[time-nuts] atomic clock articles

A nice pair of articles on the origins and workings of atomic clocks in the January issue of Physics Today. Started off as an atomic interferometer developed by Norman Ramsey. dON -- "Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for the

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

On 1/23/13 9:45 PM, li...@lazygranch.com wrote: I doubt the impedance would be designed so nobody gets a right match. Anyway, the geometric mean, which is how you would do such a compromise is 61.24 ohms. I suspect that it's more like.. the mfr builds a prototype that has the right pattern,

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

I doubt the impedance would be designed so nobody gets a right match. Anyway, the geometric mean, which is how you would do such a compromise is 61.24 ohms. -Original Message- From: Jim Lux Sender: time-nuts-boun...@febo.com Date: Wed, 23 Jan 2013 20:50:00 To: Reply-To: Discussion of

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

On 1/23/13 8:50 PM, Jim Lux wrote: On 1/23/13 7:26 AM, li...@lazygranch.com wrote: For a single frequency use like GPS, the impedance should be close to the target. It is true for scanners and such, 50 ohms is quite nominal. (This notion of DC to daylight and maintaining 50 ohms is fantasy. ) Bu

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

On 1/23/13 7:26 AM, li...@lazygranch.com wrote: For a single frequency use like GPS, the impedance should be close to the target. It is true for scanners and such, 50 ohms is quite nominal. (This notion of DC to daylight and maintaining 50 ohms is fantasy. ) But for a GPS, you know exactly the

Re: [time-nuts] One Kg Quartz Resonator

Hi Not having a bar sitting here to play with, it's hard to tell how the bar is mounted. If it's mounted by the points on the disks, then they must be non-moving nodal points. If that's what they are, I'm a bit surprised that the bar has nodes at the ends. Bob On Jan 23, 2013, at 6:57 PM, Fab

Re: [time-nuts] Thunderbolt Monitor

Hi My original comment was in reply to your suggestion of porting Lady Heather into a MSP430. I took that to be your outline of your project. My reply was simply that Lady Heather is a very complex and full featured program. It does *way* more than just look at a serial stream and tell you a fe

Re: [time-nuts] Is there any way to use a TIC to measure time of reflection on a PCB?

On 01/23/2013 07:03 PM, David Kirkby wrote: On 23 January 2013 15:22, Jim Lux wrote: On 1/23/13 6:48 AM, David Kirkby wrote:>> A student needs to find the open-circuit fringing capacitance of a piece of microstrip line. For this he needs to know the time between the reference plane of the SMA

[time-nuts] IEEE P1588 Study Call for Participation - Standard for a Precision Clock Synchronization Protocol

This announcement landed in my in-box today, I thought it might be of interest to time nuts: - The IEEE P1588 Study Group (SG) announces a Call for Participation (CFP) to develop a Project Authorization Request (PAR) for the revision of IEEE 1588™ -2008, Standard for a

Re: [time-nuts] One Kg Quartz Resonator

Il 2013-01-23 13:39 Bob Camp ha scritto: the mode that the bar is resonating in, it's a bit hard to guess where the nodes will be. Just looking at the bar, you wouldn't *guess* that the end points would be nodes... Bob Sorry Bob I didnt understand last part. You say that the end faces are no

Re: [time-nuts] Thunderbolt Monitor

You realy can't know if a processor is to large or small until you have at least a outline of the software design.In this case the uP is reading test from a serial port at a low data rate. It is running a filter and sending a small amount of text back to the GPS. So the load on the CPU is t

Re: [time-nuts] Is there any way to use a TIC to measure time of reflection on a PCB?

On 23 January 2013 15:22, Jim Lux wrote: > On 1/23/13 6:48 AM, David Kirkby wrote:>> >> A student needs to find the open-circuit fringing capacitance of a >> piece of microstrip line. For this he needs to know the time between >> the reference plane of the SMA connector and the open circuit >> mic

Re: [time-nuts] time-nuts Digest, Vol 102, Issue 89

On 01/23/2013 11:35 PM, J. L. Trantham wrote: Russ, You might want to consider stopping to think about it now. Otherwise, you'll wind up with a Cesium Standard to check the GPSDO, a collection of OCXO's and Rb's to see which is the best, not to mention all the test equipment needed to carry out

Re: [time-nuts] time-nuts Digest, Vol 102, Issue 89

Don't forget the ion fountain to check the H Maser :-) Sent from my iPhone On Jan 23, 2013, at 5:35 PM, "J. L. Trantham" wrote: > Russ, > > You might want to consider stopping to think about it now. Otherwise, > you'll wind up with a Cesium Standard to check the GPSDO, a collection of > OCXO'

