[time-nuts] Arduino GPIB
I thought everyone here would find this of interest. I stumbled across it a few days ago on the 'net. It is a Prologix GPIB-USB compatible made with an Arduino Uno. http://egirland.blogspot.com/2014/03/arduino-uno-as-usb-to-gpib-controller.html Like on his web site, I just took a cheap GPIB cable, cut off about 12 inches and shoved the wires into the socket holes on an Uno. I uploaded his program and did some minor testing so far. BTW, it didn't work the first time due to poor contact. I shoved some pin headers in, after the wires and now it works fine. John's Prologix config program works just fine with this cobbled together GPIB adapter. I attached it to my HP 3457A and then ran the demo program that comes with Ulrich's EZGPIB. It is logging data as I type this. I will do more testing with other instruments, as I have time. As mentioned on the web page linked above, a few commands are not yet implemented, although they appear to be little used commands (except perhaps the ++savecfg command). I think I have a way to implement the ++rst command using the watchdog timer. For ++savecfg, it shouldn't be too difficult to store things in the Arduino EEPROM. I have some cheap Arduino Nano's and PCB-mount GPIB connectors on order. I will be making a couple of these Proligix-compatible adapters with those parts, so that they aren't just wires shoved into a board. I'll have to find a small box to house things. I have also ordered some buffer chips to add to the design. Total cost should be under $20 for each adapter. The firmware uses a serial baud rate of 115200, which I assume is the same as a real Prologix. I'm going to try some higher baud rates to see how fast the Arduino can push bits without losing them. I understand that with the default 16 MHz clock, non-standard baud rates that are evenly divisible into the clock rate should work even better I'll report back. One question about the baud rate - are there any reasons not to change from 115200? Since we are simply moving bits through a USB/Serial adapter, does any software really care what the baud rate is, as long as we don't drop any bits? Joe Gray W5JG ___ 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] Sources for Mission Time Clock
Martin, 1) Check out www.masterclock.com - they regularly exhibit at PTTI with a wide variety of metrology-grade clock displays. The prices were reasonable, although you could make one yourself for half the price if you spend a couple of weeks of your own time. 2) Scroll through http://www.google.com/search?tbm=isch&q=IRIG+LED+display+IRIG+timecode 3) On eBay you can sometimes find wonderful 2 or 3 or 4 foot long time displays by Austron or Datum; nixie or plasma or LED. Unless you need one next week or next month, something will turn up on eBay eventually. It will both be functional and have that classic retro NASA look. 3) For a DIY solution consider some of the networkable matrix LED display modules: https://www.sparkfun.com/products/760 https://forum.sparkfun.com/viewtopic.php?t=7257 And there are many more examples all over the web. See if some of these appeal to you: http://www.google.com/search?tbm=isch&q=large+LED+matrix+clock+display Lastly, this "12ft GPS Wall Clock" wins the prize... https://www.sparkfun.com/tutorials/47 4) The television monitor ideas are an easy solution. Use a PC or Raspberry Pi. One example here: https://www.youtube.com/watch?v=vBQ3uqMep58 /tvb - Original Message - From: "Martin A Flynn" To: "Bill Hawkins" ; "'Discussion of precise time and frequency measurement'" Sent: Sunday, January 11, 2015 9:22 AM Subject: Re: [time-nuts] Sources for Mission Time Clock > Bill, > Not adverse to using a flat panel and PC hardware. > > Been looking for surplus. Pretty slim pickings available. > > Hold is required, Clock will not provide control to external devices > > Martin Flynn ___ 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] Sources for Mission Time Clock
I think that display was built using modules like this: http://www.decadecounter.com/vta/articleview.php?item=511 I see them on e-bay from time to time under "in-line readout", but they're rather expensive and you'd need quite a few, If you can settle for 7 segment, a modern display you could use is: https://www.sparkfun.com/products/8530 Or, perhaps these: http://www.seeedstudio.com/depot/7-Segment-Display-3-Inches-Green-p-1224.html But, 7 segment just doesn't quite capture that retro feel, IMO. Wayne On Sun, Jan 11, 2015 at 7:30 AM, Martin A Flynn wrote: > I am looking for a GMT/GET mission time clock that has the following > characteristics: > > * Reads T minus prior to launch or deployment, T plus after. > * Second display for GMT. > * Simulating it on a PC display would be OK, would prefer an LED/LCD >version for wall mounting > > There is a example of what I am looking for in the background of this > photo: https://www.hq.nasa.gov/alsj/a16/A16_116_13_15.jpg . We have > NTP, IRIG-B, and a 1 PPS source to work with. > > Any suggestions on a cost-effective way to accomplish this? > > Cheers > Martin Flynn > > > > ___ > 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] Sources for Mission Time Clock
