Re: [time-nuts] Overheard from NASA
On 05/10/2011 02:21 AM, Jim Lux wrote: A USO (quartz oscillator in a temperature controlled dewar) isn't in this class of performance (and is big and power hungry to boot). If you had a good onboard oscillator, you can do VLBI type measurements to measure not only range, but angle to a higher precision than is currently possible. Would CSAC type of oscillator be of use? Fairly small, fairly power starved. 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] Overheard from NASA
I suspect that was his point, beneath the hyperbole. And, yes, we will. On Tue, May 10, 2011 at 9:20 PM, Chuck Forsberg WA7KGX N2469R c...@omen.comwrote: It's NASA's job to push technology. That was half the reason for the moon project. If we get a $5 10-14 XO we'll find a use for it, no? On 05/09/2011 08:25 AM, William H. Fite wrote: Overheard from a senior NASA research metrologist: The only reason we're doing it is because we *can* (improving clock accuracy, said in the context of the aluminum clock). We can already time so accurately, just as an example, that if we launched a spacecraft today toward Sirius we could predict its location when the craft arrived many thousands of years from now, to within a thousand miles or so. That's not a precise quote but it is a close paraphrase. Heck, I thought that was why time nuts did it, anyway. Because it's there. George Mallory, 1924 ___ 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. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] Overheard from NASA
The problem is to fit the x-ray pulsar into the spacecraft without a) killing everyone and b) collapsing the spacecraft under its gravitational field :-) Regards, David Partridge -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: 10 May 2011 04:46 To: Discussion of precise time and frequency measurement Cc: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Overheard from NASA And if someone figures out how to use xray pulsars in a flight qualified way, ___ 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] Overheard from NASA
Why xray pulsars? Millisecond pulsars have shown themselves to be very accurate - wouldn't an ensemble of those be a better choice? Jim On 10 May 2011 13:45, Jim Lux jim...@earthlink.net wrote: I wasn't intending to cast aspersions... I was more giving an example of somewhere that atomic clocks need more work. And, I'm pleased that this group/list exists.. It's pointed me towards some useful stuff to solve some problems with the KaTS, and, as well, the archives are a great resource to which to point colleagues for help on Allan dev, etc. FWIW, for flight, the hot ticket is going to be Hg ion, if they can ever get it qualified...the physics package is pretty well there, but the rest is slogging along. And if someone figures out how to use xray pulsars in a flight qualified way, we'll fall on them with gratitude. On May 9, 2011, at 18:37, William H. Fite omni...@gmail.com wrote: Jim, keep in mind that that was not my statement but one made to a small group of people, including me, over at the Cape. The guy is a PhD (I know, I know, I am too, and what does it get me?) senior research scientist at NASA whose specialty is metrology. Now, you may be convinced that he is a complete idiot but I work with NASA quite often and I can assure you that they don't hire idiots as senior research scientists. I'm a statistician and in no way qualified even to have an opinion on this topic. Just thought it might interest the group. Bill On Mon, May 9, 2011 at 8:21 PM, Jim Lux jim...@earthlink.net wrote: On 5/9/11 8:25 AM, William H. Fite wrote: Overheard from a senior NASA research metrologist: The only reason we're doing it is because we *can* (improving clock accuracy, said in the context of the aluminum clock). We can already time so accurately, just as an example, that if we launched a spacecraft today toward Sirius we could predict its location when the craft arrived many thousands of years from now, to within a thousand miles or so. That's not a precise quote but it is a close paraphrase. Heck, I thought that was why time nuts did it, anyway. When it comes to good clocks on spacecraft, we're a long way away from better than we need, particularly for small power/mass/volume. Having a atomic clock on board would let you do things like one-way ranging, particularly techniques such as delta DOR, which can give you cross range measurements (i.e. azimuth). Knowing the position to 1000s of km may not be particularly useful, even at long distances, but as a practical matter, we want to know distances to cm or mm at Jupiter or Saturn distances. Given that Jupiter is about 600-800E9 meters away (call it a round 1E12 meters), that's a precision of 1 part in, say, 1E14. We use precise measurements of range rate (on the order of mm/s) to determine the gravity field, and from that the internal structure of a planet. The Juno spacecraft has a coherent transponder that contributes Allan deviation of around 1E-15 or 1E-16 over 1000 seconds, with the rest of the measurement system (transmitter on earth, receiver on earth, propagation uncertainty at 32/34 GHz) contributing roughly comparable amounts. The transponder (KaTS) receives a signal at 34 GHz from earth at a fairly low SNR and generates a carrier at 32 GHz with a fixed ratio of phase/frequency to transmit back. The SNR is limited by the power we can transmit on Earth (tens of kW, with BIG antenna gain) and the size of the antenna on Juno. IF we had a good clock on board, we wouldn't need to worry about the transmitter on earth and one way propagation uncertainty for the outbound path. A USO (quartz oscillator in a temperature controlled dewar) isn't in this class of performance (and is big and power hungry to boot). If you had a good onboard oscillator, you can do VLBI type measurements to measure not only range, but angle to a higher precision than is currently possible. ___ 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. ___ 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] Overheard from NASA
