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From: "PA1SDB, Peter" <pa1sdb@amsat.org>
To: <rsgb_lf_group@blacksheep.org>
References: <a3ab7a8e59cc48f5a6714915278e05f6@kabelmail.de> <B113BF3D526D426DB240EE3730BB1C54@White> <B288B88E668242CAA91FC4A2F15EA298@Extensa> <5310AEE1.3090209@freenet.de>
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Date: Fri, 28 Feb 2014 16:10:01 -0000
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Subject: Re: LF: SL. 47 uHz vs. 16 uHz @ 8270.005 Hz
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Tnx Wolf for the quick explanation !
Perhaps 100uHz is the limit here, or perhaps 30 uHz.
Experiment continues :-)

  ----- Original Message ----- 
  From: wolf_dl4yhf
  To: rsgb_lf_group@blacksheep.org
  Sent: Friday, February 28, 2014 3:44 PM
  Subject: Re: LF: SL. 47 uHz vs. 16 uHz @ 8270.005 Hz


  Hi Peter and all,

  Am 28.02.2014 16:21, schrieb PA1SDB, Peter:

    Hello VLF.
    Just a experience message !

    It seems that there is somewhere a perfect setting in "Width of FFT-bin", but where ?

  A good question.. and not easily answered. I'd say "it all depends".
  In this case, it depends on the soundcard's oscillator stability, despite stabilisation from the GPS sync pulse.
  At 16 uHz frequency we seem to have reached a limit (for this type of oscillator drift compensation).

  The next logical step would be building an A/D converter, or modifying a USB audio device to take the samping clock directly off a 
low-noise 'rock-solid reference' (a good GPS disciplined OCXO for example).
  I have fragments for such a project laying on the workbench (a low-cost Cortex-M3 microcontroller development kit) but no time yet 
to put the bits (bytes) and pieces together.
  At least, one would know of the Ionosphere (stability of the path length) or whatever else is the limiting factor.


  GL and all the best,
    Wolf .


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<DIV><FONT face=3DGeorgia>Tnx Wolf for the quick explanation =
!</FONT></DIV>
<DIV><FONT face=3DGeorgia>Perhaps 100uHz is the limit here, or perhaps =
30=20
uHz.</FONT></DIV>
<DIV><FONT face=3DGeorgia>Experiment continues :-)</FONT></DIV>
<DIV>&nbsp;</DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; =
PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV=20
  style=3D"FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: =
black"><B>From:</B>=20
  <A title=3Ddl4yhf@freenet.de =
href=3D"mailto:dl4yhf@freenet.de">wolf_dl4yhf</A>=20
  </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Drsgb_lf_group@blacksheep.org=20
  =
href=3D"mailto:rsgb_lf_group@blacksheep.org">rsgb_lf_group@blacksheep.org=
</A>=20
  </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Friday, February 28, 2014 =
3:44=20
  PM</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: LF: SL. 47 uHz vs. =
16 uHz @=20
  8270.005 Hz</DIV>
  <DIV><BR></DIV>
  <DIV class=3Dmoz-cite-prefix>Hi Peter and all,<BR><BR>Am 28.02.2014 =
16:21,=20
  schrieb PA1SDB, Peter:<BR></DIV>
  <BLOCKQUOTE cite=3Dmid:B288B88E668242CAA91FC4A2F15EA298@Extensa =
type=3D"cite">
    <META name=3DGENERATOR content=3D"MSHTML 8.00.6001.19088">
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    <DIV><FONT face=3DGeorgia>Hello VLF.</FONT></DIV>
    <DIV><FONT face=3DGeorgia>Just a experience message !</FONT></DIV>
    <DIV>&nbsp;</DIV>
    <DIV><FONT face=3DGeorgia>It seems that there is somewhere a perfect =
setting=20
    in "Width of FFT-bin", but where ?</FONT></DIV></BLOCKQUOTE><BR>A =
good=20
  question.. and not easily answered. I'd say "it all depends".<BR>In =
this case,=20
  it depends on the soundcard's oscillator stability, despite =
stabilisation from=20
  the GPS sync pulse.<BR>At 16 uHz frequency we seem to have reached a =
limit=20
  (for this type of oscillator drift compensation).<BR><BR>The next =
logical step=20
  would be building an A/D converter, or modifying a USB audio device to =
take=20
  the samping clock directly off a low-noise 'rock-solid reference' (a =
good GPS=20
  disciplined OCXO for example).<BR>I have fragments for such a project =
laying=20
  on the workbench (a low-cost Cortex-M3 microcontroller development =
kit) but no=20
  time yet to put the bits (bytes) and pieces together.<BR>At least, one =
would=20
  know of the Ionosphere (stability of the path length) or whatever else =
is the=20
  limiting factor.<BR><BR><BR>GL and all the best,<BR>&nbsp; Wolf=20
.<BR><BR></BLOCKQUOTE></BODY></HTML>

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