I worked at a place where we actually did launch rockets, big ones. We did have a few LED displays that were driven by IRIG but really the "clocks" were mostly computer displays with time in the corner some place. The display is ether on a monotor of it is projected on a screen. Projectors have gotten cheap. Most of those special purpose displays were stored in closets under boxes IBM punch cards or the like. For a display time-nut level accuracy is not really even needed because the refresh rate on the display is on the order of 1/100 second soi. NTP over Ethernet is more than enough for a visual display. The screen refresh is the weak link, (well really the human eye/brain is.) Now for real time keeping (vs. the display) you probably want something that runs off GPS. On Sun, Jan 11, 2015 at 9:12 AM, Bill Hawkins wrote: > Martin, > > It seems like the only cost-effective way to get that display is to > find a surplus source. If that's not possible, how about mounting a > flat panel computer monitor on the wall and driving it with some > custom software in a commercial computer with a standard operating > system. There are standard ways to handle NTP, IRIG-B, and 1 PPS. > > Do you need to hold the countdown the way NASA does? Does the clock > provide the electrical signal to launch or deploy? > > Bill Hawkins > > -Original Message- > From: Martin A Flynn > Sent: Sunday, January 11, 2015 9:31 AM > > I am looking for a GMT/GET mission time clock that has the following > characteristics: > > * Reads T minus prior to launch or deployment, T plus after. > * Second display for GMT. > * Simulating it on a PC display would be OK, would prefer an LED/LCD > version for wall mounting > > There is a example of what I am looking for in the background of this > photo: https://www.hq.nasa.gov/alsj/a16/A16_116_13_15.jpg . We have > NTP, IRIG-B, and a 1 PPS source to work with. > > Any suggestions on a cost-effective way to accomplish this? > > Cheers > Martin Flynn > > > ___ > 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. -- Chris Albertson Redondo Beach, California ___ 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] 53132A Cooling fan
Hi All - this fan is also available at Digikey and Newark and others - http://www.digikey.com/product-detail/en/MB40201V2-000U-A99/259-1554-ND/2757779 $5.82 US. Regards, John K1AE -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Götz Romahn Sent: Sunday, January 11, 2015 10:41 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 53132A Cooling fan Loïc, I bought this one http://www.kessler-electronic.de/Luefter/Sunon_DC-Luefter/40x40x20mm/MB40201V2-A99_i1828_40187_0.htm (in Germany of course), the quietest I could find. Götz Am 11.01.2015 um 06:59 schrieb Loïc Moreau: > Hi, > My 53132A cooling fan is becoming extremely noisy so I have to fix it or find > ear plugs fast. > > If anybody as encountered the same problem witch I suppose is common I will > be interested if there is replacement part easily available for that purpose. > > Regards > Loïc > > ___ > 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] 53132A Cooling fan
Hello The Net: Mike, thanks for the 53132A fan info. I also have a noisy fan. I have considered adding a proportional fan controller since more colling is needed if aditional options are added, like a more stable internal reference or a prescalar to 3 GHz or 12 GHz. Less cooling is needed if no internal options are included. Less cooling can mean a slower fan speed and lower acoustic noise. Anyone have any thoughts on exactly where to put a temperature sensor for a proportional fan controller? The W1GHZ.ORG website had a fan controller. Anyone have any thoughts on how to increase the intensity of the dim display ? Is it a power supply issue ? I use my 53132A with TimeLab to measure the performance of different oscillators. Stan, W1LECape Cod FN41sr On 11-Jan-15 8:29 AM, Mike George wrote: I replaced one last year. I used a Delta EFB4012HD from Digi-Key but it isn't in stock currently. I just looked up the specs on the fan I removed and matched it to the fans available. There were multiple suitable substitutes. On 1/11/2015 00:59, Loïc Moreau wrote: Hi, My 53132A cooling fan is becoming extremely noisy so I have to fix it or find ear plugs fast. If anybody as encountered the same problem witch I suppose is common I will be interested if there is replacement part easily available for that purpose. Regards Loïc ___ 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] June 30 2015 leap second
