Re: [time-nuts] EMI and CE certification

On 5/11/15 12:52 PM, Adrian Godwin wrote: Is it driven as an inductive loop? That might put it under different regulations. On 11 May 2015 17:47, "Chuck Harris" wrote: Yes, but in the case of the lawnmower fence, and the invisible dog fence, the transmitter drives the fence as an antenna. In

Re: [time-nuts] Time in a cave

On 5/12/15 4:00 PM, Tucek, Joseph wrote: I'm looking for information on non-GPS time sources. For background, I need to provide PTP to a cluster where we don't have line of sight to the sky, and are unlikely to get roof-rights without a fight. There are CDMA solutions that would work (e.g. En

Re: [time-nuts] iGPS?

On 5/18/15 11:06 AM, Brooke Clarke wrote: Hi Bob: In the link in the message from Brian it explains that iGPS is for military users of the Iridium system. The key feature is to allow a moving vehicle to lock on the GPS signal while being jammed. They do that and also get a more accurate fix by

Re: [time-nuts] iGPS?

On 5/18/15 7:59 PM, Chris Albertson wrote: Yes GPS can do better than 50M but we are talking about a single fix from a cell phone in a moving car not a survey receiver. . The displayed location is better because the phone applies a filter to the location data. Some thing like a Kalman filter.

Re: [time-nuts] USB problems and solutions - Some what Off Topic --> USB-C

On 6/2/15 4:07 AM, Bob Camp wrote: Hi The one thing I would be a bit careful about is the power levels. Consider an 8 port hub: 5V 3A from each would be 24A total. That’s pretty unusual. Most hubs give you one or two high current outputs. There are very few 8 port hubs and lots of 7 port hub

[time-nuts] PHK quoted in Slate online article about leap second

http://www.slate.com/articles/health_and_science/science/2015/06/next_leap_second_june_30_dangers_to_software_military_gps_banking_air_traffic.2.html ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mail

[time-nuts] Close in phase noise of microwave VCOs

I'm looking for some representative data for inexpensive microwave VCOs (in the 2.5-6 GHz range, in general). Not in a locked loop situation, but just bare: with a DC voltage on the tuning input. I'm particularly interested in data closer than 100 Hz. Most of the data sheets (e.g. from Minici

Re: [time-nuts] Close in phase noise of microwave VCOs

On 6/17/15 1:08 PM, Richard (Rick) Karlquist wrote: On 6/17/2015 8:22 AM, Jim Lux wrote: I'm looking for some representative data for inexpensive microwave VCOs (in the 2.5-6 GHz range, in general). Not in a locked loop situation, If the phase noise data you have goes to a low e

Re: [time-nuts] Close in phase noise of microwave VCOs

On 6/17/15 1:08 PM, Magnus Danielson wrote: Jim, John Miles have been a bit active: http://www.ke5fx.com/brick/brick.htm Just to give you a start-sample. those seemed to be all PLL outputs.. I didn't see the bare VCO data. And, I'm really interested in the 1 Hz to 100 Hz kind of range. _

Re: [time-nuts] Close in phase noise of microwave VCOs

On 6/17/15 6:15 PM, John Miles wrote: Also see http://www.ke5fx.com/gunnpll.html , a quick and dirty but successful attempt at locking a Gunnplexer in a relatively low (1 kHz) loop bandwidth. The inband noise is likely too high for good performance in a radar application, but the basic idea is w

Re: [time-nuts] Close in phase noise of microwave VCOs

On 6/18/15 3:46 AM, Bob Camp wrote: Hi Be careful when you do find the data. When you go very close in on something like a VCO, you get much higher phase noise than we normally worry about. Some of the “assumptions” that underly the measurements are no longer true. Small angle of modulation i

Re: [time-nuts] Close in phase noise of microwave VCOs

On 6/18/15 10:05 AM, Mark Sims wrote: If you want to play with a homodyne doppler radar, search Ebay for "hb100 microwave sensor". It is a cute little 10 GHz doppler module that costs around $6. It can be operated in continuous or pulsed mode. The output does require a couple of op-amps t

Re: [time-nuts] Close in phase noise of microwave VCOs

On 6/18/15 1:46 PM, Brooke Clarke wrote: Hi Mark: Is there any documentation on the HB100? first hit on google for "HB100 microwave sensor" (recognizing that what comes up as *my* first hit will probably be different than *your* first hit)... https://www.openimpulse.com/blog/products-page/pr

