Re: [time-nuts] 100 MHz Source
I have a HP70310A. It's the time reference for the HP/Agilent modular MMS system. It seems that the ebay prices for this stuff varies quite a lot depending on random factors. I think I got mine for a couple of hundred dollars. It has a McCoy OCXO and provides 10MHz and 100MHz outputs. You can externally reference to a 10MHz GPSDO if you like (that's what I do). jeff Richard W. Solomon wrote: I need a 100 MHz source to lock up a F/W brick. I have 10 MHz available from my GPSDO. Anyone know an easy way to get 100 MHz using the 10 MHz source ? Maybe another PLO ? If I multiply then I need some pretty decent filtering which might be difficult. Thanks, Dick, W1KSZ ___ 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 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] Power monitoring
Poul-Henning Kamp wrote: In message [EMAIL PROTECTED], Jim Lux writ es: As long as I'm dreaming... Suppose I wanted to measure the power my whole house is drawing. What's available along the lines of a current transformer on the main lines? My first thought is that nobody does that (for homes) so it's probably horribly expensive. On the other hand there is a lot of interest in energy conservation these days so it might only be somewhat expensive. Lots of these available, in the few hundred dollar range.. The best and likely cheapest solution is to get the data from your utility meter. Most meters have a S0 output which sends a pulse evern X Wh. If you can't find it, ask your power-company for access. Tell them you want to monitor your energy conservation effort and they'll likely not charge you for it. If that fails, search google for gasdims :-) I like this thing http://www.digital-loggers.com/epcr2.html It has two busses, one can be powered by a UPS and the other directly off the mains. You can measure power and voltage on both busses, it has a reasonable web interface, you can turn the outlets on/off from the network. I think it's a deal for $295, but they also have a cheaper model. jeff ___ 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] Racal-Dana 1992 switches
How do you pick the optimal difference frequency? I see that 1kHz has a nice numerical property where you can read the frequency directly off the counter, you just need to mentally prepend the first 4 digits. With computers it's not that important, the difference can easily be a strange number if it optimizes performance. I'm wondering what difference frequency optimizes the performance of the mixer thing or if it really matters? Do you worry about the phase-noise contribution of the 10.001MHz source? As I do the math, it seems that the phase noise of the mixing signal is subtracted out after the mixing, so it shouldn't mater that the 10.001Mhz source comes from a frac-N synthesizer and has a few random spurs. You say this isn't state of the art. Why not? Can't you run the timing collection for longer runs and get higher resolution results? jeff Pete wrote: This topic has been addressed earlier; though with some debate. I have proposed a simple heterodyne scheme for beating 2 stable sources against each other observing a 1KHz difference frequency to resolve 1uHz deltas. This is NOT a state-of-the-art scheme, but it will provide better than 1E-12 resolution in less than 10s. This scheme does require some non-standard items. 1. You need a stable synthesizer with external clock capability to yield 10.001 Mhz, phase locked to one of your sources. The HP3336C or a PTS040 work fine. 2. You need a 1KHz zero crossing detector to drive your counter input with low jitter. The ZCD requires 2 opamps a few passive parts, including 2 inductors you'll need to wind by hand. 3. You need a level 7 double balanced mixer to heterodyne the second source the 10.001Mhz signal. Mixers optimized as phase detectors, like the mini-circuits SYPD-1 work well for this. You also need a diplexer on the mixer output to separate the 1KHz beat signal from the other mixer products. The diplexer is 6 passive parts. The results are stable provide counter readings of 9 significant digits down to 1uHz with the leading 4 digits of frequency assumed from the mixing process. The counter gate time setting provides useful often necessary averaging of the readings; so a variable gate time counter is handy. I've used a H-P 5335A, don't know much about the Racal 199x series, but I suspect they would do just fine. Pete Rawson ___ 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 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] GPS PRN07 tracking
And they turned off PRN 10 the next day after making PRN 07 valid. It's like they're playing GPS wack-a-mole. jeff Magnus Danielson wrote: Hi! Earlier this month the launched the latest of the GPS IIR-M sats, and today I had the oppertunity to observe it. It seems it was brought quickly on air as operational. It runs at PRN 07. Cheers, Magnus ___ 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 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] TADD-1 six channel RF distribution amplifier
Bruce Griffiths wrote: Steve wrote: I'm thinking about using the TAPR TADD-1 six channel RF distribution amplifier to distribute the 10MHz output of my Trimble Thunderbolt to a few pieces of test equipment. What does the TADD-1 do to the phase noise characteristics of its outputs as compared to the phase noise characteristics of its input? Improve? Degrade? Little or no change? Thanks. Steve K8JQ I've been using a TADD-1 for about 6-months now and I'm quite happy with it. You certainly can't beat the price. I added the optional 10MHz BPF and tuned it with a tracking generator and spectrum analyzer. The outputs are very clean. I've never tried to measure phase noise, but the op amps and the rest of the circuit seem to be good choices to me. tvb did some analysis of the box you might find interesting: http://www.leapsecond.com/pages/tadd-1/ jeff ___ 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] Buffering the 1pps output from a Z3801A