Tom Van Baak wrote: I haven't looked at the raw data, but using the windows apps: a Trimble Resolution SMT is showing the leap pending a Motorola UT+ is not. lady heather is not Interesting. I don't see any leap-pending from a Z3801A. (or a KS-24361) Hi Hal, It's not that simple. There are many different levels of leap second notification. 1) IERS updates their ftp site (for bots) and sends email (for humans) indicating when the next leap second will occur. Days or weeks (and sometimes months) later, 2) GPS ground control uploads almanac information to the satellites with updated UTC parameters. Four values in page 18 of subframe 4 give the current UTC leap second delta and also an optional future UTC delta, with a GPS week (LS_f) and day number (DN) when that future delta will be current. By definition the leap second will occur at the end of a UTC (not GPS) day. In this way GPS can provide up to 256 weeks (~4.9 years) of advanced leap second information and support positive or negative leap seconds. Yes, and since the GPS UTC parameters just provide the difference to GPS time (in seconds) before and after the leap event time, they could even announce a leap event where more than 1 second is inserted or deleted at once. ;-) I'm not aware of any other timing system that could handle this, though. Note there is no "leap second warning" *bit* in the GPS spec, per se. 3) Starting up to 12.5 minutes later, GPS receivers will see page 18 of subframe 4 from some or all SV and thus know not only the current UTC offset, bit when/if a different UTC offset will be valid in the distant future. Prior to this (e.g., cold start) there is no certainty of either the UTC offset or leap second state. 4a) Since UTC and leap seconds are not needed for navigation, some GPS receivers do not bother to tell the user about leap seconds at all. 4b) Some GPS receivers only give the user a leap second warning and so they must wait until the month in which the leap second is to be applied before they issue the warning. That means they may sit on the internal leap second information for many months. 4c) Other GPS receivers give the future date of the next leap second (if any). This is not a warning bit, but just the date/time of the next leap second. 4d) Especially dangerous are any GPS receivers that report only a leap second warning bit, but don't tell you which month it will occur. 5) Host software (e.g., GPSDO firmware, operating system, drivers, or apps) take this information and must only operate on it at the end of the appropriate UTC month. Hardcoded rules for June and December are frowned upon. It would be nice if we pooled together our resources and made a list of which GPS/GNSS receivers are 4a, 4b, 4c, or 4d. It also depends on *how* the leap second warning is made available. If an application can read the GPS UTC parameter set then it can compute it as soon as the sats start to broadcast it. There are formats of time string output by GPS receivers which only include the leap second warning 1 hour or 1 day before the event. NMEA sentences don't include it at all, AFAIK. Binary messages may, depending on the manufacturer. IRIG time code signals also don't provide a leap second *warning* flag, except the IEEE codes 1344 and C37.118, which only output this 10 seconds or 1 minute (don't remember exactly without looking) before the event. Martin ___ 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] June 30 2015 leap second
Tom Van Baak wrote: Keep in mind that this system drives you to having pretty bad time for the better part of a whole day, on purpose... I realize that when the Hi Didier, The google article never claims the smear spans an entire day. I think you may be confusing references to the leap smear with a DIY digital clock someone on the list wanted to build (and they proposed using a slow 86400 second slew). The google code is "lie(t) = (1.0 - cos(pi * t / w)) / 2.0" and they are wise not to publish the actual window value, w. If it were me I'd make it somewhere between a couple of seconds or couple of minutes but I too would not make it a published or hardcoded constant. Hm, the article says, "It also made sure the updates were sufficiently small so that any software running on the servers that were doing synchronization actions or had Chubby locks wouldn't lose those locks or abandon any operations." So I think they smeared it over more than just a few minutes. I'd expect some hours, so standard NTP clients would just notify this as clock drift (oscillator frequency offset) which they'd