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Date: Thu, 16 Feb 2012 16:44:41 +0100
From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: Re: WRC-12 Approves the New 472-479 kHz Amateur Radio Allocation
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Thanks for the useful explanations, Roelof.

73, Stefan/DK7FC

Am 16.02.2012 13:03, schrieb Roelof Bakker:
> Hello all,
>
> I believe it is time to put things into the right perspective.
>
> Technically speaking, NDB's are obsolete.
> However in practice, they are not.
> NDB's are in widely use in the offshore industry for guiding 
> helicopters to offshore installations and special purpose offshore 
> vessels.
> New work ships build today and equipped with a heli-deck carry also a 
> NDB.
>
> When America is not your best friend, it seems sensible that for 
> aeronautical direction finding, you won't rely on the US GPS system.
> NDB's are very reliable and cheap to maintain and not easily wiped out 
> all together, so the system has good redundancy.
> For that reason it can be understood why some countries ask for some 
> protection for this service.
>
> Regarding the NIB issue, the EIRP of most NDB's is in the same class 
> as the EIRP of the amateur license for 472-479 kHz.
> The NDB band covers 190 kHz to 1740 kHz and that includes the MW 
> broadcast band.
> Many Russian NDB's transmit in the range 530 - 1250 kHz and though 
> many powerful broadcast stations reside in the same frequency range, 
> this does not seem to pose a problem.
>
> The requirements for the service area of a NDB is a fieldstrength of 
> 70 uV/m at the borderline.
> So to cause noticeable interference, the offending signal must be 
> rather strong.
> Many NDB's share the same channel, apparently without problems.
> Unless you actually live in or near the service area of a NDB in the 
> 472-479 kHz frequency range, the NIB regulations won't pose a problem.
> It is also interesting to note that quite a few offshore NDB's in the 
> Norwegian part of the North Sea operate between 530 and 600 kHz.
>
> So this NIB requirement won't spoil he fun!
>
> 73,
> Roelof Bakker, pa0rdt