Re: [time-nuts] How dangerous if a Rb lamp broken?
7. RbOs show up on ebay military black market (TM), an ATF sting operation, hugely overpriced... 8. The war on Rb goes on, hunting for the evil terrorists which purchased, and intend to use RbOs. 9. Time-n... err. terrorists get a drone visit, with some Hellfires placed through their chimney. 10. The MII complex is happily counting their profits, while the world is getting a safer place point 1 correction - it's DHS... not TSA. The TSA goons have still some time to wait until getting armed. For now they have to please themselves only with naked pictures, and groping genitalia, of the sheeple. On 7/10/2013 8:20 AM, Perry Sandeen wrote: Hui and all, You have absolutely NOTHING to fear. Here is why: If in the USA it was found that it MIGHT possibly hurt something on the endangered species list [Humans might count also in some situations.] The following would happen. 1. A Transportation Security Agency [1.6 Billion bullets and counting] heavily armed and masked SWAT team would appear at Rb owners houses. They know where we are thanks to NSA wire taps and the fact that every piece of mail in the US mail system is photocopied on each side and stored. 2. The rubidiums would be seized. Next: A. The owner would be fined for having an unregistered WMD. B. The owners name would go on a WMD offenders list. Offenders would have to report to the police wherever they live and would be barred from contact of anyone below the age of 18 and could not reside within one mile of a school. 3. The administration branch of our US government would declare that: The War On Dangerous Rb’s Has Been Won and the US citizens are now safer. 4. Bonus’s will be awarded. 5. Congressional oversight committees will ask the TSA what has been done with seized rubidiums. The TSA will not tell congress who authorized the seizer and where the Rubidiums are. Any TSA leaders subpoenaed will take the 5th amendment. Congress will get really, really mad and stop their feet. Nothing more will happen. It will fade away as the administration spokesman will say: “It is old news and really doesn’t matter compared to what I tell you today”. 6. Magically, as no one knows anything, the Rubidiums will end up in a third world country without environmental law to be salvaged and the sold to mainland China. See, it really is simple. Regards, Perrier ___ 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] Very stable synthesizer, alternative to PTS(Programmed Test Sources) x10 or 040?
Hi Having hooked up a 9854 and tried it with realistic settings - it's not that great. If you run it at magic frequencies (where it's essentially just a divider) it looks like a divider. Bob On Jul 9, 2013, at 5:03 AM, Anders Time anderst...@gmail.com wrote: Thanks a lot for the input. I have been looking at the Fluke 6160b, but I thought that there might be something as good out there that is not 40years old! I want to use the synthesizer as a flexible offset source for beat frequency measurements. So the frequency range is 5 to 30MHz approx. I read Rubiola et al. Phase noise and amplitude noise in DDS yesterday and thinks that it might be worth a try to test the AD9854 or AD9912 to see if it is good enough. If I understand the paper right they get really good results. Is there any one with experience? Thanks Anders ___ 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] How dangerous if a Rb lamp broken?
You must really be a legend in your own mind, and now, a self-proclaimed time-nuts cop. - Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Charles P. Steinmetz Sent: Wednesday, July 10, 2013 1:59 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] How dangerous if a Rb lamp broken? Perrier wrote: You have absolutely NOTHING to fear. Here is why Please keep your political comments to yourself and off the list (however humorous you might think they are). This is simply not the place for them. Thank you, Charles ___ 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] How dangerous if a Rb lamp broken?
Hello Charles: Don't worry about it, my brain auto ignore any comments of technology irrelevant. Hui At 2013-07-10 13:58:47,Charles P. Steinmetz charles_steinm...@lavabit.com wrote: Perrier wrote: You have absolutely NOTHING to fear. Here is why Please keep your political comments to yourself and off the list (however humorous you might think they are). This is simply not the place for them. Thank you, Charles ___ 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] How dangerous if Rb lamp broken?
Hello Robert: I am a little confuse how exactly much Rb87 in a bulb? Some people say that it's couple millgram, but you tell me it's half a millgram, which is ture? You message is good new to me, it let me relax, but I don’t understand Bq/gram unit, would you please convert it to mSV unit, I can know the how many mSV of human is safety by search by internet. I mean in extreme situration, if all Rb87 of buld sprinkled in my table, how many exposure value will I accepet in 24 Hour? I found some people (other electronics fan) wrote a formula about Rb87 radioactivity calculation, that is: 1mg Rubidium * 27.835 * 0.27835 * 6.02 *10^23 / 87/4.88/10^10/2/365/24/3600*1=625. So, decay energy=0.283MeV, about 600 electron per second, Is this calculation correct? 27.835=Percent of Rb87 6.02*10^23 = Avogadro's constant 87= Atomic weight 4.88*10^10== Half time of Rb87 (Year) 2 = Rb87 decay to half 365 = day of year 24 = hour of day 3600 = second of hour I am very glad to read many relay of my email, I want say thanks for everyone. As you said why people be afraid of Rb87 but not other things, I think maybe because we don’t understand it. Such as, I don’t afraid of RF exposure, because I know it, I am a HAM and learned many RF exposure knowledge, but of atom and radioactivity, I have only poor knowledge. Thanks everyone again, this is amazing mail-list. Say sorry for my poor English. Hui At 2013-07-09 19:40:50,Robert Atkinson robert8...@yahoo.co.uk wrote: Hi Hui, Most bulbs use a mix of Rb87 and Rb85 with an activity of around 1500 Bq/gram with less than half a millgram in a typical bulb, that's less than a Bq per bulb (about 20 picocuries). You will get more ardiation from using low sodium salt (potassium chloride) on your food. Potasium is essential for life and Rb is chemically similar. In short don't worry. Robert G8RPI (also a geiger nut and collector of radioactive material) From: Hui Zhang ba...@163.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, 9 July 2013, 5:07 Subject: [time-nuts] How dangerous if Rb lamp broken? Dear Group: I have four compact Rb Stanard, but I am worried about what if my Rb lamp broken in accident someday? How dangerous of this situration? Is Rb87 came out from Rb lamp will be a disaster? You know I haven't any beta rays detect instrument. Hui ___ 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] How dangerous if a Rb lamp broken?
I just tried calling your cell because you seem to be the legitimate person to ask. I don't read all the time-nuts postings but has anyone ever brought up the most logical aspect of ionizing radiation for the group: the radium dial wrist watch? or are they all too young to have experienced that? I think I got one for Christmas when I was 12 or 13. I'm still here at 74! I do think that all reflector's are at their best when they are entertaining---maybe not exactly on topic! Regards, Lee MushelI live about 20 miles from the Mississippi and 50 miles north of the Illinois border. We simply try to enjoy life, our garden, our flowers, our dogs and our cats. Best to stay away from neighbors and social media! - Original Message - From: Mike Feher mfe...@eozinc.com To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Wednesday, July 10, 2013 7:00 AM Subject: Re: [time-nuts] How dangerous if a Rb lamp broken? You must really be a legend in your own mind, and now, a self-proclaimed time-nuts cop. - Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell ___ 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] How dangerous if a Rb lamp broken?
Public perceptions of risk change with time. In WWII, Radium dial watches, aircraft instruments, dial and switch markings, were ubiquitous. But so were explosives, bombs, bayonettes, and a bunch of other things. So people didn't have the luxury of concerns over minor things. Now that is not so. -John === I just tried calling your cell because you seem to be the legitimate person to ask. I don't read all the time-nuts postings but has anyone ever brought up the most logical aspect of ionizing radiation for the group: the radium dial wrist watch? or are they all too young to have experienced that? I think I got one for Christmas when I was 12 or 13. I'm still here at 74! I do think that all reflector's are at their best when they are entertaining---maybe not exactly on topic! Regards, Lee MushelI live about 20 miles from the Mississippi and 50 miles north of the Illinois border. We simply try to enjoy life, our garden, our flowers, our dogs and our cats. Best to stay away from neighbors and social media! - Original Message - From: Mike Feher mfe...@eozinc.com To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Wednesday, July 10, 2013 7:00 AM Subject: Re: [time-nuts] How dangerous if a Rb lamp broken? You must really be a legend in your own mind, and now, a self-proclaimed time-nuts cop. - Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell ___ 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] How dangerous if a Rb lamp broken?
