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Message-ID: <5.1.0.14.0.20020517112857.00ab3498@gemini.herts.ac.uk>
Date: Fri, 17 May 2002 13:12:50 +0100
To: rsgb_lf_group@blacksheep.org
From: "James Moritz" <j.r.moritz@herts.ac.uk>
Subject: LF: Re: USA 136kHz proposals
In-reply-to: <002501c1fd03$6ce28bc0$1ee8fc3e@l8p8y6>
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Dear Mal, LF Group,

At 18:58 16/05/2002 +0100, you wrote:
>I think Jim you have missed the point about the band plan. In EU as you say
>we operate at the bottom end of the band 135.920 khz approx to avoid a
>receive problem at the Canadian and USA end because of CFH, which hardly
>effects us here in Europe, and therefore if they transmit on 137.6 khz
>approx that avoids any problem. So what is your point!!!!!

The point is - If , like in Europe, the vast majority of US stations 
operate in normal CW most of the time, most of the European band plan CW 
segment could be rendered unusable to those anywhere near CFH. They would 
have to use a different part of the band towards the band edges, used for 
QRSS in the European band plan. Likewise the "data" segment.

>A lot of experience has already been gained over this past couple of years
>transatlantic about how to conduct a LF QSO.

So far there have been a grand total of 2 two way LF transatlantic QSOs - 
G3AQC and VA3LK stuck to the band plan on alternate days,  but in the 
G3LDO/VE1ZJ/VE1ZZ QSO, VE1ZZ used a frequency around 136.5k for his own 
reasons. VA3LK used 137.79kHz, so 137.6kHz has not been tried for this 
purpose, and whether it would be any good remains to be seen. The "window" 
around 135.923 was moved there from a lower frequency after QRM from SXV. 
The objective of the window was to allow several transmitting stations with 
similar signals transmitting nearly continuous beacon signals to be 
monitored simultaneously by several receiving stations using specified 
settings on a particular piece of software (ie. ARGO in 30 or 60s dot 
mode), without usually attempting 2 way communications. This is not likely 
to be applicable to "normal" amateur operation with stations independently 
using different modes and speeds. Changing from 30s to 3s QRSS for example 
would require a new choice of frequency. Experience shows that success or 
failure often depends on carefully selecting an individual frequency that 
suits both ends - a fraction of a Hz often makes all the difference. There 
are a wide  range of different modes available, and new and improved ones 
developing as a result of experience gained. On HF, band plans have evolved 
over several decades, and will have to continue to evolve as communications 
technology develops. Since we are still in the early days of amateur LF 
operation, and already it is proving very different to the experience with 
HF and above, trying to apply the exact same principles used on HF does not 
seem sensible to me.

Cheers, Jim Moritz
73 de M0BMU