Re: [time-nuts] Compensating phase differnces in dual frequency GPS receviers?

On 12/2/11 7:28 AM, Attila Kinali wrote: dispersion in the components after the comb generator. You may generate them all in phase at the diode, but by the time they've propagated through the buffer amplifier, filter, coax, they're no longer aligned. Again, if you're just looking for nanosecond

Re: [time-nuts] Compensating phase differnces in dual frequency GPS receviers?

On 12/2/11 6:28 AM, Attila Kinali wrote: On Fri, 02 Dec 2011 05:57:35 -0800 Jim Lux wrote: Combs are used all the time for this kind of thing (e.g. calibrating Deep Space Network). There's an old paper about calibrating a interferometer radio telescope at Stanford using this kind of

Re: [time-nuts] Compensating phase differnces in dual frequency GPS receviers?

On 12/2/11 4:59 AM, Attila Kinali wrote: On Thu, 1 Dec 2011 19:56:12 -0800 Peter Monta wrote: So, that'd mean there would be an automatic calibration system inside the device, because i dont have any equipment with which i could calibrate delays over a temperature range. I suppose they could

Re: [time-nuts] Compensating phase differnces in dual frequency GPS receviers?

On 12/2/11 12:05 AM, Hal Murray wrote: Well, it would have to be the front end. DSP doesn't drift with temperature. What if the crystal driving the DSP changes frequency with temperature? That's really no different than the local clock changing frequency, isn't it? It's essentially one o

Re: [time-nuts] Tongue Testing battery charge levels....

On 11/29/11 3:38 PM, David VanHorn wrote: Google it. :) From: time-nuts-boun...@febo.com [time-nuts-boun...@febo.com] On Behalf Of J. L. Trantham [jlt...@att.net] Sent: Tuesday, November 29, 2011 3:58 PM To: 'Discussion of precise time and frequency me

Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

On 11/26/11 11:13 AM, Chris Albertson wrote: On Fri, Nov 25, 2011 at 10:36 PM, Raj wrote: How about this way: Amplifying capacitance.. (Base/Ground cap * Beta) http://sound.westhost.com/project15.htm The above actually uses several quite large electrolytic. It is a good example of why you

Re: [time-nuts] PC time app

On 11/25/11 9:56 PM, Steve . wrote: I'm curious as to what folks are doing with PC's that require micro second accuracy for days or weeks or what have you. Any examples? not microseconds, but milliseconds... Running multi-day tests in a spacecraft testbed where you've got PC-based test equ

Re: [time-nuts] SDR GPS

On 11/24/11 9:33 AM, Collins, Graham wrote: Perhaps not in the same league or with the same gee-whiz appeal as a SDR GPS receiver but how about your own DIY GPS receiver: http://dangerousprototypes.com/2011/11/24/homemade-gps-receiver/ and the authors web page: http://www.holmea.demon.co.uk/

Re: [time-nuts] SDR GPS

On 11/24/11 3:38 AM, Attila Kinali wrote: On Thu, 24 Nov 2011 11:19:37 + Poul-Henning Kamp wrote: Has any of you played with this: http://www.sparkfun.com/products/8238 I had a look at this (and a few other GPS SDR solutions) back a year or two ago and decided that they are eith

Re: [time-nuts] The GPS velocity of light versus neutrinos

On 11/21/11 9:05 PM, Chris Albertson wrote: You guys missed my point. I did not mean that survey and timing errors are so large What I meant was that even if you assume unreasonably large errors (like a surveyor being off by a full meter) you still don't get 60nS. If I were to bet money, stil

Re: [time-nuts] The GPS velocity of light versus neutrinos

On 11/21/11 5:15 PM, Bob Camp wrote: Hi You can have a surveyor come out and locate your gizmo to sub one inch accuracy for a lot less than a clock trip costs. A one meter ( or 3 ns) error would be pretty large these days. Both have been demonstrated / proven so often that they aren't really

Re: [time-nuts] FE 5680A "new version" - Filtering the 10 MHz

On 11/15/11 3:06 PM, Alan Melia wrote: Another approach to filtering is a 10.7 MHz IF filter... they're common, fairly wide band, but not too wide. Can't say much about the tempco. Minicircuits BLP-10.7 or BLP-15 for instance or BBP-10.7 (which is about 2 MHz wide) __