You're still here, but what about the young women who painted those watches who aren't? The problem was that they needed sharp points on the brushes to fill the tiny voids in the hands. So they twirled the brush tips between their lips. They could probably bring back radium dials today with no problem, because of automation. Bob - AE6RV From: Lee Mushel herbe...@centurytel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, July 10, 2013 10:14 AM Subject: Re: [time-nuts] How dangerous if a Rb lamp broken? I just tried calling your cell because you seem to be the legitimate person to ask. I don't read all the time-nuts postings but has anyone ever brought up the most logical aspect of ionizing radiation for the group: the radium dial wrist watch? or are they all too young to have experienced that? I think I got one for Christmas when I was 12 or 13. I'm still here at 74! ___ 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] Posting Rules
Charles wrote: Please keep your political comments to yourself and off the list (however humorous you might think they are). This is simply not the place for them. Charles, On the two lists we both subscribe to, you always seem to have something to say about almost every post. Often it falls into the category of Mother says: now don’t forget to do ___. (You can fill in the blank space.) I see you doing this in a very condescending manner. On the R-390 list, I’ve forgotten more about the R-390A receiver than you will ever know. I was trained on them, serviced them in the military, developed parts kits for them, wrote the Y2KR3 manual and have had a number of published technical articles about them. At least on the R 390A radio you have done nothing that I’m aware of and I follow information on it very carefully. You don’t own or administer this list. All members have the right to make civil posts of their opinion whether others agree with them on not. My mother died many years ago and I don’t need you to be her replacement. You have the same privilege of all of us to post or delete. Kind Regards, Perrier ___ 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] Lead acid battery noise levels
a...@bardagjy.com said: The SRS 560 and 570, low noise voltage and current preamplifiers respectively, both use bog standard sealed lead acid batteries. Is that to reduce power supply noise or to get a clean ground that isn't connected to wall power? -- 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.
Re: [time-nuts] How dangerous if a Rb lamp broken?
The watch workers were a tragedy, based on ignorance of the risks. At the time, there were probably only a handful of people who'd ever sustained injury from radioactive materials. It's not clear that the bosses even knew the women were putting the brushes in their mouths or that they knew the risks. These kind of things do happen. Consider Asbestos, DES, Thalidomide, Phen-Phen, Avandia, etc. However, that does not excuse the media, public interest groups, or especially government for hyping risk totally out of proportion for their self-serving political ends. I think the bigger risk from a broken Rb bulb would come from the glass shards. -John === You're still here, but what about the young women who painted those watches who aren't? The problem was that they needed sharp points on the brushes to fill the tiny voids in the hands. So they twirled the brush tips between their lips. They could probably bring back radium dials today with no problem, because of automation. Bob - AE6RV From: Lee Mushel herbe...@centurytel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, July 10, 2013 10:14 AM Subject: Re: [time-nuts] How dangerous if a Rb lamp broken? I just tried calling your cell because you seem to be the legitimate person to ask. I don't read all the time-nuts postings but has anyone ever brought up the most logical aspect of ionizing radiation for the group: the radium dial wrist watch? or are they all too young to have experienced that? I think I got one for Christmas when I was 12 or 13. I'm still here at 74! ___ 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] Posting Rules
Perrier You are out of line Charles is right on, this list has deteriorated that many of us are now off list conducting time nuts business, the looser is the list which has deteriorated in to a chat room and 90%+ messages are deleted because they are irrelevant, off subject or BS. Who ever is responsible needs to step up to the plate and clean house, starting with you. Bert Kehren In a message dated 7/10/2013 11:35:15 A.M. Eastern Daylight Time, sandee...@yahoo.com writes: Charles wrote: Please keep your political comments to yourself and off the list (however humorous you might think they are). This is simply not the place for them. Charles, On the two lists we both subscribe to, you always seem to have something to say about almost every post. Often it falls into the category of Mother says: now don’t forget to do ___. (You can fill in the blank space.) I see you doing this in a very condescending manner. On the R-390 list, I’ve forgotten more about the R-390A receiver than you will ever know. I was trained on them, serviced them in the military, developed parts kits for them, wrote the Y2KR3 manual and have had a number of published technical articles about them. At least on the R 390A radio you have done nothing that I’m aware of and I follow information on it very carefully. You don’t own or administer this list. All members have the right to make civil posts of their opinion whether others agree with them on not. My mother died many years ago and I don’t need you to be her replacement. You have the same privilege of all of us to post or delete. Kind Regards, Perrier ___ 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] Posting Rules
I think I pretty much agree with Perry. This list has occasionally gone quite aways OT, but it invariably finds its way back, and certainly more than quickly enough. However, a mother replacement does absolutely nothing to speed up the process, least of all a sanctimonious, holier-than-thou one. Thomas Valerio Charles wrote: Please keep your political comments to yourself and off the list (however humorous you might think they are). This is simply not the place for them. Charles, On the two lists we both subscribe to, you always seem to have something to say about almost every post. Often it falls into the category of Mother says: now don't forget to do ___. (You can fill in the blank space.) I see you doing this in a very condescending manner. On the R-390 list, I've forgotten more about the R-390A receiver than you will ever know. I was trained on them, serviced them in the military, developed parts kits for them, wrote the Y2KR3 manual and have had a number of published technical articles about them. At least on the R-390A radio you have done nothing that I'm aware of and I follow information on it very carefully. You don't own or administer this list. All members have the right to make civil posts of their opinion whether others agree with them on not. My mother died many years ago and I don't need you to be her replacement. You have the same privilege of all of us to post or delete. Kind Regards, Perrier ___ 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] Posting Rules
Consider this thread finished. I am taking it up with the individuals involved, off-line. Please do you part to keep all postings, and especially all replies, technical, friendly, and on-topic. If there's something about the list, please email me directly. Thanks, /tvb http://www.leapsecond.com/time-nuts.htm ___ 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] How dangerous if a Rb lamp broken?
I wonder if that would be possible? I bet the government paperwork would make the watches costs far out of reach for most people. Tom WA3PZI - Original Message - From: Bob Stewart b...@evoria.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, July 10, 2013 11:25 AM Subject: Re: [time-nuts] How dangerous if a Rb lamp broken? You're still here, but what about the young women who painted those watches who aren't? The problem was that they needed sharp points on the brushes to fill the tiny voids in the hands. So they twirled the brush tips between their lips. They could probably bring back radium dials today with no problem, because of automation. Bob - AE6RV From: Lee Mushel herbe...@centurytel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, July 10, 2013 10:14 AM Subject: Re: [time-nuts] How dangerous if a Rb lamp broken? I just tried calling your cell because you seem to be the legitimate person to ask. I don't read all the time-nuts postings but has anyone ever brought up the most logical aspect of ionizing radiation for the group: the radium dial wrist watch? or are they all too young to have experienced that? I think I got one for Christmas when I was 12 or 13. I'm still here at 74! ___ 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] How dangerous if a Rb lamp broken?
In brief, Gamma rays are just another form of light... that is to say photons. What makes them special is they are much higher energy than visible light. What makes them potentially dangerous is they have enough energy to knock electrons off of many atoms, turning them into ions that could combine chemically in your body in ways that wouldn't normally happen. If it happens to the right molecule... say a DNA strand... it could cause a mutation that could result in cancer. Most such mutations result in premature cell death, and are harmless... unless there happens to be millions of them all at once. Your body is mostly water. Somewhere around 45 to 60% by weight. The rest of your weight are minerals and things like bone. The molecules in your body are mostly free space... that is to say vacuum... a high energy gamma photon is more likely to pass right on through your body than to hit anything. And if it does hit something, it is most likely going to be water, or bone. Think back to the last time you had an X-Ray. What showed up? When you look at a normal light source, say a candle, what you are seeing is a spray of photons radiating out in all directions from the source. There are so many photons that the light source appears to your eye to be continuous. When a light source gets small enough, it appears dim, and if it is dim enough, it starts to appear grainy. The grains you see are individual photons. Your eye doesn't see all of the visible photons that strike it, perhaps only 50%... Eyes are amazing! One of the earliest ways of measuring radioactivity was the geiger-muller tube. It can count individual gamma photons that strike the tube. Even still, some of the gamma photons will pass right through, and not be counted. It catches about 30%, as I recall. A source like a radium dial watch will make a geiger counter clatter pretty good, but you can still hear the clicks caused by individual photons. If the radioactive source was emitting photons at the same rate as a candle, the geiger counter tube would be completely overwhelmed, and you would not be able to count the deluge of photons hitting it. The moral of this story is that the probability of any given gamma photon, that irradiates a human body, even hitting something is small. The probability of anything it hits being more interesting than water is even smaller, and the probability of it doing dangerous damage is terribly small. It is only when the flux of gamma photons becomes quite large that these probabilities start to tip into the direction of likely damage, or cancer. A tiny, low flux source of radiation, like a radium dial watch, is highly unlikely to cause you any harm... it could happen, but the odds of it doing so make winning the lottery look like a sure thing. The odds drop very quickly the farther the watch is from your body... its one of those radius squared things. -Chuck Harris Lee Mushel wrote: I just tried calling your cell because you seem to be the legitimate person to ask. I don't read all the time-nuts postings but has anyone ever brought up the most logical aspect of ionizing radiation for the group: the radium dial wrist watch? or are they all too young to have experienced that? I think I got one for Christmas when I was 12 or 13. I'm still here at 74! I do think that all reflector's are at their best when they are entertaining---maybe not exactly on topic! ___ 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] Optical lattice atomic clock could 'redefine the second'
I follow a BBC news site and this article popped up to bring us back on topic. Hope it's not old news http://www.bbc.co.uk/news/science-environment-23231206 Bob - AE6RV ___ 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] How dangerous if a Rb lamp broken?