I suppose that Jim refers to receive the signal from the already avaliable and conveniently fitted ones (at a safe distance from the spacecraft and users :) ) instead of having one on-board Regards, Javier El 10/05/2011 12:22, David C. Partridge escribió: The problem is to fit the x-ray pulsar into the spacecraft without a) killing everyone and b) collapsing the spacecraft under its gravitational field :-) Regards, David Partridge -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: 10 May 2011 04:46 To: Discussion of precise time and frequency measurement Cc: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Overheard from NASA And if someone figures out how to use xray pulsars in a flight qualified way, ___ 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] Overheard from NASA
On 10 May 2011 22:56, Javier Herrero jherr...@hvsistemas.es wrote: I suppose that Jim refers to receive the signal from the already avaliable and conveniently fitted ones (at a safe distance from the spacecraft and users :) ) instead of having one on-board Just to point out, I guess you may have overlooked the smiley at the end of David's post. Regards, Steve Regards, Javier El 10/05/2011 12:22, David C. Partridge escribió: The problem is to fit the x-ray pulsar into the spacecraft without a) killing everyone and b) collapsing the spacecraft under its gravitational field :-) Regards, David Partridge -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: 10 May 2011 04:46 To: Discussion of precise time and frequency measurement Cc: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Overheard from NASA And if someone figures out how to use xray pulsars in a flight qualified way, ___ 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. -- Steve Rooke - ZL3TUV G8KVD The only reason for time is so that everything doesn't happen at once. - Einstein ___ 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] Overheard from NASA
On 5/10/11 3:43 AM, Jim Palfreyman wrote: Why xray pulsars? Millisecond pulsars have shown themselves to be very accurate - wouldn't an ensemble of those be a better choice? Jim I think it's an energy/flux density thing. you need a big antenna to detect the millisecond pulsars.. bigger than will fit on a spacecraft a few meters on a side. Cassini was huge (4+ meters in diameter, maybe twice that long), but a lot of spacecraft are much smaller. The vault on Juno is about a 1 meter cube. ___ 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] Overheard from NASA
On 5/10/11 3:56 AM, Javier Herrero wrote: I suppose that Jim refers to receive the signal from the already avaliable and conveniently fitted ones (at a safe distance from the spacecraft and users :) ) instead of having one on-board Yes.. I've been working on a portable one in my garage...I think that's a suitable time-nutty project, eh? My wife likes the fact that the gravitation field is sucking in and crushing all the junk I've collected over the years, but it does make it inconvenient in other ways.grin jim ___ 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] Overheard from NASA
El 10/05/2011 15:10, Steve Rooke escribió: Just to point out, I guess you may have overlooked the smiley at the end of David's post. I did not ;) Did you see mine? (I was just too tempted) Regards Javier -- Javier HerreroEMAIL: jherr...@hvsistemas.com Chief Technology Officer HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.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] Overheard from NASA
On 11 May 2011 01:21, Javier Herrero jherr...@hvsistemas.es wrote: El 10/05/2011 15:10, Steve Rooke escribió: Just to point out, I guess you may have overlooked the smiley at the end of David's post. I did not ;) Did you see mine? (I was just too tempted) I don't blame you but did you see the implied smiley in my posting. Shame you can't just pick off a jam jar sized piece of one of these to put inside the spacecraft :) Best regards, Steve Regards Javier -- Javier Herrero EMAIL: jherr...@hvsistemas.com Chief Technology Officer HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.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. -- Steve Rooke - ZL3TUV G8KVD The only reason for time is so that everything doesn't happen at once. - Einstein ___ 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] Overheard from NASA