have to compensate. Since ntpd's control loop is pretty slow it wouldn't respond quickly to smears over a few seconds our hours. Here's the link again: http://googleblog.blogspot.com/2011/09/time-technology-and-leaping-seconds.html Again, I don't know what value they use, or even if they use the same value from one leap second to the next. If any of you have inside contacts with google and can find out let me know, off-list. > Regardless, it should be possible to experimentally determine the smear duration by repeatedly using some google service that returns time-stamps during the day, hours, minutes, or seconds before and after June 30. It would make a nice posting for a time nut, or a research paper for a high school student or undergrad: Experimental Confirmation of Google's Leap Smear Algorithm. Yes, interesting idea! Martin ___ 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] 53132A Cooling fan
Loïc, I bought this one http://www.kessler-electronic.de/Luefter/Sunon_DC-Luefter/40x40x20mm/MB40201V2-A99_i1828_40187_0.htm (in Germany of course), the quietest I could find. Götz Am 11.01.2015 um 06:59 schrieb Loïc Moreau: Hi, My 53132A cooling fan is becoming extremely noisy so I have to fix it or find ear plugs fast. If anybody as encountered the same problem witch I suppose is common I will be interested if there is replacement part easily available for that purpose. Regards Loïc ___ 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] Sources for Mission Time Clock
Low cost is on a PC with a large font. It in no way will resemble the 1962 clock in your picture. This used Plexiglas digits with actual lamps like a 327 as an example. I had a display like that many years ago. That said I don't know what you would have to drive the down count and then upcount. Unless you just start the clock at some negative number and when it hits zero it counts up. Good luck on your project Paul WB8TSL On Sun, Jan 11, 2015 at 10:30 AM, Martin A Flynn wrote: > I am looking for a GMT/GET mission time clock that has the following > characteristics: > > * Reads T minus prior to launch or deployment, T plus after. > * Second display for GMT. > * Simulating it on a PC display would be OK, would prefer an LED/LCD >version for wall mounting > > There is a example of what I am looking for in the background of this > photo: https://www.hq.nasa.gov/alsj/a16/A16_116_13_15.jpg . We have > NTP, IRIG-B, and a 1 PPS source to work with. > > Any suggestions on a cost-effective way to accomplish this? > > Cheers > Martin Flynn > > > > ___ > 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] Sources for Mission Time Clock
Bill, Not adverse to using a flat panel and PC hardware. Been looking for surplus. Pretty slim pickings available. Hold is required, Clock will not provide control to external devices Martin Flynn On 1/11/2015 12:12 PM, Bill Hawkins wrote: Martin, It seems like the only cost-effective way to get that display is to find a surplus source. If that's not possible, how about mounting a flat panel computer monitor on the wall and driving it with some custom software in a commercial computer with a standard operating system. There are standard ways to handle NTP, IRIG-B, and 1 PPS. Do you need to hold the countdown the way NASA does? Does the clock provide the electrical signal to launch or deploy? Bill Hawkins -Original Message- From: Martin A Flynn Sent: Sunday, January 11, 2015 9:31 AM I am looking for a GMT/GET mission time clock that has the following characteristics: * Reads T minus prior to launch or deployment, T plus after. * Second display for GMT. * Simulating it on a PC display would be OK, would prefer an LED/LCD version for wall mounting There is a example of what I am looking for in the background of this photo: https://www.hq.nasa.gov/alsj/a16/A16_116_13_15.jpg . We have NTP, IRIG-B, and a 1 PPS source to work with. Any suggestions on a cost-effective way to accomplish this? Cheers Martin Flynn ___ 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] 53132A Cooling fan
Following your comments, i have opened the enclosure, disconnected the power supply and measured the fan current ( 40mA) when connected to AC line. Ordered a 4020 model 12V with the proper current, seems very common My 53132A will be back on stage very soon Thanks for your help. Regards Loïc -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Bob Camp Envoyé : dimanche 11 janvier 2015 15:22 À : Discussion of precise time and frequency measurement Objet : Re: [time-nuts] 53132A Cooling fan Hi A very normal “spiral of death” on the 53132 is the fan going out and the power supply following it a month or two later. The supply apparently does need the fan cooling to keep it happy. Since the fan runs whenever the counter is plugged in, the fan logs a lot of hours. If you do loose the power supply, the one in the 53181 will swap over to the 132. It’s not a cheap fix, but better than scrapping a 132. Bob > On Jan 11, 2015, at 12:59 AM, Loïc Moreau wrote: > > Hi, > My 53132A cooling fan is becoming extremely noisy so I have to fix it or find > ear plugs fast. > > If anybody as encountered the same problem witch I suppose is common I will > be interested if there is replacement part easily available for that purpose. > > Regards > Loïc > > ___ > 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] June 30 2015 leap second
