Re: [time-nuts] GPS Timing Antenna Failure - Long

lmcda...@lmceng.com said: > To make this very long story into a short one, I learned that the HP/ > Symmetricom 58532A GPS Reference (timing) antennas use a simple patch > antenna instead of a quadrafilar antenna and that old solder flux residue > will attenuate the even amplified GPS signal

Re: [time-nuts] Datametrics SP-100 Time Code Generator

Correct, Dan- nothing received-still interested though, if something pops up. Unit is still here and a friend has a sidereal version but no data. DaveB, NZ -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan Veeneman Sent: Saturday, May 12, 2018 11:38

[time-nuts] Possibly interesting book

WSJ had review of The Perfectionists by Simon Winchester May 5-6( Books). Sounds right up this group's alley. As the reviewer states, it: corrals a large cast of eccentric individuals." Many of which it might have been fun to spend time with. I've read a few of his other 29 books and most

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

Hi: Here's some great ideas from Clifford Stoll: https://www.ted.com/talks/clifford_stoll_on_everything?language=en The transcript is available in 27 languages. PS He has an on line business selling Klein Bottles (some with calibration certificates:) http://www.kleinbottle.com/ I got a

Re: [time-nuts] GPS Timing Antenna Failure - Long

Thanks, Dave, for reporting your failed GPS antenna; at least, I am not alone in having this failure. It will be interesting to understand what you find when you open your failed 58532A. Removing the radome is very easy, just 4 screws and some wiggling or gentle prying. If yours does not have

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

Using a pendulum to measure gravity requires precision timekeeping. Wikipedia has a nice discussion of this at https://en.wikipedia.org/wiki/Pendulum#Gravity_measurement There are number of very clever techniques developed long ago, such as Henry Kater's design for a reversible, dual pivot

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

At telecom wavelengths GDD can be quite low. Laser source spectral widths can also be low. At visible wavelengths an fiber length imbalance of 1m with a 1nm bandwidth light source makes interferometry impossible/difficult without GDD compensation even if delays are matched. The moodulation

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

How about a demonstration of how GPS works, substituting sound waves for radio ? Maybe three sound sources with harmonically-related frequencies, then measure their phase difference on an oscilloscope. Cheat a bit : you don't need to do cdma acquisition. Have one reference at a low frequency,

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

Indeed; however, with single mode fiber the limit is not too bad. At Arecibo we routinely ran bandwidths in excess of 1 GHz through fibers of about 1500 ft length with no problems. For the science fair project a bandwidth of a few MHz should suffice for lengths of, say, 500 ft. It's just that I

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

Would it be too simple a project to have a GPS demonstration: * GPS time, leap seconds (need for) * UTC time * Local Time Zone time (rise, set, noon) * Solar Time (rise, set, noon) * Solid Earth Tides * and a custom sun dial, marked for solar time and local time (a lamp can simulate

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

Even with single mode fiber its finite group delay dispersion will likely restrict the usable light source bandwidth. Bruce > On 13 May 2018 at 03:38 Dana Whitlow wrote: > > > It may be that a nicely-written request to Corning could yield the loan of > a big spool of

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

Like this so called star target?: https://www.edmundoptics.com/test-targets/resolution-test-targets/1-black-1-white-glass-star-target-5deg-wedge-pair-angle/ Bruce > On 13 May 2018 at 02:45 Bob kb8tq wrote: > > > Hi > > > > > On May 12, 2018, at 7:01 AM, jimlux

Re: [time-nuts] Question about frequency counter testing

On 05/12/2018 09:41 PM, Bob kb8tq wrote: > Hi > > >> On May 12, 2018, at 1:20 PM, Oleg Skydan wrote: >> >> Hi! >> >> From: "Bob kb8tq" >>> There is still the problem that the first post on the graph is different >>> depending >>> on the technique. >> >>

Re: [time-nuts] Question about frequency counter testing

Hi, On 05/12/2018 08:38 PM, Oleg Skydan wrote: > Hi! > > From: "Magnus Danielson" >> ADEV assumes brick-wall filtering up to the Nyquist frequency as result >> of the sample-rate. When you filter the data as you do a Linear >> Regression / Least Square estimation,

