[hpsdr] Excalibur - Rubidium Standard Calibration Question - Phase Question

[Graham / KE9H]

John:

If it is taking a total of 16 seconds to complete a cycle on the beat 
indicator,
then, yes, your error is about 1/16 of a Hertz.  Since the Excalibur 
oscillator
can walk around a half Hertz with day-night temperature changes, there is no
reason to try to set it any closer than that.

If you are using a known accurate reference, then do NOT use the 10 MHz
calibrate function in PowerSDR.  Or set it to no-correction.  In that case,
the frequency accuracy of the HPSDR system is that of the reference.

The accuracy of the auto frequency calibration mechanism in PowerSDR is
plus/minus one panadaptor bin, which is much greater than the fraction
of a Hertz that you just set on your Excalibur.

 From memory, one panadaptor bin is your sample rate divided by 4096,
so about 48 kHz/4096 = 11 Hz.

If you know your reference is accurate, then you are better off NOT also 
using
the auto-calibrate function.

--- Graham / KE9H

==

On 4/2/2012 1:47 PM, John Westmoreland wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
>
> HPSDR,
>
> Borrowed a Rubidium Standard from AE6PM - to calibrate Excalibur - 
> have a few questions -
>
> 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?
>
> 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.
>
> 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.)
>
> I then ran the 10MHz calibrate function on PowerSDR.  If the above is 
> indeed working - then my error is 1/16 Hz - correct?
>
> 73's,
> John
> AJ6BC
>
>
>
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