Re: [time-nuts] Loran Europe Lessay seems to be back on air?
The 2015 shutdown was of the Research Information Network, but I guess the OP may have meant the Royal Institute of Navigation? Hard to believe anyone responsible from the latter would decry eLoran, unless perhaps the operational cost was seen to be unreasonable. On 2016-01-06 18:39, Alan Melia wrote: Yeah well its all done by computers now you dont need qualified navigators, the Captain can easily run it aground on his own :-)) It took a little longer than dumping ROs but not much. Alan G3NYK - Original Message - From: "Brian Inglis" <brian.ing...@systematicsw.ab.ca> To: <time-nuts@febo.com> Sent: Wednesday, January 06, 2016 9:44 PM Subject: Re: [time-nuts] Loran Europe Lessay seems to be back on air? On 2016-01-04 14:11, Alan Melia wrote: I remember being told by a senior member of the RIN that he thought it was a "dead duck" and a waste of money. It appears someone also thought RIN was a "dead duck" and a waste of money as it too shut down at the end of 2015! -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada ___ 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] KS-24361 off by 45 seconds for 13 minutes, end of Jan 01 UTC
On 2016-01-05 11:59, Hal Murray wrote: Is anybody watching the output of their KS-24361? Mine was off by 45 seconds for 13 minutes at the end of Jan 01. I didn't see any problems on a Z3801A. Receiver time output may have been delayed while receiving an almanac update at the end of the UTC day? Almanac takes about 12.5 minutes to transmit, which would jive with ~13 minutes. Clockstats should output the last message received about once per poll period - is minpoll 6? TFOM byte after time stayed the same at 3 => < 1us uncertainty if same as Z3801A; FFOM two bytes after time went from 0 to 2 so the PLL unlocked and went into holdover, and at the end of that period went to 1 so stabilizing; presumably got back to 0 later. The following Leap, Request for Service, and Valid bytes did not change. Assumptions are that operation and status are the same as for HP Smart Clocks. Here is part of ntpd's clockstats. The second column is the system time - seconds this day. The 4th column is the data from the KS-24361 The 220160101 is the date. Following that is HHMMSS. The <== mark the first and last samples that are off. 57388 85270.045 127.127.26.0 T2201601012341113001031 48 0 57388 85330.045 127.127.26.0 T2201601012341263201039 52 0 <== 57388 85394.045 127.127.26.0 T2201601012342303201035 52 0 57388 85458.045 127.127.26.0 T220160101234334320103A 56 0 57388 85522.045 127.127.26.0 T220160101234438320103F 56 0 57388 85586.045 127.127.26.0 T220160101234542320103B 52 0 57388 85650.045 127.127.26.0 T2201601012346463201040 48 0 57388 85714.045 127.127.26.0 T220160101234750320103C 44 0 57388 85778.045 127.127.26.0 T2201601012348543201041 56 0 57388 85842.045 127.127.26.0 T2201601012349583201046 48 0 57388 85906.045 127.127.26.0 T2201601012351023201034 36 0 57388 85970.045 127.127.26.0 T2201601012352063201039 52 0 57388 86034.045 127.127.26.0 T2201601012353103201035 48 0 <== 57388 86098.045 127.127.26.0 T2201601012354593101042 60 0 -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada ___ 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] Loran Europe Lessay seems to be back on air?
On 2016-01-04 14:11, Alan Melia wrote: I remember being told by a senior member of the RIN that he thought it was a "dead duck" and a waste of money. It appears someone also thought RIN was a "dead duck" and a waste of money as it too shut down at the end of 2015! -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada ___ 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] PPS phase between two GPS units.
On 2015-12-21 18:24, d...@irtelemetrics.com wrote: So I've been playing with some timing hardware here, and have noticed something rather curious. I have two otherwise identical Lea-6T GPS modules, configured exactly the same. These units are tied to the same antenna, with a splitter with the same length cables running to each unit. They were given the same survey coordinates. Initially there was not any appreciable difference between the PPS outputs. The outputs were on average within about one nS of each other. However after a day or two they started to display a difference of about 21nS between the PPS outputs. This is also evident in the GPSDO output, as the phase of the 10Mhz is also skewed by 21nS or so. A few days ago I started a 48 hour survey. The came up virtually identical coordinates at the end of that survey. After the survey the phase is still 21nS different. At this point, my only thought is the GPS splitter. It's DC coupled to one unit, and AC coupled to the other. It is possible there are some delays on one output vs. the other due to the blocking caps and bypass inductor in the splitter. I've tried swapping the GPSDO units on the splitter, so we'll see what happens there. Can anyone offer any insight as to why the two units may have a different PPS output timing? It's not really a problem, more of a curiosity and mildly academic exercise. A sampling difference of 1 cycle with 48Mhz clocks would give you ~21ns offset if not using sawtooth correction. Can you do the sawtooth correction and see if the offset is reduced? -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada ___ 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] Hydrogen maser frequency jumps