Re: [time-nuts] Off topic (was - Re: Serial to Excel utility

On 11/7/11 3:48 PM, Thomas A Frank wrote: On Nov 7, 2011, at 11:30 AM, Jim Lux wrote: (this is an argument I have with senior microwave engineers wanting to do their own sysadmin work.. we've got dozens of people who can do sysadmin work, we have very few who can design 94GHz cir

Re: [time-nuts] Serial to Excel utility

On 11/7/11 6:24 PM, Justin Pinnix wrote: On Mon, Nov 7, 2011 at 11:30 AM, Jim Lux wrote: $100k/hr -> about $1000/day.. If the $250 widget and an hour meets the need, it's a win. Might oughta check your math there, buddy. $100K/hr is quite a lot of money :-) Oh no... I guess I

Re: [time-nuts] Serial to Excel utility

On 11/7/11 7:21 AM, paul swed wrote: Wow for the rich and famous I see. $259 is about what a whole laptop costs. :-) Yes, but then you still need to write the software for that laptop. Think of it this way.. you're a non-software-developer kind of person but highly paid.. $100k/yr kind of se

Re: [time-nuts] SLIP vs Ethernet for NTP

On 10/23/11 11:39 AM, Poul-Henning Kamp wrote: In message<4ea45815.5080...@earthlink.net>, Jim Lux writes: I'd have to go back to some pretty old databooks, but I'll bet the x8 thing has been around since the 70s. Why 8, and not 4, is a better question... The origina

Re: [time-nuts] SLIP vs Ethernet for NTP

On 10/23/11 10:02 AM, Tijd Dingen wrote: Jim Lux wrote: if you're talking asynchronous RS232 (the by far most common, these days) off hand, I'd expect the jitter to be on the order of 1/8 bit time, uniformly distributed. An awful lot of UART implementations generate a 8x clock

Re: [time-nuts] SLIP vs Ethernet for NTP

On 10/23/11 6:15 AM, Poul-Henning Kamp wrote: In message<4ea411f5.1030...@rubidium.dyndns.org>, Magnus Danielson writes: On 10/23/2011 02:37 PM, Tijd Dingen wrote: The danger of Ethernet is that it has high capacity and a interconnect friendly interface. Thus, you might feel inclined to toss

Re: [time-nuts] Noise source measurement

On 10/22/11 5:50 AM, Javier Herrero wrote: Hello all, Perhaps a bit OT, but I'm measuring the output noise density of a noise source at a puntual frequency. I've fed the noise output to a 8566B spectrum analyzer, BW set to 1MHz and video BW set to 1kHz so the displayed trace is flat. I obtain a

Re: [time-nuts] Frequencies used for GPS

On 10/19/11 6:25 PM, David Kirkby wrote: Can anyone tell me the transmission frequencies used for GPS? Wikipedia says 1.57542 GHz (L1 signal) and 1.2276 GHz (L2 signal), but I'm confused about what the L2 signal is. Is this only of use to the military since the data is encrypted, or can consumer

Re: [time-nuts] Rubidium (Rb) or Caesium (Cs)

On 10/18/11 3:32 PM, Tom Van Baak wrote: ** Choke ring, ground plane -- this has been covered before. Along with temperature stabilized antenna, cables, and/or receiver, it's an inexpensive way to gain some performance. I don't have numbers but it seems at the point people use dual-frequency and

Re: [time-nuts] need example frequency vs temp equation

On Oct 15, 2011, at 7:50, Ivan Cousins wrote: > Hi Jim, > When you mentioned > "I found a thesis from someone who was modeling this kind of thing (actually > he was developing an set of tools to design it) and I can probably crib his > matlab code.". > > I was interested so I did a Google sc

Re: [time-nuts] need example frequency vs temp equation

On 10/12/11 10:10 PM, Bernd Neubig wrote: Hi Jim, There are different types of TCXO compensation techniques on the market. Each of them generating a different style of f(T) characterisitcs. Furthermore the f(T) response varies from unit to unit, because each TCXO is usually uindividually compens

Re: [time-nuts] HBG swiss time transmitter shutdown

On 10/12/11 5:42 PM, Dan Mills wrote: On Thu, 2011-10-13 at 02:11 +0200, Magnus Danielson wrote: I have wondered if not amateurs could set up small frequency broadcasts of their own. Say a 10 W transmitter or something. It's called a beacon and at least the UK license does allow them (25W max

