Re: [time-nuts] Centering ocxo
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 hmur...@megapathdsl.net wrote: docdai...@gmail.com 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-c. 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 -- time-nuts@febo.com 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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Centering ocxo
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 docdai...@gmail.com 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 hmur...@megapathdsl.net wrote: docdai...@gmail.com 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-c. 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 -- time-nuts@febo.com 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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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.
Re: [time-nuts] Centering ocxo
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 saidj...@aol.com 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 docdai...@gmail.com 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 hmur...@megapathdsl.net wrote: docdai...@gmail.com 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-c. 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 -- time-nuts@febo.com 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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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. ___ 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.
Re: [time-nuts] Centering ocxo
Please don't adjust the dampening, you might find it floating... adjust the damping if you need to change the settling time. Yours in pedantry-one of my hot buttons :-) Don Bill Dailey 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 hmur...@megapathdsl.net wrote: docdai...@gmail.com 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-c. 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 -- time-nuts@febo.com 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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ 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.
Re: [time-nuts] Centering ocxo
docdai...@gmail.com 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-c. 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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