If microwave ovens could be an issue, could current popular mobile phone/tablet (Qualcomm Snapdragon, Samsung Exynos, Apple A7/M7) and low power desktop (Intel Core) processors running at nominal 1.4GHz also be an issue? On 2015-12-05 09:06, Tom Van Baak wrote: Jim, Check IF level and H2 pressure. Also see if OCXO tuning is near a rail. Go back through the past month and look at trends on all the parameters. You are logging all channel data, I hope. Also check your microwave ovens: http://arxiv.org/pdf/1504.02165v1.pdf ;-) Less technical links: http://www.nature.com/news/microwave-oven-blamed-for-radio-telescope-signals-1.17510 http://www.skyandtelescope.com/astronomy-news/microwave-ovens-spark-radio-signals-peryton-05122015/ http://phenomena.nationalgeographic.com/2015/04/10/rogue-microwave-ovens-are-the-culprits-behind-mysterious-radio-signals/ /tvb Has anyone here who is familiar with hydrogen masers ever experienced a sudden jump in phase of the 5MHz output? We have found they occur semi-regularly (few times a week) and are trying to find a culprit. The weird thing is that the jump is ~0.7ns and that 1/0.7E-9 is close-ish to 1420.4MHz which is the hydrogen line. Too much of a coincidence for me. These seem to be appearing at three different locations with the same model of maser at each location. I won't mention the model publicly. We're still investigating various potential causes (e.g. power spikes, cables being moved), but this 0.7ns figure is niggling me. Has anyone here ever seen such a thing before? Jim ___ 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. -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada ___ 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] Coordinated Universal Time (UTC) to retain “leap second”
http://www.itu.int/net/pressoffice/press_releases/2015/53.aspx -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada ___ 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] Using borked Galileo sats to measure relativity
On 2015-11-09 22:14, Mark Sims wrote: http://www.theregister.co.uk/2015/11/10/borked_eu_gps_satellites_braincheck_einstein/ Now, for 140E-6 bonus points, spot the error in the article... The Reg claims "clock 10,000 kilometers up ran 140 parts in a million of a second faster than the same device on Earth" but the original article actually states "confirming [Einstein's] prediction to within 140 parts in a million" and "will go on to test Einstein’s theory down to 2–3 parts per million." http://www.esa.int/Our_Activities/Navigation/Galileo_satellites_set_for_year-long_Einstein_experiment However the original article also says "clocks...run faster in orbit than on the ground – a few tenths of a microsecond per day" which should be about 40us/day ~ 0.4ppb for Galileo if the graph is correct in article: https://en.wikipedia.org/wiki/Time_dilation#Time_dilation_due_to_gravitation_and_motion_together and seems more reasonable given TVB's project GREAT results of ~ 20ns. -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada ___ 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] Dipleidoscope
On 2015-11-09 15:05, Larry McDavid wrote: Actually, it is an Edward John Dent dipleidoscope, or E. J. Dent, not I. E. Dent. But, hand engraving an "I" is much easier than engraving a "J" so many (not all) dipleidoscope covers were in fact engraved, "E. I. Dent." This letter substitution is similar to that seen in the often-engraved, "TRVTH" seen on buildings. Dent is a famous watch and chronometer maker, with offices in London. Edward John Dent designed, but did not live to see built, the famous London Great Clock, popularly known as, "Big Ben." Dent manufactured to Denison's design (later ennobled as Grimthorpe and that name used for the three-legged gravity escapement in that clock and others - see http://trin-hosts.trin.cam.ac.uk/clock for measurements of a similar clock) and Airy's specs (including first stroke of the hour to be within one second of GMT and performance telegraphed to Greenwich for checking) http://www.parliament.uk/about/living-heritage/building/palace/big-ben/building-clock-tower/building-great-clock [The bell and hammers were manufactured separately to Denison's design, and after only two months operation, the hammers cracked the bell, blamed on the hammers being more than double the maximum weight specified by the foundry https://en.wikipedia.org/wiki/Big_Ben#cite_ref-wbfbb_1-3 - a mistake unlikely to have been made by Dent.] Airy was the Astronomer Royal who established GMT, distributed it via telegraph wires throughout the UK, and compared time at the top and bottom of deep mine shafts to calculate gravitational differences and mean earth density: definitely a Time Nut. Surprisingly, the Dent & Company survives today and still produces custom clocks, spanning three centuries of clock making excellence. Alas, through personal correspondence, the Dent & Company today seems unaware of the Dent Dipleidoscope. They misspell it differently twice on their History page under Patents and 1843: diplied[ao]scope - http://www.dentlondon.com/about/history.php The company appears to have passed out of the family in the 1960s ending up with a different family owned jewellery and insignia private company http://www.aim25.ac.uk/cgi-bin/vcdf/detail?coll_id=16723_id=118 -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada ___ 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] How did they distribute time in the old days?
On 2015-10-15 08:32, Tom Van Baak wrote: Nick Sayer writes: The WU standard time service goes back further than the turn of the 20th century. It started in 1870. Also, for a screen full of irresistible SWCC photos, try this: https://www.google.com/search?tbm=isch=self-winding+clock+company My understanding (perhaps incorrect) was that the sync pulse was once daily and, as you said, would cause the hands to “snap” to 12. The trailing edge of the pulse was synchronized and would release the clock to operate normally. That they had something as accurate and widespread as it was so early is astonishing. Oh, Padawan, that's just the tip of the iceberg when it comes to the deep and fascinating history of precise timekeeping. Recently restored (after a building fire where some were lost) to working 19 Art Nouveau master/slave clocks from 1910: http://www.gsaarchives.net/2013/04/mackintosh-clocks-feature-on-bbc-news/ more pictures in linked articles from BBC -- Take care. Thanks, Brian Inglis ___ 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] How did they distribute time in the old days?
hus enabling her to find her longitude exactly. This seems to be the earliest example of a ship at sea receiving a time signal by other than visual means. One of the earliest uses of the new cable was to redetermine the longitude difference between the observatories of Greenwich and Harvard University at Cambridge, Mass. This was conducted in October 1866 by Dr B. A. Gould of the US Coast Survey, in co-operation with Airy." -- Take care. Thanks, Brian Inglis ___ 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] A new time nut - and a question!
