How to configure pxi-6653 to take external reference and provide 10MHz referance

[gsrikanth]

Hi,

I would like to know if I can configure NI PXI 6653 timing module to take an external clock (say 19.2 MHz) and provide a 10MHz output which is in sync with the input clock.

The 10MHz clock output from the PXI should be in sync with the input clock (say 19.2MHz). I would like to use this to sync all the instrumentation.

Thanks,

[KyleTTU]

Hi gsirkanth, 

May I ask what the overall goal of this system is?  I ask because what you are requesting isn't really possible.  There isn't a way to modify the PXI 10 MHz timebase so that it aligns to your 19.2 MHz and you can not have two clocks on the backplane without using a STAR line. 

What we can do is to use the 6653 to Phase Lock Loop (PLL) your 19.2MHz signal to the 10 MHz TCXO onboard oscillator of the 6653 and then use that to drive the backplane clock. This would create a 10 MHz clock signal that is disciplined to your 19.2 MHz, however will be as accurate as your 19.2 MHz.  So the next question is how accurate is this external clock source?  

If you use the NI Sync command to PLL the external source to the TCXO oscillator and then use that to overide the backplane clock we can then export that signal to clock out (which will be a 10 MHz signal PLL'ed with the 19.2 MHz) but you wont have the 19.2 MHz anywhere on the chassis. 

Regards, 

Kyle S

[Robert__R]

gsirkanth,

The 6653 can't lock to a 19.2 MHz clock because it can only lock to multiples of 1 MHz (19 MHz would work, but not 19.2 MHz).  The OCXO on the 6653 is also quite accurate and stable, so it can't lock to things that aren't pretty close to what they're supposed to be.  Otherwise it works like Kyle stated.

- Robert