Re: [time-nuts] GPS Timing Antenna Failure - Long

Hi As mentioned a number of times, quadrafilar antennas were only popular for a very short while back in the 1980’s. Once people started using GPS for “stuff” they rapidly lost out in the antenna race. They were made popular by an early NIST paper. Later on NIST effectively said “oops !!” in

[time-nuts] GPS Timing Antenna Failure - Long

I recently had an unexpected failure of a white-conical-dome HP/Symmetricom 58532A GPS antenna that had been in-place about 5 feet above the roof of my two-story home in Southern California for about ten years. I have two similar GPS antennas located about ten feet apart on this roof, one fed

Re: [time-nuts] Question about frequency counter testing

Hi > On May 12, 2018, at 1:20 PM, Oleg Skydan wrote: > > Hi! > > From: "Bob kb8tq" >> There is still the problem that the first post on the graph is different >> depending >> on the technique. > > The leftmost tau values are skipped and they "stay"

Re: [time-nuts] Commercially available empty ovens for oscillator testing?

Hi There are places that sell them. Most are looking for a couple thousand dollars for one. If that is inside your budget you might get in touch with them. Far cheaper to get an eBay scrap OCXO and use its parts. An OCXO depends on the combination of two things to make it stable: 1) The

Re: [time-nuts] Question about frequency counter testing

Hi Oleg, On 05/12/2018 07:20 PM, Oleg Skydan wrote: > Hi! > > From: "Bob kb8tq" >> There is still the problem that the first post on the graph is >> different depending >> on the technique. > > The leftmost tau values are skipped and they "stay" inside the counter. > If I setup

Re: [time-nuts] Question about frequency counter testing

Hi! From: "Magnus Danielson" ADEV assumes brick-wall filtering up to the Nyquist frequency as result of the sample-rate. When you filter the data as you do a Linear Regression / Least Square estimation, the actual bandwidth will be much less, so the ADEV measures

Re: [time-nuts] Commercially available empty ovens for oscillator testing?

Julien Yes you could stabilize the temperature at some level. But your really adding complexity that will tend to interact. You have the natural TCXO behavior and then the oven behavior. Hard to say how it all will behave. But I suspect your suggesting warming the TCXO to something in its best

Re: [time-nuts] Question about frequency counter testing

Hi! From: "Bob kb8tq" There is still the problem that the first post on the graph is different depending on the technique. The leftmost tau values are skipped and they "stay" inside the counter. If I setup counter to generate lets say 1s stamps (ADEV starts at 1s) it will

[time-nuts] Commercially available empty ovens for oscillator testing?

Does anyone know if there's anyone who sells essentially just the oven & casing for an OCXO on its own? I have a project for which I'm currently using a VCTCXO, but I'm wondering if enclosing a plain VCXO, plus the control DAC & voltage reference in a single small oven would end up more stable,

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

It may be that a nicely-written request to Corning could yield the loan of a big spool of fiber for the duration of a science fair project. Another alternative, perhaps easier to implement, might be an electrically-driven light modulator at the detector end. For the source, an LED or diode

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

How about a Stroboscope? - Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 ___ 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

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

Hi > On May 12, 2018, at 7:01 AM, jimlux wrote: > > On 5/11/18 9:08 PM, Jeff Woolsey wrote: >> David.vanhorn wrote: >>> Measuring the speed of light (Fizeau or Michelson method? Other ways) >>> >>> >>> I saw a great demo of this at the Exploratorium in SF. They had a

Re: [time-nuts] Help Identifying this surplus Timing Module

Hi Ok, the gizmo on the front it an Altera CPLD. Not a lot of gates, so not a lot going on there. Whatever the real functions are, they are in the chip with no labeling. Even with the full information (let’s say): Takes in a 16 stream OC-blah blah and provides the following alarms on the

[time-nuts] TruePosition GPSDO Holdover Issues

Today using Lady Heather I have observed the TruePostion GPSDO dropping into holdover as the number of tracked sats dropped from four to three. There does seem to be some hysteresis in the system though, the number of tracked sats eventually dropped to two and then the unit came out of holdover

Re: [time-nuts] Anybody have suggestions for time related science fair projects?

On 5/11/18 9:08 PM, Jeff Woolsey wrote: David.vanhorn wrote: Measuring the speed of light (Fizeau or Michelson method? Other ways) I saw a great demo of this at the Exploratorium in SF. They had a long spool of fiber optic, a disc with holes, and a light source. When static, if the light