I don't know for sure which category the Ball/Efratom MGPS (as found in the MFS-XXX Modular Frequency Standard frames) is in yet But the MGPS has a screen labeled "Current Leap Second", that according to the manual: "The display indicates the date and time of the current leap second. Leap second data are hourly updated by GPS satellite transmission (automatically). A leap second can also be programed by the operator. To program a leap second date and time, it is first necessary to select the Edit menu by pressing the pushbutton "E"" I had to remove the lithium cell from my unit when I was servicing it, so it is now displaying some hard reset default value: Date 17 05 27 Time 23:59:00 If the "Current Leap Second" is indeed updated hourly, and my display persists in showing a nonsense value, I am wondering if it might be that it thinks it is in a manually programmed leap second mode? Perhaps I should manually program it to: 00 00 00 00:00:00, and, hope it will get the clue that it is supposed to automagically update the Current Leap Second from the GPS packets? I would hate for my MGPS to miss the leap second party because the manual was unclear. -Chuck Harris Tom Van Baak wrote: I haven't looked at the raw data, but using the windows apps: a Trimble Resolution SMT is showing the leap pending a Motorola UT+ is not. lady heather is not Interesting. I don't see any leap-pending from a Z3801A. (or a KS-24361) Hi Hal, It's not that simple. There are many different levels of leap second notification. 1) IERS updates their ftp site (for bots) and sends email (for humans) indicating when the next leap second will occur. Days or weeks (and sometimes months) later, 2) GPS ground control uploads almanac information to the satellites with updated UTC parameters. Four values in page 18 of subframe 4 give the current UTC leap second delta and also an optional future UTC delta, with a GPS week (LS_f) and day number (DN) when that future delta will be current. By definition the leap second will occur at the end of a UTC (not GPS) day. ... ___ 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] Sources for Mission Time Clock
On 1/11/15 7:30 AM, Martin A Flynn wrote: I am looking for a GMT/GET mission time clock that has the following characteristics: * Reads T minus prior to launch or deployment, T plus after. * Second display for GMT. * Simulating it on a PC display would be OK, would prefer an LED/LCD version for wall mounting There is a example of what I am looking for in the background of this photo: https://www.hq.nasa.gov/alsj/a16/A16_116_13_15.jpg . We have NTP, IRIG-B, and a 1 PPS source to work with. Any suggestions on a cost-effective way to accomplish this? What does "cost effective" mean in this context? Do you have a max cost? Is your time cheap and cash dear, so you're willing to build stuff, or do you just want to buy something off the shelf so you can get it going. How big does it have to be? that's probably going to be the big design driver: these days, large flat panel TV/monitor driven by a small computer is probably the easiest way. If you want to go more "traditional", then there are those "flipping disk" or flipping page displays, there have been some enormous 7-segment displays (not counting the one with 4x8 foot sheets of plywood and a team of artists). There's also "rotating drums" for the digits. Cheers Martin Flynn ___ 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] Sources for Mission Time Clock
Martin, It seems like the only cost-effective way to get that display is to find a surplus source. If that's not possible, how about mounting a flat panel computer monitor on the wall and driving it with some custom software in a commercial computer with a standard operating system. There are standard ways to handle NTP, IRIG-B, and 1 PPS. Do you need to hold the countdown the way NASA does? Does the clock provide the electrical signal to launch or deploy? Bill Hawkins -Original Message- From: Martin A Flynn Sent: Sunday, January 11, 2015 9:31 AM I am looking for a GMT/GET mission time clock that has the following characteristics: * Reads T minus prior to launch or deployment, T plus after. * Second display for GMT. * Simulating it on a PC display would be OK, would prefer an LED/LCD version for wall mounting There is a example of what I am looking for in the background of this photo: https://www.hq.nasa.gov/alsj/a16/A16_116_13_15.jpg . We have NTP, IRIG-B, and a 1 PPS source to work with. Any suggestions on a cost-effective way to accomplish this? Cheers Martin Flynn ___ 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] Sources for Mission Time Clock