I once read that if you were to wear a radium dial watch face down you would get a radiation burn on your arm. I wonder who would do such a thing. I also wonder if the writer knew what he was writing about or if he was just speculating. Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: Chuck Harris cfhar...@erols.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, July 10, 2013 11:48 AM Subject: Re: [time-nuts] How dangerous if a Rb lamp broken? In brief, Gamma rays are just another form of light... that is to say photons. What makes them special is they are much higher energy than visible light. What makes them potentially dangerous is they have enough energy to knock electrons off of many atoms, turning them into ions that could combine chemically in your body in ways that wouldn't normally happen. If it happens to the right molecule... say a DNA strand... it could cause a mutation that could result in cancer. Most such mutations result in premature cell death, and are harmless... unless there happens to be millions of them all at once. Your body is mostly water. Somewhere around 45 to 60% by weight. The rest of your weight are minerals and things like bone. The molecules in your body are mostly free space... that is to say vacuum... a high energy gamma photon is more likely to pass right on through your body than to hit anything. And if it does hit something, it is most likely going to be water, or bone. Think back to the last time you had an X-Ray. What showed up? When you look at a normal light source, say a candle, what you are seeing is a spray of photons radiating out in all directions from the source. There are so many photons that the light source appears to your eye to be continuous. When a light source gets small enough, it appears dim, and if it is dim enough, it starts to appear grainy. The grains you see are individual photons. Your eye doesn't see all of the visible photons that strike it, perhaps only 50%... Eyes are amazing! One of the earliest ways of measuring radioactivity was the geiger-muller tube. It can count individual gamma photons that strike the tube. Even still, some of the gamma photons will pass right through, and not be counted. It catches about 30%, as I recall. A source like a radium dial watch will make a geiger counter clatter pretty good, but you can still hear the clicks caused by individual photons. If the radioactive source was emitting photons at the same rate as a candle, the geiger counter tube would be completely overwhelmed, and you would not be able to count the deluge of photons hitting it. The moral of this story is that the probability of any given gamma photon, that irradiates a human body, even hitting something is small. The probability of anything it hits being more interesting than water is even smaller, and the probability of it doing dangerous damage is terribly small. It is only when the flux of gamma photons becomes quite large that these probabilities start to tip into the direction of likely damage, or cancer. A tiny, low flux source of radiation, like a radium dial watch, is highly unlikely to cause you any harm... it could happen, but the odds of it doing so make winning the lottery look like a sure thing. The odds drop very quickly the farther the watch is from your body... its one of those radius squared things. -Chuck Harris Lee Mushel wrote: I just tried calling your cell because you seem to be the legitimate person to ask. I don't read all the time-nuts postings but has anyone ever brought up the most logical aspect of ionizing radiation for the group: the radium dial wrist watch? or are they all too young to have experienced that? I think I got one for Christmas when I was 12 or 13. I'm still here at 74! I do think that all reflector's are at their best when they are entertaining---maybe not exactly on topic! ___ 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] How dangerous if a Rb lamp broken?
In message 5DEED07BE9DE486C9E668636A2949A62@BACKROOM, Max Robinson writes: I once read that if you were to wear a radium dial watch face down you would get a radiation burn on your arm. I wonder who would do such a thing. I also wonder if the writer knew what he was writing about or if he was just speculating. You would. He did. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] time-nuts Digest, Vol 108, Issue 55
On 7/10/2013 11:35 AM, time-nuts-requ...@febo.com wrote: Public perceptions of risk change with time. In WWII, Radium dial watches, aircraft instruments, dial and switch markings, were ubiquitous. But so were explosives, bombs, bayonettes, and a bunch of other things. So people didn't have the luxury of concerns over minor things. Now that is not so. -John Not to fan the fire. But you can still buy tritium glow in the dark sights for pistols (It is standard on a lot of them now). You can even add tritium glow in the dark tubes to custom flashlights and I think even knives... :) Dan ___ 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] How dangerous if a Rb lamp broken?
We had a Lab in Bldg 6 at MIT (Physics Dept.) that had an old Soapstone sink in it. I remember talking to an Old-Timer (now this was in the early 60's) who told me that sink was used to clean the bones of deceased Watch Company workers. They were then tested for Radioactivity levels. It was a long time before I could get myself to go near that sink, never mind use it !! 73, Dick, W1KSZ On 7/10/2013 9:12 AM, J. Forster wrote: The watch workers were a tragedy, based on ignorance of the risks. At the time, there were probably only a handful of people who'd ever sustained injury from radioactive materials. It's not clear that the bosses even knew the women were putting the brushes in their mouths or that they knew the risks. These kind of things do happen. Consider Asbestos, DES, Thalidomide, Phen-Phen, Avandia, etc. However, that does not excuse the media, public interest groups, or especially government for hyping risk totally out of proportion for their self-serving political ends. I think the bigger risk from a broken Rb bulb would come from the glass shards. -John === You're still here, but what about the young women who painted those watches who aren't? The problem was that they needed sharp points on the brushes to fill the tiny voids in the hands. So they twirled the brush tips between their lips. They could probably bring back radium dials today with no problem, because of automation. Bob - AE6RV From: Lee Mushel herbe...@centurytel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, July 10, 2013 10:14 AM Subject: Re: [time-nuts] How dangerous if a Rb lamp broken? I just tried calling your cell because you seem to be the legitimate person to ask. I don't read all the time-nuts postings but has anyone ever brought up the most logical aspect of ionizing radiation for the group: the radium dial wrist watch? or are they all too young to have experienced that? I think I got one for Christmas when I was 12 or 13. I'm still here at 74! ___ 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] time-nuts Digest, Vol 108, Issue 55
Tritium is very different from radium. I'm a little out of my field of expertise here but I think that tritium is mainly a beta source while radium is a gamma emitter. Also the body can get rid of tritium if ingested because it is chemically similar to hydrogen. I'm sure I will be corrected if wrong. Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: Dan Kemppainen d...@irtelemetrics.com To: time-nuts@febo.com Sent: Wednesday, July 10, 2013 12:11 PM Subject: Re: [time-nuts] time-nuts Digest, Vol 108, Issue 55 On 7/10/2013 11:35 AM, time-nuts-requ...@febo.com wrote: Public perceptions of risk change with time. In WWII, Radium dial watches, aircraft instruments, dial and switch markings, were ubiquitous. But so were explosives, bombs, bayonettes, and a bunch of other things. So people didn't have the luxury of concerns over minor things. Now that is not so. -John Not to fan the fire. But you can still buy tritium glow in the dark sights for pistols (It is standard on a lot of them now). You can even add tritium glow in the dark tubes to custom flashlights and I think even knives... :) Dan ___ 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] time-nuts Digest, Vol 108, Issue 55
My last two wrist watches (I know, that makes me an anachronism on this list) both have hands that glow in the dark, but I assume it is the result of absorbing photons for later release, not some radioactive source. Am I wrong? Tom Holmes, N8ZM Tipp City, OH EM79 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan Kemppainen Sent: Wednesday, July 10, 2013 1:11 PM To: time-nuts@febo.com Subject: Re: [time-nuts] time-nuts Digest, Vol 108, Issue 55 On 7/10/2013 11:35 AM, time-nuts-requ...@febo.com wrote: Public perceptions of risk change with time. In WWII, Radium dial watches, aircraft instruments, dial and switch markings, were ubiquitous. But so were explosives, bombs, bayonettes, and a bunch of other things. So people didn't have the luxury of concerns over minor things. Now that is not so. -John Not to fan the fire. But you can still buy tritium glow in the dark sights for pistols (It is standard on a lot of them now). You can even add tritium glow in the dark tubes to custom flashlights and I think even knives... :) Dan ___ 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] Speaking of Costas loops (WAAS)
On 07/09/2013 04:25 AM, Joseph Gwinn wrote: Yes, of course, but I don't think I explained very well. The issue was more economic than technical. There isn't much spare space, weight, or power in the birds, technology moves rapidly, and the satellite companies don't want to have expensive satellites that no longer generate rental income because something became obsolete. So they ruthlessly simplify. A bent pipe will handle any possible band-limited modulation, no matter if currently known or not, and so is the safest solution. Now WAAS may have become important enough to command dedicated hardware, but that came later, to the degree it came at all. A bent pipe is more generic, but there are limits to how much you can alter the output frequency too. If the payload is long-term contracted already when the bird is in the planning stage, then it is another issue. 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] Very stable synthesizer, alternative to PTS(Programmed Test Sources) x10 or 040?