Re: [time-nuts] time-nuts Digest, Vol 102, Issue 89

Russ, You might want to consider stopping to think about it now. Otherwise, you'll wind up with a Cesium Standard to check the GPSDO, a collection of OCXO's and Rb's to see which is the best, not to mention all the test equipment needed to carry out those measurements, and, perhaps, a MASER to ch

Re: [time-nuts] time-nuts Digest, Vol 102, Issue 89

Hi Russ, When testing rubidiums in my lab yesterday, I found that my main counter-pair (a CNT-90 and a SR-620) was way off, it seems like my primary GPSDO (a Thunderbolt) didn't like the situation. Will have to check things. A few rounds more. Also considering that I have a few (more) cesiums

Re: [time-nuts] time-nuts Digest, Vol 102, Issue 90

Yep, been there, done that. I'm a Ham and have several receivers. However, that method falls a bit short for what I think I need and have decided to look for something a bit better. What has been unknown to me is what result I might get if I take a GPS solution such as this: http://www.adafruit.com

Re: [time-nuts] Is there any way to use a TIC to measure time of reflection on a PCB?

On 01/23/2013 03:48 PM, David Kirkby wrote: There's a fairly interesting (to me at least), discussion on an Agilent forum devoted to the calibration of vector network analyzers. http://www.home.agilent.com/owc_discussions/thread.jspa?threadID=34809&tstart=0 The title of the thread is "Coefficie

Re: [time-nuts] Thunderbolt Monitor

Hi I do believe I included the size of the DOS exe as well as the Windows version. Both get *some* support from the OS that you will need to implement in your code. It's not just program space either. You only have 512 bytes of RAM on the larger of the two processors. Bob -Original Message

Re: [time-nuts] time-nuts Digest, Vol 102, Issue 89

Hi Bob, That's a good point and not nit picking. While my particular HP 5334A counter (sans 1.3 GHz channel C option) only measures with this kind of resolution at lower frequencies, I will be using the source for my Fluke 6060B (instead of the 5334A's output as I do now) which can produce a 1050

Re: [time-nuts] Thunderbolt Monitor

-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Absolutely - however, I suspect the MSP430 might be a little too small. I'd be looking at something like a Raspberry Pi and a serially attached screen. Adafruit do some lovely boards like these: http://www.adafruit.com/products/1115 It's not $5 but i

Re: [time-nuts] time-nuts Digest, Vol 102, Issue 89

Hi Magnus, The idea of not having to wonder if I can trust the source, i.e. a GPSDO, is appealing for sure, and one more antenna isn't going to hurt :-) Thanks for your reply. Russ On Wed, Jan 23, 2013 at 1:45 PM, wrote: > Message: 5 > Date: Wed, 23 Jan 2013 20:17:01 +0100 > From: Magnus Dani

Re: [time-nuts] Thunderbolt Monitor

You can't compare the size of a Windows binary to a uP RAM. If you look inside the .exe file you see that 90% of it is dealing with the Windows OS. The actual computations are very, very small and don't use even half the 16KB Flash. On Wed, Jan 23, 2013 at 10:10 AM, Bob Camp wrote: > Hi > >

Re: [time-nuts] Least costly 10 MHz reference solution

Hi Not to pick nits, but 7 decimal places at what input frequency? Seven places is 10 ppb at 10 MHz. If the input was 100 MHz, it would be 1 ppb. The distinction is significant, since it crosses a boundary. At 10 ppb a free running Rb is fine with no adjustments. At 1 ppb, some adjustment might

Re: [time-nuts] Least costly 10 MHz reference solution

No question, You want a GPSDO. Yes you can buy a Rb or a high-end OCXO but neither of these is connected to any kind of standard and will need to be calibrated to be of use. The GPS serves as a "standard" and you need that before the other options. The next question is "which GPSDO?" For most

[time-nuts] One Kg Quartz Resonator

On 1/22/2013 8:25 PM, time-nuts-requ...@febo.com wrote: Interestingly, this experiment may also become the first time we ever needed to know PI better than 355/113 outside abstract mathematics. Good thing this is easy now. It took a long TIME, but I ran PI out to 80 billion points using a 3.5Gh

Re: [time-nuts] Least costly 10 MHz reference solution

Russ, Welcome! On 01/23/2013 05:48 PM, Russ Ramirez wrote: Greetings, I have been reading what I can find on Rubidium and GPSDO approaches, but there are some fine points that do not make it clear which is the best 'bang for the buck' solution. My requirement/desire is to have a 10 MHz standar