On 2015-10-01 06:05, Christopher Glass wrote: Hi list, I recently got time to build my first stratum-1 GPS timeserver around a raspberry-pi (first model) and one of these [1]. I would ideally like to have it work as a completely standalone time source, only getting timing information from the GPS signal it is receiving (no network peers). As such, I built ntpd with --with-NMEA, and tweaked things around to the point where I *think* I got it working, however, my simple question is: Can somebody tell me whether it's *actually* working? :) The output I get from "ntpq -c pe -c as -c rl" on the system [2] is confusing me a little since I see the GPS source being selected as sys_peer, but the event showing says "no_sys_peer". Is this expected in case no network source is available? The last section of the output furthermore shows a difference between the "reftime" and "clock" fields. Should I understand that reftime is the GPS time and "clock" the state of the system clock? In that case, should I see the clocks converge over time? I apologize if these are easily answered by reading a manual somewhere - like I said, it's my very first venture in the world of timekeeping, and I would benefit from having somebody explain things to me. Have you looked at: http://ava.upuaut.net/?p=726 Have you run the GPS module in one place long enough to do a survey and set it into Stationary mode? Is PPS enabled and being received? Have you specified 'prefer' on your server conf line to provide a time stamp for PPS? Have you configured a drift file to save frequency and speed up restart? Have you enabled logging with 'logconfig =allall'? Check your syslog with dmesg and see what messages have been or are being issued - there aren't many, except at startup, even with a bunch of network peers or servers configured: most are network issues also logged in protostats (below). More details at: http://www.ntp.org/ntpfaq/NTP-s-trouble.htm Your pastebin shows: remote refid st t when poll reach delay offset jitter == *GPS_NMEA(0) .GPS.0 l3 1670.000 -0.040 0.043 reach is only 7 - 3 samples - needs 8 samples - 377 - to prime the filters offset 40us and jitter 43us is higher than expected - should be low us associd=0 status=c418 leap_alarm, sync_uhf_radio, 1 event, no_sys_peer, version="ntpd 4.2.6p5@1.2349-o Sat Sep 26 08:08:22 UTC 2015 (1)", processor="armv6l", system="Linux/4.1.7+", leap=11, stratum=1, leap_alarm and leap=11 say unsynced - should be leap_none and leap=00 precision=-20, rootdelay=0.000, rootdisp=1937.748, refid=GPS, rootdisp=1937.748 is really high - should be less than 0.5 reftime=d9b79166.599b08f6 Thu, Oct 1 2015 13:03:02.350, clock=d9b79169.f52bbe6f Thu, Oct 1 2015 13:03:05.957, peer=33608, tc=4, reftime is the last ref clock time used - clock is just the current time mintc=3, offset=0.000, frequency=-27.210, sys_jitter=0.043, offset=0.000 says the system time is not yet set - should be low us frequency=-27.210 has to stay within 1ppm for it to be an accurate estimate of your system clock drift - may take some time to settle clk_jitter=0.015, clk_wander=0.000 clk_jitter=0.015, clk_wander=0.000 look good - low us and zero Add ntpq '-c cv' to see your reference clock variables which should look like: associd=0 status=0011 , 1 event, clk_no_reply, device="NMEA GPS Clock", timecode="$GPRMC,154611,A,5108.3494,N,11411.5630,W,000.0,000.0,011015,014.7,E,D*0E", poll=43905, noreply=1, badformat=0, baddata=0, fudgetime1=0.000, stratum=0, refid=GPS, flags=0 A few event counts are normal at startup - high means comms problems! More details on all this at: https://www.eecis.udel.edu/~mills/ntp/html/ntpq.html Have you created and defined 'statsdir /var/log/ntp/' and 'statistics clockstats loopstats peerstats protostats sysstats' to record and monitor operation? 'filegen' is not required with default UTC day file dating and rollover. More details at: https://www.eecis.udel.edu/~mills/ntp/html/monopt.html If you have network routing, a few good servers close by, or a country 'pool CC.pool.ntp.org iburst' conf will keep your system from becoming a falseticker if there are any GPS issues. Email off list if you need more info. -- Take care. Thanks, Brian Inglis ___ 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] Trimble Resolution [T, SMT, SMT GG] - spontaneous GPS loss of signal events, multiple locations
Hi, Probably the vendor if no one else experiences or knows of Resolution issues. You can contact Trimble UK or Trimble Navigation Europe in Hampshire and they may know about any product or vendor OEM issues. If you can get the timing down to 30s GPS frame times or 750s/12.5m message times, it could possibly be a GPS system issue like updates, and you can report problems at: http://www.gps.gov/support/user/ which links to the form at: http://www.navcen.uscg.gov/?pageName=gpsUserInput -- Take care. Thanks, Brian Inglis On 2015-09-14 05:28, Wojciech Owczarek wrote: Hello Time Nuts, I was wondering if other people have seen this. 20+ receivers and they all use different variants of the Resolution boards - majority are the old Resolution T.We have observed sudden GPS loss of signal occurring. Seemingly nothing unusual, these things happen, that's what holdover is for, etc... however: - All devices are connected via decent distribution amps, - All installations use roof-mounted antennas with unobstructed 180 degree sky view - All devices see about 11 birds most of the time - None of these events coincided with known GPS SV outages And here's the fun part: - This is happening in multiple locations in the US, AND in the UK - The log timestamps (UTC) for the alarms, are *exactly the same* across all sites, down to the second. This happens twenty to ten seconds before midnight, and usually recovers within two or three minutes. The last event was on 5th September, at 23:59:37 UTC. We have seen this happening anywhere between once every month to once every two months. Time may differ by a few seconds, but it's the same across all devices. I'm trying to establish whether the issue is with Trimble or with the vendor who embedded Trimble. Because of what I refer to as "vendor anal-digital decoupling delay", I have to investigate in parallel. Has anyone seen this with Resolution? Unfortunately I have no visibility into firmware versions in the Resolution boards. Any pointers welcome. ___ 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] monitoring NTP servers?
