Thanks Said. This is a learning experience but it is fun watching it settle down. I will stop fiddling with the settings and just let it do it's thing. I am watching the output with my qs1r direct digital to spectrumlab. This way I don't have to worry about any audio glitches. I have been recording frequency every minute the entire time to see what it is doing.
Sent from mobile On Oct 3, 2012, at 10:39 AM, Said Jackson <[email protected]> wrote: > Doc, > > You are on the right track, efc scale affects SD as you can see. > > The phaseco parameter is used to push down the average TI to 0ns. Higher > values push faster. > > If your ocxo is still drifting (aging and or retrace) it will take about 48 > hours for the aging measurement and correction to kick in, and bring the > offset down to 0ns. > > Bye > Said > > Sent From iPhone > > On Oct 3, 2012, at 3:46, Bill Dailey <[email protected]> wrote: > >> ok.. So that may very well be true of this unit. Electrical tuning is >> 3E-7 0 - 5v (+/-). It also lists a digital tuning range of +- 3Hz at >> 10MHz. Correct me if I am wrong but that appears to mean 3Hz electrical >> and 6Hz digital tuning range. I am not doing digital tuning but thought I >> would throw that out there. >> >> I have been trying to "optimize" parameters on this Fury board but it seems >> my "optimization" has just been increasing the deviation. Running 1.8 ns >> sd overnight with an average TI of about 26ns (was with my "optimized" >> settings)...the original settings were giving me a much lower deviation...I >> didnt log it but looking at the graph of frequency in excel I would say >> probably between 0.1-0.6 ns. I just put it back on the original settings >> and am letting it settle now. Was adjusting Dampening, EFCSCALE and DAC >> gain. My observations reveal dampening makes it a bit slower to respond >> and perhaps settles it some, The efcscale seems to act as pure gain on top >> of the baseline dac gain which is essentially determined by the tuning >> range as you referred to. What I saw with a low efcscale is that the TI >> was higher but the SD lower... with efc scale higher the TI was lower but >> the SD suffered. >> >> Since my goal here is low noise and very good short term stability I prefer >> the lower efcscale (low gain with low SD). >> >> Let me know if I have any gross conceptual errors here or if I am looking >> at this properly. >> >> Doc >> KX0O >> >> >> On Tue, Oct 2, 2012 at 11:54 PM, Hal Murray <[email protected]> wrote: >> >>> >>> [email protected] said: >>>> I am ok for awhile but how do you center the efc of an ocxo? I >>> understand >>>> there is something (screw) to adjust the ocxo so it is approximately on >>> freq >>>> with 2.5v efc. >>> >>>> Specific oscillator datum-1111c. I have he datasheet but doesn't say >>> "coarse >>>> frequency adjust this screw" or some such. >>> >>> There may not be a coarse adjustment. If the tuning range is big enough to >>> cover the aging over your design life, you don't need one. >>> >>> >>> There is a tradeoff between adjustment range and the number of bits you >>> need >>> in a DAC to get a required accuracy. >>> >>> Suppose I have an adjustment range of 1 Hz (peak to peak) on a 10 MHz >>> oscillator. That's 1 part is 10^7. If I have a 10 bit DAC, I can adjust >>> to >>> 1 part is 10^10. A 20 bit DAC can get to 1 part is 10^13. >>> >>> But if the tuning range is 10 Hz, the same 20 bit DAC setup only gets you >>> to >>> 1 part is 10^12. >>> >>> >>> >>> -- >>> These are my opinions. I hate spam. >>> >>> >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> >> >> >> -- >> Doc >> >> Bill Dailey >> KXØO >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
