Re: [time-nuts] Neat little cesium box
Greg, the only power source I am aware off that can provide the ~5W power required by that Novus box for 10-12 years with 20lbs weight limit without any external power sources or maintenance is a radioisotope thermoelectric generator (RTG) such as those used on Spacecraft. The Russians used to use those also in light houses. Maybe the atomic decay could be counted and used for improving timing some how?! That said the radiation would probably have a very negative effect on any electronics near it for long-term stability. I would also not call that solution disposable anywhere on earth. Definitely not hobby level stuff.. bye, Said In a message dated 6/13/2013 17:15:45 Pacific Daylight Time, engineer...@mt.net writes: Tom, Thank you for your concern. I unfortunately cannot disclose many details about the proposed project only to say that the application transcends much of the typical Time-Nuts areas of normality. At present we are evaluating typical frequency references to see if they will fit into this project. What I can say is that phase noise is of little interest but log-term frequency drift is. The completed unit will unfortunately not see GPS signals during most of its lifetime, be constrained to a weight not exceeding 20 lbs, be considered non-recoverable (disposable) due to areas of deployment thereby require a relatively cost-conscious design, have no access to a source of power let alone any natural power-producing resources and have an expected lifetime of 10-12 years without maintenance access. Most of the problems have been solved including the power source. This is not your typical kitchen table project. And, as new frequency references are developed and the design feasibility phase is still open, small and minimal power-consuming products such as the Novus unit will garner our attention. Thanks for your offer, Greg ___ 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] Neat little cesium box
Sounds like a space based systemPerhaps those mining probes Sent from my iPhone On Jun 14, 2013, at 2:11 AM, saidj...@aol.com wrote: Greg, the only power source I am aware off that can provide the ~5W power required by that Novus box for 10-12 years with 20lbs weight limit without any external power sources or maintenance is a radioisotope thermoelectric generator (RTG) such as those used on Spacecraft. The Russians used to use those also in light houses. Maybe the atomic decay could be counted and used for improving timing some how?! That said the radiation would probably have a very negative effect on any electronics near it for long-term stability. I would also not call that solution disposable anywhere on earth. Definitely not hobby level stuff.. bye, Said In a message dated 6/13/2013 17:15:45 Pacific Daylight Time, engineer...@mt.net writes: Tom, Thank you for your concern. I unfortunately cannot disclose many details about the proposed project only to say that the application transcends much of the typical Time-Nuts areas of normality. At present we are evaluating typical frequency references to see if they will fit into this project. What I can say is that phase noise is of little interest but log-term frequency drift is. The completed unit will unfortunately not see GPS signals during most of its lifetime, be constrained to a weight not exceeding 20 lbs, be considered non-recoverable (disposable) due to areas of deployment thereby require a relatively cost-conscious design, have no access to a source of power let alone any natural power-producing resources and have an expected lifetime of 10-12 years without maintenance access. Most of the problems have been solved including the power source. This is not your typical kitchen table project. And, as new frequency references are developed and the design feasibility phase is still open, small and minimal power-consuming products such as the Novus unit will garner our attention. Thanks for your offer, Greg ___ 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] Neat little cesium box
