Message-ID: <3A73C58C.4B20F438@alg.demon.co.uk>
Date: Sun, 28 Jan 2001 07:09:00 +0000
From: "Steve Rawlings" <steve@alg.demon.co.uk>
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To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: This and that
References: <3A7246CB.FF3090A0@alg.demon.co.uk> <3A7322C1.A2927B65@usa.net>
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Hi Alberto - Greetings from Chepstow!

GW4ALG wrote:
> > I agree.  But, if QRSS is such an ideal mode, why do QRSS
> > operators need to use the whole of our tiny 2.1 kHz allocation to
> > do it?
> > [snip]

 I2PHD wrote:
 > A QRSS signal takes less than 1 Hz of band.
 > Any greater 'apparent' band occupancy is to blame on the
receiver.

Thank you for the opportunity to clarify my question above. 
Let's take a look at the 136 kHz band in more detail . . . 

It is my understanding that, where possible, operators try to use
the following suggested bandplan:
135.7 to 135.8: QRSS ('visual CW')
135.7 to 136.0: TX tests & beacons
136.0 to 137.4: Normal ('conventional') CW
137.4 to 137.6: Data modes
137.6 to 137.8: QRSS ('visual CW')

References:
- http://home.t-online.de/home/dk8kw/bandplan.htm
- 'Radcom', January 2000, p71


Assuming a separation on QRSS of 1 Hz, this provides the QRSS
operators with, say, 150 notional channels (taking into account
those frequencies displaying Loran lines, RTTY, etc.).

With a separation on CW of, say, 200 Hz, the CW operators get
about 8 notional 'channels' (assuming concurrent operation on
136.0; 136.2; 136.4; 136.6; 136.8; 137.0; 137.2; 137.4.).  

(Of course, it is fortunate that there is such diversity of
interest on LF.  If everyone operated only CW at peak times, 136
kHz might appear rather crowded!)

For several months, the above plan worked well, and almost
everyone fitted in with this agreement of gentlefolk.  There were
some minor transgressions, but points of view were hotly debated
and resolved.  Harmony and fair play abounded.

Over the past six months we have seen the arrival of several UK
stations with the ability to run high power QRSS.  It is
important to remember that the QRSS and CW modes are incompatible
for continued harmony - that is, we can't mix QRSS and CW within
a given operating segment.  (Let me know if you would like me to
clarify this point separately.)  If the emerging high powered
QRSS stations had stayed within the generally accepted bandplan,
harmony would have continued.  

Recently, however, high power QRSS started appearing within, or
close to, the CW segment.  To understand why this upsets the CW
operator, you need to be aware that:
- QRSS operation within the CW segment reduces the number of
notional CW 'channels';
- it was always felt that, ideally, there needed to be a guard
band between the CW and QRSS segments; and,
- QRSS is not compatible with CW.

The first blow to CW operators occurred last year when high
powered QRSS suddenly appeared during peak operating periods just
below 136.0.  This had the effect of reducing the number of
notional CW channels from 8 to 7.  (Of course, with the erosion
of the guard band 135.8 - 136.0, those with only average CW
filters have found that much of the lower part of the CW segment
has been effectively sterilised by the high power stations on
135.95.)

Most recently, it has become common practice by QRSS operators
such as G3LDO to further erode the number of notional CW channels
by operating high power QRSS within the CW segment.  Over the
past month I have heard QRSS for long periods on 136.5 and
136.3.  G3LDO has also admitted to operating QRSS on 136.5 and
136.4.  Last year we also heard QRSS on 137.0 and 137.1 kHz.

So, there you have it.  I am still puzzled: If QRSS only needs a
1 Hz bandwidth, why do the 20 or so QRSS operators need a 2.1 kHz
segment from 135.7 to 137.8 kHz?  

I trust that this clarifies my earlier question.

Regards to all,
Steve GW4ALG