Re: [time-nuts] Close in phase noise of microwave VCOs

On 6/19/15 9:30 PM, Bob Camp wrote: Hi One of the most interesting things about the last paper mentioned: On Jun 19, 2015, at 8:57 PM, Charles Steinmetz wrote: Rick wrote: However, a better tutorial would be the one written by HP's Dieter Scherer which was published in Microwaves & RF Magaz

Re: [time-nuts] potential source for cheap copy of labview

On 6/20/15 3:03 PM, Dave Daniel wrote: I wish the MathWorks would resume that practice. Back in the late 90s they would sell one licenses for MatLab and SimuLink for an affordable price if one singed an agreement that restricted one to personal (specifically, non-commercial) use. My copy from bac

Re: [time-nuts] potential source for cheap copy of labview

On 6/21/15 11:28 AM, Don Latham wrote: Just for fun, went to the site. $149 for basic, but by the time I added all the toolboxes I thought (!) I needed, I was over $750. sigh. Don Hence the popularity of the student license (or Octave) ___ time-nut

Re: [time-nuts] magnetic electronic components

On 6/22/15 12:02 PM, Attila Kinali wrote: Hi, I was looking up some stuff and realized (again) that I don't know anything about how magnetic electronic components (inductors/solenoids, transfomers, baluns, ferrite beads...) work. Yes, I can calculate the inductance, I know how to get from the AL

Re: [time-nuts] magnetic electronic components

On 6/23/15 4:25 AM, Tim Shoppa wrote: "Experimental Methods in RF Design" has a half-dozen pages specifically on the choices of powdered iron and ferrite materials, and lots of working circuits and designs with measurements. Aka EMRFD. http://www.arrl.org/shop/Experimental-Methods-in-RF-Design H

Re: [time-nuts] magnetic electronic components

On 6/23/15 4:02 PM, Tim Shoppa wrote: Yes, for ferrites, many (all?) of the Amidon FT-xxx parts are perfectly standard Fair-Rite cores available from full-line distributors like Mouser, Newark, etc. Iron powder cores are not stocked by any of the standard distributors that I know of, but kitsand

[time-nuts] windows and leap seconds

https://support.microsoft.com/en-us/kb/909614 basically: ignore the leap second, so your computer is "fast" relative to UTC, and next time you resynchronize time it adjusts Windows, these days, runs NTP http://blogs.msdn.com/b/mthree/archive/2015/01/08/leap-seconds-010815.aspx http://blogs.ms

Re: [time-nuts] GPS/UTC time

On 7/3/15 9:45 PM, Brek Martin wrote: Hi Guys, I feel like I missed “The Big Thing” in time keeping land. I should have watched my Ublox LEA-5T. What is the difference if it is in the reporting mode for GPS or UTC time? If they skip a second UTC, surely the GPS time isn’t run incorrectly fore

[time-nuts] beaglebones, time, web services

I've got a project I'm working on to make a sophisticated sundial with moving mirrors. I've got a batch of Arduinos that move the mirrors to the appropriate places, given the current sun angle, etc. I've got a beaglebone that runs some python code to calculate sun angle based on time The be

Re: [time-nuts] beaglebones, time, web services

On 7/4/15 11:45 AM, Bill Dailey wrote: Pysolar Sent from mobile "Pysolar: staring directly at the sun since 2007" excellent.. thanks.. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/lis

Re: [time-nuts] beaglebones, time, web services

I should finally de-lurk since I can perhaps offer some useful opinion on this. Comments inline. On Sat, Jul 04, 2015 at 06:13:06AM -0700, Jim Lux wrote: I've got a project I'm working on to make a sophisticated sundial with moving mirrors. I've got a batch of Arduinos that move

Re: [time-nuts] beaglebones, time, web services

On 7/4/15 12:31 PM, Bob Camp wrote: Hi As silly as it sounds, having a separate board for the user i/o is probably the best way to go. You already have an empire of devices that (somehow) chat with each other. The barrier of “it’s all on one device” has been broken even before i/o has been add

Re: [time-nuts] beaglebones, time, web services

On 7/4/15 1:42 PM, Simon Marsh wrote: Pretty much every webserver ever written allows you to run a script in response to a request. Nowadays there are frameworks that integrate closely with the language of your choice and do all the heavy lifting for you. If fact, the problem is really too mu