We use an Agilent 8644B where I work as the master oscillator for an electron cyclotron storage ring. Electrons at 2GeV don't like to be pushed around and are very sensitive to phase noise, so the feedback loop that adjusts the frequency uses the FM input for fine adjustment. -- eric On Wed, Jul 10, 2013 at 3:57 AM, Bob Camp li...@rtty.us wrote: Hi Having hooked up a 9854 and tried it with realistic settings - it's not that great. If you run it at magic frequencies (where it's essentially just a divider) it looks like a divider. Bob On Jul 9, 2013, at 5:03 AM, Anders Time anderst...@gmail.com wrote: Thanks a lot for the input. I have been looking at the Fluke 6160b, but I thought that there might be something as good out there that is not 40years old! I want to use the synthesizer as a flexible offset source for beat frequency measurements. So the frequency range is 5 to 30MHz approx. I read Rubiola et al. Phase noise and amplitude noise in DDS yesterday and thinks that it might be worth a try to test the AD9854 or AD9912 to see if it is good enough. If I understand the paper right they get really good results. Is there any one with experience? Thanks Anders ___ 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] How dangerous if Rb lamp broken?
Hi Hui, This is a little off-topic for time nuts, but here goes. the Becquerel is a measurement of radioactivity, 1Bq being one decay per second. Bg/gm is specific activity so if you have 1g of material with a specific activity of 200Bq/g you will have 200 decays per second. We need to use this as not all the Rb in a lamp is Rb 87 and the weight quoted includes it all. The Sievert is a measurement of effective dose. It depends on time, quantity of radioactive material, type and energy of radiation emitted, distance and the organ exposed. It is not a simple calculation or conversion. As Rb87 is a beta emitter with a maximum energy of 272 keV, it will only produce localised effects. externally it will only cause skin exposure and you would need megabecquerels in direct contact to cause something like a sunburn. Anything else would need internal exposure. Rb87 is of so little concern that the standard dose rate calculation program I use does not even list it. Chemically Rb is similar to potassium, K, which is essential to humans. Natural K contains 0.0117% of the radioactive isotope K40. A typical 70kg human male is 0.2%K so has more than 3000Bq of K40. So if you swallowed 2mg of the Rb from a bulb AND the body absorbed ALL of it, the total additional dose would be less than 0.1% of that you are getting from the natural K in your body. In practice it would be even less because your body would not absorb it all and that it did absorb would probably displace some K. Intact Rb cells cells have on detectable external radiation. My half gram estimate came from a web search of peer reviewed articles. The US occupational ingestion limit is 1mCi or 37000Bq per year. Inhallation is twice that. US labs can discharge water to the sewer with 370Bq/liter of Rb87 Rb cells are perfectly safe for all practical purposes. An injury from the broken glass is probably much more of a risk! HTH,Robert G8RPI. From: Hui Zhang ba...@163.com To: Robert Atkinson robert8...@yahoo.co.uk; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, 10 July 2013, 14:53 Subject: Re:Re: [time-nuts] How dangerous if Rb lamp broken? Hello Robert: I am a little confuse how exactly much Rb87 in a bulb? Some people say that it's couple millgram, but you tell me it's half a millgram, which is ture? You message is good new to me, it let me relax, but I don’t understand Bq/gram unit, would you please convert it to mSV unit, I can know the how many mSV of human is safety by search by internet. I mean in extreme situration, if all Rb87 of buld sprinkled in my table, how many exposure value will I accepet in 24 Hour? I found some people (other electronics fan) wrote a formula about Rb87 radioactivity calculation, that is: 1mg Rubidium * 27.835 * 0.27835 * 6.02 *10^23 / 87/4.88/10^10/2/365/24/3600*1=625. So, decay energy=0.283MeV, about 600 electron per second, Is this calculation correct? 27.835=Percent of Rb87 6.02*10^23 = Avogadro's constant 87= Atomic weight 4.88*10^10== Half time of Rb87 (Year) 2 = Rb87 decay to half 365 = day of year 24 = hour of day 3600 = second of hour I am very glad to read many relay of my email, I want say thanks for everyone. As you said why people be afraid of Rb87 but not other things, I think maybe because we don’t understand it. Such as, I don’t afraid of RF exposure, because I know it, I am a HAM and learned many RF exposure knowledge, but of atom and radioactivity, I have only poor knowledge. Thanks everyone again, this is amazing mail-list. Say sorry for my poor English. Hui At 2013-07-09 19:40:50,Robert Atkinson robert8...@yahoo.co.uk wrote: Hi Hui, Most bulbs use a mix of Rb87 and Rb85 with an activity of around 1500 Bq/gram with less than half a millgram in a typical bulb, that's less than a Bq per bulb (about 20 picocuries). You will get more ardiation from using low sodium salt (potassium chloride) on your food. Potasium is essential for life and Rb is chemically similar. In short don't worry. Robert G8RPI (also a geiger nut and collector of radioactive material) From: Hui Zhang ba...@163.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, 9 July 2013, 5:07 Subject: [time-nuts] How dangerous if Rb lamp broken? Dear Group: I have four compact Rb Stanard, but I am worried about what if my Rb lamp broken in accident someday? How dangerous of this situration? Is Rb87 came out from Rb lamp will be a disaster? You know I haven't any beta rays detect instrument. Hui ___ 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
Re: [time-nuts] Question about effect of sample interval on ADEV
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[time-nuts] RE Rb danger
Please relax Rb is rubidium. It has a large number of isotopes but almost all rubidium is either stable (AW=85), or an isotope that is a beta (ie. electron) emitter. Electrons generally don't travel too far. Rubidium is used in fireworks (Ok guys who make fireworks are maybe a bit overly brave). I imagine a broken lamp will just allow the gas to diffuse into the air. Leave a window open for a while and things should be safe. If you ingest it, rubidium is not particularly toxic, wiki states a 70 kg person typically has .36 gm of rubidium in them, and 10-100 x this amount appears to be fine. Potassium has a similar radioactive isotope (very small fraction however) that we routinely ingest with bananas. In fact, Rb readily substitutes for K because they are both alkali metals. Radium is Ra. Mike ___ 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] Leica L1 GPS Choke Ring Antenna
I just scored a Leica L1 GPS choke ring antenna. Of course I am anxious to get it up (pardon the pun) Sorry tom ;) But its huge, I mean its 14 across the base and 12 high excluding the spike. It came with a ½ and ¾ adaptor so I can choose mounting pole thread. Obviously, the top of the roof is the place, but what can support such a massive object without getting blown over. I have a tin roof. Has anyone got experience with mounting such a large GPS antenna, please? -marki ___ 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] Question about effect of sample interval on ADEV
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Re: [time-nuts] Leica L1 GPS Choke Ring Antenna
I have two chokerings on my roof. Get something to mount a TV antenna or a small satellite dish. Use a threaded water pipe instead of the normal antenna mast. If this is the oem version from Aeroantenna (AT575-90), there are also 3 bolt holes around the outer rim. Given a flat surface its pretty steady just resting on these bolts. Good luck! Björn Originalmeddelande Från: Mark C. Stephens ma...@non-stop.com.au Datum: 2013-07-10 22:09 (GMT+01:00) Till: time-nuts@febo.com Rubrik: [time-nuts] Leica L1 GPS Choke Ring Antenna I just scored a Leica L1 GPS choke ring antenna. Of course I am anxious to get it up (pardon the pun) Sorry tom ;) But its huge, I mean its 14 across the base and 12 high excluding the spike. It came with a ½ and ¾ adaptor so I can choose mounting pole thread. Obviously, the top of the roof is the place, but what can support such a massive object without getting blown over. I have a tin roof. Has anyone got experience with mounting such a large GPS antenna, please? -marki ___ 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] Speaking of Costas loops (WAAS)
On Wed, Jul 10, 2013 at 08:10:45PM +0200, Magnus Danielson wrote: On 07/09/2013 04:25 AM, Joseph Gwinn wrote: Yes, of course, but I don't think I explained very well. The issue was more economic than technical. There isn't much spare space, weight, or power in the birds, technology moves rapidly, and the satellite companies don't want to have expensive satellites that no longer generate rental income because something became obsolete. So they ruthlessly simplify. A bent pipe will handle any possible band-limited modulation, no matter if currently known or not, and so is the safest solution. Now WAAS may have become important enough to command dedicated hardware, but that came later, to the degree it came at all. A bent pipe is more generic, but there are limits to how much you can alter the output frequency too. It seems completely inconceivable to me that either the antenna system (particularly feeds) or transponder RF hardware on any commercial Ku or C or Ka or X band satellite could possibly be frequency agile enough to tune to 1575.42 MHz unless it was purpose designed to radiate on that frequency from the start. So any hosted WAAS payload is completely application specific. What is not clear from anything I have read so far is whether the UPLINK of the modulated WAAS signal is somewhere in the normal (usually 6 GHz for C band satellites) uplink frequency band (probably off one end or the other of the frequency range used). Seems rather likely that the ability to reuse the UPLINK common RF hardware (reflector, feeds, filters, plumbing, maybe transponder front ends and preamps) would make this a very natural design. It also seems clear that doppler and bent pipe conversion oscillator correction is done closed loop by having the ground station that generates the uplinked WAAS signal monitor the downlink from the bird.Obviously correcting for the uplink doppler is a matter of computation from knowing the bird's orbit orbit precisely, something that would certainly be aided by constantly monitoring the range to the bird from that WAAS uplink ground station and maybe another couple (for ionospheric corrections). Apparently the newer stuff uses two L band frequencies to improve this (correct for plasma delay). And the WAAS signal of course allows continuous measurement of range accurately. Correcting for a generally stable but slowly aging conversion oscillator should be pretty straightforward as well, and presumably such a closed loop system could hold the downlink frequency to rather tight tolerances given a reasonably predictable stable oscillator on the bird. The 240 ms up and back delay does make the loop a bit more complex, but the bandwidth is very low I would think since the major perturbation is probably thermal (satellite going into eclipse once a day at certain times, and changes in sun angle over a day). For an observer on the ground it is of course necessary to correct for the satellite orbit induced doppler... which can be up to a couple of hundred Hz or more at 6 GHz - especially with inclined orbit birds such as the INMARSATs. The downlink carrier, while more stable in frequency than GPS bird downlinks is hardly a highly accurate frequency reference on its own. But knowing the geo bird ephemeris (which is broadcast on the WAAS) should allow single signal time and frequency solution for an observer at an accurately known location - by correcting for bird movement. How good the closed loops are relative to the precision clocks on GPS satellites is an interesting question, there seems to be no obvious design need to reach that level of stability... but it does not seem impossible to get pretty close. And much of what has been achieved here seems related to a cost/power trade off in the hosted payload in regards to its reference oscillator. -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ 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] time-nuts Digest, Vol 108, Issue 55
