> First getting 1 E-13 per second accuracy is not possible with a FE5680 > because of tuning steps of 6.8 E-13. Even 1 E-12 may not be possible.
Bert, I'm pretty sure the short-term noise of Rb standards like FE5680 is significantly greater than the DAC resolution in your case. See the ADEV plot at http://www.ke5fx.com/rb.htm for example. Therefore -- all you have to do is dither the DAC to achieve whatever fractional frequency or phase resolution you want. You can change the DDS tuning words almost as many times per minute or per second as you wish to achieve the desired average accuracy. Don't let the LSB spec limit you. Remember all our discussions about frequency and phase tuning words on your AD9913 project (www.leapsecond.com/pages/ad9913/). /tvb _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
