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<DIV><SPAN class=187273203-13012013><FONT face=Arial><FONT color=#0000ff><FONT
size=2><SPAN
class=890574214-14012013>
</SPAN>Hi Joe, Dave,</FONT></FONT></FONT></SPAN></DIV>
<BLOCKQUOTE style="MARGIN-RIGHT: 0px" dir=ltr>
<DIV><SPAN class=187273203-13012013><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV><SPAN class=187273203-13012013><FONT color=#0000ff size=2
face=Arial>Thank you for your comments.</FONT></SPAN></DIV>
<DIV><SPAN class=187273203-13012013><FONT color=#0000ff size=2
face=Arial>Dave's reply reminded me of some discussion on the list. I searched
e-mails by a keyword "frequency", then I found mails whose title is
"Frequency Calibration in PowerSDR" dated in 2012, two years
back.</FONT></SPAN></DIV>
<DIV><SPAN class=187273203-13012013><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV><SPAN class=187273203-13012013><FONT color=#0000ff size=2 face=Arial>I've
never done the frequency calibration with HPSDR neither with Hermes so
far.</FONT></SPAN></DIV>
<DIV><SPAN class=187273203-13012013><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV><SPAN class=187273203-13012013>
<DIV><SPAN class=187273203-13012013><FONT color=#0000ff size=2
face=Arial>Joe's case is quite good -0.000 00000 030 at 3530KHz, by that my
OCXO is very poor, but t</FONT></SPAN></SPAN><SPAN
class=187273203-13012013><FONT color=#0000ff size=2 face=Arial>he transmit
frequency difference between HPSDR and Hermes exits in may
case.</FONT></SPAN></DIV></DIV>
<DIV><SPAN class=187273203-13012013><SPAN class=187273203-13012013><FONT
color=#0000ff size=2 face=Arial>So the suspicious part in case of my
Hermes might be OCXO used, so I used two different OCXOs for Hermes there was
no change between them. However I didn't verify the clock just in the Hermes
board.</FONT></SPAN></SPAN></DIV>
<DIV><SPAN class=187273203-13012013><SPAN class=187273203-13012013><FONT
color=#0000ff size=2 face=Arial>There was a loose contact in the connector of
10MHz. The output level of OCXO is 1.7dBm terminated to 50ohm, but the level
at the board e.g., at C215 was around -30dBm.</FONT></SPAN></SPAN></DIV>
<DIV><SPAN class=187273203-13012013><SPAN class=187273203-13012013><FONT
color=#0000ff size=2 face=Arial>That was the cause. Now the transmit frequency
by Hermes is quite correct in terms of my OCXO
accuracy.</FONT></SPAN></SPAN></DIV>
<DIV><SPAN class=187273203-13012013><SPAN class=187273203-13012013><FONT
color=#0000ff size=2 face=Arial></FONT></SPAN></SPAN> </DIV>
<DIV><SPAN class=187273203-13012013><SPAN class=187273203-13012013><FONT
color=#0000ff size=2 face=Arial>Thank you again.</FONT></SPAN></SPAN></DIV>
<DIV><SPAN class=187273203-13012013><SPAN class=187273203-13012013><FONT
color=#0000ff size=2 face=Arial></FONT></SPAN></SPAN> </DIV>
<DIV><SPAN class=187273203-13012013><SPAN class=187273203-13012013><FONT
color=#0000ff size=2 face=Arial>73</FONT></SPAN></SPAN></DIV>
<DIV><SPAN class=187273203-13012013><SPAN class=187273203-13012013><FONT
color=#0000ff size=2 face=Arial>Tokio Endo</FONT></SPAN></SPAN></DIV>
<DIV><SPAN class=187273203-13012013><SPAN class=187273203-13012013><FONT
color=#0000ff size=2 face=Arial>JA1CCA</FONT></SPAN></DIV></SPAN>
<DIV><SPAN class=187273203-13012013><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV><SPAN class=187273203-13012013><FONT color=#0000ff size=2
face="ＭＳ Ｐゴシック"></FONT></SPAN> </DIV>
<DIV><SPAN class=187273203-13012013><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<BLOCKQUOTE style="MARGIN-RIGHT: 0px" dir=ltr>
<DIV dir=ltr class=OutlookMessageHeader align=left><FONT size=2
face=Tahoma>-----Original Message-----<BR><B>From:</B> Joe Martin K5SO
[mailto:k5so@valornet.com]<BR><B>Sent:</B> Sunday, January 13, 2013 3:23
AM<BR><B>To:</B> Tokio Endo<BR><B>Cc:</B>
hpsdr@lists.openhpsdr.org<BR><B>Subject:</B> Re: [hpsdr] Further
Information: Help Needed: PowerSDR TX
FrequencyInaccuracy<BR><BR></FONT></DIV>Hi Tokio,
<DIV><BR></DIV>
<DIV>The absolute frequency accuracy issue has been discussed here
previously. As Dave mentioned, the finite size CORDIC steps
necessarily result in less-than-perfect frequency output for some frequency
selections and this is highly dependent upon the exact frequency specified.
Some frequencies are essentially perfect whereas others suffer
somewhat, just as you indicate. However, I have never found any
frequency more than 1Hz off here, with most frequency selections yielding
errors of less than a few tens of milli-Hertz absolute error. </DIV>
<DIV><BR></DIV>
<DIV>The specific frequency of 3.530 000 you mention yields only a -0.000
000 030 MHz error (-30 milli-Hertz error) here on my system when running
with a Rb-vapor frequency standard into the 10 MHz ext 10MHz clock port on
Hermes (and properly selected via J20 on Hermes, of course!), as measured
using an HP-5345A counter locked to a second Rb-vapor frequency standard.
</DIV>
<DIV><BR></DIV>
<DIV>If, on the other hand, I do not use the ext 10 MHz input ref clock but
use the on board 10 MHz osc on Hermes I observe a +2.903 Hz error at 3.530
000 Tx; not surprisingly. </DIV>
<DIV><BR></DIV>
<DIV>I don't observe any unreasonalble/unexpected behavior at all with
frequency accuracy here. </DIV>
<DIV><BR></DIV>
<DIV>73, Joe K5SO</DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
<DIV>
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