On 2015-08-26 01:47, Anders Wallin wrote: Hi all, Is there a ready made set of scripts for monitoring a bunch of NTP servers? Preferably for generic unix/linux like ubuntu. I imagine it would look something like: 1. measure data with a test machine, either use output of ntpq -p or perhaps python and ntplib. Variable measurement interval, perhaps 60s or so. 2. store relevant data into RRDTool database (offsets, delay, jitter, etc) 3. produce graphs with RRDGraph, and possibly Alarms (e-mail?) if a server goes offline or way out of sync. Servers run by others or your own? If your own, implied above, enable all relevant statistics collection, and use your favourite plotting tool to generate graphs to your taste from the daily *stats files. Wrap the plotting in cron scripts and schedule them to your taste. Use of ntpq should really be limited to checking the state of your servers and their sources. My taste runs to bash, awk, gnuplot, html and png output - YMMV. PM if interested. -- Take care. Thanks, Brian Inglis ___ 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] SRS PRS10 repair
Hi, You have too many 1s in your startup string compared to the expected PRS_10\r. If the MCU clock is not 10Mhz then the integrated UART rates will be off, which should produce framing errors, but do UARTs still detect and systems report these nowadays, or just pass along garbled data? Otherwise, garbled data is most often a result of inadequate pin contact, if the connectors are not seated properly, or the pins or sockets are loose in their shells. Age and rough treatment can have that effect. Internal hardware jumpers allow these pins to be configured as analog outputs to monitor the lamp intensity and varactor voltage for complete compatibility with the FRS. Have you checked the jumpers in the manual Configuration Notes: Pin 4: TXD/PHOTO The default configuration uses this pin as an output for RS-232 data. Many system parameters (including the lamp intensity) may be monitored via the RS-232 interface. The function of this pin may be changed to an analog monitor for the lamp intensity by removing one resistor (R347) and installing a 10 kΩ resistor for another (R348) on the microcontroller PCB. On 2015-08-24 22:40, Brian M wrote: I tried through the weekend, double and triple checking wiring and setup. I've tried the following methods of getting serial comms working: PRS10 - Arduino Uno (with processor bypassed) - USB Host PRS10 - Level Shifter - BBB UART PRS10 - MAX232 - USB Serial adapter Shortly after power is applied to the PRS10, I do get a string of characters. Believe it should be the model information. Instead I get: wy+VPgy I guess the good news is that this output appears consistent with each power cycle of the device. And I'm getting the same results through all the hookup methods I've tried. My minicom settings are for software flow control at 9600 8N1 - from what the manual states, this should be the right settings. I've tried screen as well - and get the same text. I went crazy trying several other rates and setting combinations. No luck. Maybe I've missed something obvious. I agree that getting comms going to the MCU are going to be an important step. How do people address this type of problem? Scope the serial and try to decode by hand? The 10Mhz to the MCU looks OK on a scope. Are there further steps people try after that? If nothing else I think there's some interesting stuff to learn here. I also wouldn't mind tearing out the electronics, determining if the lamp is good, and attempt to build from there. I don't know the datecode for the unit, the PCB is marked with a datecode suggesting 2003? I don't have the full case. I'm trying to assess what are reasonable next steps. How do I determine if the MCU is healthy? If the MCU is fried, how do I determine if I just need to squeeze a new MCU board in there? Thanks! I appreciate the input so far! - Brian PS - after looking again at the signal on the scope, it does seem like it is 9600 baud. ~100µS per bit. The data out on the MCU itself looks like what I saw on the main connector. On Sat, Aug 22, 2015 at 2:04 PM Mike Cook michael.c...@sfr.fr wrote: Le 22 août 2015 à 03:40, Bob Camp kb...@n1k.org a écrit : Hi On any microprocessor based gizmo, getting the micro running (again) is generally priority number one. It sets everything up and gives you the diagnostic info you need to go further. Garbled serial is better than none at all. It suggests something short of a total MCU death spiral … Bob On Aug 21, 2015, at 7:26 PM, Brian M brayn...@gmail.com wrote: Dear list - I have come into possession of a for parts prs 10. I'd like to try to repair this device. What I've noticed so far. Serial is garbled. (Even at varying baud rates). You don’t say how you are connecting to the Rb. The manual states: RS-232 data is sent to the host on pin 4, received from the host on pin 7. The baud rate is fixed at 9600 baud, 8 bits, no parity, with 1 start and 1 stop bit. No DTR or CTS controls are used; rather, the XON/XOFF protocol has been implemented. The transmit drive level is 0 and 5 V, not the +/-12 V normally associated with RS-232. These levels are compatible with most RS-232 line receivers, but does not require their use (a TTL inverter may be used instead), hence simplifies the interface when used inside an instrument at the sacrifice of degraded noise immunity over long lines. So make sure that you adhere to that. Lamp isn't lit. What’s the date code. Early versions may be reaching EOL, though 20yrs id quoted. Doesn't look great. I'd like to know if anybody else has wandered down this path. What are common failure modes? Anything match up with what I describe? Voltages to check would be helpful. The 10MHz out looked okay on a scope. Haven't gone further yet. I suspect the crystal is fine. Thanks in advance. Happy hacking! - Brian ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] SRS PRS10 repair
Looking at the data expected and received on the wire, there could be an extra inversion after some bits delay until an inverted 1 is detected as a start bit: 1101 0011 00110001 0101 01010011 01010010 0101 .01_SRP - what you should see on your scope 0001 01100111 0101 01010110 00101011 0001 01110111 ygPV+yw - what you probably see on your scope You should be able to connect your output data directly into any current PC serial port as they should both work with 0-5V nowadays. On 2015-08-25 11:35, Brian M wrote: The earlier suggestion of a missing inverter seems to be the right thing to chase this evening. I was able to add an inverter and decode the first few characters on a scope. I get the expected DC1-CR-P-R-S sequence. Thanks for the input on this. I'll reply back after I've had more time to hack at this. On Tuesday, August 25, 2015, Brian Inglis brian.ing...@systematicsw.ab.ca mailto:brian.ing...