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From: =?UTF-8?Q?Wolfgang_B=c3=bcscher?= <dl4yhf@freenet.de>
Message-ID: <932b67ff-64a8-1004-ac28-14176950d3df@freenet.de>
Date: Tue, 25 Oct 2016 12:52:47 +0200
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Subject: Re: LF: Idiot's guide to receiving Ebnaut? - Tutorial part2
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It will possibly work if the software (SL) would not expect a 'normal' 
rectangular pulse, look for the "valid" low->high transition (because 
some cards have the bad habit of inverting the polarity), expect a 
minium amplitude (to tell the PPS- from the NMEA signal that is 
optionally fed into the soundcard on the *same wire*), etc.

http://www.qsl.net/dl4yhf/speclab/GPS_pps_nmea_combiner.png

But out of curiosity, I will experiment with such an "almost-Dirac" 
pulse myself, and see what arrives after the signal passed through the 
soundcard's sigm-delta converter.

Cheers,
    Wolf .


Am 24.10.2016 um 22:22 schrieb Andy Talbot:
> Won't the sound card's input filter, the anti-alias filter, extend 
> this pulse, however short it is, into something the sampling rate will 
> always see?  So there is no need to deliberately lenghen it.
>
> The only real advantage to doing so, perhaps, would be to increase the 
> pulse energy within a one sample period leading to a hight amplitude 
> in the capture.
>
> The 1 PPS from my HP-5061 is only 1us in width, but can still be 
> detected on a soundcard stream at any sampling rate chosen.
>
> Andy  G4JNT
>
>
> On 24 October 2016 at 21:07, Wolfgang Büscher <dl4yhf@freenet.de 
> <mailto:dl4yhf@freenet.de>> wrote:
>
>     Hello Jim,
>
>     I still wonder why the sync pulses from the Thunderbolt E are so
>     short - you mentioned 10 us in your email, but what is the exact
>     pulse length ? With a slightly modified software (SL) it may be
>     possible to use them as they are.. if they are longer than a
>     sample from the soundcard.
>
>     73,
>        Wolf DL4YHF
>       (not QRV on LF+MF unfortunately..)
>


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    It will possibly work if the software (SL) would not expect a
    'normal' rectangular pulse, look for the "valid" low-&gt;high
    transition (because some cards have the bad habit of inverting the
    polarity), expect a minium amplitude (to tell the PPS- from the NMEA
    signal that is optionally fed into the soundcard on the *same
    wire*), etc.<br>
    <br>
    <a class="moz-txt-link-freetext" href="http://www.qsl.net/dl4yhf/speclab/GPS_pps_nmea_combiner.png">http://www.qsl.net/dl4yhf/speclab/GPS_pps_nmea_combiner.png</a><br>
    <br>
    But out of curiosity, I will experiment with such an "almost-Dirac"
    pulse myself, and see what arrives after the signal passed through
    the soundcard's sigm-delta converter.<br>
    <br>
    Cheers,<br>
       Wolf .<br>
    <br>
    <br>
    <div class="moz-cite-prefix">Am 24.10.2016 um 22:22 schrieb Andy
      Talbot:<br>
    </div>
    <blockquote
cite="mid:CAA8k23QEk2PtiXm2s_YctZMiByyM_DopEdz6eRg3e=e-QPz_VA@mail.gmail.com"
      type="cite">
      <div dir="ltr">Won't the sound card's input filter, the anti-alias
        filter, extend this pulse, however short it is, into something
        the sampling rate will always see?  So there is no need to
        deliberately lenghen it.  
        <div><br>
        </div>
        <div>The only real advantage to doing so, perhaps, would be to
          increase the pulse energy within a one sample period leading
          to a hight amplitude in the capture.</div>
        <div><br>
        </div>
        <div>The 1 PPS from my HP-5061 is only 1us in width, but can
          still be detected on a soundcard stream at any sampling rate
          chosen.</div>
        <div><br>
        </div>
        <div>Andy  G4JNT</div>
        <div><br>
        </div>
        <div class="gmail_extra"><br>
          <div class="gmail_quote">On 24 October 2016 at 21:07, Wolfgang
            Büscher <span dir="ltr">&lt;<a moz-do-not-send="true"
                href="mailto:dl4yhf@freenet.de" target="_blank">dl4yhf@freenet.de</a>&gt;</span>
            wrote:<br>
            <blockquote class="gmail_quote" style="margin:0 0 0
              .8ex;border-left:1px #ccc solid;padding-left:1ex">
              <div bgcolor="#FFFFFF" text="#000000"> Hello Jim,<br>
                <br>
                I still wonder why the sync pulses from the Thunderbolt
                E are so short - you mentioned 10 us in your email, but
                what is the exact pulse length ? With a slightly
                modified software (SL) it may be possible to use them as
                they are.. if they are longer than a sample from the
                soundcard.<br>
                <br>
                73,<br>
                   Wolf DL4YHF <br>
                  (not QRV on LF+MF unfortunately..)<br>
              </div>
            </blockquote>
          </div>
        </div>
      </div>
    </blockquote>
    <br>
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