Re: [time-nuts] Measurements
Sanjeev, That sounds like the Repeating Theodolite, used for the survey from Dunkirk - Paris - Barcelona Exactly! Thanks for your help Ulrich -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im Auftrag von Sanjeev Gupta Gesendet: Samstag, 22. August 2009 10:56 An: Discussion of precise time and frequency measurement Betreff: Re: [time-nuts] Measurements On Sat, Aug 22, 2009 at 15:19, Ulrich Bangert df...@ulrich-bangert.dewrote: Which in turn lead to the invention of a new class of surveyor instruments, which in turn enabled the French to measure the distance from the equator to the north pole (assumed to be 1/4 of the circumference) with a precision that must be admired even from a today point of view. I do not know the english term for it but in German these instruments are called Repetitionskreis. You can find a pictue of one here: http://www.bistumsmuseen-regensburg.de/html/ausstellungen_moenche_repe tition skreis.htmhttp://www.bistumsmuseen-regensburg.de/html/ausstel lungen_moenche_repetition%0Askreis.htm That sounds like the Repeating Theodolite, used for the survey from Dunkirk - Paris - Barcelona http://en.wikipedia.org/wiki/Repeating_circle The basic idea is to mark out repeatedly the angle to be measured, but actually measure the sum, _only_ at the end, which you then divide. It gives you the arithmetic mean of the value directly. The major advantage over doing this mechanically, rather than adding it up in your notebook, is a that you have reduced the least-count of your graduated scale. -- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane ___ 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] gnat sizing
I'm from the SE of England, Brighton and Ipswich, and this is the measurement as I remember it from a very long time ago too Peter. Steve - G8KVD - that dates me just a bit ZL3TUV 2009/8/23 Peter Vince pvi...@theiet.org: Maybe I was brought up in a more genteel part of West London, but the unit of measurement I was brought up with was a Gnat's Whisker. I don't think that was just my parents cleaning it up, as that expression seemed pretty common. Sometimes abbreviated to just a gnat's, but it was definitely its whisker that was understood. Peter Vince (G8ZZR, London, England) On Wed Aug 19 22:49 , 'Lux, Jim (337C)' james.p@jpl.nasa.gov sent: I realize we are straying afar.. but inquiring minds may wish to know. Referring to A handbook of the gnats or mosquitoes: giving the anatomy and life history of the Culicidae by George Michael James Giles, 2nd edition, 1902 (thank you google for digitizing this book from the Stanford library) The forward says that the second ed is much better than the first ...the result of a couple of months of constant work with the microtome. So I think we can consider this a reliable reference. Now I readily confess that this book seems devoted to only members of family Culicdae, and it's not clear that when referring to gnat anatomy as an unit of measure whether these are the gnats being referred to. The common name gnat seems to be applied to many small (often biting) Dipterid Insects, and Wikipedia seems to restrict the gnat terminology to other families. It would appear that the rectum of the gnat is about 1/10th the diameter of the abdomen (there's a drawing of a transverse section of the abdomen on page 91). If the page is about 6 wide (judging from the type size, and the image of the checkout card in the back page this is reasonable.. it's probably octavo size), then the 100x drawing is 2 across, so that rectum is .002 inches across (call it 0.05 mm, or 50 microns) . This is much larger than the 1E-4 inches (2.5 microns) previously cited, but well within the range for human hair diameters (given as 17 to 181 micron in a variety of online sources, but a much smaller range of 50-90 micron is cited in Forensic Examination of Hair, albeit for scalp, J. Robertson, Ed.) Now, to return to the original question of position accuracy for your timing receiver. Whether 50 microns will result in a significant timing error? 1 nanosecond is 300 mm light time. 300 microns is 1 picosecond, so that 50 micron position error is down in the femto seconds.. James Lux, P.E. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Steve Rooke - ZL3TUV G8KVD A man with one clock knows what time it is; A man with two clocks is never quite sure. ___ 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] gnat sizing
I also remember small distances being referred to by a 'fag paper'. Meaning the thickness of a roll your own cigarette paper. 73 Steve 2009/8/23 Steve Rooke sar10...@gmail.com: I'm from the SE of England, Brighton and Ipswich, and this is the measurement as I remember it from a very long time ago too Peter. Steve - G8KVD - that dates me just a bit ZL3TUV 2009/8/23 Peter Vince pvi...@theiet.org: Maybe I was brought up in a more genteel part of West London, but the unit of measurement I was brought up with was a Gnat's Whisker. I don't think that was just my parents cleaning it up, as that expression seemed pretty common. Sometimes abbreviated to just a gnat's, but it was definitely its whisker that was understood. Peter Vince (G8ZZR, London, England) -- Steve Rooke - ZL3TUV G8KVD A man with one clock knows what time it is; A man with two clocks is never quite sure. ___ 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] Using cheap sound cards for measurements