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

Just a few comments on the cable and VSWR business. The short version is that unless the run is longer than 100 Ft any antenna with a preamp gain of more than 30 dB will probably do and the VSWR business does not matter at all unless it is truly terrible. For example the loss due to mismatch fo

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

On 01/23/2013 03:59 PM, John Lofgren wrote: < snip> And it's not clear that there's actually "loss" due to mismatch. Most antennas/preamps/receivers don't have exactly 50 ohm impedances. 75/50 is only 1.5:1, and there's an awful lot of antennas and receivers out there that only claim 2:1 VSWR

Re: [time-nuts] Thunderbolt Monitor

Chris Albertson wrote: > The TB is best kept in some light-out > closet and who wants to stand of a step > stool to read an LCD when a web interface > could put a better display on your smart > phone or computer I don't have a way to play with it right now, but in the single-user case, is LH

[time-nuts] Least costly 10 MHz reference solution

Greetings, I have been reading what I can find on Rubidium and GPSDO approaches, but there are some fine points that do not make it clear which is the best 'bang for the buck' solution. My requirement/desire is to have a 10 MHz standard for my lab that I can trust to an accuracy of 7 decimal place

Re: [time-nuts] Thunderbolt Monitor

What about Didier's original design?.. _http://ko4bb.com/Timing/GPSMonitor/_ (http://ko4bb.com/Timing/GPSMonitor/) Regards Nigel GM8PZR In a message dated 23/01/2013 16:32:36 GMT Standard Time, maj...@sc.rr.com writes: I have been following this on the list for a while now and wa

Re: [time-nuts] Racal MA-259 Crystal frequency standard on UK eBay

Well its some sort of a knock off of the sulzer oscillators. I have two and they are very good. Low noise stable maybe not in a time-nuttery sense but considering they were 1960ish pretty darn good. If shipping were not an issue and within the next few hours the price does not go up several dozens

Re: [time-nuts] Thunderbolt Monitor

Hi Heathdos.exe 123 KB Heather.exe 572 KB Server.exe 176 KB (each would be plus what ever they pull from DLL's and the OS) Ti LaunchPad MSP-EXP430G2 - MSP 430 version ($4.30): MSP-430G2553 Microcontroller: 16 KB flash 512 B RAM MSP-430G2452 Microcontroller: 8 KB flash 256 B RAM I suspect yo

Re: [time-nuts] Thunderbolt Monitor

John and Ken that did the trick. I ended up trying the easiest option first since I already had device manager up and it worked like a charm. I'll look into Arduino for some options for the lcd project. I keep my Thunderbolt right beside my frequency counter and leave both of them on all the

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

The Thunderbolt book suggests using RG6 (75 ohm) up to some given length and then other cable like RG8if the length is longer. I can't look it up right now. They claim the rg6 is very good because of the double shield. Trimble claims the 75 v. 50 mismatch is trivial. On Wed, Jan 23, 2013 at 1

Re: [time-nuts] Thunderbolt Monitor

I was looking into porting much of LH into an Arduino or TI Launch Pad (msp430) And then a display would be web based. But then I decided to go back to grad school and there went any free time. But I think that is that way to go. The TB is best kept in some light-out closet and who wants to stan

Re: [time-nuts] Thunderbolt Monitor

I can't help you with the outboard monitor, but I can help with the haywire / mouse situation. Windows thinks that the serial port has a mouse connected because of the 1 / second transmissions from the T-Bolt. At boot time Win looks for serial mice and it gets fooled by seeing something active

Re: [time-nuts] Racal MA-259 Crystal frequency standard on UK eBay

Agreed, and about 30 miles from where I live. However, do I really need one? :-) Rob K -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: 23 January 2013 14:18 To: Discussion of precise time and frequency measurement Sub

[time-nuts] Thunderbolt Monitor

I have been following this on the list for a while now and was curious if anyone is actively working on a open source monitor. I see the one made by Adam VK4GHZ is no longer being sold. This got me back on track for wanting to make one of my own. I have been using either tbmon or lady heathe

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

For a single frequency use like GPS, the impedance should be close to the target. It is true for scanners and such, 50 ohms is quite nominal. (This notion of DC to daylight and maintaining 50 ohms is fantasy. ) But for a GPS, you know exactly the application. The loading could effect the anten

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

Fat fingers. Replace "test" with "rest". < snip > And it's not clear that there's actually "loss" due to mismatch. Most antennas/preamps/receivers don't have exactly 50 ohm impedances. 75/50 is only 1.5:1, and there's an awful lot of antennas and receivers out there that only claim 2:1 VSWR.

