Re: [time-nuts] GPS 1 PPS accuracy limits
Hi Does accuracy include temperature change over -55 to +85 C at a 1 C / minute rate? Is accuracy measured after a 5 minute cold start at any temperature? Does accuracy include a contribution internal to the synthesizer (like DDS step size)? Is accuracy simply where we set it when we shipped it? There are *lots* of variations to this particular spec Bob On Apr 20, 2010, at 5:59 PM, saidj...@aol.com wrote: Hi Magnus, Life speed, what does accuracy mean? Average (rms, 1-Sigma) frequency accuracy? If yes, over what time frame is the average? Or is this the peak to peak allowable deviation? Over what temperature range, and after how long of a warmup? To give you an example, a typical Fury desktop unit with DOCXO is capable of better than 2us holdover drift per day after 3 to 5 days of constant operation. That equates to an average frequency accuracy over one day without GPS of 2.3 x 10^-11. With GPS the accuracy on average is better than 2E-012 after about an hour or so averaging. bye, Said In a message dated 4/20/2010 13:07:53 Pacific Daylight Time, mag...@rubidium.dyndns.org writes: life speed wrote: Time Nuts; I have a customer request for a microwave frequency synthesizer with extreme accuracy requirements; 4 X 10^-11, or 0.04 PPB. Obviously this is way out of quartz oscillator territory. Is GPS 1 pulse-per-second useable, or do they need an atomic clock? Maybe they don't realize what they are spec'ing. I really think you should ask them to motivate themselves on that spec, the intended use etc. They can certainly get a spec like that, but is it what they need? You certainly want something like a GPS clock to feed that thing if they really need that level of accuracy. Or do they only need that level of resolution? Cheers, Magnus ___ 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] GPS 1 PPS accuracy limits
Date: Tue, 20 Apr 2010 18:59:20 -0700 From: jimlux jim...@earthlink.net Subject: Re: [time-nuts] GPS 1 PPS accuracy limits Do they have other requirements (Allan deviation? phase noise?) Over what time span do they want 4E-11 accuracy? 1 second, 1000 seconds, days? A synthesizer locked to a Stanford Research PRS10 (datasheet accuracy 5E-11) is in that ballpark. They have phase noise requirements, which aren't achievable for the price they want to pay. But phase noise is determined by the OCXO and other circuitry. I suspect the most likely answer is they wrote the spec wrong, and don't really mean 1 Hz absolute accuracy. I'll talk to them and clarify. ___ 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] GPS 1 PPS accuracy limits
life speed wrote: Time Nuts; I have a customer request for a microwave frequency synthesizer with extreme accuracy requirements; 4 X 10^-11, or 0.04 PPB. Obviously this is way out of quartz oscillator territory. Is GPS 1 pulse-per-second useable, or do they need an atomic clock? Maybe they don't realize what they are spec'ing. I really think you should ask them to motivate themselves on that spec, the intended use etc. They can certainly get a spec like that, but is it what they need? You certainly want something like a GPS clock to feed that thing if they really need that level of accuracy. Or do they only need that level of resolution? Cheers, Magnus ___ 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] GPS 1 PPS accuracy limits
Hi What is their calibration interval and environment? With GPS you will have the usual when locked and stable disclaimer. With some cost / effort you can get limited holdover at that level. For a true good for a year/running autonomously, type spec - you need a cesium standard. Getting one that will meet a rugged environment spec may be difficult. I'd bet the spec you are looking at has / should have a sub-spec that reads when locked to an external reference. The implication being that the reference is exactly on frequency. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of life speed Sent: Tuesday, April 20, 2010 1:27 PM To: time-nuts@febo.com Subject: [time-nuts] GPS 1 PPS accuracy limits Time Nuts; I have a customer request for a microwave frequency synthesizer with extreme accuracy requirements; 4 X 10^-11, or 0.04 PPB. Obviously this is way out of quartz oscillator territory. Is GPS 1 pulse-per-second useable, or do they need an atomic clock? Maybe they don't realize what they are spec'ing. ___ 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] GPS 1 PPS accuracy limits
Hi Magnus, Life speed, what does accuracy mean? Average (rms, 1-Sigma) frequency accuracy? If yes, over what time frame is the average? Or is this the peak to peak allowable deviation? Over what temperature range, and after how long of a warmup? To give you an example, a typical Fury desktop unit with DOCXO is capable of better than 2us holdover drift per day after 3 to 5 days of constant operation. That equates to an average frequency accuracy over one day without GPS of 2.3 x 10^-11. With GPS the accuracy on average is better than 2E-012 after about an hour or so averaging. bye, Said In a message dated 4/20/2010 13:07:53 Pacific Daylight Time, mag...@rubidium.dyndns.org writes: life speed wrote: Time Nuts; I have a customer request for a microwave frequency synthesizer with extreme accuracy requirements; 4 X 10^-11, or 0.04 PPB. Obviously this is way out of quartz oscillator territory. Is GPS 1 pulse-per-second useable, or do they need an atomic clock? Maybe they don't realize what they are spec'ing. I really think you should ask them to motivate themselves on that spec, the intended use etc. They can certainly get a spec like that, but is it what they need? You certainly want something like a GPS clock to feed that thing if they really need that level of accuracy. Or do they only need that level of resolution? Cheers, Magnus ___ 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] GPS 1 PPS accuracy limits
life speed wrote: Time Nuts; I have a customer request for a microwave frequency synthesizer with extreme accuracy requirements; 4 X 10^-11, or 0.04 PPB. Obviously this is way out of quartz oscillator territory. Is GPS 1 pulse-per-second useable, or do they need an atomic clock? Maybe they don't realize what they are spec'ing. Do they have other requirements (Allan deviation? phase noise?) Over what time span do they want 4E-11 accuracy? 1 second, 1000 seconds, days? A synthesizer locked to a Stanford Research PRS10 (datasheet accuracy 5E-11) is in that ballpark. ___ 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.