@systematicsw.ab.ca wrote: You have too many 1s in your startup string compared to the expected PRS_10\r. If the MCU clock is not 10Mhz then the integrated UART rates will be off, which should produce framing errors, but do UARTs still detect and systems report these nowadays, or just pass along garbled data? Otherwise, garbled data is most often a result of inadequate pin contact, if the connectors are not seated properly, or the pins or sockets are loose in their shells. Age and rough treatment can have that effect. Internal hardware jumpers allow these pins to be configured as analog outputs to monitor the lamp intensity and varactor voltage for complete compatibility with the FRS. Have you checked the jumpers in the manual Configuration Notes: Pin 4: TXD/PHOTO The default configuration uses this pin as an output for RS-232 data. Many system parameters (including the lamp intensity) may be monitored via the RS-232 interface. The function of this pin may be changed to an analog monitor for the lamp intensity by removing one resistor (R347) and installing a 10 kΩ resistor for another (R348) on the microcontroller PCB. On 2015-08-24 22:40, Brian M wrote: I tried through the weekend, double and triple checking wiring and setup. I've tried the following methods of getting serial comms working: PRS10 - Arduino Uno (with processor bypassed) - USB Host PRS10 - Level Shifter - BBB UART PRS10 - MAX232 - USB Serial adapter Shortly after power is applied to the PRS10, I do get a string of characters. Believe it should be the model information. Instead I get: wy+VPgy I guess the good news is that this output appears consistent with each power cycle of the device. And I'm getting the same results through all the hookup methods I've tried. My minicom settings are for software flow control at 9600 8N1 - from what the manual states, this should be the right settings. I've tried screen as well - and get the same text. I went crazy trying several other rates and setting combinations. No luck. Maybe I've missed something obvious. I agree that getting comms going to the MCU are going to be an important step. How do people address this type of problem? Scope the serial and try to decode by hand? The 10Mhz to the MCU looks OK on a scope. Are there further steps people try after that? If nothing else I think there's some interesting stuff to learn here. I also wouldn't mind tearing out the electronics, determining if the lamp is good, and attempt to build from there. I don't know the datecode for the unit, the PCB is marked with a datecode suggesting 2003? I don't have the full case. I'm trying to assess what are reasonable next steps. How do I determine if the MCU is healthy? If the MCU is fried, how do I determine if I just need to squeeze a new MCU board in there? Thanks! I appreciate the input so far! - Brian PS - after looking again at the signal on the scope, it does seem like it is 9600 baud. ~100µS per bit. The data out on the MCU itself looks like what I saw on the main connector. On Sat, Aug 22, 2015 at 2:04 PM Mike Cook michael.c...@sfr.fr wrote: Le 22 août 2015 à 03:40, Bob Camp kb...@n1k.org a écrit : Hi On any microprocessor based gizmo, getting the micro running (again) is generally priority number one. It sets everything up and gives you the diagnostic info you need to go further. Garbled serial is better than none at all. It suggests something short of a total MCU death spiral … Bob On Aug 21, 2015, at 7:26 PM, Brian M brayn...@gmail.com
Re: [time-nuts] wtd: WWVB info
Hi Donald, On the page referenced by Alex later in this thread, there is a link to Galleon as a US distributor of the HKW modules and WWVB receiver chip: http://www.ntp-time-server.com/wwvb-receiver/wwvb-receiver.html where the price may or may not be lower than direct shipping from EU, or availability could be as vaporous as elsewhere. -- Take care. Thanks, Brian Inglis On 2015-08-09 20:38, Donald wrote: I wish to thank you all for the information presented here about WWVB receivers. A few years ago I had been building some LED clocks for friends, more art then electronics. Those clocks had a WWVB receiver I got from Digikey. Today I am re-visiting those clocks as Word Clocks. Letters instead of numbers forming words, I am sure you have seen them around. People keep saying there are WWVB chips available, but I can not find any chips. When I ask for information about these chips, no response. I have asked about discrete designs and Digital designs, no response. I am not able to design these myself. So any tangible information would help. Ok, I can not get chips/modules here in the US. I do find modules from Europe and China. I am in Boulder, Colorado. This is where Sparkfun is located. I asked them about the receiver modules they had carried for years, They said they can not get them any more, OK. But why ? Nobody knows. Digikey won't even answer my emails about them. I had asked a China manufacture for 2 units, but they can not sell me 2 units. But if I buy 20 units (I would be a manufacture) then they can sell them to me. So, bottom line. I can only get modules from Europe/China at $20 each. OK. If I have come across too pick your favorite term, I apologize. I thought this would be a simple question with a simple answer. On another note, I have found a WiFi module for $3.00 and I can connect to an NNTP server. ESP-8266, if you need a serial to WiFi connection. I will re-start my project with a new direction. Thank You for your response. ___ 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] wtd: WWVB info
On 2015-08-07 14:43, Donald wrote: On 8/7/2015 8:13 AM, Brian Inglis wrote: Given a $10 60kHz receiver, This is the problem. I can not find $10 receivers any more. I can find $15-$20 receivers (from the UK), add shipping and it minimum $20+. Even the older chips still work with the new format, its just finding them, cheaply. US sources probably have low demand - so 10 euro/pound now - possibly as much for shipping - Scott Newell's post gives sites - found these search filters show the items of interest: http://www.pvelectronics.co.uk/index.php?main_page=advanced_search_resultsearch_in_description=1keyword=wwvb http://www.hkw-shop.de/index.php?cl=searchsearchparam=60khz - see what SH come to. -- Take care. Thanks, Brian Inglis ___ 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] wtd: WWVB info
On 2015-08-04 21:36, Hal Murray wrote: kb...@n1k.org said: So far there have not been any home brew design radios show up that will demodulate and lock to the new data format. There is plenty of info on the transmit format. The demodulation approach is not crazy hard. That said, there’s still a lot of work to get a receiver running. Has anybody looked into a software approach? What sort of front end would you want? WWVB is a 1 baud trinary (0/1/marker) AM signal which goes low at the start of the second and goes high after 200ms, 500ms, or 800ms, and a 1 baud binary PM signal with possible phase inversion on the carrier 100ms after the start of each second. Given a $10 60kHz receiver, the AM data should be readable by any UART running at 10bps, with 1 start bit, 8 data bits including Mark parity, 1 stop bit. Each character could then be decoded into one of the three symbols transmitted. If all you want is the PPS and AM time code, it can also be done with an 8kHz audio codec. The NTP CHU ref clock driver will decode CHU Bell 103 300bps signals in software. For the PM signal, you need an LF receiver and a detector for the possible phase change before and after 100ms after PPS to extract the binary data. -- Take care. Thanks, Brian Inglis ___ 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] Loran C returning to a station near you...