[time-nuts] need example frequency vs temp equation

I'm putting together some examples of oscillator behavior vs temperature and I'm looking for some plausible coefficients and simple equations to use to generate nice looking curves. oscillators are TCXO and run of the mill whatever they use for computer clock oscillators (AT cut?). Something

Re: [time-nuts] Could someone please recommend GPIB card

On 10/10/11 8:10 AM, Bob Camp wrote: Hi 64 bit Windows 7 is the most restrictive OS I have seen so far in terms of drivers. 32 bit is a bit more forgiving. I would *guess* that 32 bit Windows will be a bit of a dinosaur three to five years from now. Just as you are still running Win 98, that doe

Re: [time-nuts] Could someone please recommend GPIB card

On 10/9/11 7:11 PM, Chuck Forsberg WA7KGX N2469R wrote: The PCI and USB HPib interfaces I've seen are terribly expensive. Wpuld it be possible to fake an interface with a parallel port and bit banging? Possibly an Arduino? Sure... but surplus NI cards turn up pretty cheap, and the Prologix and

Re: [time-nuts] Could someone please recommend GPIB card

On 10/9/11 3:36 PM, Paul A. Cianciolo wrote: Hello, I am looking for a PCI-GPIB card to use in a machine running windows XP. After looking on Ebay there are many different options at many different prices. I am not sure which would be compatible with my set up. Currently I have a ACER Laptop,

Re: [time-nuts] Measuring short term stability minus linear drift

On 10/8/11 7:56 AM, Magnus Danielson wrote: On 08/10/11 16:45, Jim Lux wrote: On 10/7/11 9:32 PM, Rick Karlquist wrote: I want to measure the short term stability of a source with substantial linear drift. I would like some measure of stability along the lines of Allan deviation, but I only

Re: [time-nuts] Measuring short term stability minus linear drift

On 10/7/11 9:32 PM, Rick Karlquist wrote: I want to measure the short term stability of a source with substantial linear drift. I would like some measure of stability along the lines of Allan deviation, but I only want to measure the "noise" and ignore the "drift". AFAIK, ADEV treats linear drif

Re: [time-nuts] the care and feeding of LPRO's

On 10/7/11 11:16 AM, Eric Garner wrote: fortunately, everything in the "lab"(basement) is on UPSs so in theory the input voltages to the equipment should be pretty constant and I was already planning on using a linear supply. What kind of UPS? A static inverter? Most UPSes just feed the line

Re: [time-nuts] multi input counter

On 10/6/11 4:24 PM, Magnus Danielson wrote: Consider that you have 7 digits of time-stamp value and 8 digits of hex code for time-stamped inputs and a carrige return, you need to output 16 bytes. Considering that it takes 32 read-outs a second in peak. This means 512 bytes a second or a rate of

[time-nuts] multi input counter

since I rudely tagged onto someone else's search for a suitable counter, I'll restate my need here.. I want to set up an experiment to characterize a bunch (several dozen?) of cheap XOs (e.g. SiTime parts) over temperature and time and power cycles. I'm not looking for 1e-15 adev at 100 second

Re: [time-nuts] Looking for a Counter

On 10/6/11 8:46 AM, Chuck Forsberg WA7KGX N2469R wrote: I would like to get a counter that a) has 10 MHz clock input b) counts directly to 30 MHz (50 or 145 preferred) I would like it to be maintainable and well under $100 including shipping. I have seen Fluke 1953a counters advertised on Ebay.

Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging

n the $100 range depending on the model. A few years ago when it first came out, it was a pain because it was Windows only, with limited protocol doc. But now they've got Linux, Mac, Windows, with bindings for just about every language -Original Message----- From: Jim Lux Sender:

Re: [time-nuts] 2 (Spoofing)

On 10/5/11 5:30 AM, Raj wrote: Some subscribe to lists of interest and harvest email IDs. A decade ago I collected all the digests from another similar type of group and harvested the emails and then made an analysis as to who posted more on the group. The stats were interesting! not for spamm

Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging

On 10/4/11 8:03 AM, Kevin Rosenberg wrote: So, if you know of any simple ADC to UART firmwares available, that'd be great so he can just reference someone else's code. The picPET is a perfect device at the perfect time. But, we can't rely on tvb to come up with a 'picADC' at a similarly serendip

Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging

On 10/3/11 5:20 PM, Neville Michie wrote: That looks like a great solution for monitoring oscillators/GPSDOs. Where to find an application that inputs RS232 and writes a file? Hyperterm? Minicom? in a DOS box > mode COMn:9600,n,8,1 > copy COMn filename You could suffer great mental pain and

Re: [time-nuts] (OT) Patents...