That's a cool box, but I took a more quick and dirty approach that has served me well. There's a TTL level PPS inside the box, if I remember correctly the part has quite a lot of drive and is fine for driving a 50-ohm cable. I needed a proper UTC PPS signal for a radio astronomy project and I made the following mod to my z3801a: solder a 50-ohm resistor to the TTL PPS signal inside the Z3801A. Use a nibbler tool to widen a cooling hole enough for a piece of rg-58. Zip tie a short piece of rg-58 coax into the hole in the side of the box. I have a female connector dangling outside the box. Wire the coax to ground and the 50-ohm resistor of the TTL drive. This has served me well for many years and driven a variety of spectrometers. The signal looks great on a scope when terminated to 50-ohms, but it is a bit of a quick and dirty solution that might not be appealing to some. I can't tell you which chip/pin is the PPS signal, it was several years ago. I'll remove the lid and tell you the proper pin if you take this approach. jeff John Franke wrote: See; http://www.realhamradio.com/sidecar.htm John WA4WDL - Original Message - From: Peter Vince [EMAIL PROTECTED] To: time-nuts@febo.com Sent: Wednesday, March 26, 2008 9:29 AM Subject: [time-nuts] Buffering the 1pps output from a Z3801A Bruce, et al, The 1pps output of an HP Z3801A and Trimble Thunderbolt is only available (as far as I know) as a balanced ECL signal on the 25-pin connector, with dire warnings in the manuals about not earthing either side of the ECL signals. Would you be able to advise on a simple buffer circuit that would allow me to drive the usual unbalanced 50-ohm coax please? Thanks, Peter Vince (London, England) ___ 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] Close-in phase noise measurements
This is a half-baked idea I've thinking about for awhile. I wonder if it might be possible to create a single measurement to combine allan variance and phase noise in the same plot. Allan variance usually plots tau in seconds on the x-axis. Instead, you might plot 1/s or frequency on the x-axis. This way, allan variance looks more like very close-in phase noise. For example, a point where tau=1000s becomes the phase noise at 1mHz (milli-hertz) from the carrier. Combining this with more typical phase noise measurements, you can create a single log-log graph covering micro-hertz to hundreds of kilo-hertz. The advantage of combining the measurements into a single entity is that you get most of the characterization parameters for a timebase in a single graph. Would this work? Half-baked, I know... jeff Shane wrote: Do you know much about the RS FSUP50? http://www2.rohde-schwarz.com/en/products/test_and_measurement/product_categ ories/spectrum_analysis/FSUP-%7C-Key_Facts-%7C-4-%7C-966.html -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bruce Griffiths Sent: Tuesday, March 25, 2008 8:22 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Close-in phase noise measurements Shane wrote: Wenzel has a setup you can purchase at low cost. http://www.wenzel.com/pdffiles1/PNTS%201000/BP-1000-SC.pdf Phase noise test sets can be pricey... $200K Shane Their calibration method is somewhat problematic at the low frequency end where the effect of the PLL and the audio amplifier low frequency cutoff may be significant. The NIST calibration technique: http://tf.nist.gov/timefreq/general/pdf/1000.pdf is far superior. Bruce ___ 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] 58532a ANTENNA CABLE?
I use 100 feet of LMR-400, which is fantastic, but overkill. It probably loses about 6db for 100-feet at 1.5GHz. There are a lot of online vendors that will sell you any length you want with N-type connectors on both ends. jeff jshank wrote: Hi, I am in the process of setting up a Z3801A and would like to know what type of cable I should use for a 50' run to an 58532A antenna. Also I need to purchase one of the monitoring software programs for this Z3801A, any suggestions. jshank ___ 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 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] hp 5065A Rb AC power connector ?
Tom Van Baak wrote: Does anyone know the Amphenol part number for this one? The manual gives only an HP part number... Thanks, Dan MS-3106A-18-22S; see also: http://www.leapsecond.com/museum/hp5065a/conn.htm /tvb You are getting way too organized... jeff ___ 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] FEI 5680A
I think that I might purchase a GPS disciplined oscillator instead of rubidium standard for a cal lab. There's no physics package in danger of wearing out and no worries about local settings changing accuracy. They are also low power and something like the Trimble unit is very compact. jeff Rex wrote: Jean-Christophe Deschamps wrote: Dear group, I'm a newbie here, so please bear with me. I'm about to buy a FEI 5680A Rubidium frequency standard off ebay. From what I've gathered, these units were used in the telco industry for about 10 years, but are still useable for my needs. I wish to have a reasonably good frequency standard for calibrating test equipment (scope calibrators, function generators, etc), say every 6 months or once a year. For such use I really don't need extreme stability/accuracy. Only hope is that the physics part isn't completely dead. These units typically only produce a 1pps signal, but have the capacity to produce the classical 10 MHz sine wave. I've found a number of documents explaining how to have the 10 MHz produced by these versions. Two of them give consistent informations and seem to be sufficiently documented to be of real value. Drop me a mail at [EMAIL PROTECTED] if you feel posting the files could help someone. I don't know how to post files so that readers of this list can access them. Anyway, I'll postpone distributing the files at large until I check by myself their contents is useful. Feedback welcome! It seems there were many versions of the 5680A that look about the same but are very different. Some run on just +15 V and some need that and +5V. I suspect there are other voltage options too. Some are adjustable in frequency with software commands or a C-field screw. I bought one in early 2005. I figured out by reverse engineering that it needed both +15 and +5 V. It provides both 10 MHz and 1pps outputs on the D-connector. I never found a way to get it to respond to any serial commands, although it has rs-232 interface chips and the signals were propagating inside. I never found any way to adjust the frequency on this one. Other people clearly have units that run on just +15V and do respond to serial commands to set the frequency. One person reported they were able to adjust the frequency on theirs with a screw setting. So it is hard to say what you may get. You may want to search the time-nuts archives, particularly in 2005. ___ 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 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] Atomic clock on ISS