Re: [time-nuts] GPS/UTC time

On 7/4/15 12:18 PM, Brian Inglis wrote: (the Japan earthquake in 2011 sped the earth up by 1.8 microseconds/day. The Sumatra quake on 26 Dec 2004 had a bigger effect: 6.8 microseconds) By my calculations, that should mean the earth rotated 3mm farther/day at the equator after Sumatra. Anyone

Re: [time-nuts] GPS/UTC time

On 7/4/15 2:01 PM, Tom Van Baak wrote: (the Japan earthquake in 2011 sped the earth up by 1.8 microseconds/day. The Sumatra quake on 26 Dec 2004 had a bigger effect: 6.8 microseconds) Hi Jim, Just in case you didn't know -- these are theoretical results only. There's a guy at JPL (Richard Gros

Re: [time-nuts] GPS/UTC time

On 7/4/15 10:25 PM, Brian Inglis wrote: Thanks for the good and interesting refs. One of the interesting points was that normal variations are multiples of those caused by earthquakes, and annual variations are up to 1ms and 1m. Another was that the jet streams produce large short term variation

Re: [time-nuts] beaglebones, time, web services

On 7/4/15 7:53 PM, Hal Murray wrote: jim...@earthlink.net said: Exactly... I've got an array of mirrors on az/el mounts (two servos stacked) and the reflection from the mirrors on the wall forms the display. How many pixels in that display? Or what is the unit of quality measurement? What s

Re: [time-nuts] beaglebones, time, web services

On 7/5/15 8:43 AM, Bob Camp wrote: Hi On Jul 5, 2015, at 8:46 AM, Jim Lux wrote: On 7/4/15 7:53 PM, Hal Murray wrote: jim...@earthlink.net said: Exactly... I've got an array of mirrors on az/el mounts (two servos stacked) and the reflection from the mirrors on the wall forms the di

Re: [time-nuts] beaglebones, time, web services

On 7/6/15 3:19 PM, Tom Harris wrote: Since you want simple just use a CGI script written in your language of choice. Very easy technology to learn, Python has support libraries out of the box if you want. You have a webpge with carious simple controls on it like buttons etc, you click a special b

Re: [time-nuts] US export regulations for TICs

On 7/7/15 6:28 AM, Attila Kinali wrote: Moin, As we need a need a proper TIC here to do our research, we are going to buy one from ebay form a seller in the US and let a friend who is in the US at the approriate time and can pick it up to bring it back in the plane. Now the big question is, are

Re: [time-nuts] beaglebones, time, web services

On 7/7/15 9:59 PM, Brian Inglis wrote: On 2015-07-04 07:13, Jim Lux wrote: I've got a project I'm working on to make a sophisticated sundial with moving mirrors. I've got a batch of Arduinos that move the mirrors to the appropriate places, given the current sun angle,

Re: [time-nuts] Number of GPS sats in the sky?

On 7/10/15 6:23 AM, Azelio Boriani wrote: From Block IIA: 3 operational Block IIR and IIR(M): 19 operational Block IIF: 9 operational so they should be 31 satellites working. Plus various and sundry WAAS and similar signals? __

Re: [time-nuts] OCXO with ADEV of 1E-13 on Pluto Mission

On 7/16/15 8:17 AM, John Stuart wrote: Here is an interesting link to the New Horizons Mission to Pluto radio system design. Note last section describes an OCXO with ADEV = 1E-13 at 1s, and aging rate of <1E-11 per day. That's no ordinary OCXO. That's a USO made at APL. The crystal is in a s

Re: [time-nuts] 5 x 2 x 3 = 30 MHz

The whole USO is about $1M, the vast majority of which is labor.   Analysis, testing, paperwork, etc Jim Original message From: Bob Camp Date: 07/18/2015 02:10 (GMT+00:00) To: tim...@timeok.it, Discussion of precise time and frequency measurement Subject: Re: [time

Re: [time-nuts] wtd: WWVB info

On 8/5/15 12:41 PM, Donald wrote: On 8/4/2015 9:36 PM, Hal Murray wrote: kb...@n1k.org said: So far there have not been any home brew design radios show up that will demodulate and lock to the new data format. There is plenty of info on the transmit format. The demodulation approach is not craz

