Date: Tue, 5 Jul 2016 17:23:45 +0200
From: Michel Brunel <f5wk@mterrier.net>
Message-ID: <1172051038.20160705172345@mterrier.net>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <577BC820.9090809@posteo.de>
References: <5772DAC0.7080001@df3lp.de> <CAA8k23TGuNuOZcnJA42=EDxZgHMAVNeq9SM7=UhvTz6Noqa_FA@mail.gmail.com> <5773CA12.50009@posteo.de> <5773D53A.5070900@abelian.org> <577B9E96.8070807@posteo.de> <577BC820.9090809@posteo.de>
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Subject: Re: LF: Portable VLF/ULF recording system with PPS+NMEA
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Hallo Stefan,

Looks promising, what sound card are you using and if you can read it, what=
 is the audio codec chip ? =20
I recently tried to replace the 12 MHz crystal of a CUA-202, but the onchip=
 PLL of the PCM2902 ruined my effort (too bad a jitter)

For my future Ebnaut operation,  I just set up a "Stratum 1 time box" with =
a Raspberry PI2 and a tiny GPS receiver (VK16E)
The 1PPS is directly sent to a GPIO and managed by the kernel (Raspbian Jes=
sie) NTPQ reports an accuracy of 2E-19 which
translates to 2 ms=20
Ah, Wolf's ntp client works like a charm with the Rpi ntp server !  That's =
a great internet free solution.

73,

Michel - f5wk


Le mardi 5 juillet 2016 =C3=A0 16:45:52, DK7FC =C3=A9crivait :

> Hi all,

> I've completed my portable VLF/ULF(audio) recording system.
> See:=20
> https://dl.dropboxusercontent.com/u/19882028/ULF/VLFesULF%20portable%20re=
cording.jpg


> The system consists out of a:
> - Raspberry Pi 2B
> - DC/DC converter with a 5.0V output (80% efficiency)
> - 7 Ah lead acid battery
> - Stereo input soundcard
> - 32 GB USB stick
> - NEO-6M GPS module (including antenna)
> - (shut down button)
> - (switch for starting/stopping a recording)

> The latest add-on, the GPS module now allows to record 1PPS impulses and=
=20
> NMEA data for most accurate and glitch-free(corrected) recordings,=20
> absolute timestamps as well as location data.
> The recording is stred as a wav file to the USB stick directly.
> It consumes 160 mA at 12V during a record. With the battery it should be=
=20
> no problem to record for nearly 2 days.
> Future ULF reception tests can now be done with this improved technique...

> 73, Stefan


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<html><head><title>Re: LF: Portable VLF/ULF recording system with PPS+NMEA<=
/title>
<META http-equiv=3DContent-Type content=3D"text/html; charset=3Dutf-8">
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<span style=3D" font-family:'Calibri'; font-size: 12pt;">Hallo Stefan,<br>
<br>
Looks promising, what sound card are you using and if you can read it, what=
 is the audio codec chip ? &nbsp;<br>
I recently tried to replace the 12 MHz crystal of a CUA-202, but the onchip=
 PLL of the PCM2902 ruined my effort (too bad a jitter)<br>
<br>
For my future Ebnaut operation, &nbsp;I just set up a "Stratum 1 time box" =
with a Raspberry PI2 and a tiny GPS receiver (VK16E)<br>
The 1PPS is directly sent to a GPIO and managed by the kernel (Raspbian Jes=
sie) NTPQ reports an accuracy of 2E-19 which<br>
translates to 2 ms&nbsp;<br>
Ah, Wolf's ntp client works like a charm with the Rpi ntp server ! &nbsp;Th=
at's a great internet free solution.<br>
<br>
73,<br>
<br>
Michel - f5wk<br>
<br>
<br>
<br>
Le mardi 5 juillet 2016 =C3=A0 16:45:52, DK7FC =C3=A9crivait :<br>
<br>
<span style=3D" font-family:'courier new'; font-size: 9pt; color: #800000;"=
><b>&gt; Hi all,<br>
<br>
&gt; I've completed my portable VLF/ULF(audio) recording system.<br>
&gt; See:&nbsp;<br>
</b></span></span><a style=3D" font-family:'courier new'; font-size: 9pt;" =
href=3D"https://dl.dropboxusercontent.com/u/19882028/ULF/VLFesULF%20portabl=
e%20recording.jpg">&gt; https://dl.dropboxusercontent.com/u/19882028/ULF/VL=
FesULF%20portable%20recording.jpg</a><br>
<br>
<br>
<span style=3D" font-family:'courier new'; font-size: 9pt; color: #800000;"=
><b>&gt; The system consists out of a:<br>
&gt; - Raspberry Pi 2B<br>
&gt; - DC/DC converter with a 5.0V output (80% efficiency)<br>
&gt; - 7 Ah lead acid battery<br>
&gt; - Stereo input soundcard<br>
&gt; - 32 GB USB stick<br>
&gt; - NEO-6M GPS module (including antenna)<br>
&gt; - (shut down button)<br>
&gt; - (switch for starting/stopping a recording)<br>
<br>
&gt; The latest add-on, the GPS module now allows to record 1PPS impulses a=
nd&nbsp;<br>
&gt; NMEA data for most accurate and glitch-free(corrected) recordings,&nbs=
p;<br>
&gt; absolute timestamps as well as location data.<br>
&gt; The recording is stred as a wav file to the USB stick directly.<br>
&gt; It consumes 160 mA at 12V during a record. With the battery it should =
be&nbsp;<br>
&gt; no problem to record for nearly 2 days.<br>
&gt; Future ULF reception tests can now be done with this improved techniqu=
e...<br>
<br>
&gt; 73, Stefan<br>
<br>
<br>
<br>
<br>
<br>
<br>
</b><span style=3D" font-family:'arial'; font-size: 8pt; color: #c0c0c0;"><=
i>--&nbsp;</body></html>
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