Today's astronomy picture of the day says that future experiments in the new ISS Columbus laboratory include an atomic clock to measure miniscule timing effects: http://antwrp.gsfc.nasa.gov/apod/ap080219.html Does anyone know somthing about the sort of clock they're going to put in the new lab? Presumably they'll also need a way to do time transfer and make precise timing measurements. If I lived on a space station I would demand an atomic clock. jeff ___ 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] Fake leap second ntp servers
There's probably a good NTP hacker hanging around on this list, but the best place to answer your question is probably the NTP hackers mailing list: https://lists.ntp.org/mailman/listinfo jeff Maciej Żenczykowski wrote: Hey folks, I just joined your email list to inquire about something which some of you may have some knowledge of... I'm developing some code (for linux with an ntp server/client running), for which I would like to verify that it handles positive (and negative) leap seconds correctly (I need good time stamps for cross-machine synchronization). Obviously this is hard to do in practice due to the extreme rarity of these events. (even more so, considering my home servers running ntp apparently for some reason saw leap seconds at the end of 2007...) I've thought about switching to djb's suggestion of keeping a non-posix time zone on the machines in question, but this is not feasible because of existing legacy code... Thus I am curious to know if someone somewhere has perhaps set up fake ntp servers which regularly insert and delete leap seconds (ie. reset their time every couple days and randomly simulate a positive or negative leap second 2-3 days down the line). If not, does anyone know how to go about setting up such a fake ntp server for testing purposes? Also, is there a known good list of ntp servers which are known to provide correct leap second announcements (as mentioned above, the stratum 1s at least 2 of my machines were synched to apparently broadcast a leap second at the end of 2008). I've heard horror stories about time synchronization going haywire the last time there was a leap second and some upstream ntp servers announced leap-seconds and others didn't (the time mis-synchronization brought down the application)... Cheers, Maciej. ___ 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 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] Clock Powers of Ten
Very nice, it reminded me of a NYT article about a year ago that describes the long zoom as one of the defining aspects of this generation: http://www.nytimes.com/2006/10/08/magazine/08games.html?ei=5090en=d551133c9414ebbdex=131796partner=rssuserlandemc=rsspagewanted=all jeff John Ackermann N8UR wrote: Very cool, Tom! John Tom Van Baak said the following on 01/31/2008 04:55 PM: There are good clocks and bad clocks. Most need power, one needs food, another runs all by itself. Take a trip across 15 orders of magnitude of clock performance: http://www.leapsecond.com/ten/ /tvb ___ 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 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 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] Prologix, Linux and bash
I have excellent luck using a Prologix device on a couple of different machines running ubuntu linux (7.04 and 7.10). I find it totally painless. You might run usbview and see if the device is being recognized or look at /var/log/messages while plugging in the device. Something like: % sudo tail -f /var/log/messages You should see the device get recognized and a message telling you what device it is assigned to. I use the ser2net daemon with the prologix device. This acts as a proxy for accessing serial devices over the network. This way you can telnet to the GPIB device from the local machine or over the network. This makes it really convenient to access GPIB devices over the local network. As far as programming the GPIB devices, I use perl, it's a lot cleaner than a bunch of crazy echo commands in a bash script. The Telnet module in perl makes it easy to access the ser2net proxy to the GPIB device. There are a lot of different ways to do it, but that's what works best for me. jeff Patrick wrote: Hi Everyone I know that my Prologix device is functioning thanks to Ulrich's EZGPIB. I however want to use this device under Linux. My Ubuntu box cannot find /dev/ttyUSB0 but a Mepis Linux live CD can. I have tried the following commands: echo ++auto 0 CR /dev/ttyUSB0 echo ++auto 1 CR /dev/ttyUSB0 echo ++auto 0 \r /dev/ttyUSB0 echo ++auto 1 \r /dev/ttyUSB0 echo ++auto 0 \n /dev/ttyUSB0 echo ++auto 1 \n /dev/ttyUSB0 echo ++auto 0 \r\n /dev/ttyUSB0 echo ++auto 1 \r\n /dev/ttyUSB0 I have not been able to switch the led on from talk to listen. Could someone give me a bash sample of the correct syntax to use? Thanks in advance-Patrick ___ 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 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] accurate portable time source
Ronald Held wrote: This request is different than the last one. The most accurate TCXO watch is about 1 seconds/year, with regular wear and lots of adjustment. [...] Really? What watch is good to 1s per year? Can you point me at one? That's amazing for a watch. jeff ___ 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] Stuff I bought
Neon John wrote: On Wed, 26 Dec 2007 11:30:05 -0800, Jeff Mock [EMAIL PROTECTED] wrote: Smart Tweezers http://www.advancedevices.com/ It's an RLC meter packaged in a pair of tweezers. It's accurate and fast, feels good to use on the bench. When working with SMT parts, particularly capacitors that typically aren't marked with values, this tool makes it easy to deal with tiny parts on the bench. Truth be told, this product is probably the version before the one you really want to own. I've found a couple of bugs in the software and the industrial design should be nicer, but it's still a good product. Oh crap! There goes the food budget for next month. :-) Jeff, did you buy yours directly from them or did you locate a dealer with a better price? I got mine off ebay. The manufacturer sells directly on ebay for a discount. That was the cheapest I found... jeff ___ 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] Stuff I bought
