[time-nuts] Some comments on GPS timing

Perhaps it is time that I step in to point the newer members of Time-Nuts to some of the historical (hysterical?) info on using  GPS to achieve sub-microsecond global timing sync. I refer you all to the website http://gpstime.com   that Rick Hambly (http://cnssys.com) maintains to document so

[time-nuts] Jackson GPSTCXO question

I'm evaluating a Jackson GPSTCXO that was in a Symmetricom Eval Kit. It's showing impressive perfomance with just the antenna in the window. I'm using either the Z38xx or GPSCon software. Are there commands that would allow me to 1. Force the receiver to do a self-survey and/or 2. Force the po

[time-nuts] SK -- Den Connors, KD2S

about 25 years ago to work at Wang Computers, and lived in Pepperell, Massachusetts. 73, Den -- you will be missed by all your friends! Tom Clark, K3IO ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/m

[time-nuts] Den Connors, KD2S

I'm sure that many early TAPRites remember TAPR's first President, Den Connors, KD2S. Den was active in Tucson circa 1982-83 at the formation of TAPR, during the TNC-1 days. Some info on Den can be seen at [1]http://www.tapr.org/history.html, as documented in the first PSR ([2]http:/

Re: [time-nuts] homebrew 13 dBm distribution amplifier based on NIST design 5 to 100 MHz

Gerhard -- the discussion between you and Bruce has been very interesting. I asked a VLBI colleague to look over your design and he had this comment. In VLBI, H-Maser frequency standards used to generate local oscillators at microwave frequencies. We have problems with amplitude

[time-nuts] Distribution Amplifier

mp;pgraph=4> Thanks -- Tom Clark ___ 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] The name "Totally Accurate Clock"

site for more details. In the meantime, I retired from NASA in 2001 but I still stay involved with the VLBI and timing communities as the resident curmudgeon and referee of mis-spoken factoids. So that's where the name came from and how it evolved. Tom Clark References 1. http://gp

Re: [time-nuts] time-nuts Digest, Vol 49, Issue 4

Jim Palfreyman noted I took my recently acquired Thunderbolt, along with my 5370B, to the observatory on the weekend and plotted its residual against the NR Active Hydrogen Maser. See the attached graph (ignore the "line of best fit" heading - 0.00 was simply the starting point). Note that I

Re: [time-nuts] New leap second

Chuck Harris commented Two leap seconds in as many years! It must be that global warming. -Chuck Harris UT1 is the time measured with respect to the stars, while UTC and TAI are based on the rate of laboratory atomic clocks; I like to say that UT1 is the time you would

Re: [time-nuts] AMSAT Goes to the Races -- April 27

After posting the note about Jim Jaeger, I found another excellent report on the fire on the Channel 9 WCPO web site (http://www.wcpo.com/news/local/story.aspx?content_id=e73830c8-2941-455d-bd43-d18e86344af5). This includes extensive video coverage as broadcast the nite of the fire, including

[time-nuts] AMSAT Goes to the Races -- April 27

Many of you know, or have heard of, Jim Jaeger from Cincinnati. Jim is a MAJOR time-nut, owning a bunch of Cesiums and a couple of H-Masers in his basement time lab. Jim got his electronics start making amateur radios at RL Drake, and then he and Mike Valentine formed Cincinnati Micr

Re: [time-nuts] is there a "best bet" advanced hobbyist buildable GPSDOdesign?