Look at how well a couple of projects have gone: o privatize NIST NTP server operation - the NTP pool is recommended everywhere and good enough for most; separate providers supply high accuracy, precision, and stability timing for financial markets internationally; and GPS serves the rest o provide WWVB PM decoders - older precision timing equipment no longer works; but compatibility for RC Atomic clocks and watches was maintained; does not appear that there is any commercial interest in developing decoders; the new PM features might as well be dropped, or they could go back to the old AM format. See also the UT1 NTP service http://www.nist.gov/pml/div688/grp40/ut1_ntp_description.cfm which states it will use IERS schedule A data, and may offer only the weekly official projections rather than the daily rapid predictions, which vary by 0.1ms; they also mention providing DUT1 and EOP data as a text string from a separate service. They may be looking at this for a UTC like backup if the ITU drops the leapsecond. But the US, EU, Russia, China, and Japan can each afford a GNSS constellation, with upgraded features as desired. If a country can not provide an adequate market for products, then they will have to either do without a backup, ormake do with what markets elsewhere demand - eLoran. OTOH the civil business focus of currently successful projects leads me to hope that the ITU will be told to leave UTC alone as a legal and political requirement for solar civil time, use TAI or GPS time if they want to keep to a uniform time scale, or come up with a better time scale of their own. -- Take care. Thanks, Brian Inglis On 2015-07-14 16:49, Bob Camp wrote: Not to be to much of a downer here but ….. Loran for timing and an “Eastern WWVB” are two projects that seem to each have a life of their own. They seem to come up on some sort of cycle related to sun spots. Both have zero (or possibly less than that) percent mind share among those who would need to implement them into systems. Since there is major cost on the systems end, it would take “mandatory use” legislation to get them designed in. Without those design in’s, *having* a backup system is pretty useless. You are talking about billions of dollars and years of effort to hook them up …. If you are talking about “infinite budget” military systems, some of that may happen. I notice in the papers that “infinite budget” does not seem to apply to the US DOD these days. For commercial systems, nobody will significantly cut into profits to do something like this. Should they do this - sure. Will they do it - nope. On Jul 14, 2015, at 4:49 PM, paul swed paulsw...@gmail.com wrote: The reason to stay with the LORAN C style pulses is very very simple. It allows our time-nuts Austrons and SRS to work. Its the only way I get any of my tax dollars back. :-) The good news is no official government person reads time-nuts. On Tue, Jul 14, 2015 at 12:16 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 55a4ac81.1030...@rubidium.dyndns.org, Magnus Danielson writes: The safety is relative, in that it takes quite a bit of more infrastructure compared to the jamming of GPS, and that lies in the wavelength of the signal than anything else. If the goal is a reliable backup for GPS, there are smarter ways to use the 100kHz band than Loran-C pulses, and there really isn't much reason to stay compatible with Loran-C receivers. ___ 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] US export regulations for TICs
On 2015-07-07 07:28, Attila Kinali wrote: As we need a need a proper TIC here to do our research, we are going to buy one from ebay form a seller in the US and let a friend who is in the US at the approriate time and can pick it up to bring it back in the plane. Now the big question is, are there any export regulations regarding such equipment and if yes, where do I find it? (my search didnt show up anything approriate). Yes I know it's a boat anchor and that takeing it in a plane is kind of iffy, but it's better than shipping it. Time Interval Meter seems to be the only relevant hit in the CCL at ECCN 3A999.e.2: http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=1ty=HTMLh=Ln=15y2.1.3.4.45r=PART#ap15.2.774_12.1 then search for 3A999: 3A999 Specific Processing Equipment, n.e.s., as Follows (See List of Items Controlled). License Requirements Reason for Control: AT [i.e. Anti-Terrorism] Control(s): Country Chart. AT applies to entire entry. A license is required for items controlled by this entry to North Korea for anti-terrorism reasons. The Commerce Country Chart is not designed to determine AT licensing requirements for this entry. See §742.19 of the EAR for additional information. [e.g. Sudan, Iraq, etc.] List Based License Exceptions (See Part 740 for a description of all license exceptions) ... e.2. Multi-channel (three or more) or modular time interval meter and chronometry equipment with resolution of 50 nanoseconds or less over time intervals of 1 microsecond or greater; -- Take care. Thanks, Brian Inglis ___ 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] beaglebones, time, web services
On 2015-07-04 07:13, Jim Lux wrote: I've got a project I'm working on to make a sophisticated sundial with moving mirrors. I've got a batch of Arduinos that move the mirrors to the appropriate places, given the current sun angle, etc. I've got a beaglebone that runs some python code to calculate sun angle based on time The beaglebone will have a GPS feeding it to get time. BUT now, I'd like to add a web interface, so that it can be manipulated by a mobile device using a browser. One way I can think of is to run some sort of limited web server. there are a couple that come with the beaglebone, including the python simplehttpserver. But I'm sort of stuck on the interface between the webserver and the other code running. I've done this kind of thing where the one task goes out and updates files in the tree that's being served by the web server, and that works fine for status display kinds of things that don't update very quickly. It's also nicely partitioned. but I want to be able to change the behavior of the system (e.g. by having the server respond to a PUT or something) Is the best scheme to go in and modify the webserver code to look for specific URLs requested, and then fire off some custom code to do what I want? May want to start with a control web page with an HTML FORM element and embedded input elements - easy even if you have not done much form design and entry implementation. Submit target can be any URL designating a Python CGI script, which generates at least a Content-type header and HTML on stdout returned to the browser. HTML output normally includes a copy of the original FORM (with values passed selected for editing) as well as HTML output and maybe inline or linked graphics. You only need a web server that supports the CGI interface, with some way to configure it and say where the scripts are. See Python cgi, html, http module docs to DIY. -- Take care. Thanks, Brian Inglis ___ 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/UTC time