Re: [time-nuts] wtd: WWVB info

On 8/5/15 8:27 PM, Donald wrote: On 8/5/2015 7:55 PM, Bob Camp wrote: Hi Analog Devices has some very nice ADC’s that are directly targeted at doing this general sort of thing. They do not have any “odd” filtering approach that creates issues. Some of the early 192 KHz audio parts did not do ve

Re: [time-nuts] wtd: WWVB info

On 8/5/15 8:03 PM, Donald wrote: On 8/5/2015 6:44 PM, Jim Lux wrote: I'm not sure it would buy you much.. you'd have something running at 240kHz switching the inputs to the detector? It's MUCH easier to just digitize the 60kHz with a high resolution converter. And have a nice

Re: [time-nuts] wtd: WWVB info

On 8/7/15 1:40 AM, Hal Murray wrote: kb...@n1k.org said: Well, at least *some* of the chips out there do not make it to 96 KHz when sampling at 192 KHz. It’s been a few years since I dug into them. Back then a chip that had an internal filter that went to 96K was very much the exception rath

Re: [time-nuts] wtd: WWVB info

On 8/9/15 4:33 PM, Bob Camp wrote: Hi If you never have tried to keep an IC in production, there are some basic things that may not be very obvious: There's always Rochester Electronics.. "leaders in the trailing edge" (no kidding, that's their slogan).. They buy old fabs, masks, etc, and

Re: [time-nuts] wtd: WWVB info

On 8/9/15 7:57 PM, John Allen wrote: Hi Jim - You wrote: At some point, multiproject wafers (like MOSIS) might become a hobby product. So far, it's in the "several kilobuck" minimum purchase, and, as well, the tools aren't easy to come by. Or, more properly, good design tools are expensive, ted

Re: [time-nuts] Serial Ballpoint issue again

On 8/11/15 5:20 AM, David C. Partridge wrote: I just installed Windows 10 (yes I know how rash), and now my Thunderbolt is being detected as a Microsoft Serial Ballpoint Mouse (yes, just like before inder Windows 7). I had set something up on Windows 7 in the boot.ini to stop this, but for the l

Re: [time-nuts] Cavity frequency air filled vs vacuum?

On 8/18/15 10:30 PM, Bruce Griffiths wrote: The ratio of the resonant frequency of the evacuated cavity to that of the air filled cavity increases by the square root of the relative permittivity of the ambient air or around 300ppm or so. Bruce I believe that there are systems that measure h

Re: [time-nuts] GPS outage? 19:00-2100 UTC Tue

On 8/19/15 10:12 PM, Hal Murray wrote: t...@radio.sent.com said: I think that Menlo Park is somewhat under 300 NM (nautical miles) from China Lake (depending on exactly where the test was located), and the expected interference range was about 252 NM. So you might have been at the edge of the a

[time-nuts] looking for SMT oscillator SC cut, with no oven

For a project at work, I'm looking for a good close in phase noise oscillator (better than -100dBc@ 10Hz, -120dBc would be nice) at 100 MHz in a SMT form factor. But it doesn't need good temperature stability. There's tons of SMT OCXOs out there with reasonably good performance, but they draw

Re: [time-nuts] looking for SMT oscillator SC cut, with no oven

On 8/26/15 1:04 PM, Javier Herrero wrote: Hello, Jim, I suppose that one of the alternatives that you've explored are the ABLNO from Abracon http://www.abracon.com/Precisiontiming/ABLNO.pdf They say that they are 3rd overtone, but it seems more an AT-cut than a SC, and anyway is around 10dB poo

Re: [time-nuts] looking for SMT oscillator SC cut, with no oven

On 8/26/15 1:28 PM, steve heidmann via time-nuts wrote: Rakon has always impressed me . I'll take a look. The online datasheets don't have phase noise data for close in frequencies (at least the 3 I looked at).. some give a "integrated jitter" but it's for 12kHz and out, and I've noticed the

Re: [time-nuts] looking for SMT oscillator SC cut, with no oven

On 8/26/15 2:38 PM, Gerhard Hoffmann wrote: Am 26.08.2015 um 22:04 schrieb Javier Herrero: I suppose that one of the alternatives that you've explored are the ABLNO from Abracon http://www.abracon.com/Precisiontiming/ABLNO.pdf looks just like this one from Crystek: < http://www.digikey.de/pr