Bruce Griffiths wrote: > Data delay devices (http://www.datadelay.com) also do programmable delay > lines their minimum order is $US75 which isnt too bad particularly if > more than one sawtooth corrector is to be built. > They even do ECL programmable delays as do Micrel (http://www.micrel.com). >

[time-nuts] John Vig elected President of IEEE

The following just appeared on the web. For those of you who don't know of John, he is THE "go to" guy for information on crystal oscillators. Seasons Greetings -- Tom IEEE Members Select John Vig As 2008 IEEE President-Elect 12/5/2007 [1]Request Free Information Piscata

Re: [time-nuts] paralleling regulator redux

christopher hoover wrote: > The October 2007 bulletin from Linear announces a new part : the LT3080 low > drop regulator. They claim: "The LT3080 is the first adjustable linear > regulator that can be directly paralleled to spread the current load and > thus spread dissipated heat." The architect

Re: [time-nuts] 53131A or 5370B

); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I have been a strong advocate for the 53131/2 counter since I first encountered in in 1993. Most of my applications are for a time-interval counter (TIC) measuring the time interval between an atomic clock and GPS (s

[time-nuts] Sorry -- Wrong Allan

); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Said wrote: > I talked to Paul Allan (Mr. Allan deviation) and Jack Kusters who both > worked on the Z3816A development . . . . Sorry, but Said picked the wrong Allan. The Allan (often wrongly spelled Allen) of ADEV fame is D

[time-nuts] Ron Bracewell, SK

a/B/BracewellR.html); be sure to read his 1975 book The Galactic Club. Rest well, Ron. Your genius profoundly affected many lives! Tom Clark References 1. http://news-service.stanford.edu/pr/2007/pr-bracewell-082207.html 2. http://www-star.stanford.edu/people/bracewell.html 3. http:

Re: [time-nuts] Oncore VP problem

or at members discount from TAPR (http://www.tapr.org/gps_tac32.html). Tom Clark ___ 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] Exact Rubidium frequency

); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: To the best of my knowledge, the best measurement of the Rb ground state hyperfi ne frequency comes from the LPTF group in Paris, 6 834 682 610.904 333 Hz, with an accuracy of a few parts in 10^15, by dire

Re: [time-nuts] Software Sawtooth correction prerequisites?

Bruce Griffiths wrote: > > The Dallas delay lines aren't all that accurate, you need to calibrate > them to acheive 1ns accuracy (read the specs) and then you have to > worry about temperature variations. > To use them you need to decode the sawtooth correction message from > the GPS timing receiv

Re: [time-nuts] Updated VLBI tutorial available on gpstime.com

Brooke Clarke asked: > I didn't see in the VLBI slides what was done to "tune" the delay > line, but did see a hint that there's been a firmware upgrade for it. > Can you elaborate? Rick's latest version uses a delay line with more per-bit precision (now 150 psec steps). We also found that Motorol

[time-nuts] Updated VLBI tutorial available on gpstime.com

Next week the VLBI community is having another TOW (Technical Operations Workshop) at the Haystack Observatory NW of Boston. The audience for the TOW is mainly the technicians at each site who drive the telescopes and keep the hardware running. VLBI is crucially dependent on timing and every statio

[time-nuts] Comments on ADEV, MDEV, TDEV, etc

I'll try to answer several of the questions at one time Brooke (no relation) Clarke Why is the Datum2000 so much better than the other receivers? It is a GPSDO. It is pretty obvious that the "handover" from the 2000's Rb to GPS is at ~1,000-10,000 seconds. Brooks Shera:

Re: [time-nuts] Frequency counter recommendations

For over a decade in the VLBI world, we found that the HP53131 and 53132 (now Agilent, of course -- see http://cp.literature.agilent.com/litweb/pdf/5967-6039EN.pdf) were very good, low cost counters well suited to the time-interval world. GPIB is always a pain, and we found that the 131/132 counter

[time-nuts] An Excellent Tutorial on Precision Clocks

I just stumbled on an excellent tutorial on low-noise clocks -- National Semiconductors free downloadable "[1]Clock Conditioner Owner's Manual". This 88 page document is a 3.7 MB PDF. 73 de Tom, K3IO References 1. http://www.national.com/appinfo/interface/files/clk_conditioner_ow

[time-nuts] A Visit from St. Nicholas for Intellectuals Pursuing Interests in Horology

· A VISIT FROM ST. NICHOLAS FOR READERS IN THEIR 23RD YEAR OF SCHOOLING 'Twas the nocturnal segment of the diurnal period preceding the annual yuletide celebration, and throughout our place of residence, kinetic activity was not in evidence among the possessors of this p

