[time-nuts] Synchronisizing a 100MHz TCXO with Tbold

EWKehren at aol.com EWKehren at aol.com
Tue Sep 20 01:01:06 UTC 2011


Peter, it will be difficult to degrade -138dBc/10kHz using a ADF 4001. I  
have PLL's using selected $ 1.00  Xtals getting better than  -153dBc/10kHz. 
.Axtal has units with -174dBC  but out of most price ranges  but I thought 
you were looking at below -150,very doable with ADF 4001.
Bert
 
 
In a message dated 9/19/2011 5:53:22 P.M. Eastern Daylight Time,  
krengeldatec at gmx.de writes:

Thank  you all for your suggestions.

@ Attila:
I think your suggestion  would be "a little bit"
too complicated. I dont want to write a  dissertation :))
My idea was to simply get a low jitter out of the  100MHz
TCXO clocking the FPGA etc..
The fine TCXO I like to use is a  AXLE20-12 from AXTAL.
I think its expensive enough for my experiments  (about 100,- EUR) and it 
also
got a electronic frequency control input  as well as a even much
more expensive OCXO which would cost me 180,- EUR or  more.
As I said as the ADCs are working in cascade they have to  be
enabled and disabled as exact as possible to avoid sampling errors.
A  jittering clock would do a bad job in that circuit while long time  
stability is not a problem.

@ Chuck:
A good idea in principle  but I only have one tbold which
controlles all my measurement equipment  like spectrum analyzer,
signal generators a.s.o. I also dont know whether a  synchronisation
of the 100MHz TCXO to the tbold will really give me
a  better noise figure than running the TCXO stand alone.
The TCXO I like to  use gives me a low noise of -138dBc/10kHz
and as far as I know tbold comes  with -142 or even better.
So the main question is whether a synchronisation  will give
better results or not. If so an additional effect would be  the
fact that all equipment is then working synchronous. The ADCs
I use  will get a part of a homemade 1GHz DSO.

@ Bert:
Thank you for the  hint. I think to use a ADF4001 is an easy task
so I like to start my  experience first using your idea.

Again thank you for even more  suggestions.
Regards
Peter, DG4EK  


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