Re: [time-nuts] looking for SMT oscillator SC cut, with no oven

On 8/26/15 4:46 PM, Alex Pummer wrote: But if he needs 100dBc at 10Hz that is Wenzel's stronghold [https://twitter.com/ultralownoise] look that: http://www.wenzel.com/wp-content/parts/501-04517.pdf Yep.. got one of those sitting on my desk (or one that's very similar).. but it's a 2x2" block

Re: [time-nuts] looking for SMT oscillator SC cut, with no oven

On 8/27/15 4:46 PM, Bob Camp wrote: Hi On Aug 27, 2015, at 3:58 AM, Hal Murray wrote: kb...@n1k.org said: Is there anything fundamental about SC that forces the turn over temperature to be high? Simple answer yes. More complicated answer : that depends. The crystal curve on an AT or

[time-nuts] equations for crystals, frequency vs temp vs angles

Someone was asking about changing cut angles and the effect. You might find some useful stuff in Mark Haney's thesis "Design Technique for Analog Temperature Compensation of Crystal Oscillators" http://scholar.lib.vt.edu/theses/available/etd-11262001-111453/unrestricted/etd.pdf Here's a matla

Re: [time-nuts] looking for SMT oscillator SC cut, with no oven

On 8/29/15 7:19 PM, Alex Pummer wrote: Hi Bob, go to your local city library get membership[ here in California it is free] , and ask them to get from the university library, it will take some time than they cal you the your stuff is there, you could have it for four weeks if you need you cou

Re: [time-nuts] algorithms and hardware for comparing clock pulses

On 9/21/15 12:13 PM, Robert LaJeunesse wrote: The Teensy 3.1 (http://www.pjrc.com/store/teensy31.html ~$20) has a Flex Timer Module that appears to allow a single counter to be captured into independent registers from independent inputs. Not sure, but PJRC tends to run the clock fast (96MHz) s

Re: [time-nuts] algorithms and hardware for comparing clock pulses

On 9/21/15 12:13 PM, Robert LaJeunesse wrote: The Teensy 3.1 (http://www.pjrc.com/store/teensy31.html ~$20) has a Flex Timer Module that appears to allow a single counter to be captured into independent registers from independent inputs. Not sure, but PJRC tends to run the clock fast (96MHz) s

Re: [time-nuts] algorithms and hardware for comparing clock pulses

On 9/21/15 12:13 PM, Robert LaJeunesse wrote: The Teensy 3.1 (http://www.pjrc.com/store/teensy31.html ~$20) has a Flex Timer Module that appears to allow a single counter to be captured into independent registers from independent inputs. Not sure, but PJRC tends to run the clock fast (96MHz) s

[time-nuts] teensy as time capture device

I've got a teensy3.1 hooked up to a 33120 function generator (not exactly a super stable device) and generating period data for a 1 Hz square wave. The period is in "ticks" of the 48 MHz clock, so my thinking is that if I hook up a good 1pps, what I'm really measuring is the frequency of the

[time-nuts] first teensy3.1 data

a bit more than 5 minutes of data. Now to go get a real 1pps source that's decent. ___ 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] more teensy timer stuff

Got the Rb hooked up. 1E-8, 1E-9 kind of AVAR (after linear trend removal) for 10 minute run. next, we'll try running it clocked at 96 MHz ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listi

Re: [time-nuts] teensy as time capture device

On 9/23/15 10:08 PM, Poul-Henning Kamp wrote: In message <5602f65b.6050...@earthlink.net>, Jim Lux writes: I've got a teensy3.1 hooked up to a 33120 function generator (not exactly a super stable device) and generating period data for a 1 Hz square wave. That is

Re: [time-nuts] first teensy3.1 data

some data files and a better test setup. You want to understand the systematics when it looks like that. Cheers, Magnus On 09/23/2015 09:09 PM, Jim Lux wrote: a bit more than 5 minutes of data. Now to go get a real 1pps source that's decent. _

Re: [time-nuts] teensy as time capture device

On 9/24/15 7:13 AM, cfo wrote: On Thu, 24 Sep 2015 05:30:35 -0700, Jim Lux wrote: What would be interesting is if there's a pin on the Arduino/Teensy that you could feed a high quality oscillator to, and then do counting with that. The K20 microcontroller has a mindbendingly large numb

Re: [time-nuts] teensy as time capture device

On 9/24/15 11:02 AM, Hal Murray wrote: xne...@luna.dyndns.dk said: External Oscillator (the system clock clock) , or External Timer clock (limited to system clock/4) That sounds like they are running the external signal through a synchronizer and then doing all the logic on the system clock.