On 10/1/11 3:13 PM, k6...@comcast.net wrote: From a previous (now hijacked) thread-- I wouldnt try to read patents. These are convoluted beasts, written by lawyers for lawyers. If you want to understand the technology, read the papers. Most of them are eithe freely available or for a small fee

Re: [time-nuts] GPS Interference Question

On 10/1/11 1:38 AM, Magnus Danielson wrote: On 30/09/11 18:06, Chris Albertson wrote: One sure-fire "fix" to the problem is to open up the military frequencies to everyone. GPS broadcasts on more than just the common L1 freq. but also on 1.2Ghz. Again, not really pratical because of the huge co

Re: [time-nuts] GPS Interference Question

On 9/30/11 6:44 AM, Jason Rabel wrote: Please don't start a political discussion, I just have a SIMPLE TECHNICAL QUESTION that I'm hoping someone can answer (and I don't think it was discussed in the past). In all the stuff I've glanced over about L2, they talk about better filtering for GPS m

Re: [time-nuts] Looking for 8-digit LED clock

On 9/28/11 12:28 PM, Christopher Quarksnow wrote: Wondering whether anyone would know of an off-the-shelf (even used) LED clock with 1/100th of seconds and switchable to 24H mode (e.g going up to 23:59:59.99) The closest I found was at Pylones a director's clock, yet the last 2 digits were for fr

Re: [time-nuts] You can build a fountain from the things you find at home...

On 9/27/11 1:46 PM, J. Forster wrote: As to making one, I'd use stainless Conflat parts from eBay, used commercial pumps, feedthroughs, fittings, etc. You can spend a lot of time trying to leak check home brew stuff. The home built fusor list (http://www.fusor.net/) is one place to look f

Re: [time-nuts] You can build a fountain from the things you find at home...

On 9/27/11 1:11 PM, Magnus Danielson wrote: Trying to approach any of these would require reading up on a large number of articles and patents to kind of "learn" the field. In alla of these, getting full performance would involved much effort. This is the book you want to start with: http://w

Re: [time-nuts] Any thoughts on best rubidium?

On 9/26/11 6:18 AM, shali...@gmail.com wrote: There are aftermarket color LCD replacement available for the HP 8566 and HP 8568 analyzers, either as a do-it-yourself kit, or as a turn-key service. Didier KO4BB Fascinating.. We've got bunches of those units floating around the lab, with dea

Re: [time-nuts] Fast than light neutrino

On 9/25/11 3:26 PM, Hal Murray wrote: javier.serrano.par...@gmail.com said: A fiber-based time-transfer would be nice complementary as it would provide an independent timing path. Any ideas on how to proceed? This is unknown territory for me. You can get a lot of good ideas from the radio as

Re: [time-nuts] seeking a time/clock software architecture

On 9/24/11 1:58 AM, Magnus Danielson wrote: It would be interesting to see what a combination of mutual synchronisation within a constellation and central synchronisation would yield. Your constellation would maintain contact with each other and pull eachother to some form of average time (acco

Re: [time-nuts] seeking a time/clock software architecture

On 9/23/11 4:01 PM, Poul-Henning Kamp wrote: In message<4e7d0353.2040...@earthlink.net>, Jim Lux writes: But as we move towards constellations of spacecraft with LONG light time to earth, that whole time correlation process needs to be done autonomously. So the process of converting

Re: [time-nuts] seeking a time/clock software architecture

On 9/23/11 2:24 PM, Chris Albertson wrote: On Fri, Sep 23, 2011 at 12:32 PM, Jim Lux wrote: On 9/23/11 10:50 AM, Chris Albertson wrote: Yes, in the general case, but in the spacecraft case, I think we're more concerned about smoothness and such over time spans of days, maybe week

Re: [time-nuts] seeking a time/clock software architecture

On 9/23/11 2:00 PM, Chris Howard wrote: Seems like a lot of unknowns. You would have to have sensors monitoring the sensors. I think the "clock model" (insofar as variations in the oscillator) are outside the scope, as long as the effect of that variation can be represented cleanly. For ex