I am looking for a GMT/GET mission time clock that has the following characteristics: * Reads T minus prior to launch or deployment, T plus after. * Second display for GMT. * Simulating it on a PC display would be OK, would prefer an LED/LCD version for wall mounting There is a example of what I am looking for in the background of this photo: https://www.hq.nasa.gov/alsj/a16/A16_116_13_15.jpg . We have NTP, IRIG-B, and a 1 PPS source to work with. Any suggestions on a cost-effective way to accomplish this? Cheers Martin Flynn ___ 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] June 30 2015 leap second
Hi If section 4 is going to turn in to a list of suspects to investigate and tabulate, I would add: 4 e) CDMA runs on GPS (not UTC) time. A “pure CDMA” GPSDO may be coded to ignore leap second data altogether. The ones I’m thinking about are the GPSTM boxes that put out very CDMA specific timing (pulse very other second not pps and all the rest). 4 f) GPS gizmos that report the leap second correctly and then handle it incorrectly (in a variety of ways..) when it occurs. Each time we have a leap second the net explodes with reports of these bugs. Yes, the second one opens a whole other can of worms. It’s pretty well documented already that different firmware rev’s have different issues. Since the Motorola Oncore modules have been around the longest, they seem to have the most information about these bugs. There is an old Motorola notification on the VP, UT, GT and M12 issues (notification_oncore.pdf). It’s no longer on the Motorola site, but its hopefully out on the net somewhere. Bob > On Jan 11, 2015, at 9:02 AM, Tom Van Baak wrote: > >>> I haven't looked at the raw data, but using the windows apps: >>> a Trimble Resolution SMT is showing the leap pending a Motorola UT+ is not. >>> lady heather is not >> >> Interesting. I don't see any leap-pending from a Z3801A. (or a KS-24361) > > Hi Hal, > > It's not that simple. There are many different levels of leap second > notification. > > 1) IERS updates their ftp site (for bots) and sends email (for humans) > indicating when the next leap second will occur. Days or weeks (and sometimes > months) later, > > 2) GPS ground control uploads almanac information to the satellites with > updated UTC parameters. Four values in page 18 of subframe 4 give the current > UTC leap second delta and also an optional future UTC delta, with a GPS week > (LS_f) and day number (DN) when that future delta will be current. By > definition the leap second will occur at the end of a UTC (not GPS) day. > > In this way GPS can provide up to 256 weeks (~4.9 years) of advanced leap > second information and support positive or negative leap seconds. Note there > is no "leap second warning" *bit* in the GPS spec, per se. > > 3) Starting up to 12.5 minutes later, GPS receivers will see page 18 of > subframe 4 from some or all SV and thus know not only the current UTC offset, > bit when/if a different UTC offset will be valid in the distant future. Prior > to this (e.g., cold start) there is no certainty of either the UTC offset or > leap second state. > > 4a) Since UTC and leap seconds are not needed for navigation, some GPS > receivers do not bother to tell the user about leap seconds at all. > > 4b) Some GPS receivers only give the user a leap second warning and so they > must wait until the month in which the leap second is to be applied before > they issue the warning. That means they may sit on the internal leap second > information for many months. > > 4c) Other GPS receivers give the future date of the next leap second (if > any). This is not a warning bit, but just the date/time of the next leap > second. > > 4d) Especially dangerous are any GPS receivers that report only a leap second > warning bit, but don't tell you which month it will occur. > > 5) Host software (e.g., GPSDO firmware, operating system, drivers, or apps) > take this information and must only operate on it at the end of the > appropriate UTC month. Hardcoded rules for June and December are frowned upon. > > It would be nice if we pooled together our resources and made a list of which > GPS/GNSS receivers are 4a, 4b, 4c, or 4d. > > /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.