Re: [time-nuts] Some long-term data

As a comment on this dialogue: > > Such as temperature and humidity. One of the Cesiums seemed to have a rathe r > > large frequency offset. Did you drift-compensate your ADEV measures or not? > > No, I ran the ADEV in Stable32 without removing drift. My understanding > is that linea

[time-nuts] Hanging Bridges

[1]ftp://ftp.cnssys.com/pub/PTTI/PTTI_2006.pdfHal Murray said: > Noise like the oncore sawtooth isn't always a bad thing. I was going to comment on that area... Thanks for the reminder. The problem is that the sawtooth isn't noise in the normal Gaussian sense. If you happen to hit a long/w

Re: [time-nuts] Time Nuts at PTTI this past week

[EMAIL PROTECTED] wrote: Hi Tom, how many M12M iLotus samples did you test to find the one with 30ns offset? Were these pre-production samples or mass production units? How did the other ones perform? Seems iLotus may not test/calibrate/inspect as thoroughly as Motorola

Re: [time-nuts] Time Nuts at PTTI this past week

Magnus Danielson wrote: FYI -- the slides from Rick & my paper entitled "Improving the Performance of Low Cost GPS Timing Receivers" presented at PTTI are now available at [1][1]http://gpstime.com/ as[2] [2]ftp://ftp.cnssys.com/pub/PTTI/PTTI_2006.pdf and That one is not there!!

[time-nuts] Time Nuts at PTTI this past week

K8RQ, Cincinnati) Peter Lothberg(SM4KEL/W4KEL, Stockholm) Bob McGwier (N4HY, Princeton) Doug Hogarth (K4UTC, Seattle) Rick Hambly (W2GPS, Balto/Wash) Tom Clark (K3IO, Balto/Wash) Jim DeYoung(KG4QWC, Alexandria) Clive Green(G3???, UK) In the list above are counted 8 privately owned H-Masers, nearly 20 Ce

Re: [time-nuts] time-nuts Digest, Vol 26, Issue 5

The question was asked:: A more basic question. Do these degradations affect ordinary users? The reason I ask is that I have a GPS navigation system on in my truck 24/7 and use it every waking hour (I'm a retired engineer who's living a childhood fantasy - driving a long-haul 18-wheeler :-)

Re: [time-nuts] GPS Timing prob

[EMAIL PROTECTED] wrote: Hi Tom, yes, this clock granularity would be of interest. Do you have a more detailed description of how you guys implemented this? Also, how do you handle negative delays, e.g. the M12 is sending it's 1PPS too late? thanks, Said The "

Re: [time-nuts] GPS Timing prob

Faisal Khan wrote: > Hi Tom, > Thank you for your reply. This is Faisal, who is working on the GPS > timing problem and you recommended me some papers from GPStime > website. I looked those papers. I am getting similar sawtooths as > well. But could you explain me what is causing the suspension bri

[time-nuts] Sawtooth Effects in 1PPS

Faisal Kahn asked I am currently working on problems with GPS timings, as I said in my previous e mails. I presented some of my problems and got quite helping feedbacks. I just wanted to update regarding my progress If u visit the page [1]http://www.leapse cond.com/pages/m12/sawtooth.htm you

Re: [time-nuts] Relationship of relative stability between distant locations using GPS and environmental factors

Way back on June 30th, Stephan asked: A number of recent entries to this list have mentioned topics relating to GPS timing and environmental corrupting factors (e.g. Ionosphere, Temp., Humidity, etc.). Personally, I am very interested in setting up a very precise relative time between location

Re: [time-nuts] 10811 Extra Lagging etc

TVB noted: If you are using the 10811 as part of a GPSDO the PLL should take care of any number of slow-moving changes in frequency; whether it's temperature, humidity, voltage, OCXO ageing, DAC drift, phase-of-the-moon, etc. So I don't see a compelling need to "protect" the OCXO in the ways