I hope this might start a holiday thread of cool stuff other people have purchased recently. Here are a few things that I've bought this year that I really like. jeff -- Smart Tweezers http://www.advancedevices.com/ It's an RLC meter packaged in a pair of tweezers. It's accurate and fast, feels good to use on the bench. When working with SMT parts, particularly capacitors that typically aren't marked with values, this tool makes it easy to deal with tiny parts on the bench. Truth be told, this product is probably the version before the one you really want to own. I've found a couple of bugs in the software and the industrial design should be nicer, but it's still a good product. SMA wrench http://www.smelectronics.us/coaxialtorquewrenchessmatypendin.htm I've never known how much to tighten an SMA connector. As time goes by I have more and more SMA connectors. I've seen real RF guys with SMA torque wrenches, but never broken down and bought one until this year. The 5/16 ST-SMA3 is very satisfying and I never worry about SMA connections (but it's a little too expensive). I think 8 in.lbs is the right number. Suunto Tandem compass and clinometer http://www.suunto.com (click on precision instruments) This is a really fantastic machined aluminum compass and clinometer. It's super precise and has optical sites on both instruments. I find it amazingly accurate with a little practice. I can look up an Iridium flare on heavens-above.com, point the device at the sky and find the precise az/el location just before the flare. It's made in Finland, that seems good for some unknown reason. Sure Electronics http://stores.ebay.com/Sure-Electronics They are an ebay seller in mainland China that ships directly to buyers worldwide. They sell a bunch of junk, but the nice things they sell are designer kits of passive components. They are a little slow, it seems to take a couple of weeks to get an item, but they have some really nice design kits. You can get a 2000 piece kit of 0805 capacitors, each value in neatly labeled boxes for less than $20 including shipping. This is about $100 from Digikey and not nearly as nice. ___ 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] Stuff I bought
Brooke Clarke wrote: I have a Suunto wrist computer and like it very much. The normal time, date, alarm, stop watch functions plus compass, altimeter/barometer and thermometer. Which compass did you get? I didn't get the wristwatch, The Suunto tandem is a hunk of aluminum with a liquid filled compass and a liquid filled clinometer machined into the case and optical sites for both. It has a long red strap you can hang around your neck, no electronics, no batteries... The website is difficult to link to, click on the precision instrument section. I learned about it from a cinematographer friend. Evidently it's popular with film types for planning shots with the sun or moon. You see the instrument on the Discovery Channel show Sunrise Earth, the main photographer guy always has it hanging around his neck during interviews. In addition to being pretty accurate, it's the sort of product that feels really nice in your hand, it makes you look for excuses to use it. jeff ___ 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] WIRED Time Nuts, NPR
I think you were just great. The Bryant Park personalities seem to adopt this position that they use a lot of technology, but they'll act like a dufus if they actually discuss some technology. They like to say blog a lot, but never with understanding about how internet tech works. I think it makes it really difficult for BPP to talk to people that want to talk about how things work, they would rather be amazed by something than understand it. It's disappointing, but I do listen to BPP in the afternoon if I'm working in the lab. It was a pleasant surprise to hear you serendipitously. jeff Tom Van Baak wrote: Following the WIRED article, here's an NPR time nuts interview: http://www.npr.org/templates/story/story.php?storyId=17345235 Not sure it came out quite right; I can see now that talking live with off-the-wall questions is a bit more difficult than slowly composing/editing email or web pages. Also next time I'll get them to pronounce my name right! /tvb (Van Baak: rhymes with JS Bach, or clock). ___ 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] Units of Fame
Well, if Lamm is the unit for for fame, Kath must be be the unit for stupidity, google will fill in the gaps. The funniest one I heard is that the standard measure for ego is the Mandelbroit. If you've ever heard him speak, you can see that like the Farad it's most often found as pico- or micro- in the field... jeff Doug Millar wrote: I believe the unit of fame time is the Lamm and is related to the standard second at one to one. He wrote the one hit wonder, Does Anybody Really Know What Time it Is? That is my offering. Perhaps other names come to mind. Submit yours and we can vote. The trouble is that given fifteen minutes of fame, it is easy to forget who they are! Doug Millar ___ 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] SVN37 offline
I'm sure you all noticed, SVN37 (PRN07) went offline today. I tracked it yesterday afternoon, but it is gone today: http://www.mock.com/test/z3801a/ Looks like it might be gone for good, now we only have 29 GPS satellites online... ftp://tycho.usno.navy.mil/pub/gps/gps.txt jeff ___ 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] need recomendation for a portable 10mhz referenceoscilator
[EMAIL PROTECTED] wrote: Hi Bill, a Rubidium would take about 15 to 20 Watts, and they don't usually work at 12V battery voltage typically. At 20 Watts we would consume 1.67A at 12V, so a (large) 80Ah car batt would only last two days in best conditions at room temperature. If we add the OCXO power and low battery temperatures, then we are probably down to 20 to 24 hours of operation or so. BTW: interestingly Lead battery capacity is also related to discharge current, not just temperature. bye, Said I think the situation is somewhat better than that. I'm looking at my LPRO-101. It's about 18-watts while warming up, but once the physics package is up to temp and locked, the power consumption drops to about 5-watts. The larger rubidium modules are probably more power hungry, but the small onces aren't so bad once they are running. You still might need a trunk full of batteries though... jeff ___ 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] Super stable BVA Quartz resonators... BVA??
