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Date: Sun, 18 Sep 2011 02:51:35 -0700
From: Scott Tilley <sthed475@telus.net>
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Subject: Re: LF: T/A ... and uHz grabber
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On 9/17/2011 1:54 PM, Markus Vester wrote:
> Scott, the slow SpecLab settings are fairly straightforward - I use 
> 11025 Hz samplerate, complex decimation by 768, FFT size 32768, and 
> 600 seconds per FFT.
Gotcha...  What I needed to reduce implementation time...  Mind you, 
I'll need to run at a higher sample rate, see below...

>  The center frequency and display offset will depend on your 
> receiver's precise LO frequency (watch out for DDS rounding errors).

132.000KHz. Will look at the actual 'delta phase word' and calculate 
true LO QRG for use as the new offset.
> Finally you will want to inject a known audio tone for samplerate 
> tracking (eg. GPS-derived 5 kHz), or alternatively 1-pps pulses plus 
> NMEA (which I haven't tried yet).

A GPS derived 10KHz signal is already injected into the audio stream and 
used for sample rate tracking on all grabber plots...  So good to go here...

I should have time to setup in a couple of days.

Scott

PS - YO 153KHz broadcaster noted for the first time this season.




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    On 9/17/2011 1:54 PM, Markus Vester wrote:
    <blockquote cite="mid:87921B1A33264C65B0A8BBEBBCBD1A04@White"
      type="cite">
      <div><font face="Arial" size="2">Scott, the slow SpecLab settings
          are&nbsp;fairly straightforward -&nbsp;I&nbsp;use 11025 Hz samplerate,
          complex decimation by 768,&nbsp;FFT size 32768, and 600 seconds per
          FFT.</font></div>
    </blockquote>
    Gotcha...&nbsp; What I needed to reduce implementation time...&nbsp; Mind you,
    I'll need to run at a higher sample rate, see below...<br>
    <br>
    <blockquote cite="mid:87921B1A33264C65B0A8BBEBBCBD1A04@White"
      type="cite">
      <div><font face="Arial" size="2">&nbsp;The&nbsp;center frequency and display
          offset will depend on your receiver's precise&nbsp;LO frequency
          (watch out for DDS rounding errors).</font></div>
    </blockquote>
    <br>
    132.000KHz. Will look at the actual 'delta phase word' and calculate
    true LO QRG for use as the new offset.<br>
    <blockquote cite="mid:87921B1A33264C65B0A8BBEBBCBD1A04@White"
      type="cite">
      <div><font face="Arial" size="2"> Finally&nbsp;you&nbsp;will want to&nbsp;inject
          a known audio tone&nbsp;for samplerate tracking (eg.&nbsp;GPS-derived 5
          kHz),&nbsp;or&nbsp;alternatively 1-pps pulses plus NMEA (which I haven't
          tried yet).</font></div>
      <div>&nbsp;</div>
    </blockquote>
    <br>
    A GPS derived 10KHz signal is already injected into the audio stream
    and used for sample rate tracking on all grabber plots...&nbsp; So good
    to go here...<br>
    <br>
    I should have time to setup in a couple of days.<br>
    <br>
    Scott<br>
    <br>
    PS - YO 153KHz broadcaster noted for the first time this season.<br>
    <br>
    <br>
    <br>
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