Re: [time-nuts] time-nuts Digest, Vol 21, Issue 22

VE2VM commented But Isn't Cesium drift-free? Since the SI second is standardized as de duration of 9192631770 oscillation of the hyperfine transition of the atom 133Cs? If Cesium drifts, theren should be a more formal definition of the second (Such as density, maximum C-field or level of puri

[time-nuts] How Rubidiums make their frequency

Christopher Hoover asked: one issue remains: i have to crank the magnetic field setting almost to its high limit (9.91/10.00) to get 5 MHz out; lower settings give a frequency that is too low. i presume this is unusual. i have a rudimentary understanding of the rubidium oscillator

Re: [time-nuts] IC for 1 PPS Output

John Ackermann took my name in vain: > Hi Brooke -- > > The circuit I use is stolen from Tom Clark's TAC -- paralleling > several sections of a 74AC04 hex inverter through 47 ohm resistors. > For the current TADD projects, I'm using three sections that way, so > each chip gives me two outputs,

Re: [time-nuts] GPS Selective Availability. Is it On or Off?

Chuck said > I got the notion that it was turned off during Desert Storm, > by virtue of being involved in the e-warfare effort that lead > up to, and followed the event. > > I haven't been paying much attention since. I knew that they > had intended to turn SA back on after production of the p-c

[time-nuts] S/A, Receiver Glitches, Y2K etc

Don did not mention which basic receiver is inside his AUTEC box. Some receivers do exhibit glitches. Some of these are documented in my 2000 ION paper Low-cost, High Accuracy GPS Timing available on [1]http://gpstime.com. You might find some of the Timing for VLBI tutorials to be o

Re: [time-nuts] Rain, Water, etc

[EMAIL PROTECTED] wrote: David and Tom opined: Rain should have an effect on the timing of the signal, since the propagation speed of radio waves through water is different from that through air. It will also attenuate the signal, causing worse S/N ratio which would cause the lower-eleva

Re: [time-nuts] Thought experiment on a low cost timing board

I have done several GPSDOs using the NAVMAN receiver, so I add a few comments to the discussion: 1. Both the G3RUH ([1]http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm) and I2PHD ([2]http://gpsdo.i2phd.com/) designs use 74HC390 divider chips; I also tried them. What I

Re: [time-nuts] time-nuts Digest, Vol 18, Issue 48

observatory, and it is now a part of the ROG (Royal Observatory Greenwich) Museum. A more detailed definition can be read at [10]http://www.apparent-wind.com/gmt-explained.html and [11]http://aa.usno.navy.mil/faq/docs/UT.html. Tom Clark References 1. mailto:[EMAIL PROTECTED]

[time-nuts] Re: time-nuts Digest, Vol 17, Issue 6

He's using almost 150 semiconductor diodes, isn't that sort of cheating ? He's also using fairly modern (TO-5 can size) trim-pots to tweak each stage. A true vintage unit would have used 3/8" hole, 1/4" shaft (or their metric equivalent) style pots, or else hand-tweak the resistors either

[time-nuts] Leap second talks are postponed

At risk of re-opening a discussion that seems to have (finally :-D ) quieted down, the BBC is now carrying this news item: [1]http://news.bbc.co.uk/2/hi/science/nature/4420084.stm Regards, Tom References 1. http://news.bbc.co.uk/2/hi/science/nature/4420084.stm

Re: [time-nuts] Xtal Oscillator Aging

at <[10]http://metrologyforum.tm.agilent.com/xtals.shtml>. Hope I didn't confuse people with my simplified, one paragraph explanations! 73, Tom Clark References Visible links 1. http://www.ieee-uffc.org/freqcontrol/quartz/vig/vigtoc.htm 2. http://www.ieee-uffc.org/fre

[time-nuts] Xtal Oscillator Aging

768 Hz oscillators operate at low power is so that watches can run for years on small batteries. But even at that, the mechanical xtal resonator (which is built as a tuning fork for these low frequencies) is much better than any watch escapement ever was! 73, Tom Clark ___