Re: [time-nuts] seeking a time/clock software architecture

On 9/23/11 1:45 PM, Poul-Henning Kamp wrote: In message<4e7cdeb0.8070...@earthlink.net>, Jim Lux writes: Actually, the really annoying one is where I have a good clock that's stable, but I need to keep adjusting "time" to match someone else's terrible clock. Mo

Re: [time-nuts] Fast than light neutrino

On 9/23/11 1:23 PM, Brooke Clarke wrote: Hi again: What is the speed of light in rock? that's a really interesting question, because it's not like a EM wave propagating, where the dielectric constant is what you care about. OTOH, I suppose that since EM waves are also photons, there must b

Re: [time-nuts] Any thoughts on best rubidium?

On 9/23/11 10:54 AM, Brooke Clarke wrote: Hi Jim: Do you know how the HP/Agilent 4395A stacks up as a SA? I really like the true RMS power detection and the 1 Hz RBW (not video).

Re: [time-nuts] seeking a time/clock software architecture

On 9/23/11 10:50 AM, Chris Albertson wrote: I'd like to propose a standard description of a higher order model of time and the transformation between raw clock and time (in some agreed upon time scale). A good time transform will let you transform between time scales at points in the far futur

Re: [time-nuts] seeking a time/clock software architecture

On 9/23/11 10:25 AM, Jim Lux wrote: One aspect of why at least a standardized second order model would be nice is that it allows you to make smooth non-discontinuous changes in rate. the transformation from count to time would be discontinuous in rate of rate (i.e. it would go from zero, to

Re: [time-nuts] seeking a time/clock software architecture

On 9/23/11 10:13 AM, Poul-Henning Kamp wrote: In message<4e7cbca1.9010...@earthlink.net>, Jim Lux writes: What I'd like to do is take the next step beyond what you promulgated with a representation of time and the conversion between count and time with a linear equation. I'd l

Re: [time-nuts] Any thoughts on best rubidium?

On 9/23/11 10:04 AM, Jose Camara wrote: I think you are right, often the internal, free running osc will give you better results. You can use the GPS or rubidium to calibrate the internal one just before you need some more accurate absolute frequency measurements on the SA. It will depend on

Re: [time-nuts] seeking a time/clock software architecture

On 9/23/11 8:35 AM, Poul-Henning Kamp wrote: Take a look at FreeBSD's timecounters, what you are asking for sounds pretty much like what I did 15 years: http://phk.freebsd.dk/pubs/timecounter.pdf I used a 32.64 internal format, to avoid rounding errors, particularly in your "k1" term.

[time-nuts] seeking a time/clock software architecture

Here's topic that I hope will provoke some useful discussion (and maybe the problem has already been solved?) I'm working with a software defined radio (SDR) for spacecraft which conforms to a new architecture standard for such radios ( referred to as STRS) (and I'm also one of the authors of

[time-nuts] uses of time-nuttery Re: Fast than light neutrino

On 9/23/11 4:15 AM, Peter Gottlieb wrote: I was just wondering, what real use is the kind of accuracy most of the list members strive for, and there is the answer. I can give you some other day to day practical uses of what gets discussed on this list: - radio science in deep space explorat

Re: [time-nuts] Tek high voltage probes

On 9/22/11 10:34 AM, NeonJohn wrote: On 09/21/2011 04:57 AM, David C. Partridge wrote: Howsabout HFC-236fa - very similar properties to R114 but not banned. Tektronix used a Freon in their 40 KV High Voltage probes. The Vapor pressure of some of those compounds is low at 70F, but they do ha

Re: [time-nuts] Subject: Listening to the List Owner

top posting works very nicely with mail clients that have a preview screen, as well. And, yes, the whole "threading thing" gets implemented in a variety of ways (even within the same product). I use, variously, thunderbird, Outlook, Outlook Web Access (OWA)-lite via Firefox/Safari, the iPhone

Re: [time-nuts] Making a 10811 better

On 9/20/11 12:46 PM, J. Forster wrote: Likely one of the Freons (TM) or Sulphur Hexafluoride. Tektronix used a Freon in their 40 KV High Voltage probes. The Vapor pressure of some of those compounds is low at 70F, but they do have to be sealed. Unfortunately, virtually all Freon useage has been