Thanks for the description, it is very interesting. I have a follow up question if you don't mind. How does crystal aging look on a graph of temp versus frequency. This graph has some temperature point where the slope of frequency variation goes to zero and the crystal is quite stable around this temperature. What does this graph look like as a crystal ages? Does the optimal operating temperature change over time, that is, does the graph tend to move left and right, or does aging tend to move the graph vertically (the optimal freq stays the same, but the optimal operating temperature changes as a result of aging). I hope this makes sense... jeff Bernd T-Online wrote: Hi all, For explanation how the BVA works, please see the attached slide which shows schematically its internal construction. (The explaning text is in German, as it is from my periodically given crystal seminar.) The key points which yield the BVA's improved aging are, that - the whole resonator package is made from quartz, consisting of the resonationg quartz plate in the middle section and the two mounting sealing plaates on top and bottem - you may call it a Hamburger style ;-) - the resonating plate is held through quartz bridges rather than metal suspensions, thus reducing mounting stress. - the BVA is electrodeless, as the electrodes are evaporated on the inner side of the upper and lower mounting plates. Therefore no stress between the quartz surface and the metal eletrode. - Therefore the energizing electrical field is applied through an airgap, which represents two small load capacitors in series to the resonator, thus making the resonator electrically stiffer and less sensitive to circuit influences. On the other side you may imagine the main problems associated with such a construction: - The difficulty to manufacture the convex and concave shaped parts with such a precision, that the curvature yields a constant and very small airgap. - To realize the fine adjustment to frequency, because the unit cannot be tuned in the conventional way, i.e. by plating some metal on the electrode. - The frequency accuracy to which the resonator has to manufactured, because the resonator frequency cannot be pulled with the external circuit elements by more than some hundred ppb. It may be interesting to note, that there was a company BVA Industries, which wanted to generate their income solely from making BVA - which failed. Maybe because of the cost could not be covered by the revenues from the rather limited market. Bernd DK1AG __ AXTAL GmbH Co. KG Facility MOS Wasemweg 5 D-74821 Mosbach / Germany fon: +49 (6261) 939834 fax: +49 (6261) 939836 www.axtal.com ___ 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 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] Cesium Oscialltors and Low Phase Noise Frequency Standard
It sounds like a really nice oscillator. I'm sure that everyone would love to hear about the challenges and tradeoffs in designing such a high performance quartz oscillator. Do you guys cut your own crystals? How much of the improvement comes from a better SC-cut crystal and how much from better electronics or better ovens? I could go on and on, you wouldn't want to sit next to me on a plane. jeff Martyn Smith wrote: Hi, Is there anyone out there clever enough to design me a cesium frequency standard?? There's only two manufacturers that I know of and there's room for another supplier. Also you may be interested to read we have just developed what we believe to be the worlds lowest close-in phase noise 10 MHz oscillator. It makes -121 dBc/Hz @ 1 Hz. Noise floor is only -162 dBc/Hz at the moment, but we are working on reducing this a further 5 to 10 dB. Enter your order number here.. Best Regards Martyn This Email is from: Martyn Smith Precision Test Systems LTD Tel: +44 (0) 1245 329608 Email: [EMAIL PROTECTED] Web: www.ptsyst.com ___ 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 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] HP 8566B repair
Thanks so much, that's just the encouragement I need to crack open the RF section. I'll take a look at the electrolytic caps you suggest. Assuming that I find something, do you think it's worth replacing other caps in the area figuring that they will also go bad soon enough? jeff John Miles wrote: Never fear. I have seen this a few times, in a couple of 8566Bs that I have owned as well as in some others. The YTO UNLOCK error always seems to come down to an open electrolytic on the YTO driver or pretune DAC boards, under the hinged plastic cover toward the rear of the RF section. Check power supply voltages first, then check ESR of all of the axial-lead electrolytics on all boards under that cover. Then, if those areas are both OK, go through the YTO calibration procedure in the manual until you either successfully recalibrate the pretune/driver system, or reach a particular step that you can't complete. -- john, KE5FX -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Jeff Mock Sent: Thursday, December 06, 2007 7:38 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] HP 8566B repair Does anyone have any suggestions or advice about 8566B repair? I've had an 8566B for 7-8 years, it's been a faithful tool, never had a problem with it. It's reasonably clean unit that's never seen a tough life. It sits in the storeroom 90% of the time and is on my bench maybe 10% of the time. So, this week, after a 4 month hiatus, I've been using it on the bench and it starting producing a YTO UNLOCK message, the trace seems to basically work properly but is clearly unlocked and the trace will randomly slide to the left or right. The Yttrium oscillator is clearly unlocked. I'm hopeful that the problem is in one the control loops outside the oscillator module. I read the repair guide that Agilent kindly keeps on their website, they have some good instructions and narrow the problem to 3-4 modules, but I've never opened up the instrument and am a little apprehensive about making things worse. My hunch is that the problem is an electrolytic cap that has dried out over the years and has failed. Any suggestions for either self repair or outside repair and re-calibration is appreciated... In full disclosure, I also have a 70908A based spectrum analyser that that has much better specs, especially in microwave. It can completely replace the 8566B, but I'm quite fond of the 8566B, I can operate it blind folded, it's like an old friend and I would really like to fix it. ___ 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 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] HP 8566B repair