[time-nuts] Leap Seconds in the News

Not intending to re-start the old controversy, but see this BBC News item: http://news.bbc.co.uk/2/hi/science/nature/4271810.stm Tom Clark ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

[time-nuts] Re: time-nuts Digest, Vol 14, Issue 28

lock their radios with time constants ~1 second in order to improve the ratty signal. In some later standards (including even the inexpensive SRS unit), the tail-end frequency and FM are generated by a DDS driven from a "clean" unmodulated xtal and are not subject to as mu

[time-nuts] A couple of answers to recent questions

tput with the pulse error as does the ONCORE. Aside from that difference, the Jupiter-T is as good a timing receiver as any of the Motorola products. Tom Clark References 1. ftp://ftp.cnssys.com/pub/ION-GPS2000/ion-time.pdf 2. ftp://ftp.cnssys.com/pub/ivs-tow-2005/tow-time2005.ppt

[time-nuts] Network Synchronization

States Naval Observatory, Washington DC" Tom Clark References 1. http://gpstime.com/ 2. http://ivscc.gsfc.nasa.gov/meetings/tow2005/notebook.html 3. ftp://ftp.cnssys.com/pub/PTTI-2002/PTTI_2002_CNS_Testbed.pdf 4. ftp://ftp.cnssys.com/pub/PTTI-

[time-nuts] Rescuing the Huygens Probe with VLBI

Since I had posted some information on VLBI here, I thought you might find this article about VLBI tracking of the Huygens probe to be interesting. This was "my" program until I retired a couple of years ago: http://www.rtcmagazine.com/home/article.php?id=100355

[time-nuts] Jupiter-T

Rick Putz asked To All, Has anyone done any studies on the Nav Man Jupiter T and Pico T series receiver s? They use the SiRF chip set and provide a 10 Khz output that is said to be co herent with the 1PPS. Just curious. I did a lot of testing on the Jupiter-T that has an ONCORE VP physical

[time-nuts] Atmospheric effects in Geodesy

Poul-Henning Kamp asked: Could you explain one little detail for me ? What is the mechanism that makes air pressure affect antenna height ? Is it simply the weight of the air on the ground ? Or is it because it affects the speed of light in the atmosphere ? The radio waves from outside

[time-nuts] H-Maser FYI

/TOW/tow2005/notebook/Diegel.Sem.pdf For the masochists interested in the details of VLBI, the entire notebook of lectures presented is at http://ivscc.gsfc.nasa.gov/meetings/tow2005/notebook.html. (Yes, I'm the Tom Clark listed on several of the presentations O:-) ) 73

[time-nuts] Re: time-nuts Digest, Vol 12, Issue 63

e collected over a couple of decades. Tom Clark ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

[time-nuts] RE: Micro phase stepper

Ulrich, DF6JB asked can someone please explain to me how a micro phase stepper works? Is it a pure digital device or does it make use of analog delay line techniques? What is the maximum delay and what is the delay step size? Here I describe two different types of phase

[time-nuts] Re: time-nuts Digest, Vol 12, Issue 20

's 1272 document "GPS and Precision Timing Applications" at http://mysite.verizon.net/w3iwi/hpan1272.pdf. Tom Clark ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

[time-nuts] Re: VLBI

David Forbes wrote: > At 12:06 AM -0400 7/7/05, Tom Clark wrote: > >> [As an aside, for many years until I retired, I headed NASA's VLBI >> program -- [3]see more about the Goddard VLBI group here. You >> might enjoy some of my tutorials on ho

[time-nuts] Re: time-nuts Digest, Vol 12, Issue 15

ded NASA's VLBI program -- [3]see more about the Goddard VLBI group here. You might enjoy some of my tutorials on how the VLBI stations get their UTC reference time so that their measurements of UT1-UTC can be derived at the catch-all repository [4]http://gpstime.com