Re: [time-nuts] more teensies

On 9/25/15 11:40 AM, Jim Lux wrote: I ran 5 teensys in parallel, driven from the same Rb source for an hour.. They track reasonably well. and AVAR from the same run ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https

Re: [time-nuts] advice for buying VCXO

On 10/6/15 5:46 AM, Can Altineller wrote: Hello Jim, Yes i need a VCXO or even a VCTCXO. However when I search them on ebay, unfortunately, since they included every term for XO, I am lost in the noise. Any recomendations for buying VCXO's that are surplus, and not ebay? do you want a Oven

Re: [time-nuts] advice for buying VCXO

On 10/6/15 12:46 PM, Can Altineller wrote: Hello, I was hoping for a cheap VCXO. I think those ovenized ones are more expensive. Where would I get a brand new VCXO, that has < 1ppm, and specs that are true. (as in the declared spec would match the actual performance, these days when we buy from

Re: [time-nuts] Iridium source?

On 10/7/15 1:16 AM, Tom Van Baak wrote: Stu, Thanks for the heads up. If you can leak anything from the upcoming paper please let us know. Since you're an Iridium expert, would you be able to answer the question? The OP (John Todd) was asking about reception deep indoors, where GPS signals fa

Re: [time-nuts] Digital Phasae Lock Loops

On 10/16/15 7:45 AM, Martyn Smith wrote: Hello, I want to design a digital phase lock loop. I intend to lock a 10 MHz ultra low noise oscillator that we make to an external frequency standard. I need a digital PLL as I’m trying to get a loop bandwidth < 0.1 Hz. are you locking the oscillat

Re: [time-nuts] Digital Phasae Lock Loops

On 10/17/15 6:17 AM, Alex Pummer wrote: actually, that is a ketch 22, if the loop bandwidth is to low, you will have low noise , but it may will not lock at all, an other way to try to filter out the noise, also you may make the loop filter digital, but leave the the PLL analog, that could have

Re: [time-nuts] looking for rakable GPSDO

On 10/19/15 7:10 AM, Stéphane Rey wrote: Hello, I'm looking for a 10 MHz output GPSDO with external antenna which would be rackable. Symmetricon doesn't seem to propose some neither Keysight. MicroSemi now has the product line.. They've got tons of rack mounted GPS disciplined stuff. We have

Re: [time-nuts] Celestial Navigation instruction being reinstated in the US Navy

On 10/25/15 9:37 AM, jim s wrote: Somewhat time related. The Navy realizes that GPS might not always work. I don't imagine that aircraft in the US Air Force will be able to do this very reliably, and the article doesn't mention that service. I'm guessing that a lot of strategic Air Force aircr

Re: [time-nuts] GPS Crystal Frequencies

On 10/26/15 7:06 PM, Brooke Clarke wrote: Hi: I understand 10.230 MHz since when multiplied it gives 1176.45,1227.60, 1381.05 & 1575.42 MHz, all GPS carrier frequencies. http://www.prc68.com/I/DAGR.shtml#GPSs But I've got a number of GPS receivers that have Rakon unit oscillators with a frequenc

Re: [time-nuts] The Pendulum Paradigm by Martin Beech, 2014

On 10/28/15 7:23 AM, Peter Reilley wrote: I have been pondering pendulum clocks. I was wondering what the ADEV of a pendulum would show. I assume that you could see the errors in the gear train. You should see the period of each gear. You should see the spring wind down and being rewound.

Re: [time-nuts] The Pendulum Paradigm by Martin Beech, 2014

On 10/28/15 7:48 PM, Jim Lux wrote: On 10/28/15 7:23 AM, Peter Reilley wrote: I have been pondering pendulum clocks. I was wondering what the ADEV of a pendulum would show. I assume that you could see the errors in the gear train. You should see the period of each gear. You should see the

Re: [time-nuts] Low noise quartz crystal oscillator by Bruce Griffiths

On 10/28/15 4:29 PM, Adrian wrote: That's chapter 6 of his book. http://rubiola.org/indexx-oscillator-noise.html Just scroll down for the phase noise plots. The left hand column of plots contains the essentials. Adrian what would be nice is some similar simple analysis for lower performing

