DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=mime-version:in-reply-to:references:date:message-id:subject:from:to
         :content-type;
        b=H2WPxnr/HsBDpY9PP8LaDUA4jdtkEdg1gVP2OsH1WN3GwR8numbBxVNMG6WialZzjN
         LSii/sxx1AzpOvrtRPl6ZD9CAR6NJeZGOueOjW4ECN23uNU7nYWE4ofe/wPkVsDtF4in
         LIp92va+oU8wDivIbWe6seJbeoVyE1wZ3adGs=
MIME-Version: 1.0
In-Reply-To: <4D23A78D.90100@toya.net.pl>
References: <AANLkTi=XJZh8hitDc14JfA99hQVdjCMX7=HsKqDw6T2S@mail.gmail.com>
	<4D23931B.50505@toya.net.pl>
	<AANLkTi=K-ARQjfV7ymgR6X5-0+_a_TEOOShkWumOE0WJ@mail.gmail.com>
	<4D23A78D.90100@toya.net.pl>
Date: Tue, 4 Jan 2011 23:22:28 +0000
Message-ID: <AANLkTinjnMP34fKo+7M-TWF7Lp+2W2tx5NN4E0P2apVn@mail.gmail.com>
From: Andy Talbot <andy.g4jnt@gmail.com>
To: rsgb_lf_group@blacksheep.org
DomainKey-Status: good (testing) 
Subject: Re: LF: WSPR Reports
Content-Type: multipart/alternative; boundary=90e6ba4fc4c6c9367f04990d8a5d
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


--90e6ba4fc4c6c9367f04990d8a5d
Content-Type: text/plain; charset=ISO-8859-1

The WSPR software does its own digital filtering to the 200Hz wide
input band - with associated passband edges,  and calculations are based on
the bandwidth defined  there.
It will therefore work, and noise level calculation will be
correct, provided the input signal cointains a flat noise spectrum wider
than the internal filter bandwidth and encompasing the roll-off.

Signal level is measured in the 1.46Hz FFT bin then just normalised to a
convenient reference 2.5kHz bandwidth used for reporting purposes.  Chosen
because its nar enough an SSB filter's BW   It is a pity this bandwidth
value was used as it has lead to misunderstandings amongst several ops, but
has become the norm and we have to just accept 2.5kHz reference bandwidth
for nearly all datamode operation now.

Hindsight suggests we should all have normalised to 1Hz, quoting S/N in this
width, but what's a constant 34dB offset  amongst friends :-)

Andy
www.g4jnt.com


On 4 January 2011 23:04, Piotr Mlynarski <sq7mpj@toya.net.pl> wrote:

> Andy Talbot pisze:
>
>
>> 300Hz wide CW filters made a fraction of a dB difference, compared with an
>> SSB filter used as a reference;
>>
> well, indeed , in my free time i have to look inside the wspr code ..
> i just thought  that it was simply 3000 Hz (ssb)/ 300 Hz (cw) = 10
>
>
>                                                                     73,
> Piotr, sq7mpj
> qth: Lodz /jo91rs/
>
>

--90e6ba4fc4c6c9367f04990d8a5d
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

<div>The WSPR software does its own digital filtering to the 200Hz wide in=
put=A0band - with associated passband edges, =A0and calculations are based=
 on the bandwidth defined=A0=A0there.=A0=A0=A0 </div>
<div>It will therefore work, and noise level calculation will be correct,=
=A0provided the input signal cointains a flat noise spectrum wider than th=
e internal filter bandwidth and encompasing the roll-off.</div>
<div>=A0</div>
<div>Signal level is measured in the 1.46Hz FFT bin then just normalised=
 to a convenient reference 2.5kHz bandwidth used for reporting purposes.=
=A0 Chosen because its nar enough an SSB filter&#39;s BW=A0=A0 It is a pit=
y this bandwidth value was used as=A0it has lead to misunderstandings=A0am=
ongst several ops,=A0but has become the norm and we have to just accept 2.=
5kHz reference bandwidth for nearly all datamode operation now.=A0=A0=A0</=
div>

<div>=A0</div>
<div>Hindsight suggests we should all have=A0normalised to 1Hz, quoting S/=
N in this width, but what&#39;s a constant 34dB offset=A0=A0amongst friend=
s :-)</div>
<div>=A0</div>
<div>Andy</div>
<div><a href=3D"http://www.g4jnt.com/">www.g4jnt.com</a></div>
<div>=A0</div>
<div>=A0</div>
<div>On 4 January 2011 23:04, Piotr Mlynarski <span dir=3D"ltr">&lt;<a hre=
f=3D"mailto:sq7mpj@toya.net.pl">sq7mpj@toya.net.pl</a>&gt;</span> wrote:<b=
r></div>
<div class=3D"gmail_quote">
<blockquote style=3D"BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8e=
x; PADDING-LEFT: 1ex" class=3D"gmail_quote">Andy Talbot pisze:=20
<div class=3D"im"><br>
<blockquote style=3D"BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8e=
x; PADDING-LEFT: 1ex" class=3D"gmail_quote"><br>300Hz wide CW filters made=
 a fraction of a dB difference, compared with an SSB filter used as a refe=
rence;<br>
</blockquote></div>well, indeed , in my free time i have to look inside th=
e wspr code ..<br>i just thought =A0that it was simply 3000 Hz (ssb)/ 300=
 Hz (cw) =3D 10=20
<div>
<div></div>
<div class=3D"h5"><br><br>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
 =A0 =A0 =A0 =A0 73, Piotr, sq7mpj<br>qth: Lodz /jo91rs/<br><br></div></di=
v></blockquote></div><br>

--90e6ba4fc4c6c9367f04990d8a5d--