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 <59C5428F.17051.114F75@roelof.ndb.demon.nl> <Pine.LNX.4.64.1709221920500.6198@plato.ucs.mun.ca>
 <59C63EC4.12309.B636CA@roelof.ndb.demon.nl>
From: Andy Talbot <andy.g4jnt@gmail.com>
Date: Sat, 23 Sep 2017 12:12:06 +0100
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To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: CW 477.7 kHz
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WSPR works with a noise bandwidth of 1.46Hz, and by virtue of the strong
FEC, allows copy at a S/N *IN THAT BANDWIDTH  *of about +4dB.    This
equates to -24dB S/N in 2.5kHz

10WPM morse has a noise bandwith of about 8Hz, and as you are only using
audible / visual human interpretation needs probably a S/N of perhaps +6dB
to +10dB depending on the operator's experience to decode perfectly.
 That equates to about -20dB S/N in 2500Hz best case

So 10WPM CW is going to be at least 4dB worse, and possibly as much as 10dB
 if operator experience is lower.

Andy  G4JNT


On 23 September 2017 at 12:00, Roelof Bakker <roelof@ndb.demon.nl> wrote:

> Hello Joe,
>
> The signal was much better last night.
> I have attached an audio clip.
>
> This is made with Linrad using a 10 Hz wide filter.
> The keying sidebands are well within the filter passband.
>
> I believe slow Morse, say 10 WPM, received with a 10 Hz filter will
> achieve about the same signal to noise ratio as WSPR. In this case
> this is 24 dB compared to a 2500 Hz SSB bandwidth.
>
> 73,
> Roelof, pa0rdt
>
> The following section of this message contains a file attachment
> prepared for transmission using the Internet MIME message format.
> If you are using Pegasus Mail, or any other MIME-compliant system,
> you should be able to save it or view it from within your mailer.
> If you cannot, please ask your system administrator for assistance.
>
>    ---- File information -----------
>      File:  VO1NA20170923.mp3
>      Date:  23 Sep 2017, 12:51
>      Size:  248256 bytes.
>      Type:  Unknown
>
>

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<div dir=3D"ltr">WSPR works with a noise bandwidth of 1.46Hz, and by virtue=
 of the strong FEC, allows copy at a S/N <u>IN THAT BANDWIDTH =C2=A0</u>of =
about +4dB. =C2=A0 =C2=A0This equates to -24dB S/N in 2.5kHz<div><br></div>=
<div>10WPM morse has a noise bandwith of about 8Hz, and as you are only usi=
ng audible / visual human interpretation needs probably a S/N of perhaps +6=
dB to +10dB depending on the operator&#39;s experience to decode perfectly.=
 =C2=A0 =C2=A0That equates to about -20dB S/N in 2500Hz best case</div><div=
><br></div><div>So 10WPM CW is going to be at least 4dB worse, and possibly=
 as much as 10dB =C2=A0if operator experience is lower.</div><div><br></div=
><div>Andy =C2=A0G4JNT</div><div><br><div class=3D"gmail_extra"><br><div cl=
ass=3D"gmail_quote">On 23 September 2017 at 12:00, Roelof Bakker <span dir=
=3D"ltr">&lt;<a href=3D"mailto:roelof@ndb.demon.nl" target=3D"_blank">roelo=
f@ndb.demon.nl</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" s=
tyle=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hell=
o Joe,<br>
<br>
The signal was much better last night.<br>
I have attached an audio clip.<br>
<br>
This is made with Linrad using a 10 Hz wide filter.<br>
The keying sidebands are well within the filter passband.<br>
<br>
I believe slow Morse, say 10 WPM, received with a 10 Hz filter will<br>
achieve about the same signal to noise ratio as WSPR. In this case<br>
this is 24 dB compared to a 2500 Hz SSB bandwidth.<br>
<br>
73,<br>
Roelof, pa0rdt<br>
<br>The following section of this message contains a file attachment<br>
prepared for transmission using the Internet MIME message format.<br>
If you are using Pegasus Mail, or any other MIME-compliant system,<br>
you should be able to save it or view it from within your mailer.<br>
If you cannot, please ask your system administrator for assistance.<br>
<br>
=C2=A0 =C2=A0---- File information -----------<br>
=C2=A0 =C2=A0 =C2=A0File:=C2=A0 VO1NA20170923.mp3<br>
=C2=A0 =C2=A0 =C2=A0Date:=C2=A0 23 Sep 2017, 12:51<br>
=C2=A0 =C2=A0 =C2=A0Size:=C2=A0 248256 bytes.<br>
=C2=A0 =C2=A0 =C2=A0Type:=C2=A0 Unknown<br>
<br></blockquote></div><br></div></div></div>

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