Re: [time-nuts] Beginners GPS locked frequency counter question

On 10/31/15 3:50 AM, Chris Wilson wrote: 31/10/2015 10:46 I have a Racal counter locked to 1 MHz on its rear panel external input socket from my Trimble Thunderbolt GPS. I derive the 1 Mhz from a David Partridge divider board. If I also feed the counter with the 10 Mhz direc

Re: [time-nuts] Beginners GPS locked frequency counter question

On 10/31/15 7:32 PM, Bob Camp wrote: Hi So … how good is the “calibrate and go” (not the tone on second channel) approach likely to be? If it’s a bare crystal or normal XO (not a TCXO) that is supplying the clock, the crystal will follow some fairly well known curves. Which one of the curves

Re: [time-nuts] Downsizing dilemma, HP 3335A

On 11/11/15 3:26 PM, Rob Sherwood. wrote: The EE department at the University of Colorado has an enlightened professor. http://ecee.colorado.edu/faculty/popovic.html Zoya required her students to not only get a ham license, but to build a Norcal 40A. http://ecee.colorado.edu/~ecen2420/Files/N

[time-nuts] time sync from cellphone TO microcomputer

A couple of us were kicking around the idea of a low cost JT65-like HF modem implementation, which requires that the station be synchronized to 1 second. While this is trivial with a GPS receiver, we were thinking about a very minimalist implementation, with a smart phone as the control interf

Re: [time-nuts] time sync from cellphone TO microcomputer

On 11/21/15 2:43 AM, Attila Kinali wrote: On Fri, 20 Nov 2015 15:47:27 -0800 Jim Lux wrote: While this is trivial with a GPS receiver, we were thinking about a very minimalist implementation, with a smart phone as the control interface. So, some electronics with a micro controller that do

Re: [time-nuts] Einstein Special on PBS

On 11/29/15 12:13 PM, Mark Sims wrote: Another thing to consider is the gravity anomaly caused by that hunk of granite beneath your clock (or above it in a mine). Hmmm, what is the clock shift at the top of Mt Everest that is due to the mountain and not the altitude?

Re: [time-nuts] GPS down converter question

On 12/1/15 6:41 PM, Bob Camp wrote: Hi So back to the question …. does a 70 (ish) MHz fancy filter really buy you anything ahead of the main box? If you will be multiply band limited ahead of the mixer (antenna and saw), the contribution of the 70 MHz filter will likely be minimal. Note that I’m

Re: [time-nuts] RG 6 U couplings

On 12/5/15 12:28 PM, Bert Kehren via time-nuts wrote: At my new home the GPS antenna location has turned in to a challenge. May have to splice RG 6U. Has any one done measurements on couplings and the loss associated with them. Right now I am considering a female, female coupling. Is there a

Re: [time-nuts] GPSDO and oscillator steering - EFC vs DDS schemes?

On 12/8/15 8:32 AM, Attila Kinali wrote: Moin, I've been digging through some stuff and stumbled (again) over Rick's paper on high resolution, low noise DDS generation[1] and got confused. The scheme is very simple and looks like to be quite easy and reliably to implement. If I understood it cor

Re: [time-nuts] GPSDO and oscillator steering - EFC vs DDS schemes?

On 12/8/15 3:31 PM, Bob Camp wrote: Hi Let’s see: EFC uses reference out of the OCXO. EFC comes on the OCXO at no added cost. 16 bit DAC costs ~$2 to $5 Total cost for EFC setup $2 to $5. Net result is a system with spurs that are how ever far down you wish them to be. (It’s all about groundin

Re: [time-nuts] GPSDO and oscillator steering - EFC vs DDS schemes?

On 12/9/15 4:37 AM, Bob Camp wrote: Hi On Dec 8, 2015, at 11:20 PM, Jim Lux wrote: On 12/8/15 3:31 PM, Bob Camp wrote: Hi Let’s see: EFC uses reference out of the OCXO. EFC comes on the OCXO at no added cost. 16 bit DAC costs ~$2 to $5 Total cost for EFC setup $2 to $5. Net result is a

Re: [time-nuts] GPSDO and oscillator steering - EFC vs DDS schemes?