I think that luminous dial watches still contain a little tritium to keep them glowing for many hours after the atoms that were excited by visible photons have all decayed. Without the tritium the glow would completely go dark after most of the atoms have decayed to their ground state. Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: Tom Holmes thol...@woh.rr.com To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Wednesday, July 10, 2013 1:05 PM Subject: Re: [time-nuts] time-nuts Digest, Vol 108, Issue 55 My last two wrist watches (I know, that makes me an anachronism on this list) both have hands that glow in the dark, but I assume it is the result of absorbing photons for later release, not some radioactive source. Am I wrong? Tom Holmes, N8ZM Tipp City, OH EM79 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan Kemppainen Sent: Wednesday, July 10, 2013 1:11 PM To: time-nuts@febo.com Subject: Re: [time-nuts] time-nuts Digest, Vol 108, Issue 55 On 7/10/2013 11:35 AM, time-nuts-requ...@febo.com wrote: Public perceptions of risk change with time. In WWII, Radium dial watches, aircraft instruments, dial and switch markings, were ubiquitous. But so were explosives, bombs, bayonettes, and a bunch of other things. So people didn't have the luxury of concerns over minor things. Now that is not so. -John Not to fan the fire. But you can still buy tritium glow in the dark sights for pistols (It is standard on a lot of them now). You can even add tritium glow in the dark tubes to custom flashlights and I think even knives... :) Dan ___ 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] How dangerous if a Rb lamp broken?
I wonder what that is? How come the digits don't show the same burn that the hands do? They certainly remained in the same position for longer than the hands. Hmmm? Tom - Original Message - From: Chuck Harris cfhar...@erols.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, July 10, 2013 3:41 PM Subject: Re: [time-nuts] How dangerous if a Rb lamp broken? The dials of most of the old radium dial watches have burns in them caused by the hands being parked for long periods of time as the watch invariably failed and stopped. The crystals are similarly etched from their exposure. The gamma photons did the deed... I have one such watch that was given to me by an uncle who was a physicist and was part of the Marshal Island H-Bomb tests. He was given the watch by the US Army, and wore it daily until it set off the alarms on one of the experiments he was working on After that, it sat on a shelf for 20 years before being given to me. No burns when it was put away, and a very distinct burn after sitting 20 years. So, yes, it would burn you, but at the rate that gamma comes off of a watch dial, it would take a long time, and your body would have naturally replaced the cells many times over the duration of the burn. -Chuck Harris Poul-Henning Kamp wrote: In message 5DEED07BE9DE486C9E668636A2949A62@BACKROOM, Max Robinson writes: I once read that if you were to wear a radium dial watch face down you would get a radiation burn on your arm. I wonder who would do such a thing. I also wonder if the writer knew what he was writing about or if he was just speculating. You would. He did. ___ 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] Speaking of Costas loops (WAAS)
On 07/10/2013 11:08 PM, David I. Emery wrote: On Wed, Jul 10, 2013 at 08:10:45PM +0200, Magnus Danielson wrote: On 07/09/2013 04:25 AM, Joseph Gwinn wrote: Yes, of course, but I don't think I explained very well. The issue was more economic than technical. There isn't much spare space, weight, or power in the birds, technology moves rapidly, and the satellite companies don't want to have expensive satellites that no longer generate rental income because something became obsolete. So they ruthlessly simplify. A bent pipe will handle any possible band-limited modulation, no matter if currently known or not, and so is the safest solution. Now WAAS may have become important enough to command dedicated hardware, but that came later, to the degree it came at all. A bent pipe is more generic, but there are limits to how much you can alter the output frequency too. It seems completely inconceivable to me that either the antenna system (particularly feeds) or transponder RF hardware on any commercial Ku or C or Ka or X band satellite could possibly be frequency agile enough to tune to 1575.42 MHz unless it was purpose designed to radiate on that frequency from the start. So any hosted WAAS payload is completely application specific. I was thinking along the same lines, but I have too little experience in RF design for birds. There are several potential other uses for L-band transmission if tweaking a little up or down from L1 is feasible, otherwise it's pretty application specific. WAAS links primarily provides an information channel, so it doesn't have to be very accurate. However, as you devote a channel to it, you might as well use it to produce pseudo-ranges, but it seems like they didn't care too much on the carrier-phase part compared to the code-phase, but 10 years back not many receivers used the code phase for nav at all, but carrier smoothed code should at least be common now, so for those it may not fully meet the needs. The added precision for the other channels compensate thought. 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] Speaking of Costas loops (WAAS)
David, While I can easily see how you can do closed loop correctioin for Dopplar from the transmission point for a 'bent pipe' repeater, at any other location that correction would not be valid, because the paths are not parallel. -John = On Wed, Jul 10, 2013 at 08:10:45PM +0200, Magnus Danielson wrote: On 07/09/2013 04:25 AM, Joseph Gwinn wrote: Yes, of course, but I don't think I explained very well. The issue was more economic than technical. There isn't much spare space, weight, or power in the birds, technology moves rapidly, and the satellite companies don't want to have expensive satellites that no longer generate rental income because something became obsolete. So they ruthlessly simplify. A bent pipe will handle any possible band-limited modulation, no matter if currently known or not, and so is the safest solution. Now WAAS may have become important enough to command dedicated hardware, but that came later, to the degree it came at all. A bent pipe is more generic, but there are limits to how much you can alter the output frequency too. It seems completely inconceivable to me that either the antenna system (particularly feeds) or transponder RF hardware on any commercial Ku or C or Ka or X band satellite could possibly be frequency agile enough to tune to 1575.42 MHz unless it was purpose designed to radiate on that frequency from the start. So any hosted WAAS payload is completely application specific. What is not clear from anything I have read so far is whether the UPLINK of the modulated WAAS signal is somewhere in the normal (usually 6 GHz for C band satellites) uplink frequency band (probably off one end or the other of the frequency range used). Seems rather likely that the ability to reuse the UPLINK common RF hardware (reflector, feeds, filters, plumbing, maybe transponder front ends and preamps) would make this a very natural design. It also seems clear that doppler and bent pipe conversion oscillator correction is done closed loop by having the ground station that generates the uplinked WAAS signal monitor the downlink from the bird.Obviously correcting for the uplink doppler is a matter of computation from knowing the bird's orbit orbit precisely, something that would certainly be aided by constantly monitoring the range to the bird from that WAAS uplink ground station and maybe another couple (for ionospheric corrections). Apparently the newer stuff uses two L band frequencies to improve this (correct for plasma delay). And the WAAS signal of course allows continuous measurement of range accurately. Correcting for a generally stable but slowly aging conversion oscillator should be pretty straightforward as well, and presumably such a closed loop system could hold the downlink frequency to rather tight tolerances given a reasonably predictable stable oscillator on the bird. The 240 ms up and back delay does make the loop a bit more complex, but the bandwidth is very low I would think since the major perturbation is probably thermal (satellite going into eclipse once a day at certain times, and changes in sun angle over a day). For an observer on the ground it is of course necessary to correct for the satellite orbit induced doppler... which can be up to a couple of hundred Hz or more at 6 GHz - especially with inclined orbit birds such as the INMARSATs. The downlink carrier, while more stable in frequency than GPS bird downlinks is hardly a highly accurate frequency reference on its own. But knowing the geo bird ephemeris (which is broadcast on the WAAS) should allow single signal time and frequency solution for an observer at an accurately known location - by correcting for bird movement. How good the closed loops are relative to the precision clocks on GPS satellites is an interesting question, there seems to be no obvious design need to reach that level of stability... but it does not seem impossible to get pretty close. And much of what has been achieved here seems related to a cost/power trade off in the hosted payload in regards to its reference oscillator. -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ 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] How dangerous if a Rb lamp broken?