Re: [time-nuts] Making a 10811 better

On 9/20/11 11:39 AM, Dick Moore wrote: Is there a relatively inert gas that has much higher thermal conductivity than air? Then a flask makes sense and is not the size of the basement... Helium ___ time-nuts mailing list -- time-nuts@febo.com To u

Re: [time-nuts] yet again more VMSK

On 9/16/11 5:56 AM, Luis Cupido wrote: Just read this one... I just wonder if I did anything that terrible in a past life to deserve reading this ... ;-) Recently on Microwaves and RF. http://mwrf.com/Articles/ArticleID/23644/23644.html lc. ct1dmk. Yes, Luis... you are clearly a very bad man

Re: [time-nuts] Averaging Location for Position Hold

On 9/13/11 4:24 PM, li...@lazygranch.com wrote: I think I mentioned this is a thread one before. If you are really interested in position accuracy, you look up a calibrated point from the USGS that you can safely and legally access, then take a reading. I say safely because many points are in

Re: [time-nuts] Averaging Location for Position Hold

On 9/13/11 3:10 PM, gary wrote: since they trespassed on my land (undeveloped) to place a satellite cross mark for a shoot. Needless to say I was pissed to see the big X on google earth, though now I have free pointers for NEWS. The while paper had mostly rotted away.] tangential to time nuts

Re: [time-nuts] HP quality

On 9/11/11 7:00 PM, Jim Lux wrote: On 9/11/11 3:14 PM, gary wrote: Since Demming is also the father of SPC, I'd like to know the context of that statement. I'll find it.. but I think it's in the context of the process has to be good Found it (thank you wikipedia, s

Re: [time-nuts] HP quality

On 9/11/11 3:14 PM, gary wrote: Since Demming is also the father of SPC, I'd like to know the context of that statement. I'll find it.. but I think it's in the context of the process has to be good On 9/11/2011 2:10 PM, Jim Lux wrote: On 9/11/11 12:20 PM, J. Forster wr

Re: [time-nuts] HP quality

On 9/11/11 12:20 PM, J. Forster wrote: ears ago, when I was building space payloads, I was told by a guy at MIT's Lincoln Labs: "You cannot inspect in quality." He was right, IMO. that's a classic quote from Deming He had a demonstration for this where he had a bucket of white marbles with

Re: [time-nuts] Sine to LVDS

On 9/10/11 3:20 PM, Tijd Dingen wrote: Same here. Does anyone know of an alternative source for that paper by Oliver Collins? I was trying to make sense of Bruce's generalization of the hard limiter, but found that to be a bit tricky without original paper...

Re: [time-nuts] Sine to LVDS

On 9/10/11 9:38 AM, Magnus Danielson wrote: Probably, but the horology server seems to have gone offline, which is sad since it was a good place to find almost all of Greenhalls papers. Interesting.. I just checked inside the firewall, and the hostname isn't valid (so it's not just that it's n

Re: [time-nuts] Sine to LVDS

On 9/10/11 9:15 AM, Javier Herrero wrote: Thanks, Magnus. The phrase "The JPL units use a ua709-type operational amplifier to allow a high switching speed with low noise" makes me thing a lot about how the concepts "high switching speed" and "low noise" have changed with time :) Ah.. the vene

Re: [time-nuts] Sine to LVDS

On 9/10/11 8:57 AM, Magnus Danielson wrote: On 10/09/11 05:15, Richard (Rick) Karlquist wrote: This article was in the PTTI proceedings around 1990. Highly recommended. This article might be what you refer to: http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA515384 h

Re: [time-nuts] Sine to LVDS

On 9/9/11 6:37 AM, ehydra wrote: Hi Bruce - Do you have a reference to read on for this? I imagine that's the standard cascade of limiters used in zero crossing detectors.. google for JPL and Greenhall to get started. I can't remember the exact cite (or even if Greenhall was one of the aut

Re: [time-nuts] UTC and the speed of light?

On 8/30/11 12:40 AM, Chris Albertson wrote: How is the speed of light accounted for in the definition of UTC? 00:00:00 UTC is the same time everywhere. propagation only affects it if you are transmitting a signal based on UTC. If I send a signal at 00:00:00 UTC from LA to Greenwich, they'l

Re: [time-nuts] Looking for.....

