[time-nuts] Injection locking interconnect

Jim Lux jimlux at earthlink.net
Thu Jun 28 22:15:26 UTC 2012


On 6/28/12 3:07 PM, Bill Dailey wrote:
> Guys,
>
> I am looking for info on injection locking.  I have been searching around for info.  I found an article that probably answers my question but I can't get to it.
>
> http://www.oldcitypublishing.com/FullText/JAPEDfulltext/JAPED2.1fulltext/11-24pp%20GC05-06%20%28Rajput%29.pdf
>
> Can anyone give me a reference regarding the required interconnection?  I understand the ho and why... I just am wondering how you make sure locking occurs in the right direction.  In other words the target oscillator gets locked to the injected signal and not the other way around.
>
> The application is a synthesized frequency source injection locking a tcxo to improve phase noise.
>

What you might look for is literature on "coupled oscillators", for 
which there is quite a lot.

If you have something like an isolator or other non-reciprocal device, 
then you can make sure that power flows mostly from good to bad.

I believe, also, that it has to do with the relative Q of the two 
oscillators.  The higher Q (e.g. stiffer) will drive the lower (softer), 
for equal powers transferred in each direction and equal powers out of 
the oscillators.  One way to look at it is that there is more stored 
energy in the resonator of the higher Q oscillator (Q = stored 
energy/output energy), so the "contaminating" energy has a smaller 
relative effect.

One can also demonstrate this nicely with a pair of coupled pendulums 
with different weights on the bob. (strings on a broomstick work nicely) 
with equal weights, the power couples back and forth periodically.  With 
one heavy and one light, the light one always follows the heavy.






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