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John:<br>
<br>
If it is taking a total of 16 seconds to complete a cycle on the
beat indicator,<br>
then, yes, your error is about 1/16 of a Hertz. Since the Excalibur
oscillator<br>
can walk around a half Hertz with day-night temperature changes,
there is no<br>
reason to try to set it any closer than that.<br>
<br>
If you are using a known accurate reference, then do NOT use the 10
MHz<br>
calibrate function in PowerSDR. Or set it to no-correction. In
that case,<br>
the frequency accuracy of the HPSDR system is that of the reference.<br>
<br>
The accuracy of the auto frequency calibration mechanism in PowerSDR
is <br>
plus/minus one panadaptor bin, which is much greater than the
fraction<br>
of a Hertz that you just set on your Excalibur. <br>
<br>
From memory, one panadaptor bin is your sample rate divided by 4096,
<br>
so about 48 kHz/4096 = 11 Hz.<br>
<br>
If you know your reference is accurate, then you are better off NOT
also using<br>
the auto-calibrate function.<br>
<br>
--- Graham / KE9H<br>
<br>
==<br>
<br>
On 4/2/2012 1:47 PM, John Westmoreland wrote:
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cite="mid:CAFtYB4x6W41jeZXQp6TWEyNG6nvn6K6SuAvp2hkvnouge82UiA@mail.gmail.com"
type="cite">
<pre wrap="">***** High Performance Software Defined Radio Discussion List *****
</pre>
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<br>
HPSDR,
<div><br>
</div>
<div>Borrowed a Rubidium Standard from AE6PM - to calibrate
Excalibur - have a few questions - </div>
<div><br>
</div>
<div>Is it possible the Green LED, for instance, could stay on for
a shorter period of time than the Red LED if there is an issue
with phase? Or maybe duty-cycle?</div>
<div><br>
</div>
<div>I currently have Excalibur adjusted so it is about 8-seconds
Green LED on; 8-seconds Red LED on - so I suppose that is good.</div>
<div><br>
</div>
<div>Note when I got this adjustment to work - seemed like the
on-times for both LED's stabilized a bit. (Rubidium Standard
was warmed up of-course and locked.)</div>
<div><br>
</div>
<div>I then ran the 10MHz calibrate function on PowerSDR. If the
above is indeed working - then my error is 1/16 Hz - correct?</div>
<div><br>
</div>
<div>73's,</div>
<div>John</div>
<div>AJ6BC</div>
<div><br>
</div>
<br>
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