Ok Andy
,
Thank?s for your
comment?s, The ?idea? is based on what you could call ?operating experience?
over the last year on 500. The main concept being , ?Anyone with a PC and a
sound card? could join in , hence the request for a ?pc? based system.
The clock
issues, well that?s a area that I do not have practical experience of , It would appear
events can be reasonably controlled , this would dictate the number of tx
stations and number of multiplex
measuring pulses , Quite wide guard bands may be required?
On the 5 mhz
system , well yes that?s a different ball game as out friends would say , this
system is aimed at the ?Garden shed
gang? , open to all and if anyone
wants to ?have a go? so much the
better
The ?PIC- yes ?. Mm ?. Well ? fair comment J
Tnx ? G ..
----- Original Message -----
Sent: Monday, February 11, 2008 8:07
AM
Subject: Re: LF: Windows Beacon TX/RX
Software .. can anyone code such a thing ?
A problem with the scheme you suggest, Graham, is that PC clocks maintain
time badly, and will drift by several seconds overnight which makes a
mockery of the idea of precisely timed sequential listening. They may be
able to acheive Internet synchronisation, but can this be set up to
automatically update at the rate you will need, ie. every hour or two based on
some of the clock drifts I have seen.
That is why the existing beacon chains, both 5MHz and the IBP set, use
GPS timing. Passive receiving stations have their timekeeping reset
by the actual 5MHz transmissions themselves. On your website, you do
mention MSF timing, but to do that in real time would consume another receiver
/ soundcard channel. GPS is the only obvious way to go for
transmitting stations. PCs are not reknowned for their timekeeping
abilities!
Otherwise, the software is straightforward, although rather a waste
of a PC. If the GPS is available, then a £1 PIC is all you need to
control and key a standalone transmitter that doesn't need soundcard
drive.
On 10/02/2008, Graham <[email protected]>
wrote:
Hi
all,
This is something that may be of interest ..
To a programmer or two or
three ? There exists collectively the
expertise, but can anyone see a way of
producing the
system?
The idea came initially from the 'Beacon
Bedlam' , that existed south of
Watford gap .. about the only time the
skip distance on 500 was 'useful' in
that band conditions in the north
west where quite quiet, later to prove
a
hindrance,
There already exists a similar system on 5
Mhz , however the transmission
sites are defined
and participation is only possible by 'passive reception'
not
too appealing for 'experimentation' This is a 'proposal' the concept
is
proven , but 'we' need the
services of a programmer or two !!
Similar thing's exist but are coded to
use 'pics' ,
One of
the main criteria is , that 'anyone' with a windows based pc should
be
able to download and install the tx/rx software and join in, be
it as a
TX station, simply claim a 'time slot' , or a passive
observer being
presented with all 5 slots as a amplitude/time
plot.
One of the main attractions would be : TX
stations will be able to observe
the other beacons in the
chain , eliminating the lonely vigil of being in
perm
ante
transmit mode, while providing , at a glance, band
conditions for all
involved as well as reducing tx duty cycle
time !
The number of TX stations is proposed as 5 in the
chain , more may be
possible , but the time control factor may prove too
difficult to achieve
within windows , but cw type software in beacon mode
would appear top make
a reasonable job of time control
?
Click on http://groups.google.com/group/uk500khz/web/the-big-beacon-project
-
or copy & paste it into your browser's address bar if that
doesn't
work.
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