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Date: Tue, 17 Nov 2015 16:23:43 +0000
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From: Andy Talbot <andy.g4jnt@gmail.com>
To: rsgb_lf_group@blacksheep.org, rsgb_lf_group@yahoogroups.co.uk
Subject: LF: Re: EbNaut test transmission
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Its still going.
At 1611z I ran rsNTP and it made a PC clock adjustment of 0.4 seconds,
which with the 0.5s symbols used for this transmission will glitch
slightly .

Pleased to note that a local recording I made using the  new LF Receiver
hardware and my own software to generate a .WAV file compatible with
Spectrum Lab's did generate a valid decode. Recorded at fs = 31.25Hz  That
was before the PC time had been corrected and I had to do a fair bit of
shuffling with the Start Offset value to get a decode.   Values from 0.45s
to 0.85s worked - much of that presumably due to the PC time offset in the
transmission.   But once a value in that range had been entered, zero
decode errors - which is what one would expect of a very strong local copy !

It does appear that using EbNaut with rates much faster that 2S/s could end
up very fraught with timing offsets.  Fortunately, weak signalling with
longer symbols of several seconds will have less of a problem with timing
offsets.


Andy  G4JNT

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<div dir=3D"ltr"><div class=3D"gmail_quote"><div>Its still going.</div><div=
>At 1611z I ran rsNTP and it made a PC clock adjustment of 0.4 seconds, whi=
ch with the 0.5s symbols used=C2=A0for this transmission will glitch slight=
ly=C2=A0.</div><div><br></div><div>Pleased to note that=C2=A0a local record=
ing I made using the=C2=A0 new LF Receiver hardware and my own software to =
generate a .WAV file compatible with Spectrum Lab&#39;s did generate a vali=
d decode. Recorded at fs =3D 31.25Hz=C2=A0 That was before the PC time had =
been corrected and I had to do a fair bit of shuffling with the Start Offse=
t value to get a decode.=C2=A0=C2=A0 Values from 0.45s to 0.85s worked - mu=
ch of that presumably due to the PC time offset in the transmission.=C2=A0=
=C2=A0 But once a value in that range had been entered, zero decode errors =
- which is what one would expect of a very strong local copy !</div><div><b=
r></div><div>It does appear that using EbNaut with rates much faster that 2=
S/s could end up very fraught with timing offsets.=C2=A0 Fortunately, weak =
signalling with longer symbols of several seconds=C2=A0will=C2=A0have less =
of a problem=C2=A0with timing offsets.</div></div><p><br></p><div>Andy=C2=
=A0 G4JNT</div><div><br></div><div class=3D"gmail_extra"><br></div></div>

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