The stuff that turns color is the dial paint. The numbers are painted on top. When the hands move, they expose the underlying paint to view. -John = I wonder what that is? How come the digits don't show the same burn that the hands do? They certainly remained in the same position for longer than the hands. Hmmm? Tom - Original Message - From: Chuck Harris cfhar...@erols.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, July 10, 2013 3:41 PM Subject: Re: [time-nuts] How dangerous if a Rb lamp broken? The dials of most of the old radium dial watches have burns in them caused by the hands being parked for long periods of time as the watch invariably failed and stopped. The crystals are similarly etched from their exposure. The gamma photons did the deed... I have one such watch that was given to me by an uncle who was a physicist and was part of the Marshal Island H-Bomb tests. He was given the watch by the US Army, and wore it daily until it set off the alarms on one of the experiments he was working on After that, it sat on a shelf for 20 years before being given to me. No burns when it was put away, and a very distinct burn after sitting 20 years. So, yes, it would burn you, but at the rate that gamma comes off of a watch dial, it would take a long time, and your body would have naturally replaced the cells many times over the duration of the burn. -Chuck Harris Poul-Henning Kamp wrote: In message 5DEED07BE9DE486C9E668636A2949A62@BACKROOM, Max Robinson writes: I once read that if you were to wear a radium dial watch face down you would get a radiation burn on your arm. I wonder who would do such a thing. I also wonder if the writer knew what he was writing about or if he was just speculating. You would. He did. ___ 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] Speaking of Costas loops (WAAS)
Hi On Jul 10, 2013, at 5:08 PM, David I. Emery d...@dieconsulting.com wrote: On Wed, Jul 10, 2013 at 08:10:45PM +0200, Magnus Danielson wrote: On 07/09/2013 04:25 AM, Joseph Gwinn wrote: Yes, of course, but I don't think I explained very well. The issue was more economic than technical. There isn't much spare space, weight, or power in the birds, technology moves rapidly, and the satellite companies don't want to have expensive satellites that no longer generate rental income because something became obsolete. So they ruthlessly simplify. A bent pipe will handle any possible band-limited modulation, no matter if currently known or not, and so is the safest solution. Now WAAS may have become important enough to command dedicated hardware, but that came later, to the degree it came at all. A bent pipe is more generic, but there are limits to how much you can alter the output frequency too. It seems completely inconceivable to me that either the antenna system (particularly feeds) or transponder RF hardware on any commercial Ku or C or Ka or X band satellite could possibly be frequency agile enough to tune to 1575.42 MHz unless it was purpose designed to radiate on that frequency from the start. So any hosted WAAS payload is completely application specific. What is not clear from anything I have read so far is whether the UPLINK of the modulated WAAS signal is somewhere in the normal (usually 6 GHz for C band satellites) uplink frequency band (probably off one end or the other of the frequency range used). Seems rather likely that the ability to reuse the UPLINK common RF hardware (reflector, feeds, filters, plumbing, maybe transponder front ends and preamps) would make this a very natural design. It also seems clear that doppler and bent pipe conversion oscillator correction is done closed loop by having the ground station that generates the uplinked WAAS signal monitor the downlink from the bird. Clear from what documentation? I have not seen anything that says the WAAS is any better than the doppler spec. Uncorrected doppler is still *way* below the level on the nav sats. Why correct it? Obviously correcting for the uplink doppler is a matter of computation from knowing the bird's orbit orbit precisely, something that would certainly be aided by constantly monitoring the range to the bird from that WAAS uplink ground station and maybe another couple (for ionospheric corrections). Apparently the newer stuff uses two L band frequencies to improve this (correct for plasma delay). And the WAAS signal of course allows continuous measurement of range accurately. Correcting for a generally stable but slowly aging conversion oscillator should be pretty straightforward as well, and presumably such a closed loop system could hold the downlink frequency to rather tight tolerances given a reasonably predictable stable oscillator on the bird. The 240 ms up and back delay does make the loop a bit more complex, but the bandwidth is very low I would think since the major perturbation is probably thermal (satellite going into eclipse once a day at certain times, and changes in sun angle over a day). For an observer on the ground it is of course necessary to correct for the satellite orbit induced doppler... which can be up to a couple of hundred Hz or more at 6 GHz - especially with inclined orbit birds such as the INMARSATs. The downlink carrier, while more stable in frequency than GPS bird downlinks is hardly a highly accurate frequency reference on its own. But knowing the geo bird ephemeris (which is broadcast on the WAAS) should allow single signal time and frequency solution for an observer at an accurately known location - by correcting for bird movement. That's only the first layer, you still need atmospheric correction for a low angle bird along with a few other things. How good the closed loops are relative to the precision clocks on GPS satellites is an interesting question, there seems to be no obvious design need to reach that level of stability... but it does not seem impossible to get pretty close. And much of what has been achieved here seems related to a cost/power trade off in the hosted payload in regards to its reference oscillator. I still don't see how it will be as good as a normal GPSDO, let alone better. Bob -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ 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] How dangerous if a Rb lamp broken?
The dial is painted, the hands are actually metal frame, and the luminous paint is a wax that is put on the hand kind of like a soap bubble. The luminous material in the paint is very dead, as the hands and digits no longer glow at all. I guess there is a limit to how long ZnS:Cu can take the exposure and still glow. -Chuck Harris Tom Miller wrote: I wonder what that is? How come the digits don't show the same burn that the hands do? They certainly remained in the same position for longer than the hands. Hmmm? Tom ___ 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] Lead acid battery noise levels
I wonder if lithium batteries would have a good noise figure. The nano-structure of the electrodes give them very large surface area and low resistance, but the charge carriers are different than other types of chemistry and I don't know if that's good or bad. On Wed, Jul 10, 2013 at 9:01 AM, Hal Murray hmur...@megapathdsl.net wrote: a...@bardagjy.com said: The SRS 560 and 570, low noise voltage and current preamplifiers respectively, both use bog standard sealed lead acid batteries. Is that to reduce power supply noise or to get a clean ground that isn't connected to wall power? -- 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. ___ 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] How dangerous if a Rb lamp broken?
Since this thread doesn't appear to have a half-life, perhaps this needs some explanation. The zinc sulfide fluoresces when an atom or more of radium decays. The fluorescence will still occur in the presence of ionizing radiation. The radium, OTOH, is nearly dead. Probability says that some number of atoms will leave their radioactive state and become inert (Lead? I haven't got time to look it up so I'll share my ignorance with you. Someone will correct me and the thread will never die.) The rate at which a mass of radium becomes inert is expressed as its half-life, which is the TIME that it takes for half of the remaining radium to become inert. The decay is exponential, as are so many natural things. You'll need a sensitive Geiger counter to see if there's any life left in the radium. Or you could expose the watch to a photomultiplier in total darkness to see if it scintillates. In other words, it doesn't burn out. Bill Hawkins -Original Message- From: Chuck Harris Sent: Wednesday, July 10, 2013 5:29 PM The dial is painted, the hands are actually metal frame, and the luminous paint is a wax that is put on the hand kind of like a soap bubble. The luminous material in the paint is very dead, as the hands and digits no longer glow at all. I guess there is a limit to how long ZnS:Cu can take the exposure and still glow. -Chuck Harris ___ 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] Very stable synthesizer, alternative to PTS(Programmed Test Sources) x10 or 040?
