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Date: Tue, 27 Jan 2009 04:33:40 -0800 (PST)
From: brian hodgson <g3ykb@yahoo.co.uk>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: G0NBD difficult to decode
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For what its worth, I was decoding both M0BMU and G0NBD on alternate lines l=
ast night.
I'm in Watford (only 17 km from Jim so a VERY big signal !) - G0NBD was inau=
dible.

Brian (G3YKB)

--- On Tue, 27/1/09, John P-G <gm4slv@sighthound.demon.co.uk> wrote:
From: John P-G <gm4slv@sighthound.demon.co.uk>
Subject: Re: LF: G0NBD difficult to decode
To: rsgb_lf_group@blacksheep.org
Date: Tuesday, 27 January, 2009, 10:42 AM

mal hamilton wrote:
> Johan
> I have mentioned this several times before but noone seems to know why=20
> strong signals or any visible signals do not DECODE. I get some decodes=20
> therefore I know my system is working but not sure whether the problem is
at=20
> the TX or RX end. To me wspr seems unreliable given the strength of
signals=20
> but producing only marginal decoded output.
> 73 de mal/gkev
>=20


Mal, LF,

In general WSPR is very good at decoding weak signals - that's what
it's
all about after all - and can give reliable decodes on signals that are
inaudible and only faintly visible on the waterfall. Occasionally there
seem to be certain strong signals that won't decode, when weaker signals
from the same stations are fine.

Some discussion has taken place on the WSPR forum over incompatible
soundcard sampling rates, others on HF have seem the same "won't
decode
strong signals" problems too.

In the current case, with G0NBD, I guess the problem, whatever it is, is
  at the sending end, as similarly strong signals from others (M0BMU and
G4JNT) decoded fine here, and elsewhere, yet many people had trouble
with G0NBD's signal.

I see that Chris G3XVL often reports a +13dB s/n ratio for Jim's signal,
which shows that strong signals can decode correctly.


The question of brevity in passing information (ie "having a QSO") is
moot - it's not really intended for that purpose. It's point is to
allow
monitoring of the path conditions, using low power "weak signals" -
WSPR
stands for "Weaks Signal Propagation Reporting". If you want a mode
for
conveying information and exchanging reports then there's a whole gamut
- not least among them good old CW.

WPSR allows the collection, automatically, of data showing the changes
in path conditions over time, with a centralised online database of the
results, allowing others to do whatever number crunching they care to on
the data. For this the mode is perfectly valid, and given low enough
transmit power from the stations involved it shouldn't cause too many
problems for other band users. Last night's results showed that, for
inter-G (even up to Shetland) the ERPs involved were too high. Gary,
with his 5W TX and 2mW ERP is showing the way it should be done - and
that wouldn't cause too much QRM for those seeking CW QSOs elsewhere on
the band.

Using WSPR on 160m recently I discovered that I have a regular opening
to N6TTO on the west coast of USA, and I'm often the only Eu station to
receive him. Relying on more traditional modes I'd probably never have
discovered this. It means that perhaps my location is suitable for 160m,
and might be worth some investment in time/effort to get on the band.
Without the research using WSPR I'd have not realised that my location
was special - although my low noise floor has already proved its worth
on 500kHz.

Just a few thoughts from here.

Cheers,

John
GM4SLV





     =20

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<table cellspacing=3D"0" cellpadding=3D"0" border=3D"0" ><tr><td valign=3D"t=
op" style=3D"font: inherit;">For what its worth, I was decoding both M0BMU a=
nd G0NBD on alternate lines last night.<br>I'm in Watford (only 17 km from J=
im so a VERY big signal !) - G0NBD was inaudible.<br><br>Brian (G3YKB)<br><b=
r>--- On <b>Tue, 27/1/09, John P-G <i>&lt;gm4slv@sighthound.demon.co.uk&gt;<=
/i></b> wrote:<br><blockquote style=3D"border-left: 2px solid rgb(16, 16, 25=
5); margin-left: 5px; padding-left: 5px;">From: John P-G &lt;gm4slv@sighthou=
nd.demon.co.uk&gt;<br>Subject: Re: LF: G0NBD difficult to decode<br>To: rsgb=
_lf_group@blacksheep.org<br>Date: Tuesday, 27 January, 2009, 10:42 AM<br><br=
><pre>mal hamilton wrote:<br>&gt; Johan<br>&gt; I have mentioned this severa=
l times before but noone seems to know why <br>&gt; strong signals or any vi=
sible signals do not DECODE. I get some decodes <br>&gt; therefore I know my=
 system is working but not sure whether the problem is<br>at
 <br>&gt; the TX or RX end. To me wspr seems unreliable given the strength o=
f<br>signals <br>&gt; but producing only marginal decoded output.<br>&gt; 73=
 de mal/gkev<br>&gt; <br><br><br>Mal, LF,<br><br>In general WSPR is very goo=
d at decoding weak signals - that's what<br>it's<br>all about after all - an=
d can give reliable decodes on signals that are<br>inaudible and only faintl=
y visible on the waterfall. Occasionally there<br>seem to be certain strong=20=
signals that won't decode, when weaker signals<br>from the same stations are=
 fine.<br><br>Some discussion has taken place on the WSPR forum over incompa=
tible<br>soundcard sampling rates, others on HF have seem the same "won't<br=
>decode<br>strong signals" problems too.<br><br>In the current case, with G0=
NBD, I guess the problem, whatever it is, is<br>  at the sending end, as sim=
ilarly strong signals from others (M0BMU and<br>G4JNT) decoded fine here, an=
d elsewhere, yet many people had trouble<br>with G0NBD's
 signal.<br><br>I see that Chris G3XVL often reports a +13dB s/n ratio for J=
im's signal,<br>which shows that strong signals can decode correctly.<br><br=
><br>The question of brevity in passing information (ie "having a QSO") is<b=
r>moot - it's not really intended for that purpose. It's point is to<br>allo=
w<br>monitoring of the path conditions, using low power "weak signals" -<br>=
WSPR<br>stands for "Weaks Signal Propagation Reporting". If you want a mode<=
br>for<br>conveying information and exchanging reports then there's a whole=20=
gamut<br>- not least among them good old CW.<br><br>WPSR allows the collecti=
on, automatically, of data showing the changes<br>in path conditions over ti=
me, with a centralised online database of the<br>results, allowing others to=
 do whatever number crunching they care to on<br>the data. For this the mode=
 is perfectly valid, and given low enough<br>transmit power from the station=
s involved it shouldn't cause too many<br>problems for
 other band users. Last night's results showed that, for<br>inter-G (even up=
 to Shetland) the ERPs involved were too high. Gary,<br>with his 5W TX and 2=
mW ERP is showing the way it should be done - and<br>that wouldn't cause too=
 much QRM for those seeking CW QSOs elsewhere on<br>the band.<br><br>Using W=
SPR on 160m recently I discovered that I have a regular opening<br>to N6TTO=20=
on the west coast of USA, and I'm often the only Eu station to<br>receive hi=
m. Relying on more traditional modes I'd probably never have<br>discovered t=
his. It means that perhaps my location is suitable for 160m,<br>and might be=
 worth some investment in time/effort to get on the band.<br>Without the res=
earch using WSPR I'd have not realised that my location<br>was special - alt=
hough my low noise floor has already proved its worth<br>on 500kHz.<br><br>J=
ust a few thoughts from here.<br><br>Cheers,<br><br>John<br>GM4SLV<br><br><b=
r></pre></blockquote></td></tr></table><br>



     =20

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