On 2015-07-04 15:01, Tom Van Baak wrote: (the Japan earthquake in 2011 sped the earth up by 1.8 microseconds/day. The Sumatra quake on 26 Dec 2004 had a bigger effect: 6.8 microseconds) Just in case you didn't know -- these are theoretical results only. There's a guy at JPL (Richard Gross) who does the calculations and any time there's a big seismic event he runs the simulations and out comes a number. That's pretty cool but the numbers so far are always smaller that what VLBI can actually measure. Still, it makes a nice press release and physics lesson. Buried in the articles is sometimes a clarification like the researchers concluded the Sumatra earthquake caused a length of day change too small to detect, but it can be calculated. Some recent calculations: NASA Details Earthquake Effects on the Earth http://www.jpl.nasa.gov/news/news.php?release=2005-009 Chilean Quake May Have Shortened Earth Days http://www.jpl.nasa.gov/news/news.php?release=2010-071 Japan Quake May Have Shortened Earth Days, Moved Axis http://www.jpl.nasa.gov/news/news.php?release=2011-080 All Days Are Not Created Equal http://www.jpl.nasa.gov/news/news.php?feature=15 See also: http://geodesy.unr.edu/hanspeterplag/library/projects/tsunami_loading/RotGravSigSumatraEqv4_pre.pdf While the modeled change in the Earth’s rotation that should have been caused by the 2004 Sumatran earthquake is less than the uncertainty in present-day measurements of the Earth’s rotation, it is still worth examining the measurements to see if an earthquake induced signal is present. http://www.obspm.fr/spip.php?page=imprimerid_article=2193lang=fr the effect in the movement of the pole should be of a few centimetres in the polhodie and of a few microseconds of time in the duration of the day, which is not very likely to be detected seen the current precision of the observations. The Sumatran earthquake impact on Earth Rotation from satellite gravimetric measurements https://hal-insu.archives-ouvertes.fr/hal-00117348/document For the length of the day Chao Gross (2006) modeled the increment of axial inertia moment and obtained a drop of 2-6 µs confirmed by our result (5 µs). This effect is undetectable in the LOD, because the precision on this parameter is of 20 µs. This last paper is really interesting because it compares space-based models with terrestrial models. And all this is of interest to time nuts because the earth is an oscillator and events like this affect the phase, frequency, and ADEV of the planet. Thanks for the good and interesting refs. One of the interesting points was that normal variations are multiples of those caused by earthquakes, and annual variations are up to 1ms and 1m. Another was that the jet streams produce large short term variations caused by temperature differences. Will this always turn up as an issue with all oscillators? ;^ -- Take care. Thanks, Brian Inglis ___ 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/UTC time
On 2015-07-04 07:36, Jim Lux wrote: On 7/3/15 9:45 PM, Brek Martin wrote: I feel like I missed “The Big Thing” in time keeping land. I should have watched my Ublox LEA-5T. What is the difference if it is in the reporting mode for GPS or UTC time? If they skip a second UTC, surely the GPS time isn’t run incorrectly forever. Who's to say which is correct, UTC or GPS? GPS time is derived from TAI; both are monotonically increasing, continuous, and constant rate. These are nice attributes for something you're going to use for time stamping, or controlling. No gaps, no jumps, etc. UTC (and local civil time, and GMT, etc.) have leap seconds, to adjust the time scale to the motion of the Earth; so that the sun is highest at noon (after accounting for the equation of time). While that's somewhat convenient, I doubt anyone would really object to noon being a few tens of seconds away from the zenith crossing when standing on the line. TAI is ahead of UTC by 36 seconds. They add a leap second every year and a half, so I guess in 100 years, we'll have drifted some minute or so away. (the earth has slowed down in the last 200 years.. a day is now 86400.0015 seconds long, although it's faster now than it was in the 70s, when it was 86400.003 seconds) http://tycho.usno.navy.mil/leapsec.html (the Japan earthquake in 2011 sped the earth up by 1.8 microseconds/day. The Sumatra quake on 26 Dec 2004 had a bigger effect: 6.8 microseconds) By my calculations, that should mean the earth rotated 3mm farther/day at the equator after Sumatra. Anyone know if, or how much, these perturbations affect the orbit of the earth or other planets, or where to find out? -- Take care. Thanks, Brian Inglis ___ 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] Thunderbolt Height Error
If it's not a reporting error as below, you could be getting signal bounce, making it look as if your antenna is underwater, andreducing the time accuracy - you could try bumping your elevation mask by 5 degrees, to see ifyour position improves. On 2015-05-19 13:45, Dave Martindale wrote: Which altitude do you have the Thunderbolt set up to report? If you have the datum set to WGS-84, the Thunderbolt can report either HAE (height above ellipsoid) or MSL (height above the geoid model) in its serial output. The choice is controlled by bit 2 of byte 0 of the 0x35 command packet. This can be stored in EEPROM, which determines the power-up default. HAE is mathematically simpler to calculate but bears only an approximate relationship to actual sea level. MSL requires some sort of table (inside the GPS receiver) to specify the geoid model, but since it's a fit to the actual Earth, the altitude is more likely to agree to what you think of as altitude. Many GPS receivers provide a choice of which altitude they report in their output stream, so when comparing two receivers you need to check that both the datum and the HAE/MSL altitude choices are configured the same. This should not have any effect on timing. The GPS receiver knows where it is in Cartesian coordinates in all cases. Your choice of map datum controls the conversion to latitude and longitude that the receiver reports, while the choice of HEA/MSL controls the conversion to reported altitude, but these choices should affect this output conversion only. - Dave On May 18, 2015, at 2:34 AM, Demian Martin demianm@gmail.com wrote: I have 2 GPSDO's. A Thunderbolt and an Arbiter 1083A. The Arbiter is old but it works fine (and has a Wenzel 5 MHz streamline oscillator in it). It has the 1995 firmware issue, and I could get new firmware for it ($$) but I'm not using it as a clock, just a frequency source. I just moved and have re-setup both. They share an antenna. I got both to do a self survey. The Arbiter was really close to what Google maps indicate is my location. The Thunderbolt was about the same except it has me underground. The arbiter has the height as +30M. The Thunderbolt as -6M. What setting do I have wrong in the Thunderbolt? Would it affect the operation as a frequency standard in any way? -- Take care. Thanks, Brian Inglis ___ 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] iGPS?