Jim said: It's like a HP 8663B (not the modern Agilent E8663).. very low noise, The Agilent E8663 has similar SSB phase noise spec as the older HP 8662A (-144dBc/Hz @ 10 kHz with option UNY, versus -143 for the 8662). You seem to imply they are different. Can you elaborate? Of course, the Agilent has many more features and 0.001Hz resolution, and the 8662 only goes to 990MHz (I think, I should know, I have two thanks to JohnM...), but are they that much different in pure phase noise or ADEV? Didier On Mon, Jul 8, 2013 at 10:02 AM, Jim Lux jim...@earthlink.net wrote: On 7/8/13 7:55 AM, Ed Palmer wrote: In 2002, this document: THE CRYSTAL OSCILLATOR CHARACTERIZATION FACILITY AT THE AEROSPACE CORPORATION http://www.pttimeeting.org/**archivemeetings/2002papers/**paper32.pdfhttp://www.pttimeeting.org/archivemeetings/2002papers/paper32.pdf stated: The Programmed Test Sources, Inc. PTS model #250M6NIGSX-51 low-noise frequency synthesizer is used to offset the frequency reference to obtain the desired beat frequency. In our previous system, we used a Fluke 6160B frequency synthesizer, since the Fluke 6160B frequency synthesizer had the lowest noise contribution of all the frequency synthesizers on the market at that time. The reason for having the low-noise frequency synthesizer is the synthesizer noise contributions to the system noise-floor. Unfortunately, Fluke has discontinued manufacturing and maintaining this synthesizer. Therefore, we looked at the new synthesizers on the market and found that the PTS synthesizer was the closest to the Fluke 6160B frequency synthesizer in terms of noise floor. Sounds like a working 6160B would be a nice thing to have. Unfortunately, it's too large for my already overcrowded lab. :-( It's like a HP 8663B (not the modern Agilent E8663).. very low noise, not made any more, I don't think Agilent will even repair them. We've got lots of them sitting on the floor, partly dead, at work: they were the workhorse of the Deep Space Network systems. Fluke does make a modern copy of the HP8663B with all the same peculiarities (e.g. smooth sweep, modulation input, etc.) which the Agilent does not do. (for instance, we feed the signal from a 3325 at around 10 MHz into the FM port on the 8663 and then filter to select just the modulation sideband, which then gets multiplied up to the desired frequency) __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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] How dangerous if a Rb lamp broken?
This isotope of radium has a half-life of 1600 years. It isn't dead, or even noticeably less radioactive. Most probably it has burned out the binder that holds the ZnS:Cu material together and on the digits and hands. -Chuck Harris Bill Hawkins wrote: Since this thread doesn't appear to have a half-life, perhaps this needs some explanation. The zinc sulfide fluoresces when an atom or more of radium decays. The fluorescence will still occur in the presence of ionizing radiation. The radium, OTOH, is nearly dead. Probability says that some number of atoms will leave their radioactive state and become inert (Lead? I haven't got time to look it up so I'll share my ignorance with you. Someone will correct me and the thread will never die.) The rate at which a mass of radium becomes inert is expressed as its half-life, which is the TIME that it takes for half of the remaining radium to become inert. The decay is exponential, as are so many natural things. You'll need a sensitive Geiger counter to see if there's any life left in the radium. Or you could expose the watch to a photomultiplier in total darkness to see if it scintillates. In other words, it doesn't burn out. Bill Hawkins ___ 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] Speaking of Costas loops (WAAS)
On Wed, Jul 10, 2013 at 02:42:19PM -0700, J. Forster wrote: David, While I can easily see how you can do closed loop correctioin for Dopplar from the transmission point for a 'bent pipe' repeater, at any other location that correction would not be valid, because the paths are not parallel. Sorry for my poor choice of words. That is precisely what I meant by for an observer on the ground it is necessary to correct for the satellite orbit induced doppler.This is true for ANY observer, since it would seem certain that the closed loop correction actually is structured and calculated to cause the satellite to radiate a carrier (and timing modulation on it) equivalent to what an accurate local GPS satellite reference clock would generate if one was aboard the hosted payload rather than on the ground. Anything else would make no sense as it is not incumbent on users to try to figure out ground relative timing for some unknown uplink antenna somewhere. And offsetting radiated uplink time and frequency on the ground to make it right on the satellite at the output of the bent pipe repeater is very feasible and more or less a no brainer. But if the satellite radiates what a local GPS package would and transmits ephmerides defining its position and motion it could be included in a GPS solution and could be used for timing and frequency purposes the same as any other GPS satellite subject to whatever degree of relative accuracy the bent pipe clock obtains and the degree to which the ephemerides in the format transmitted allow an accurate position to be determined. And from what I have read it seems very likely the WAAS birds meet these criteria.. -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ 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] Speaking of Costas loops (WAAS)
Hi If the WAAS birds are run in a fashion that gives a true GPS payload performance, why not assign them a SN 32 or below and use them? If the WAAS birds are not in the right numbers, why bother to set them up and spend the bucks to make them behave like a nav sat? What's the payoff? Bob On Jul 10, 2013, at 7:40 PM, David I. Emery d...@dieconsulting.com wrote: On Wed, Jul 10, 2013 at 02:42:19PM -0700, J. Forster wrote: David, While I can easily see how you can do closed loop correctioin for Dopplar from the transmission point for a 'bent pipe' repeater, at any other location that correction would not be valid, because the paths are not parallel. Sorry for my poor choice of words. That is precisely what I meant by for an observer on the ground it is necessary to correct for the satellite orbit induced doppler.This is true for ANY observer, since it would seem certain that the closed loop correction actually is structured and calculated to cause the satellite to radiate a carrier (and timing modulation on it) equivalent to what an accurate local GPS satellite reference clock would generate if one was aboard the hosted payload rather than on the ground. Anything else would make no sense as it is not incumbent on users to try to figure out ground relative timing for some unknown uplink antenna somewhere. And offsetting radiated uplink time and frequency on the ground to make it right on the satellite at the output of the bent pipe repeater is very feasible and more or less a no brainer. But if the satellite radiates what a local GPS package would and transmits ephmerides defining its position and motion it could be included in a GPS solution and could be used for timing and frequency purposes the same as any other GPS satellite subject to whatever degree of relative accuracy the bent pipe clock obtains and the degree to which the ephemerides in the format transmitted allow an accurate position to be determined. And from what I have read it seems very likely the WAAS birds meet these criteria.. -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ 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] Speaking of Costas loops (WAAS)
On 07/11/2013 01:45 AM, Bob Camp wrote: Hi If the WAAS birds are run in a fashion that gives a true GPS payload performance, why not assign them a SN 32 or below and use them? If the WAAS birds are not in the right numbers, why bother to set them up and spend the bucks to make them behave like a nav sat? What's the payoff? In the old days (receiver channels are sparse resource): If you devote a receiver channel to receive it, let it contribute to position while it provides the core corrections. In todays world: Channels and GPS birds are many, WAAS only contribute to precision and validation. This assuming relatively normal commodity receivers. The fancy receivers (double-frequency, full-blown carrier-phase pseudo-ranges) had little extra use of the WAAS, except possibly somewhat quicker lock-in if not being fed from a national reference grid. 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] How dangerous if Rb lamp broken?