Re: [time-nuts] June 30 2015 leap second
> Keep in mind that this system drives you to having pretty bad time for the > better part of a whole day, on purpose... I realize that when the Hi Didier, The google article never claims the smear spans an entire day. I think you may be confusing references to the leap smear with a DIY digital clock someone on the list wanted to build (and they proposed using a slow 86400 second slew). The google code is "lie(t) = (1.0 - cos(pi * t / w)) / 2.0" and they are wise not to publish the actual window value, w. If it were me I'd make it somewhere between a couple of seconds or couple of minutes but I too would not make it a published or hardcoded constant. Here's the link again: http://googleblog.blogspot.com/2011/09/time-technology-and-leaping-seconds.html Again, I don't know what value they use, or even if they use the same value from one leap second to the next. If any of you have inside contacts with google and can find out let me know, off-list. Regardless, it should be possible to experimentally determine the smear duration by repeatedly using some google service that returns time-stamps during the day, hours, minutes, or seconds before and after June 30. It would make a nice posting for a time nut, or a research paper for a high school student or undergrad: Experimental Confirmation of Google's Leap Smear Algorithm. /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.
Re: [time-nuts] 53132A Cooling fan
Hi A very normal “spiral of death” on the 53132 is the fan going out and the power supply following it a month or two later. The supply apparently does need the fan cooling to keep it happy. Since the fan runs whenever the counter is plugged in, the fan logs a lot of hours. If you do loose the power supply, the one in the 53181 will swap over to the 132. It’s not a cheap fix, but better than scrapping a 132. Bob > On Jan 11, 2015, at 12:59 AM, Loïc Moreau wrote: > > Hi, > My 53132A cooling fan is becoming extremely noisy so I have to fix it or find > ear plugs fast. > > If anybody as encountered the same problem witch I suppose is common I will > be interested if there is replacement part easily available for that purpose. > > Regards > Loïc > > ___ > 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] 53132A Cooling fan
I replaced one last year. I used a Delta EFB4012HD from Digi-Key but it isn't in stock currently. I just looked up the specs on the fan I removed and matched it to the fans available. There were multiple suitable substitutes. On 1/11/2015 00:59, Loïc Moreau wrote: Hi, My 53132A cooling fan is becoming extremely noisy so I have to fix it or find ear plugs fast. If anybody as encountered the same problem witch I suppose is common I will be interested if there is replacement part easily available for that purpose. Regards Loïc ___ 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] June 30 2015 leap second
>> I haven't looked at the raw data, but using the windows apps: >> a Trimble Resolution SMT is showing the leap pending a Motorola UT+ is not. >> lady heather is not > > Interesting. I don't see any leap-pending from a Z3801A. (or a KS-24361) Hi Hal, It's not that simple. There are many different levels of leap second notification. 1) IERS updates their ftp site (for bots) and sends email (for humans) indicating when the next leap second will occur. Days or weeks (and sometimes months) later, 2) GPS ground control uploads almanac information to the satellites with updated UTC parameters. Four values in page 18 of subframe 4 give the current UTC leap second delta and also an optional future UTC delta, with a GPS week (LS_f) and day number (DN) when that future delta will be current. By definition the leap second will occur at the end of a UTC (not GPS) day. In this way GPS can provide up to 256 weeks (~4.9 years) of advanced leap second information and support positive or negative leap seconds. Note there is no "leap second warning" *bit* in the GPS spec, per se. 3) Starting up to 12.5 minutes later, GPS receivers will see page 18 of subframe 4 from some or all SV and thus know not only the current UTC offset, bit when/if a different UTC offset will be valid in the distant future. Prior to this (e.g., cold start) there is no certainty of either the UTC offset or leap second state. 4a) Since UTC and leap seconds are not needed for navigation, some GPS receivers do not bother to tell the user about leap seconds at all. 4b) Some GPS receivers only give the user a leap second warning and so they must wait until the month in which the leap second is to be applied before they issue the warning. That means they may sit on the internal leap second information for many months. 4c) Other GPS receivers give the future date of the next leap second (if any). This is not a warning bit, but just the date/time of the next leap second. 4d) Especially dangerous are any GPS receivers that report only a leap second warning bit, but don't tell you which month it will occur. 5) Host software (e.g., GPSDO firmware, operating system, drivers, or apps) take this information and must only operate on it at the end of the appropriate UTC month. Hardcoded rules for June and December are frowned upon. It would be nice if we pooled together our resources and made a list of which GPS/GNSS receivers are 4a, 4b, 4c, or 4d. /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.