On 8/27/11 8:22 AM, Brian, WA1ZMS wrote: Can anyone recommend a goid commercial grade freq ref synth that will generate a 10MHz output range with .1Hz step sizes based on a 10MHz ref? Agilent sig gens are not a good fit for this application. Would like a 1 RU high compact box with PC programm

Re: [time-nuts] Dead CBT

On 8/27/11 7:45 AM, Tom Van Baak wrote: I can't say the same for carbon (C14) or potassium (K40). See http://en.wikipedia.org/wiki/Banana_equivalent_dose Hmm, clocks based on the decay of C14 or K40... Definitely the other end of the timing spectrum from picoseconds. But think about it..

Re: [time-nuts] [?? Probable Spam] Re: frequency stabilty question

On 8/15/11 8:07 AM, Ulrich Bangert wrote: Jim, pardon to correct you but no apologies needed.. It's if you measured the frequency (instantaneously) at one second intervals, and calculated the standard deviation, that would be the ADEV for tau=1 second. is simply wrong in at least two aspe

Re: [time-nuts] frequency stabilty question

On 8/14/11 8:10 PM, Paul Cianciolo wrote: Folks, I amtrying to understand some of the terms used here quite often. I quoted this from Wikipedia An Allan deviation of 1.3×10−9 at observation time 1 s (i.e. τ = 1 s) should be interpreted as there being an instability in frequency between two obs

Re: [time-nuts] manuals, anyone?

On 8/4/11 9:08 AM, Dave M wrote: hn BAMA is kinda strange nowadays. According to the note on the edebris mirror page, the main BAMA site has been down for "repairs and upgrades" since 9/17/2009; almost 2 years ago. Will the main site ever come back online, or has it been written off permanently?

Re: [time-nuts] Variation in Radioactive Decay Rate with Solar Activity

On 8/3/11 2:20 PM, Brooke Clarke wrote: Hi Jim: The problem I'm having is that just counting the clicks from a source is a way to get random numbers. If you average the clicks over a large amount of time and plot that average, it will decrease over time. So to see the change in decay rate the so

Re: [time-nuts] Variation in Radioactive Decay Rate with Solar Activity

On 8/3/11 12:14 PM, J. Forster wrote: Hi Brooke, Maybe. The photon counting gear is pretty trivial. You'd need: A scintillator A PMT (Photo Multiplier Tube) and HV stable HV PS. A preamp A SCA (Single Channel Analyzer). These can be built. A counter, stable time base, and data recorder The mai

Re: [time-nuts] GPSDO for my rubber duckie

On 8/2/11 10:47 PM, David J Taylor wrote: That said of all the systems I like the Mayan one best. They defined the year as 360 days. Then after 360 days they stopped counting and had a party while they waited for the priest to watch the sun and declare the start of a new year. They got a week off

Re: [time-nuts] Discipline an oscillator with NTP?

On 7/23/11 9:42 AM, Bob Camp wrote: Hi The simple answer is that normal NTP via the net will give you accuracy similar to the "zero beat to WWV" approach. It will take a few days to get to that level. Much faster to fire up the radio and use WWV. Bob If you aren't somewhere that has no rad

Re: [time-nuts] Discipline an oscillator with NTP?

On 7/22/11 3:46 PM, brent evers wrote: "After that all you need to do is write some code to..." Oh - if I had a nickel for every time I've heard that! Brent When I worked in the physical effects business, we'd get a set of storyboards from a director, and we'd have to figure out how we were

Re: [time-nuts] Discipline an oscillator with NTP?

On 7/22/11 11:59 AM, Chuck Forsberg WA7KGX N2469R wrote: On 07/22/2011 11:48 AM, Javier Herrero wrote: El 22/07/2011 20:39, michael taylor escribió: I think all NTP server appliances have this functionality by their nature, whether or not the oscillator is of particular high quality (low nois

Re: [time-nuts] DDS'ery narrow scoped.