On Thu, 13 Jun 2013 18:15:25 -0600 Gregory Muir engineer...@mt.net wrote: Most of the problems have been solved including the power source. This is not your typical kitchen table project. And, as new frequency references are developed and the design feasibility phase is still open, small and minimal power-consuming products such as the Novus unit will garner our attention. If you are weight limited, then i'd use the CSAC directly instead of a packaged version like the Novus box. You will save quite a bit. You also want to temperature stabilize it, as this will probably be the major source for long term instability. After that comes probably the frequency wander of its small Cs vapor cell. Alternatively, look for a supplier of a Rb vapor cell that uses coherent population trapping (CPT) for interrogation instead of the standard microwave cavity vapor cells. These should be smaller and a bit more stable. But i don't think they have been around long enough for reliable long term data (at least i'm not aware of any). Also, it might be worth checking out spectratime, who are building the hydrogen masers for the Galileo satelites. Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] Neat little cesium box
Most RTG sources use Plutonium 238 or Strontium 90. Primary decay component is Alpha particles which can be stopped dead by a few mm of shielding. Good article on Wikipedia: http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of saidj...@aol.com Sent: Friday, June 14, 2013 00:11 To: time-nuts@febo.com Subject: Re: [time-nuts] Neat little cesium box Greg, the only power source I am aware off that can provide the ~5W power required by that Novus box for 10-12 years with 20lbs weight limit without any external power sources or maintenance is a radioisotope thermoelectric generator (RTG) such as those used on Spacecraft. The Russians used to use those also in light houses. Maybe the atomic decay could be counted and used for improving timing some how?! That said the radiation would probably have a very negative effect on any electronics near it for long-term stability. I would also not call that solution disposable anywhere on earth. Definitely not hobby level stuff.. bye, Said In a message dated 6/13/2013 17:15:45 Pacific Daylight Time, engineer...@mt.net writes: Tom, Thank you for your concern. I unfortunately cannot disclose many details about the proposed project only to say that the application transcends much of the typical Time-Nuts areas of normality. At present we are evaluating typical frequency references to see if they will fit into this project. What I can say is that phase noise is of little interest but log-term frequency drift is. The completed unit will unfortunately not see GPS signals during most of its lifetime, be constrained to a weight not exceeding 20 lbs, be considered non-recoverable (disposable) due to areas of deployment thereby require a relatively cost-conscious design, have no access to a source of power let alone any natural power-producing resources and have an expected lifetime of 10-12 years without maintenance access. Most of the problems have been solved including the power source. This is not your typical kitchen table project. And, as new frequency references are developed and the design feasibility phase is still open, small and minimal power-consuming products such as the Novus unit will garner our attention. Thanks for your offer, Greg ___ 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] Neat little cesium box
On 6/14/13 10:55 AM, DaveH wrote: Most RTG sources use Plutonium 238 or Strontium 90. Primary decay component is Alpha particles which can be stopped dead by a few mm of shielding. Good article on Wikipedia: http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator Dave but not ALL the radiation is alpha particles. It also generates some x rays (up to about 100keV and gammas (up to about 1 MeV). Sure, the fraction is very tiny, but when you have a lot of disintegrations/second, even a small percentage can add up (this is the problem with so-called aneutronic fusion reactions) ___ 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] Neat little cesium box
Am looking at a small cesium standard for a proposed client project: http://synreference.com/frequency-references/cesium-reference/item/37-portable-battery-powered-reference.html Greg ___ 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] Neat little cesium box
Am looking at a small cesium standard for a proposed client project: Greg, That URL confuses atom with performance. Calling something cesium in no way conveys the actual accuracy or stability of the device actually being offered for sale. A CSAC is not a 5071A is not a cesium fountain is not a GPSDO. That's why we use statistics (ADEV) instead of the periodic table. In recent years small, compact, low-voltage, low-power TCXO, OCXO, rubidium, and cesium oscillators allow companies sell products called quartz, rubidium, and cesium with no regard to actual time or frequency or noise specifications and performance plots. Even snake oil has an ADEV. Contact me *off-line* about your client and your actual requirements. /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.