Does anyone have any suggestions or advice about 8566B repair? I've had an 8566B for 7-8 years, it's been a faithful tool, never had a problem with it. It's reasonably clean unit that's never seen a tough life. It sits in the storeroom 90% of the time and is on my bench maybe 10% of the time. So, this week, after a 4 month hiatus, I've been using it on the bench and it starting producing a YTO UNLOCK message, the trace seems to basically work properly but is clearly unlocked and the trace will randomly slide to the left or right. The Yttrium oscillator is clearly unlocked. I'm hopeful that the problem is in one the control loops outside the oscillator module. I read the repair guide that Agilent kindly keeps on their website, they have some good instructions and narrow the problem to 3-4 modules, but I've never opened up the instrument and am a little apprehensive about making things worse. My hunch is that the problem is an electrolytic cap that has dried out over the years and has failed. Any suggestions for either self repair or outside repair and re-calibration is appreciated... In full disclosure, I also have a 70908A based spectrum analyser that that has much better specs, especially in microwave. It can completely replace the 8566B, but I'm quite fond of the 8566B, I can operate it blind folded, it's like an old friend and I would really like to fix it. jeff ___ 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] Modulation on Rb sources
I have a couple of Rb sources and went looking for spurs close to the carrier. One was particularly surprising. First is a GPS disciplined Rb oscillator from Berkeley Varitronics. I'm not a big fan of this box, but that's another story. Here's plot of 500Hz around 10MHz, it looks like the 10MHz signal is AM modulated with a 128Hz signal, the spurs are about -75dBc. I did the plot twice, once during normal operation, and once with the GPS control loop disabled from the front panel. The plots were identical. So, my question is whether this modulation is part of the Efratom module or introduced by the Berkeley Varitronics box? http://www.mock.com/test/rhinoii/am-128hz.png Here's a similar plot of an LPRO-101. This is just the module with a semi-crappy power supply. There's a little 60Hz (+harmonics) that I figure is power supply related leaking through the mixer. The 10MHz signal is +8dBm, so the 60Hz spurs are at least 98db below the carrier, much better than the previous graph and more like what I expected. http://www.mock.com/test/lpro-101/am60hz.png Does anyone know what's going on with the first box? jeff ___ 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] Chronometer contest sponsored by IEEE Spectrum
I found this article randomly this evening, it has some interesting tidbits about quartz oscillators in watches. I had never heard of the venerable Sieko twin quartz from 1978, good to +/- 5 seconds a year: http://people.timezone.com/msandler/Articles/CarlosFinalParadigm/FinalParadigm.html jeff Max Robinson wrote: In my experience watches come from the factory adjusted to gain about 5 seconds a month. The ones I have owned over the years seemed to be fairly stable in that. I have always wished there was a way for someone who is not a watch maker to open up such a watch and turn the trimmer capacitor, there has to be one, to set it right on. Then it would be much easier to tell how the crystal is aging. Regards. Max. K 4 O D S. Email: [EMAIL PROTECTED] Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Music site: http://www.maxsmusicplace.com ___ 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] EU funds Galileo
As a hard working US tax payer, I'm happy that someone is paying for an excuse to buy another disciplined oscillator one day... lots more plots, quibbling about differences in the 10 decimal point, etc. jeff Javier wrote: As a hard working ES tax payer, I think that the funds are right there :) I prefer not to have exlusive dependence on DoD... Javier Rob Kimberley escribió: As a hard working UK tax payer, I'd rather my money was spent elsewhere - I'm more than happy with GPS! Rob K -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Magnus Danielson Sent: 30 November 2007 09:33 To: time-nuts@febo.com Subject: [time-nuts] EU funds Galileo Hi! Just heard this and here is some details: http://investing.reuters.co.uk/news/articleinvesting.aspx?type=allBreakingNe wsstoryID=2007-11-29T235046Z_01_L29893386_RTRIDST_0_EU-GALILEO-UPDATE-3.XML Looks like it just became likelier that we will have those Galileo birds. Cheers, Magnus ___ 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 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 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 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] More details on IEEE Spectrum clock competition
Philip, I think this sounds pretty reasonable, here's my 2-cents worth. I think calibration should be part of delivering the clock. You can imagine a designer developing elaborate models for the timebase and you don't want to stifle creativity here. I think calibration is part of the delivered clock and not done by the judges. The clock should be settable by a layperson, but I think you should let people go wild calibrating the clock. The two big enemies the designer fights will likely be environmental and aging. I think you've covered a good environmental specification, but aging should be incorporated into the contest. For example, a temp compensated xtal oscillator my be calibrated to well less than 0.1 ppm and look really fantastic for a few days, but the crystal might age 2-3 ppm over the first year of operation. I imagine running the contest over a few months. At some submission date the clocks are collected at your office, set to the current time, and left to run for a few months (or however much time you have). At the end of 3-months all of the clocks are measured and a winner is picked. Maybe you can publish intermediate results for dramatic effect. Tom Van Baak has a nice story on his website about how he got interested in precision timing, http://www.leapsecond.com/. He wanted a clock that would be accurate to better than 1-second over a year so that he could appreciate and adjust the clock during a leapsecond. I don't know how, but I think that it might be possible to build a clock for this contest that meets that criteria. If so, I think the entries need a feature for measuring accuracy more precisely. I suggest requiring that the entires have a BNC connector that outputs a TTL level pulse once per second, the rising edge of the signal marks the beginning of a second (this is usually just called a PPS signal). The accuracy of the clock can be done visually to 1s resolution, finer measurement can be done with comparison against PPS from a GPS receiver. jeff [EMAIL PROTECTED] wrote: A number of people have asked for more details on IEEE Spectrum's digital clock competition, so we've formulated the following list. Throughout, the idea is to build a clock that an ordinary person would want to use, in an ordinary home. That's why we want a display that can be read with ease from across a room. Operating environment and other specs for IEEE Spectrum's Digital Clock Competition: --between 10 and 50 degrees C --between 0 and 100 percent relative humidity --with seven-segment LED display, no smaller than 0.56 inches --no limit on power --calibration should be within the grasp of a layman --lacking an oscilloscope here in the office, we will check accuracy against a WWVB or GPS signal (other suggestions--even volunteers to help in the judging--are welcome) --parts to be available from any of the big distributors (RadioShack, Mouser, DigiKey, Maplin, etc.) or, in sufficient quantities (100s, say) from a surplus store Philip E. Ross Senior editor IEEE Spectrum Magazine 212 419 7562 http://www.spectrum.ieee.org ___ 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 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] Chronometer contest sponsored by IEEE Spectrum
Jeffrey Pawlan wrote: On Thu, 29 Nov 2007, David Forbes wrote: It might be more fun to require that an OCXO be designed and built by the DIY-er out of commercially available crystals and resistors. That way, it's an engineering challenge instead of a procurement challenge, since IEEE is about engineering. -- I second David's suggestion! The only REAL challenge would be to design the circuitry. Otherwise this is just a rack stack project which is not engineering. I think it's a fantastic challenge. I imagine starting with a design goal something like tvb's original leapsecond goal. It would be kind of cool to have a $100 clock that met that criteria. I don't think an off-the shelf OCXO timebase will be competitive at this price point. I'm not aware of an inexpensive SC-cut oscillator. I think the parameters for the contest need to be tightened up. Temperature and environment are enemies for this kind of clock, I hope they specify the operating environment and time period for evaluation. I think that I would start by looking at 32kHz watch crystals, I've often wondered how good a timebase you can make out of one. The tempco is a parabola around 25C with a max slope of something like 0.05 PPM/C, so they are naturally a pretty good timebase with good aging characteristics. The crystals are really tiny, maybe insulating it with a material that has an interesting heat of fusion along with a micro to model the physics of the parabolic shape of the crystal performance. jeff ___ 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] Of rubidium life and piggy-bank anemia....
John Ackermann N8UR wrote: But on the other hand, having a free-running Rb that you calibrate against the Tbolt (or some other reference) every so often isn't a bad idea; it gives you a source that's independent of external factors. John This was the road to hell for me :) I bought a Z3801A (moral equivalent to the Trimble Thunderbolt) back in 2000. I've happily used it as my house reference for both PPS and 10MHz for many years confident that I have a solid timebase. For the last several years I've been designing spectrometers for radio telescopes and it's been convenient and sometimes essential to have a timebase that's not too much worse than a modern radio telescope. I see the lock light, I make a few plots, and I get a warm feeling that I know what time it is. http://www.mock.com/gps I recently bought an Rb source for fun. Nominally I use it as the timebase for my frequency counter and run everything else off of the z3801a. Now I live in constant state of flux not really knowing what 10MHz is anymore. I need more clocks, my Rb source is amplifying my personality quirks. jeff ___ 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] Chronometer contest sponsored by IEEE Spectrum
I think that I would start by looking at 32kHz watch crystals, I've often wondered how good a timebase you can make out of one. The tempco is a parabola around 25C with a max slope of something like 0.05 PPM/C, so they are naturally a pretty good timebase with good aging characteristics. The crystals are really tiny, maybe insulating it with a material that has an interesting heat of fusion along with a micro to model the physics of the parabolic shape of the crystal performance. jeff Maybe an ensemble of watch crystal clocks and a PIC microprocessor per David Allan paper of some years ago. After testing you could assign deferent weighting to the different clocks. Bill K7NOM Yes, an ensemble of 32kHz crystals, I like it a lot. Perhaps you can setup a temperature gradient from hot to cold across a number of crystals. If the tempco for the crystal is really a parabola, each of the crystals can be a datapoint along the parabola of crystal performance. With a little work you might be able to precisely calculate the maxima of the parabola and precisely set the frequency independent of temp and aging. Ha! jeff ___ 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] OT: Prologix GPIB and HP3478A...
