 
out side the Uk and would disadvantage the Uk operations.

Limitations at this sage could be viewed as a retrograde step and prevent 
the use of a large percentage of the newer digital modes, some  of which are 
perhaps 'too' wide even for deployment at HF but as part of a experiment may 
provide useful comparisons

I think it reasonable with the currant power levels that the possibility of 
interference to existing services by excessive bandwidth  is extremely low 
not withstanding a 'mal' adjusted system.

For example I have run simple transmission test with two or three modes 
simultaneously, which proved of general interest inside and out of the uk 
and gave the observing stations a basic head to head. I am sure such tests 
by other stations would be useful in the future but may be prohibited by a 
change to  the licence.


Propagation investigation

As can now be observed, the K1JT narrow bandwidth auto  beacon system is 
producing valid results from uk based stations able to  transmit the system 
with low power into  modest antenna arrays and as such is providing data 
over  path lengths of 4000 miles. The system has limitations in terms of 
transmitter duty cycle however it is under development  future systems may 
also provide data by the processing of the recovered audio.

In summery

I would say the uniqueness of the UK experimental allocation  should be 
maintained as long as possible and if necessary at the expenses of 
increased ERP levels which could be used to  erode the facility by the 
'prevention' of interference  to  existing services, which as far as I am 
aware has not been a issue to date ?

Notably there exists an allocation out side of the UK  of higher power than 
the Uk but with a quite constrictive  limitation on the class of emission, 
the level of activity is telling.

Graham .
G0NBD




--------------------------------------------------
From: "John W Gould" <jwgould@iee.org>
Sent: Friday, December 19, 2008 4:18 PM
To: <rsgb_lf_group@blacksheep.org>
Subject: LF: Extension of the UK's 500kHz NoVs

>
> The annual discussion with Ofcom surrounding the extension of the NoVs for
> 500kHz took place at the Ofcom/RSGB Forum yesterday.  This followed a
> request at the September Forum meeting and was backed up with a short 
> paper
> issued to them at the end November.
>
> Apart from requesting a further year's continuation of the NoV I have 
> asked
> if it will be possible to increase the ERP to +10dBW in order to bring it 
> in
> line with licence conditions in some other countries.
>
> Ofcom will obviously need to consult with the Maritime and Coastguard 
> Agency
> (MCA) and were asking questions about the coverage at this higher ERP 
> level.
> They were also asking whether we would accept a tighter definition on
> transmit bandwidth.  This is to be more assured of not causing problems to
> services within the Maritime Mobile band 505 - 510kHz and I guess for the
> NoVs to be more compliant with the Radio Regulations footnotes 5.82A and
> 5.82B for 495 - 505kHz.
>
> Getting a higher ERP limit will not necessarily be to everyone's liking,
> however, it may help investigation of the deep fades and also help those 
> in
> high noise level environments.  The ERP level and transmit bandwidth will
> probably be negotiable, but my aim is to achieve maximum flexibility in 
> use
> of telegraphy and the narrower digimodes.  Would 200Hz be sufficient or
> would we need a little more?
>
> Assuming that MCA approve of continuing the arrangements Ofcom indicated
> that their preference for extending the NoV would be as last year. This is
> to issue new NoVs to existing holders, anyone who no longer needs their 
> NoV
> can return the documents.
>
> Comments appreciated, either direct of on the reflector.
>
> Seasonal Greetings to all
>
> 73 John, G3WKL
> RSGB HF Manager
>
> g3wkl@btinternet.com
>
>
>
>
>
>
>



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