Re: [time-nuts] A small piece on HP's hydrogen maser in 1968
So what's all this about a Thallium Beam Tube??? (Isn't Thallium incredibly toxic?) n.b. One of the pictures references a Th beam tube... On Tue, Feb 25, 2014 at 2:46 AM, Poul-Henning Kamp p...@phk.freebsd.dkwrote: [Jim Lux] Wasn't that Gravity Probe B.. which finally launched in 2004, and had equivocal results. No, GPB was the gyro-experiment, it tested another part of GR than red shift was supposed to. [Tony Greene] In the back of my head, I beleive that project red shift did fly, but they dumped the hydrogen masers to use brand new lighter weight and much smaller rubidiums. I've found no trace of it. Are you sure you are not confusing it with the pathfinders for NavStar ? -- 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. ___ 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] 5370 processor boards available
Thats exciting to hear Thanks On Mon, Feb 24, 2014 at 6:59 PM, John Seamons j...@jks.com wrote: I may have a solution for the power-off problem that doesn't involve batteries or supercaps. It has the added advantage of providing instant-on. I need to run some tests.. ___ 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] A small piece on HP's hydrogen maser in 1968
So what's all this about a Thallium Beam Tube??? For info about the pro/con of Thallium beam frequency standards, see: http://tf.boulder.nist.gov/general/pdf/9.pdf http://tf.boulder.nist.gov/general/pdf/211.pdf http://leapsecond.com/history/1965-Metrologia-v1-n3-Cesium.pdf Imagine 21310.833946 MHz instead of 9192.631770 MHz... /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A small piece on HP's hydrogen maser in 1968
Thanks, also consider the HP patent: http://www.google.com/patents/US3407295 On Tue, Feb 25, 2014 at 4:40 PM, Tom Van Baak t...@leapsecond.com wrote: So what's all this about a Thallium Beam Tube??? For info about the pro/con of Thallium beam frequency standards, see: http://tf.boulder.nist.gov/general/pdf/9.pdf http://tf.boulder.nist.gov/general/pdf/211.pdf http://leapsecond.com/history/1965-Metrologia-v1-n3-Cesium.pdf Imagine 21310.833946 MHz instead of 9192.631770 MHz... /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] DS3231m 1HZ output stability
Hello, I am experimenting to compare 1PPS outputs from Dallas/Maxim DS3231m chip and 1PPS output from generic GPS module. I attached both signal to MCU timers with free run counters and measure the interval between of raising edges. Here is the typical results: # Delta GPS: 3659, Delta RTC: 3660 # Delta GPS: 3659, Delta RTC: 3659 # Delta GPS: 3658, Delta RTC: 1984 # Delta GPS: 3658, Delta RTC: 1984 # Delta GPS: 3659, Delta RTC: 3659 # Delta GPS: 3659, Delta RTC: 3660 In my tests, Delta is the number of MCU tics (counter value) and its depends of MCU clock settings. Usually Delta pretty much close for RTC and GPS. But sometimes, DS3231m shows some big difference. Meantime, 1PPS from GPS module is much more consistence. I would like to ask if somebody did measurement for that Dallas DS32XX series chips. Is that 1PPS (1HZ square wave) stable there or it has some issues ? I am thinking that burp in my tests could be because of my poor code or may be because of DS32XX doing temperature conversion every second, which cause an impact to the 1HZ output. I would be interested to hear any information about. From the datasheet of DS3231m , that 1HZ from DS32XX should be stable. Regards, V.P. ___ 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] DS3231m 1HZ output stability
I would like to ask if somebody did measurement for that Dallas DS32XX series chips. Is that 1PPS (1HZ square wave) stable there or it has some issues ? I am thinking that burp in my tests could be because of my poor code or may be because of DS32XX doing temperature conversion every second, which cause an impact to the 1HZ output. I would be interested to hear any information about. From the datasheet of DS3231m , that 1HZ from DS32XX should be stable. Both the GPS and DS32XX 1PPS should be fine. Are your free-run counters really free? It looks like a simple bug in your code. All this is very easy to debug if you have even the most basic frequency or time interval counter available to independently validate the GPS or the DS32XX 1PPS interval. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] DS3231m 1HZ output stability
# Delta GPS: 3659, Delta RTC: 3660 # Delta GPS: 3659, Delta RTC: 3659 # Delta GPS: 3658, Delta RTC: 1984 # Delta GPS: 3658, Delta RTC: 1984 # Delta GPS: 3659, Delta RTC: 3659 # Delta GPS: 3659, Delta RTC: 3660 I would like to ask if somebody did measurement for that Dallas DS32XX series chips. Is that 1PPS (1HZ square wave) stable there or it has some issues ? I am thinking that burp in my tests could be because of my poor code or may be because of DS32XX doing temperature conversion every second, which cause an impact to the 1HZ output. I would be interested to hear any information about. From the datasheet of DS3231m , that 1HZ from DS32XX should be stable. My guess would be a software bug, but I don't know anything about what you did there. You might try swapping the two input wires. Do you have a scope? Any overshoot/bounce crap? (Not likely with low power CMOS.) Notice that the 2 strange lines came when the GPS had only 3658 ticks. I have data from one of the DS32xx chips, but I was looking at a 32KHz signal rather than the a 1 Hz. I don't remember any quirks. -- 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] A small piece on HP's hydrogen maser in 1968
On 2/25/14 1:40 PM, Tom Van Baak wrote: So what's all this about a Thallium Beam Tube??? For info about the pro/con of Thallium beam frequency standards, see: http://tf.boulder.nist.gov/general/pdf/9.pdf http://tf.boulder.nist.gov/general/pdf/211.pdf http://leapsecond.com/history/1965-Metrologia-v1-n3-Cesium.pdf Imagine 21310.833946 MHz instead of 9192.631770 MHz... Excellent, connectors that cost $50 each instead of $5. Test equipment that costs 5x as much. I work a lot with 32/34 GHz (deep space Ka-band) at work, and I hate having to explain to people who haven't had to buy equipment since back when they worked with X band (7.15/8.45 GHz) that there's a BIG jump in cost when you cross that 18GHz boundary line. ___ 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] A small piece on HP's hydrogen maser in 1968
jim...@earthlink.net said: there's a BIG jump in cost when you cross that 18GHz boundary line. What's magic about 18 GHz? Why not 16 or 20? -- 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] A small piece on HP's hydrogen maser in 1968
Lot's of connectors change specification @ 18Ghz or are not rated bast 18Ghz. On Tue, Feb 25, 2014 at 11:55 PM, Hal Murray hmur...@megapathdsl.netwrote: jim...@earthlink.net said: there's a BIG jump in cost when you cross that 18GHz boundary line. What's magic about 18 GHz? Why not 16 or 20? -- 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] A small piece on HP's hydrogen maser in 1968
Solid dielectric cable and connectors of 3.5 mm size are mode limited to 18 GHz. That is why there is so much stuff rated at 18 GHz as opposed to 16 or 20 GHz. The next jump up is 26.5 GHz where 3.5 mm size works in air dielectric. It costs more to make these components and the volume is lower, hence the higher price. Also, the low price vendors may just stop at 18 GHz. Rick On 2/25/2014 9:03 PM, Bob Bownes wrote: Lot's of connectors change specification @ 18Ghz or are not rated bast 18Ghz. On Tue, Feb 25, 2014 at 11:55 PM, Hal Murray hmur...@megapathdsl.netwrote: jim...@earthlink.net said: there's a BIG jump in cost when you cross that 18GHz boundary line. What's magic about 18 GHz? Why not 16 or 20? -- 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. ___ 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.