Re: [time-nuts] June 30 2015 leap second
There are many systems for which the Google fix would not work in the current state of technology unless implemented by EVERYBODY synchronously. At least everybody who depends on precise time like banking and financial systems, let alone the physicists and many others... Keep in mind that this system drives you to having pretty bad time for the better part of a whole day, on purpose... I realize that when the alternative is a system crash, it may sound tempting, but it really is not a fix, a bandage at most. We have a term for that in French: "emplâtre sur une jambe de bois", cast on a wooden leg. Didier KO4BB On Fri, Jan 9, 2015 at 6:57 PM, Henry Hallam wrote: > Such slewing solutions are OK for Google. They wouldn't work well for > one of the systems I work with, which uses system time to calculate > the position of a LEO satellite for purpose of pointing a 7.6 meter > X-band dish. Half a second of error corresponds to a pointing error > of 0.5 degrees, well outside the main lobe of the antenna beam. > > Anecdotally yours, > Henry > > On Fri, Jan 9, 2015 at 2:30 PM, Hal Murray > wrote: > > > > t...@patoka.org said: > >> 1s/24h = 1/86400 which is approximately 12ppm. That means that Aging > Offset > >> could slow down my clock for 1 second if I'll apply the maximum value > one > >> day ahead (roughly). I need to do some experiments first. ;-) Its > looks too > >> unreliable for me. > > > > If you do it that way, your clock will be off by a whole second just > before > > midnight when the leap-second brings it back into sync. If you tweak > your > > clock from noon-noon, it will only be off by 1/2 second at midnight when > the > > sign-bit of the error flips. > > > > -- > > These are my opinions. I hate spam. > > > > > > > > ___ > > 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] June 30 2015 leap second
michael.c...@sfr.fr said: > I havenât looked at the raw data, but using the windows apps: > a Trimble Resolution SMT is showing the leap pending a Motorola UT+ is not. > lady heather is not Interesting. I don't see any leap-pending from a Z3801A. (or a KS-24361) There is another interesting worm in this can... Various software in the chain from Paris to your PC may filter the leap-pending info. There was at least one bug in ntpd where it told the kernel to leap-tonight several months early. The way it's supposed to work is that ntpd tells the kernel leap-tonight, and the kernel will add/delete a leap second at midnight. That gives the ntp servers a whole day to propagate the leap-pending info to lower stratum servers and another day to turn it off by the next midnight. The T2 string from HP GPSDOs includes a slot which is +, -, or 0 for insert, delete, or none. You can ask it when the leap is scheduled, but the code didn't do that. It just assumed the leap was scheduled for the end of the current month. The fix was to add a filter to only pay attention to that flag in June and December. -- These are my opinions. I hate spam. ___ 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] 53132A Cooling fan
Hi, My 53132A cooling fan is becoming extremely noisy so I have to fix it or find ear plugs fast. If anybody as encountered the same problem witch I suppose is common I will be interested if there is replacement part easily available for that purpose. Regards Loïc ___ 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.
