Message-ID: <4E3D859A.2060600@freenet.de>
Date: Sat, 06 Aug 2011 20:19:06 +0200
From: wolf_dl4yhf <dl4yhf@freenet.de>
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To: RSGB LF Group <rsgb_lf_group@blacksheep.org>
Subject: LF: Frequency / drift measurements (using SL, for G0BND)
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Hi Graham,

I tried to reply to you pm address, but your provider keeps bugging me 
with failed deliveries and error messages like

"We have limits for how many messages can be sent per hour and per day."

Nnnngrrrrr...


My excuse to the group for hijacking the reflector for the following 
response, which should have been sent directly.

You asked:
 >>>
Can  you  advise  on settings
I need  to  measure  the  drift  of TX , using  my  RA1778 (high  stab 
master osc)  / M-Delt 4   96K  sound   card  , to  produce audio   
frequency  of  1500 Hz
Ideal  would be  to  show   1 HZ  or  2 Hz   full  screen  (  1499 >  
1501) or     (  1499.5 > 1500.5)
If  I zoom  in  on the   frequency , the  display becomes  very  ''block 
like''
The  measurements  need  to  be  60  seconds apart , to  give a  drift  
from  cold  plot
Q  Is  it  possible to make  such  measurements   ?
<<<

If the measurements may only be 60 Hz apart, the normal FFT will not 
give the ultimate resolution (thus the screen will look block like when 
zooming in). With a measurement time of 60 seconds, the best you can get 
is something around 1/60s = 16.6 mHz effective resolution.

There are two alternatives:
A - use the experimental "time/frequency reassigned spectrogram" (it 
gives a readout resolution which is MUCH better than the FFT resolution 
dictated by the FFT length). Details about this rarely used function are 
here:

http://www.qsl.net/dl4yhf/speclab/ra_spectrogram.htm



B - use the 'phase-and-amplitude' monitor. If only produces numeric 
output (no waterfall-like display), but you could plot the frequencies 
in the 'watch window'. The phase/amplitude monitor function can also 
measure frequencies. Details are here:

http://www.qsl.net/dl4yhf/speclab/phase_amplitude_monitor.htm


For a start, the reassigned spectrogram may be the easier alternative. 
There are a few preconfigured settings which you can recall through the 
'Quick Settings' menu.

Hope this helps,
   73,   Wolf .

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    Hi Graham,<br>
    <br>
    I tried to reply to you pm address, but your provider keeps bugging
    me with failed deliveries and error messages like <br>
    <br>
    "We have limits for how many messages can be sent per hour and per
    day."<br>
    <pre wrap="">
Nnnngrrrrr...
</pre>
    <br>
    My excuse to the group for hijacking the reflector for the following
    response, which should have been sent directly.<br>
    <br>
    You asked:<br>
    &gt;&gt;&gt; <br>
    <div><font size="2" face="Arial">Can  you  advise  on settings </font></div>
    <div> </div>
    <div><font size="2" face="Arial">I need  to  measure  the  drift  of
        TX , using  my  RA1778 (high  stab master osc)  / M-Delt 4   96K
         sound   card  , to  produce audio   frequency  of  1500 Hz </font></div>
    <div> </div>
    <div><font size="2" face="Arial">Ideal  would be  to  show   1 HZ 
        or  2 Hz   full  screen  (  1499  &gt;  1501) or     (  1499.5 
        &gt; 1500.5)  </font></div>
    <div> </div>
    <div><font size="2" face="Arial">If  I zoom  in  on the   frequency
        , the  display becomes  very  ''block like''  </font></div>
    <div> </div>
    <div><font size="2" face="Arial">The  measurements  need  to  be 
        60  seconds apart , to  give a  drift  from  cold  plot </font></div>
    <div> </div>
    <font size="2" face="Arial">Q  Is  it  possible to make  such 
      measurements   ?<br>
      &lt;&lt;&lt;<br>
      <br>
    </font> If the measurements may only be 60 Hz apart, the normal FFT
    will not give the ultimate resolution (thus the screen will look
    block like when zooming in). With a measurement time of 60 seconds,
    the best you can get is something around 1/60s = 16.6 mHz effective
    resolution. <br>
    <br>
    There are two alternatives:<br>
    A - use the experimental "time/frequency reassigned spectrogram" (it
    gives a readout resolution which is MUCH better than the FFT
    resolution dictated by the FFT length). Details about this rarely
    used function are here:<br>
    <br>
    <a class="moz-txt-link-freetext"
      href="http://www.qsl.net/dl4yhf/speclab/ra_spectrogram.htm">http://www.qsl.net/dl4yhf/speclab/ra_spectrogram.htm</a><br>
    <br>
    <br>
    <br>
    B - use the 'phase-and-amplitude' monitor. If only produces numeric
    output (no waterfall-like display), but you could plot the
    frequencies in the 'watch window'. The phase/amplitude monitor
    function can also measure frequencies. Details are here:<br>
    <br>
    <a class="moz-txt-link-freetext"
      href="http://www.qsl.net/dl4yhf/speclab/phase_amplitude_monitor.htm">http://www.qsl.net/dl4yhf/speclab/phase_amplitude_monitor.htm</a><br>
    <br>
    <br>
    For a start, the reassigned spectrogram may be the easier
    alternative. There are a few preconfigured settings which you can
    recall through the 'Quick Settings' menu.<br>
    <br>
    Hope this helps,<br>
      73,   Wolf .
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