++eot_char is usually okay. The particular problem I was hacking at the time was a screen dump from a Tek scope (TDS 754A). The screen dump is an 8-bit binary file in a weird image format and you don't know exactly how many bytes are going to be dumped (~50k bytes), but it does set EOI with the last byte sent. ++eot_char doesn't work 100% since the chosen EOT character might be binary data or it might be the EOT character. The reason I asked is that the solution would be cleaner if you could do a ++read eoi and then issue some other ++ query command to ask if EOI was set on the previous read. jeff Prologix wrote: Hello Jeff, Thanks for the compliments. Much appreciated. You may configure the Prologix adapter (using ++eot_enable and ++eot_char) to send (append, really) a user-specified character to USB ouput when it detects EOI. By checking for the character you can determine if EOI was asserted. Regards, Abdul -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jeff Mock I have a slightly off-topic question about reads. When issuing a ++read eoi, is it possible to tell whether an EOI was actually returned by the instrument or whether the read was terminated by timeout or block size limitation? jeff ___ 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 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] Collecting raw timing data
Thanks so much, your description of collecting the raw timing data is really clear. I like the technique of doing timing interval measurements from a slower known reference on one channel to a DUT on a second channel. This definitely gets me started. jeff Didier Juges wrote: Jeff, I have a practical step by step example using the HP 5370, a reference oscillator (in my case, a Thunderbolt GPSDO, but you could use the counter's time base if you know it to be better than your UUT), a test oscillator (in my case an HP 10811) and the free Plotter software from Ulrich Bangert on mu web page: http://www.ko4bb.com/Timing/FAQ-1.html Look for Practical Example near the bottom. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jeff Mock Sent: Monday, November 26, 2007 1:13 PM To: time-nuts@febo.com Subject: [time-nuts] Collecting raw timing data This is mostly a question for tvb. How are you collecting raw timing timing data to calculate a typical Allan deviation plot? Something like: http://www.leapsecond.com/museum/hp58503b/log19395v.gif I've been fiddling with my HP53132A to get the right combination of settings to collect useful timing data for making Allan deviation plots. Any information on your general workflow from collecting the raw data to making a plot is appreciated. thanks, jeff ___ 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 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] OT: Prologix GPIB and HP3478A...
Prologix wrote: One solution is to turn read-after-write off (++auto 0) before connecting the adapter to 3478A, and then use ++read command to read one measurement at a time. Please see the manual (www.prologix.biz) for ++read command options. I nearly always turn off auto mode on the prologix. I've run into a number of slightly flaky problems when the prologix guesses to turn on the instrument to talk. I've never noticed a performance penalty because I need to issue a ++read command to the prologix whenever I want to read something back. I think the prologix device is great. I'm a linux guy, I haven't used windows in many years. NI has never really understood open source software. It was always a pain to have a reliable driver for the NI GPIB PCI cards, so I was quite happy to find something like the Prologix device that is reliable and has drivers that are totally open source and distributed as part of the linux kernel. I have a slightly off-topic question about reads. When issuing a ++read eoi, is it possible to tell whether an EOI was actually returned by the instrument or whether the read was terminated by timeout or block size limitation? jeff ___ 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] Collecting raw timing data
Bruce Griffiths wrote: Jeff Mock wrote: Thanks so much, your description of collecting the raw timing data is really clear. I like the technique of doing timing interval measurements from a slower known reference on one channel to a DUT on a second channel. This definitely gets me started. jeff An algorithm for unabiguously unwrapping the rollovers can be found in: http://horology.jpl.nasa.gov/papers/picket_uffc.pdf Thanks, that's a nice paper, 3-pages, lots of short declarative sentences that make sense. As I understand the problem, Fig. 1 in this paper is the key for collecting good data for measuring Allan variance. jeff ___ 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] 53131A or 5370B
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Bernd T-Online wrote: Hi Tom, Tom Clark, K3IO wrote: I have been a strong advocate for the 53131/2 counter since I first encountered in in 1993. Most of my applications are for a time-interval counter (TIC) measuring the time interval between an atomic clock and GPS (see my Timing for VLBI papers at [1]http://gpstime.com). The two reasons are 1. It is simple and cheap and reliable, especially for the casual user. 2. It has a simple RS-232 printer interface that is really easy to use. Rick Hambly used the 53131/2 simple interface to make his Tac32Plus (and Multi) software packages into an integrated TIC logging utility My question: is there a penalty in timing, if the GPIB bus is used for time interval measurement as compared to the RS-232 bus. This question may sound stupid, as I am do not write the test software in our lab by myself, but get it done. I have a 53132A, I've written code for both the GPIB and RS-232 interfaces at various times. The performance is about the same, I never noticed that one interface is faster than the other. The performance is probably more driven by the pea-brained microcontroller in the box. The 53131/2 are pretty well behaved boxes, I found them to be very reliable and easy program without too much fiddling. Sometimes GPIB equipment can be pretty badly behaved, but the 53132A is great. jeff ___ 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.