My limited experience with this USB soundcard was the ease of getting it working with Windows Vista home premium. Another PCI sound card, the Delta 44, was a big problem, at least for me. Stan, W1LE Don Latham wrote: Ok, I have looked at a few USB cards and reviews. For SD radios, and as far as I can tell for time use, the Creative E-MU 0202 will do nicely, at a reasonable cost of $99.00. According to the company info, the E-MU 0404 might be synchronizable; it costs about $150. The plug-in card (takes two slots) equivalent to the 0404 is apparently the E-MU 1212. It might be possible to modify the 0202 to provide an external clocking signal, at least to provide a more stable oscillator, I don't know. The 100 ps jitter if true is satisfactory? Oh, the 1212 input amplifiers are DC coupled (!). I suggest, of course, that interested parties have a look at the website: http://us.creative.com/products/welcome.asp?category=237 I'll probably be ordering an 0202 in the near future. Don Latham ___ 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] HP catalogs and HP 5065A
Corby Dawson wrote: Hi, I'm curious what year was the last year that HP offered the 5065A for sale and what the list price was for that year. It is in the 1993,94,95, or 96 catalog. Can any one who has one of these years catalogs check and see? OK Corby, it is NOT in the 1993 or later catalogs. I see it in 1991 offered for $36,200 for the base model, but can't find 1992. Maybe someone has that one, or there is a site with a lot of them on line as pdfs. That narrows it down a bit! 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] HP catalogs and HP 5065A
I do not show it in the 1995 or the 1998 catalog. It is in the 1970 ($7500), 1972 ($7500), 1977 ($8950), 1980 (no prices in this catalog), 1985 ($19500), 1988 ($25800) and 1992 ($42000). Brian Kirby - KD4FM Corby Dawson wrote: Hi, I'm curious what year was the last year that HP offered the 5065A for sale and what the list price was for that year. It is in the 1993,94,95, or 96 catalog. Can any one who has one of these years catalogs check and see? I seem to remember the price jumped up a bit in the last year offered. Thanks all. Corby Dawson cdel...@juno.com Free Life Insurance Quote Get a Free Quote Smart Advice! Compare Rates Save Up To 70% http://thirdpartyoffers.juno.com/TGL2141/c?cp=2h6SXHvr01WBduNAdGympQAAJ1ABLZFyqoH-WnHH1GJ345whAAQFAOXQgj4AE1lTAA== ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP catalogs and HP 5065A
for the HP-5065A, no options: 1982, page 312, 16.9K$ 1988, page 465, 25.8K$ 1991, page 507, 36.2K$ 1992, page 555, 42.0K$ not in: 1993, 1994, 1995, 1996 Stan, W1LECape Cod Dan Rae wrote: Corby Dawson wrote: Hi, I'm curious what year was the last year that HP offered the 5065A for sale and what the list price was for that year. It is in the 1993,94,95, or 96 catalog. Can any one who has one of these years catalogs check and see? OK Corby, it is NOT in the 1993 or later catalogs. I see it in 1991 offered for $36,200 for the base model, but can't find 1992. Maybe someone has that one, or there is a site with a lot of them on line as pdfs. That narrows it down a bit! 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] Using cheap sound cards for measurements
Be careful of the Emu/Creative stuff. They have always has resampling in their products in the past. This new generation doesn't but it still has an inline DSP to muck around with the bits. Also the Windows (and MAC) sound systems are notorious for resampling internally. This can be very hard to get around. You can use ASIO drivers to go around the internal engine if you write your app for that. The EMU 0202 isn't supported fully in Linux yet. Demian Martin PDS Ok, I have looked at a few USB cards and reviews. For SD radios, and as far as I can tell for time use, the Creative E-MU 0202 will do nicely, at a reasonable cost of $99.00. According to the company info, the E-MU 0404 might be synchronizable; it costs about $150. The plug-in card (takes two slots) equivalent to the 0404 is apparently the E-MU 1212. It might be possible to modify the 0202 to provide an external clocking signal, at least to provide a more stable oscillator, I don't know. The 100 ps jitter if true is satisfactory? Oh, the 1212 input amplifiers are DC coupled (!). I suggest, of course, that interested parties have a look at the website: http://us.creative.com/products/welcome.asp?category=237 I'll probably be ordering an 0202 in the near future. Don Latham ___ 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] Using cheap sound cards for measurements
Thanks, Demian. At least one of the SD radio programs uses an ASIO driver. I do not know about the rest, or about the leading spectrum analysis freebies that are out there. Don Demian Martin Be careful of the Emu/Creative stuff. They have always has resampling in their products in the past. This new generation doesn't but it still has an inline DSP to muck around with the bits. Also the Windows (and MAC) sound systems are notorious for resampling internally. This can be very hard to get around. You can use ASIO drivers to go around the internal engine if you write your app for that. The EMU 0202 isn't supported fully in Linux yet. Demian Martin PDS Ok, I have looked at a few USB cards and reviews. For SD radios, and as far as I can tell for time use, the Creative E-MU 0202 will do nicely, at a reasonable cost of $99.00. According to the company info, the E-MU 0404 might be synchronizable; it costs about $150. The plug-in card (takes two slots) equivalent to the 0404 is apparently the E-MU 1212. It might be possible to modify the 0202 to provide an external clocking signal, at least to provide a more stable oscillator, I don't know. The 100 ps jitter if true is satisfactory? Oh, the 1212 input amplifiers are DC coupled (!). I suggest, of course, that interested parties have a look at the website: http://us.creative.com/products/welcome.asp?category=237 I'll probably be ordering an 0202 in the near future. Don Latham ___ 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. -- Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