Thanks, Robert, for this detailed information. Volker Am 10.07.2013 21:01, schrieb Robert Atkinson: Hi Hui, This is a little off-topic for time nuts, but here goes. the Becquerel is a measurement of radioactivity, 1Bq being one decay per second. Bg/gm is specific activity so if you have 1g of material with a specific activity of 200Bq/g you will have 200 decays per second. We need to use this as not all the Rb in a lamp is Rb 87 and the weight quoted includes it all. The Sievert is a measurement of effective dose. It depends on time, quantity of radioactive material, type and energy of radiation emitted, distance and the organ exposed. It is not a simple calculation or conversion. As Rb87 is a beta emitter with a maximum energy of 272 keV, it will only produce localised effects. externally it will only cause skin exposure and you would need megabecquerels in direct contact to cause something like a sunburn. Anything else would need internal exposure. Rb87 is of so little concern that the standard dose rate calculation program I use does not even list it. Chemically Rb is similar to potassium, K, which is essential to humans. Natural K contains 0.0117% of the radioactive isotope K40. A typical 70kg human male is 0.2%K so has more than 3000Bq of K40. So if you swallowed 2mg of the Rb from a bulb AND the body absorbed ALL of it, the total additional dose would be less than 0.1% of that you are getting from the natural K in your body. In practice it would be even less because your body would not absorb it all and that it did absorb would probably displace some K. Intact Rb cells cells have on detectable external radiation. My half gram estimate came from a web search of peer reviewed articles. The US occupational ingestion limit is 1mCi or 37000Bq per year. Inhallation is twice that. US labs can discharge water to the sewer with 370Bq/liter of Rb87 Rb cells are perfectly safe for all practical purposes. An injury from the broken glass is probably much more of a risk! HTH,Robert G8RPI. From: Hui Zhangba...@163.com To: Robert Atkinsonrobert8...@yahoo.co.uk; Discussion of precise time and frequency measurementtime-nuts@febo.com Sent: Wednesday, 10 July 2013, 14:53 Subject: Re:Re: [time-nuts] How dangerous if Rb lamp broken? Hello Robert: I am a little confuse how exactly much Rb87 in a bulb? Some people say that it's couple millgram, but you tell me it's half a millgram, which is ture? You message is good new to me, it let me relax, but I don’t understand Bq/gram unit, would you please convert it to mSV unit, I can know the how many mSV of human is safety by search by internet. I mean in extreme situration, if all Rb87 of buld sprinkled in my table, how many exposure value will I accepet in 24 Hour? I found some people (other electronics fan) wrote a formula about Rb87 radioactivity calculation, that is: 1mg Rubidium * 27.835 * 0.27835 * 6.02 *10^23 / 87/4.88/10^10/2/365/24/3600*1=625. So, decay energy=0.283MeV, about 600 electron per second, Is this calculation correct? 27.835=Percent of Rb87 6.02*10^23 = Avogadro's constant 87= Atomic weight 4.88*10^10== Half time of Rb87 (Year) 2 = Rb87 decay to half 365 = day of year 24 = hour of day 3600 = second of hour I am very glad to read many relay of my email, I want say thanks for everyone. As you said why people be afraid of Rb87 but not other things, I think maybe because we don’t understand it. Such as, I don’t afraid of RF exposure, because I know it, I am a HAM and learned many RF exposure knowledge, but of atom and radioactivity, I have only poor knowledge. Thanks everyone again, this is amazing mail-list. Say sorry for my poor English. Hui At 2013-07-09 19:40:50,Robert Atkinsonrobert8...@yahoo.co.uk wrote: Hi Hui, Most bulbs use a mix of Rb87 and Rb85 with an activity of around 1500 Bq/gram with less than half a millgram in a typical bulb, that's less than a Bq per bulb (about 20 picocuries). You will get more ardiation from using low sodium salt (potassium chloride) on your food. Potasium is essential for life and Rb is chemically similar. In short don't worry. Robert G8RPI (also a geiger nut and collector of radioactive material) From: Hui Zhangba...@163.com To: Discussion of precise time and frequency measurementtime-nuts@febo.com Sent: Tuesday, 9 July 2013, 5:07 Subject: [time-nuts] How dangerous if Rb lamp broken? Dear Group: I have four compact Rb Stanard, but I am worried about what if my Rb lamp broken in accident someday? How dangerous of this situration? Is Rb87 came out from Rb lamp will be a disaster? You know I haven't any beta rays detect instrument. Hui ___ 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] Speaking of Costas loops (WAAS)
On Wed, Jul 10, 2013 at 07:45:39PM -0400, Bob Camp wrote: Hi If the WAAS birds are run in a fashion that gives a true GPS payload performance, why not assign them a SN 32 or below and use them? If the WAAS birds are not in the right numbers, why bother to set them up and spend the bucks to make them behave like a nav sat? What's the payoff? The patent cited here recently explains... for fixed timing purposes and basic anti jam a simple directional antenna pointed at the WAAS bird allows rejection of many interferers without elaborate and expensive active steered phased array nulling technology. And because - given a known fixed ground position - timing and frequency can work with only one bird visible, this allows timing/frequency using just the WAAS signal (or signals, they do provide more than one WAAS frequency). And potentially if the timing accuracy via the hosted payload is respectable at least for the needs of many fixed time/frequency users this might supply a solution MUCH less resistant to local (nearby) interferers than the usual more or less hemi pattern GPS antenna would - as fixed dishes with considerable gain toward the satellite could be used and in most places they would point well above the horizon and could be shielded by nearby structures to further reduce jamming susceptibility from jammers (intentional or unintentional) below or at the horizon for the site. For timing/frequency users (certainly an important subset of the GPS user population) this provides some protection by antenna pattern that is hard to obtain otherwise (and users interested in higher precision or redundancy of timing could still just use another GPS timing system based on normal hemi GPS antennas as the primary - using the normal SVs - and rely on the dedicated dish pointed at the WAAS bird only as backup in the event of jamming). The choice of using different spreading codes from the normal GPS set for WAAS or using a slightly different one is an overall system architecture decision... which I guess was made in favor of not tying up codes for regular SVs for the WAAS birds. But AFAIK a receiver with suitable firmware could still extract pseudo ranges and use them. I guess there is an issue in any frequency translation scheme with the relationship of carrier and code phase... a homodyne distortion... due to the random phase of the LO(s)... but this too can be predistorted on the ground to come out right and that kept in line via closed loop tracking of the downlink from a ground site. I do understand that this insight into a potential further use of WAAS beyond its use as a data channel and propagation beacon seems to have happened later and not initially. -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ 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] time-nuts Digest, Vol 108, Issue 55
On 7/10/13 2:15 PM, Max Robinson wrote: I think that luminous dial watches still contain a little tritium to keep them glowing for many hours after the atoms that were excited by visible photons have all decayed. Without the tritium the glow would completely go dark after most of the atoms have decayed to their ground state. luminous dials use some form of activated zinc sulfide. No radioactivity involved. Tritium is actually quite dangerous just because of the tritiated water problem. Beta emitters, sitting in a lump on the table, aren't as hazardous, because it's easily shielded. Your skin absorbs most of the beta particles (aka electrons), so you would get burned, perhaps. However, if you ingest a beta emitter, now you've got a beta emitter close to sensitive cells. Tritiated water is easily ingested, absorbed, and otherwise winding up close to sensitive tissues. It's like why plutonium or radon, alpha emitters, are such a problem. If they become airborne and ingested into your lungs, you've got a alpha emitter close to lung tissue which is peculiarly sensitive. In fact, I seem to recall that a significant reason why cigarette smoke is carcinogenic is that it has tiny particles which carry radon and other similar nuclides deep into the lungs. Getting back to Rb safety... It's pretty reactive, and all the salts are unlikely to be ingested and absorbed. Not like you're going to be sprinkling RbCl on your steak. There's a video on the web about alkali metals reacting with water, but it used pyrotechnics to enhance the Rb and Cs reactions. From practical experience, Li is the most spectacular, Na is really bright, K isn't as exciting as either, but is a pretty color. Li has that brilliant scarlet color. I think the Na is bright because of the reaction energetics, and because the sodium yellow is closer to your eye's maximum sensitivity. If you're looking for maximum bang for the buck, I think Sodium is your alkali metal of choice. I've always wanted to try a Na/K eutectic, though. ___ 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] Very stable synthesizer, alternative to PTS(Programmed Test Sources) x10 or 040?
On 7/10/13 12:29 PM, Didier Juges wrote: Jim said: It's like a HP 8663B (not the modern Agilent E8663).. very low noise, The Agilent E8663 has similar SSB phase noise spec as the older HP 8662A (-144dBc/Hz @ 10 kHz with option UNY, versus -143 for the 8662). You seem to imply they are different. Can you elaborate? Of course, the Agilent has many more features and 0.001Hz resolution, and the 8662 only goes to 990MHz (I think, I should know, I have two thanks to JohnM...), but are they that much different in pure phase noise or ADEV? Didier It's not the phase noise that raised the problems for us. It's that when you program them for a sweep, it goes in steps that aren't phase continuous AND the behavior when you feed a signal into the FM input isn't the same. The HP 8663B was, at the core, a really good phase locked VCO, so when a sweep is programmed, the output is phase continuous as it sweeps. This is a huge problem when you are testing a very narrow band tracking loop (our deep space transponders have a loop bandwidth of a few Hz) I can't remember the details on the FM input, but it too has some behavior that we depended on. We take the output of the 8663B and run it into a x7 to make the 7150 MHz uplink and/or the 8450 MHz downlink frequencies. Part of the reason we do a x7 is so that any leakage from the synthesizer isn't in band for our receiver under test. A typical input level for test is -150 to -160 dBm, so leakage at the wrong frequency can easily be more than the desired signal. ___ 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] Speaking of Costas loops (WAAS)
On Wed, Jul 10, 2013 at 07:40:50PM -0400, David I. Emery wrote: But if the satellite radiates what a local GPS package would and transmits ephmerides defining its position and motion it could be included in a GPS solution and could be used for timing and frequency purposes the same as any other GPS satellite subject to whatever degree of relative accuracy the bent pipe clock obtains and the degree to which the ephemerides in the format transmitted allow an accurate position to be determined. And from what I have read it seems very likely the WAAS birds meet these criteria.. Thinking some more about the bent pipe repeater aspect of WAAS, aside from allowing any kind of WAAS like signal someone might invent in the future to be retrofitted to existing satellites without a long replacement cycle and expensive launches being involved - there are some interesting properties of the design. One is that one COULD bury in the WAAS uplink cryptographic (eg essentially random to users not in possession of the key) spreading sequence transmissions that would be radiated globally and could be received with unique GPS hardware... such a covert channel in civilian GPS could have various purposes... and would look rather noise like to the rest of the world. -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ 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] Lead acid battery noise levels
Eric: http://tf.nist.gov/general/pdf/1133.pdf discusses the noise levels of various batteries. Regards Mark S Message: 6 Date: Wed, 10 Jul 2013 11:11:00 -0700 From: Eric Williams wd6...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Lead acid battery noise levels Message-ID: cafagtrqveohikn4op01myvn6vkdk+bdlsjpwyjrrmxp0sdd...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 I wonder if lithium batteries would have a good noise figure. The nano-structure of the electrodes give them very large surface area and low resistance, but the charge carriers are different than other types of chemistry and I don't know if that's good or bad. ___ 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.