Re: [time-nuts] Neat little cesium box
On Thu, 13 Jun 2013 10:25:52 -0600 Gregory Muir engineer...@mt.net wrote: Am looking at a small cesium standard for a proposed client project: http://synreference.com/frequency-references/cesium-reference/item/37-portable-battery-powered-reference.html The datasheet of this neat little thingy sound very much like they put a CSAC into a black box. Heck, they even took the wording from the CSAC description: --- [...]Two orders of magnitude better accuracy than oven-controlled crystal oscillators (OCXOs) -- and up to four orders of magnitude better accuracy than temperature-controlled oscillators (TCXOs). An outstanding reference for field applications when an OCXO is not sufficient without the complications of a GPS based reference. --- versus --- At two orders of magnitude better accuracy than oven-controlled crystal oscillators (OCXOs) — and up to four orders of magnitude better accuracy than temperature-controlled oscillators (TCXOs) — the CSAC’s unmatched portability opens the door to new classes of applications, such as [...] --- If i were you, i would take Tom up on his offer to review your clients requirements. He knows the stuff around all this mess we have with frequency standards :) Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] Neat little cesium box
Tom, Thank you for your concern. I unfortunately cannot disclose many details about the proposed project only to say that the application transcends much of the typical Time-Nuts areas of normality. At present we are evaluating typical frequency references to see if they will fit into this project. What I can say is that phase noise is of little interest but log-term frequency drift is. The completed unit will unfortunately not see GPS signals during most of its lifetime, be constrained to a weight not exceeding 20 lbs, be considered non-recoverable (disposable) due to areas of deployment thereby require a relatively cost-conscious design, have no access to a source of power let alone any natural power-producing resources and have an expected lifetime of 10-12 years without maintenance access. Most of the problems have been solved including the power source. This is not your typical kitchen table project. And, as new frequency references are developed and the design feasibility phase is still open, small and minimal power-consuming products such as the Novus unit will garner our attention. Thanks for your offer, Greg On Thu, 13 Jun 2013 10:59:01 -0700, Tom Van Baak wrote: Greg, That URL confuses atom with performance. Calling something cesium in no way conveys the actual accuracy or stability of the device actually being offered for sale. A CSAC is not a 5071A is not a cesium fountain is not a GPSDO. That's why we use statistics (ADEV) instead of the periodic table. In recent years small, compact, low-voltage, low-power TCXO, OCXO, rubidium, and cesium oscillators allow companies sell products called quartz, rubidium, and cesium with no regard to actual time or frequency or noise specifications and performance plots. Even snake oil has an ADEV. Contact me *off-line* about your client and your actual requirements. /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.
Re: [time-nuts] Neat little cesium box
Without spilling too many more details, can you say approximately what level of frequency accuracy or stability you need per year? Also, to the nearest decade, what is relatively cost-conscious design? I ask because a CSAC costs on the order of 1500. Note it runs out of the box (you don't need to buy from a third party in a fancy enclosure). If you don't need that level of long-term performance consider a high-performance TCXO. If power is a much greater limiting factor than budget use both; fire up the CSAC once a day (or week, etc.) for a few minutes to correct the VCTCXO. That way you get both low power and high accuracy. /tvb - Original Message - From: Gregory Muir engineer...@mt.net To: time-nuts@febo.com Sent: Thursday, June 13, 2013 5:15 PM Subject: [time-nuts] Neat little cesium box Tom, Thank you for your concern. I unfortunately cannot disclose many details about the proposed project only to say that the application transcends much of the typical Time-Nuts areas of normality. At present we are evaluating typical frequency references to see if they will fit into this project. What I can say is that phase noise is of little interest but log-term frequency drift is. The completed unit will unfortunately not see GPS signals during most of its lifetime, be constrained to a weight not exceeding 20 lbs, be considered non-recoverable (disposable) due to areas of deployment thereby require a relatively cost-conscious design, have no access to a source of power let alone any natural power-producing resources and have an expected lifetime of 10-12 years without maintenance access. Most of the problems have been solved including the power source. This is not your typical kitchen table project. And, as new frequency references are developed and the design feasibility phase is still open, small and minimal power-consuming products such as the Novus unit will garner our attention. Thanks for your offer, Greg On Thu, 13 Jun 2013 10:59:01 -0700, Tom Van Baak wrote: Greg, That URL confuses atom with performance. Calling something cesium in no way conveys the actual accuracy or stability of the device actually being offered for sale. A CSAC is not a 5071A is not a cesium fountain is not a GPSDO. That's why we use statistics (ADEV) instead of the periodic table. In recent years small, compact, low-voltage, low-power TCXO, OCXO, rubidium, and cesium oscillators allow companies sell products called quartz, rubidium, and cesium with no regard to actual time or frequency or noise specifications and performance plots. Even snake oil has an ADEV. Contact me *off-line* about your client and your actual requirements. /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.