El 10/05/2011 16:22, Steve Rooke escribió: On 11 May 2011 01:21, Javier Herrerojherr...@hvsistemas.es wrote: El 10/05/2011 15:10, Steve Rooke escribió: Just to point out, I guess you may have overlooked the smiley at the end of David's post. I did not ;) Did you see mine? (I was just too tempted) I don't blame you but did you see the implied smiley in my posting. Yes, I saw lol :) Shame you can't just pick off a jam jar sized piece of one of these to put inside the spacecraft :) Perhaps we can joint Jim's project of a garage-built portable one... but probably we will be sucked and crushed along with all his junk... ;) Best regards, Javier Best regards, Steve Regards Javier ___ 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] Overheard from NASA
It's NASA's job to push technology. That was half the reason for the moon project. If we get a $5 10-14 XO we'll find a use for it, no? On 05/09/2011 08:25 AM, William H. Fite wrote: Overheard from a senior NASA research metrologist: The only reason we're doing it is because we *can* (improving clock accuracy, said in the context of the aluminum clock). We can already time so accurately, just as an example, that if we launched a spacecraft today toward Sirius we could predict its location when the craft arrived many thousands of years from now, to within a thousand miles or so. That's not a precise quote but it is a close paraphrase. Heck, I thought that was why time nuts did it, anyway. Because it's there. George Mallory, 1924 ___ 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. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] Overheard from NASA
On 5/9/11 8:25 AM, William H. Fite wrote: Overheard from a senior NASA research metrologist: The only reason we're doing it is because we *can* (improving clock accuracy, said in the context of the aluminum clock). We can already time so accurately, just as an example, that if we launched a spacecraft today toward Sirius we could predict its location when the craft arrived many thousands of years from now, to within a thousand miles or so. That's not a precise quote but it is a close paraphrase. Heck, I thought that was why time nuts did it, anyway. When it comes to good clocks on spacecraft, we're a long way away from better than we need, particularly for small power/mass/volume. Having a atomic clock on board would let you do things like one-way ranging, particularly techniques such as delta DOR, which can give you cross range measurements (i.e. azimuth). Knowing the position to 1000s of km may not be particularly useful, even at long distances, but as a practical matter, we want to know distances to cm or mm at Jupiter or Saturn distances. Given that Jupiter is about 600-800E9 meters away (call it a round 1E12 meters), that's a precision of 1 part in, say, 1E14. We use precise measurements of range rate (on the order of mm/s) to determine the gravity field, and from that the internal structure of a planet. The Juno spacecraft has a coherent transponder that contributes Allan deviation of around 1E-15 or 1E-16 over 1000 seconds, with the rest of the measurement system (transmitter on earth, receiver on earth, propagation uncertainty at 32/34 GHz) contributing roughly comparable amounts. The transponder (KaTS) receives a signal at 34 GHz from earth at a fairly low SNR and generates a carrier at 32 GHz with a fixed ratio of phase/frequency to transmit back. The SNR is limited by the power we can transmit on Earth (tens of kW, with BIG antenna gain) and the size of the antenna on Juno. IF we had a good clock on board, we wouldn't need to worry about the transmitter on earth and one way propagation uncertainty for the outbound path. A USO (quartz oscillator in a temperature controlled dewar) isn't in this class of performance (and is big and power hungry to boot). If you had a good onboard oscillator, you can do VLBI type measurements to measure not only range, but angle to a higher precision than is currently possible. ___ 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] Overheard from NASA
Jim, keep in mind that that was not my statement but one made to a small group of people, including me, over at the Cape. The guy is a PhD (I know, I know, I am too, and what does it get me?) senior research scientist at NASA whose specialty is metrology. Now, you may be convinced that he is a complete idiot but I work with NASA quite often and I can assure you that they don't hire idiots as senior research scientists. I'm a statistician and in no way qualified even to have an opinion on this topic. Just thought it might interest the group. Bill On Mon, May 9, 2011 at 8:21 PM, Jim Lux jim...@earthlink.net wrote: On 5/9/11 8:25 AM, William H. Fite wrote: Overheard from a senior NASA research metrologist: The only reason we're doing it is because we *can* (improving clock accuracy, said in the context of the aluminum clock). We can already time so accurately, just as an example, that if we launched a spacecraft today toward Sirius we could predict its location when the craft arrived many thousands of years from now, to within a thousand miles or so. That's not a precise quote but it is a close paraphrase. Heck, I thought that was why time nuts did it, anyway. When it comes to good clocks on spacecraft, we're a long way away from better than we need, particularly for small power/mass/volume. Having a atomic clock on board would let you do things like one-way ranging, particularly techniques such as delta DOR, which can give you cross range