On 7/21/11 8:30 AM, Luis Cupido wrote: Magnus, It crossed my mind of messing somehow with the phase accumulator metrics but did not figure a way... that is a good suggestion I will investigate in that direction... (or maybe... if you do have a bit of free time to drop me a couple of lines more,

Re: [time-nuts] The future of UTC

On 7/15/11 3:17 AM, Steve Rooke wrote: Well, instead of leap seconds which seem to be the biggest bug bear for everyone, keep the second as 1/86,400 of the earths current rotation and adjust the factor used in the calculation of atomic time on a regular basis. No more leap seconds just leap atomi

Re: [time-nuts] Japan Quake May Have Shortened Earth Days, Moved Axis

On 7/15/11 12:48 AM, Tom Van Baak (lab/iPad) wrote: 1E14 we might be able to notice Hal, No. Look at the adev of the earth (earlier posting). The length of earth day varies in the *milli*second range, day to day. VLBI measurements are under 0.1 millisecond, which comes to about 1e-9 resoluti

Re: [time-nuts] Japan Quake May Have Shortened Earth Days, Moved Axis

On 7/15/11 12:10 AM, Hal Murray wrote: Does anybody have a good graph for summer vs winter? I'd expect snow loading might be big enough to show up. This is the kind of thing that Richard Gross at JPL fools with. As I recall, atmospheric drag changes on a cyclical basis too. And solid/liq

Re: [time-nuts] Japan Quake May Have Shortened Earth Days, Moved Axis

On 7/14/11 10:54 PM, Poul-Henning Kamp wrote: In message<3209.12.6.201.213.1310686158.squir...@popaccts.quikus.com>, "J. For ster" writes: If you got all the Chinese to just stand on a chair, it would increase the Moment of Inertia of the earth a smitch, and it would slow the rotation because o

Re: [time-nuts] Japan Quake May Have Shortened Earth Days, Moved Axis

On 7/14/11 6:40 AM, J. Forster wrote: So? That statement clearly imlies the Earth's period was shortened aganst some standard. If the Earth was the standard, how could it be shortened with respect to itself? It can't be. Time standards are atomic now. -John You've raised an interesting phi

Re: [time-nuts] MIT RADIATION LABORATORY SERIES 1940-1945 (28 VOLS) on eBay

On 7/14/11 6:08 AM, Steve Rooke wrote: It's a shame these, and other elderly scholarly works, can't just be released for the greater good, without all this red tape tying them down. I wonder how much better the world would advance if we could all go back to the days when we shared knowledge and s

Re: [time-nuts] MIT RADIATION LABORATORY SERIES 1940-1945 (28 VOLS) on eBay

On 7/13/11 12:13 PM, Chuck Harris wrote: I can conceive of a case where a publisher like McGraw-Hill's copyrighted book full of public domain IP could be copied if you used your own type font, and formatting of pages, pictures and text, etc... This is precisely the case with West Publishing a

Re: [time-nuts] MIT RADIATION LABORATORY SERIES 1940-1945 (28 VOLS) on eBay

On 7/13/11 8:05 AM, jmfranke wrote: The original series was copyrighted 1947 by McGraw-Hill Book Company. The agreement with the government was the copyright would later be lifted. I know in 1964 the grey colored small size book series were printed by Boston Technical Publishers, Inc. with no cop

Re: [time-nuts] MIT RADIATION LABORATORY SERIES 1940-1945 (28 VOLS) on eBay

On 7/13/11 8:02 AM, J. Forster wrote: That is apparently the case for the HC books. I'm not so sure about the CDs. A friend who is an IP attorney has told me that if you scan something, you cannot copyright the scan. You can copyright any new content you add. And you could copyright the arra

Re: [time-nuts] MIT RADIATION LABORATORY SERIES 1940-1945 (28 VOLS) on eBay

On 7/13/11 6:55 AM, J. Forster wrote: there is a Yahoo Group, MIT-Rad-Lab-Books where you might get lucky on the missing volumes. There was a complete, scanned set on two CDs around also. The copyright status is unknown though. Have to check for sure, but they might be non-copyright. Were t

Re: [time-nuts] Broadband synthesizer

On 7/13/11 5:55 AM, paul swed wrote: hp3335 then as I sent last night or 3325... we use a lot of them at work. takes a 10MHz input, settable to microhertz, etc. On Wed, Jul 13, 2011 at 8:38 AM, Bill Dailey wrote: Thanks for the input. I think i am asking for too much in one package (

Re: [time-nuts] Broadband synthesizer

On 7/12/2011 at 9:04 PM Bill Dailey wrote: Ok, I have a dds receiver locked to a gpsdo, the radio can only be tuned in 1 hz increments but should be dead on. I can feed the passband into speclab via VAC and measure a carrier OTA. No problem there...can get decent resolution but there is som

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