Re: [time-nuts] Is there any way to use a TIC to measure time of reflection on a PCB?

On 1/23/13 6:48 AM, David Kirkby wrote: There's a fairly interesting (to me at least), discussion on an Agilent forum devoted to the calibration of vector network analyzers. http://www.home.agilent.com/owc_discussions/thread.jspa?threadID=34809&tstart=0 The title of the thread is "Coefficients

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

< snip > And it's not clear that there's actually "loss" due to mismatch. Most antennas/preamps/receivers don't have exactly 50 ohm impedances. 75/50 is only 1.5:1, and there's an awful lot of antennas and receivers out there that only claim 2:1 VSWR. The usual spec for the antenna is 1.5:1

[time-nuts] Is there any way to use a TIC to measure time of reflection on a PCB?

There's a fairly interesting (to me at least), discussion on an Agilent forum devoted to the calibration of vector network analyzers. http://www.home.agilent.com/owc_discussions/thread.jspa?threadID=34809&tstart=0 The title of the thread is "Coefficients of fringing capacitance polynomial" A stu

Re: [time-nuts] How far can I push a crystal?

Hi Ed, Thanks, your explanation of single PLL helps. I see it now somewhat in the sense of "only have to BUILD a single PLL" to make things work. I can appreciate the simplified effort greatly. I also now think of the PLO as an oscillator locked to a tuned harmonic that (probably) comes from s

Re: [time-nuts] Racal MA-259 Crystal frequency standard on UK eBay

Very tempting but its a local pickup only. On Wed, Jan 23, 2013 at 8:41 AM, David C. Partridge < david.partri...@perdrix.co.uk> wrote: > > > Dave > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscrib

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

On 1/23/13 12:41 AM, Hal Murray wrote: mspencer12...@yahoo.ca said: This URL goes into some of the issues involved in using 75 ohm coax in a gps system. I do acknowledge that several GPS manufacturers have promoted the use of 75 ohm coax so some of the conclusions might be arguable.. If the

[time-nuts] Racal MA-259 Crystal frequency standard on UK eBay

Dave ___ 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] One Kg Quartz Resonator

Hi You want to mount the crystal at a point that is not moving (much) while the crystal is in resonance. For a normal AT, that's out at the edge. For most bar cuts, yes you mount it at a node. Without knowing the mode that the bar is resonating in, it's a bit hard to guess where the nodes will

Re: [time-nuts] One Kg Quartz Resonator

Hi As with the one kg resonator, you need to mount the bar *somehow*. The idea is generally to suspend the resonator at a point that least affects the resonance (a dead spot). With a large bar, making it manually adjustable is practical. Not so much with a smaller part. Bob Il 2013-01-23 01:54

Re: [time-nuts] One Kg Quartz Resonator

> >> Isn't it defined for zero sea-level, that is standard acceleration? > > How do you define sea level? http://en.wikipedia.org/wiki/EGM96 http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm2008/egm08_wgs84.html > > Daniel Kleppner's Time Too Good to Be True in > Physics Today, March 2006 > po

Re: [time-nuts] One Kg Quartz Resonator

> Isn't it defined for zero sea-level, that is standard acceleration? How do you define sea level? Daniel Kleppner's Time Too Good to Be True in Physics Today, March 2006 pointed out that the time-geeks will soon own the definition of sea level. -- These are my opinions. I hate spam.

Re: [time-nuts] "Better" gps antennas than a Symmetricom 58532A

mspencer12...@yahoo.ca said: > This URL goes into some of the issues involved in using 75 ohm coax in a gps > system. I do acknowledge that several GPS manufacturers have promoted the > use of 75 ohm coax so some of the conclusions might be arguable.. If the coax is short, the loss due to misma

Re: [time-nuts] One Kg Quartz Resonator

On 01/23/2013 02:32 AM, Mike S wrote: On 1/22/2013 3:30 PM, Bruce Griffiths wrote: But can the number and type of atoms in such a standard be counted? Otherwise its not a primary standard. Can you have a Cs under zero acceleration and at zero temperature, the only conditions for which the seco

Re: [time-nuts] LHCP patch antenna

On 01/23/2013 07:08 AM, Jim Lux wrote: On 1/22/13 9:08 AM, Joe Leikhim wrote: John; You might look into building your own, _scaling up_ from a G3RUH design (2.4 GHz) note that they were illuminating a 60 cm dish in those experiments, that's not a very big reflector for 12.5 cm wavelength at 2