measurements (i.e. azimuth). Knowing the position to 1000s of km may not be particularly useful, even at long distances, but as a practical matter, we want to know distances to cm or mm at Jupiter or Saturn distances. Given that Jupiter is about 600-800E9 meters away (call it a round 1E12 meters), that's a precision of 1 part in, say, 1E14. We use precise measurements of range rate (on the order of mm/s) to determine the gravity field, and from that the internal structure of a planet. The Juno spacecraft has a coherent transponder that contributes Allan deviation of around 1E-15 or 1E-16 over 1000 seconds, with the rest of the measurement system (transmitter on earth, receiver on earth, propagation uncertainty at 32/34 GHz) contributing roughly comparable amounts. The transponder (KaTS) receives a signal at 34 GHz from earth at a fairly low SNR and generates a carrier at 32 GHz with a fixed ratio of phase/frequency to transmit back. The SNR is limited by the power we can transmit on Earth (tens of kW, with BIG antenna gain) and the size of the antenna on Juno. IF we had a good clock on board, we wouldn't need to worry about the transmitter on earth and one way propagation uncertainty for the outbound path. A USO (quartz oscillator in a temperature controlled dewar) isn't in this class of performance (and is big and power hungry to boot). If you had a good onboard oscillator, you can do VLBI type measurements to measure not only range, but angle to a higher precision than is currently possible. ___ 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] Overheard from NASA
I wasn't intending to cast aspersions... I was more giving an example of somewhere that atomic clocks need more work. And, I'm pleased that this group/list exists.. It's pointed me towards some useful stuff to solve some problems with the KaTS, and, as well, the archives are a great resource to which to point colleagues for help on Allan dev, etc. FWIW, for flight, the hot ticket is going to be Hg ion, if they can ever get it qualified...the physics package is pretty well there, but the rest is slogging along. And if someone figures out how to use xray pulsars in a flight qualified way, we'll fall on them with gratitude. On May 9, 2011, at 18:37, William H. Fite omni...@gmail.com wrote: Jim, keep in mind that that was not my statement but one made to a small group of people, including me, over at the Cape. The guy is a PhD (I know, I know, I am too, and what does it get me?) senior research scientist at NASA whose specialty is metrology. Now, you may be convinced that he is a complete idiot but I work with NASA quite often and I can assure you that they don't hire idiots as senior research scientists. I'm a statistician and in no way qualified even to have an opinion on this topic. Just thought it might interest the group. Bill On Mon, May 9, 2011 at 8:21 PM, Jim Lux jim...@earthlink.net wrote: On 5/9/11 8:25 AM, William H. Fite wrote: Overheard from a senior NASA research metrologist: The only reason we're doing it is because we *can* (improving clock accuracy, said in the context of the aluminum clock). We can already time so accurately, just as an example, that if we launched a spacecraft today toward Sirius we could predict its location when the craft arrived many thousands of years from now, to within a thousand miles or so. That's not a precise quote but it is a close paraphrase. Heck, I thought that was why time nuts did it, anyway. When it comes to good clocks on spacecraft, we're a long way away from better than we need, particularly for small power/mass/volume. Having a atomic clock on board would let you do things like one-way ranging, particularly techniques such as delta DOR, which can give you cross range measurements (i.e. azimuth). Knowing the position to 1000s of km may not be particularly useful, even at long distances, but as a practical matter, we want to know distances to cm or mm at Jupiter or Saturn distances. Given that Jupiter is about 600-800E9 meters away (call it a round 1E12 meters), that's a precision of 1 part in, say, 1E14. We use precise measurements of range rate (on the order of mm/s) to determine the gravity field, and from that the internal structure of a planet. The Juno spacecraft has a coherent transponder that contributes Allan deviation of around 1E-15 or 1E-16 over 1000 seconds, with the rest of the measurement system (transmitter on earth, receiver on earth, propagation uncertainty at 32/34 GHz) contributing roughly comparable amounts. The transponder (KaTS) receives a signal at 34 GHz from earth at a fairly low SNR and generates a carrier at 32 GHz with a fixed ratio of phase/frequency to transmit back. The SNR is limited by the power we can transmit on Earth (tens of kW, with BIG antenna gain) and the size of the antenna on Juno. IF we had a good clock on board, we wouldn't need to worry about the transmitter on earth and one way propagation uncertainty for the outbound path. A USO (quartz oscillator in a temperature controlled dewar) isn't in this class of performance (and is big and power hungry to boot). If you had a good onboard oscillator, you can do VLBI type measurements to measure not only range, but angle to a higher precision than is currently possible. ___ 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.