(ADEV of 4E-16 at tau of 1000 seconds is a typical state of the art requirement) …. and has been since the 1970’s when I first started talking with JPL people about this :)…. They've gotten a lot smaller and probably draw less power since then. There's also the testing problem: proving tha

Re: [time-nuts] Mechanical clock sound pickup circuit

On 12/14/15 9:12 PM, ed breya wrote: This may be totally ridiculous, but maybe there's another way to get a balance wheel signal. The X-band Doppler type microwave motion detectors can pick up various object signals in free air from quite a distance, so maybe up close there would be enough resolu

[time-nuts] timestamps on downconverted data streams

Here's an interesting problem. You have a fast sampler that is collecting samples off-the-air (e.g. the end of LORAN) with a fairly wide bandwidth: say 10 Megasamples per second. Those samples get post processed in a digital downconverter (not necessarily in real time) to a narrower band repr

Re: [time-nuts] timestamps on downconverted data streams

On 12/20/15 12:17 PM, Bill Byrom wrote: Yes, you can do that. My employer (Tektronix) makes RF Signal Analyzers which sample at a high rate then use a DDC (Digital DownConverter based on decimation and digital filtering) to produce a much smaller output I/Q file at a smaller bandwidth and lower t

Re: [time-nuts] Timestamps in audio files?

On 12/21/15 3:19 AM, Tim Shoppa wrote: As an adjunct to the thread about timestamped samples of LORAN transmissions... Are there any standard consumer-type audio file formats, that support absolute time time/datestamps? Would not have to be done continuously, but something like a time and date s

Re: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator

On 11/30/12 4:58 PM, John Ackermann N8UR wrote: On Nov 30, 2012, at 7:42 PM, John Ackermann N8UR wrote: In this case, you're not looking for the RTC but rather the clock that drives the COU Read "CPU". Stupid iPad keyboard. I was wondering.. Clock Oscillator Unit? Cryptic Obfuscated Un

Re: [time-nuts] Time security musing - attacking the clock itself

On 12/3/12 9:32 AM, dlewis6767 wrote: I agree, Bob. Like the billboard on the side of the highway says: - Does Advertising Work? JUST DID - The bad guys can read this list same as the good guys. Security through obscurity never works in the long run. Much better to discuss vulnerabilities

Re: [time-nuts] Time security musing - attacking the clock itself

On 12/3/12 6:34 PM, Hal Murray wrote: li...@lazygranch.com said: I have one of those key fobs. Does the code somehow inform the power the be about the drift in the built in clock? Or is the time element of the code so sloppy that the drift is acceptable? The magic number changes every second

Re: [time-nuts] Time security musing - attacking the clock itself

"generator". What you have in the real system is dozens of coupled oscillators, all with their own "stiffness" coupled by a complex network of transmission lines with propagation delays and mismatch. On 12/3/2012 8:12 PM, Jim Lux wrote: On 12/3/12 6:34 PM, Hal Murray

Re: [time-nuts] Time security musing - attacking the clock itself

On 12/4/12 4:28 PM, Bill Hawkins wrote: Sorry about this, Tom, but there's some misinformation here. I wasn't reading this until I saw your posting. -Original Message----- From: Jim Lux Sent: Tuesday, December 04, 2012 7:58 AM On 12/3/12 9:59 PM, gary wrote: I was meditating a

Re: [time-nuts] GPSDO Alternatives

On 12/5/12 12:06 AM, Bruce Griffiths wrote: Hal Murray wrote: albertson.ch...@gmail.com said: What is the simplest phase detecter that could work? I think only that, and then a duouble oven crystal from eBay, a GPS and and Arduido. You also need a good D2A to drive the EFC on the osc. A sy

Re: [time-nuts] Very challenging phase noise measurement, does anyone have an idea??

On 12/5/12 2:45 PM, Marek Peca wrote: This last idea is interesting... could be simulated by Matlab or similar. It is known to work in ordinary non-linear transistor-based mixers. It will produce more messy spectrum than double-balanced mixer, however, for this purpose and completely within dig

Re: [time-nuts] GPSDO Alternatives

On 12/6/12 1:06 AM, Chris Albertson wrote: Yes. The idea was the simplest GPSDO that can be build with no PCB around an Arduino. We already know how to build compllelx and expensive GPSDO. That is "too easy". I think you can use the PWM DAC on the Aruino to drive the OCXO. The bandwidth of

<    1   2   3   4   5   6   7   8   9   10   >