On 2015-05-17 17:07, Chris Albertson wrote: Anyone know anything about iGPS? Apparently the Iridium low orbit communications sats are now modified via software update to send signals that when combined with GPS allow for a receiver that is MUCH more precise and harder to jam and can work in urban areas better. Apple just bought a company that is building iGPS receivers. Looks like something that they might want to put inside a cell phone but when you have an orders of magnitude important in position you'd expect better timing too, or so I would think. Seems like a very smart idea if all that was required was a software upload to existing spacecraft. From what I read this is real, not a proposal another are real receivers being tested. Background: http://www.redorbit.com/news/business/1719742/iridiumboeing_team_completes_high_integrity_gps_program_milestones News: http://www.iphoneincanada.ca/news/apple-has-reportedly-acquired-gps-firm-coherent-navigation -- Take care. Thanks, Brian Inglis ___ 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] TymServe 2100 1995 Issue - A Kludgy Fix
On 2015-05-05 11:32, Alan Ambrose wrote: It's not that simple. First, it's not 20 years, but 1024 weeks (19.6 years). And not UTC weeks (which may have leap seconds) but GPS weeks (which do not, and are always 604800 seconds long). etc Don't think it's _that_ much code though. There's some open source ACM date algorithms, and it would be easy enough to implement a quick and dirty fix, adding a number of days offset, while the rest of the algorithm is tested. See http://www.leapsecond.com/notes/gpswnro.htm This was first noted in 1996 and has been happening since the first rollover in August 1999 so some affected NTP GPS drivers have been patched to add 1024 weeks while the input is more than 512 weeks in the past. Will the next time this problem reoccurs be another 20 years? The next rollover is about April 2019, but this can happen any time an older receiver's internal date representation used for GPS to UTC conversion overflows. Looks like Tymserve 2100 picked about Sep 1995 for its date epoch so it hits now. Newer GPS receivers support the extra 3 bits added to GPS extended week allowing 8192 weeks (157 years) between rollovers - 2137 is the next big rollover problem, but NavStar will likely not be sending the same data on the same frequency then. -- Take care. Thanks, Brian Inglis ___ 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] Tymserve 2100 thinks it's 1995?
On 2015-05-05 11:58, Tom Van Baak wrote: And now I guess we can't blame Trimble either since their 15-year old Ace documentation [1] says: ACE III GPS System Designer Reference Manual Part Number: 41265-00 Revision: A Date: June 2000 Firmware: 8.08 3.5.1 Effect of GPS Week Number Roll-over (WNRO) The ACE III GPS module has been designed to handle WNRO, and there are no problems with either dates or first fix after WNRO through the year 2015. Caution Trimble OEM GPS receivers have reported the true GPS Week Number in TSIP messages 0x41 and 0x8F-20 as a number between 0 and 1023. The ACE III GPS outputs the Extended GPS Week Number as the absolute number of weeks since the beginning of GPS time or 06 January 1980. If the true GPS Week Number is desired, the system developer should ignore the extra MSBs of the Extended GPS Week Number and use only the 10 LSBs. From that, I would say we can blame Trimble as they receive the extended week number which supports operation up to 2137, but says there will be problems in 2015. Does anyone on the list know how well the http://www.heoldesign.com replacement works? Hopefully the upgrade supports operation after 2015, but it still may not work if the Tymserve 2100 does not handle the increased range. Neither the Holodesign N024 nor the Trimble Copernicus II manuals state any limits similar to that in the ACE III manual. -- Take care. Thanks, Brian Inglis ___ 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] TymServe 2100 1995 Issue - A Kludgy Fix
On 2015-05-05 11:47, Hal Murray wrote: cfhar...@erols.com said: Surely the receiver is still producing correct frames that identify the future leapsecond, and those frames could be read, and used to set a little routine that wakes up at the appropriate second, and adjusts the overall offset? Is there any leap-warning info in NMEA mode? I don't remember seeing anything like that when scanning the documentation and the NMEA driver in ntpd doesn't have any code like that. GPS provides only the current UTC offset from GPS time, which could be made available via a custom vendor message, or derived from the difference between messages which provide UTC and messages (e.g. $GPZDG) which provide GPS time. Stratum 1 NTP servers need to be provided with a copy of the NIST leap second file and will propagate the warning to higher (numeric) stratum clients. -- Take care. Thanks, Brian Inglis ___ 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] OXCO insulation
Articles about handling and cutting these make it clear that it is worse than fibreglass insulation and protectionmust alwaysbe used. Cabot Thermal Wrap blanket aerogels are low dust at higher prices: http://www.buyaerogel.com/product-category/cabot On 2015-02-25 18:24, wb6bnq wrote: It looks like some great stuff ! However, it is a material that has a big dust problem according to the manufacturer. Here is the web site listing of products : http://www.aerogel.com/products-and-solutions/all-insulation-products/ Read the SPACELOFT safety data sheet on the product at this URL : http://www.aerogel.com/_resources/common/userfiles/file/Data%20Sheets/Spaceloft_MSDS.pdf It is not dangerous, but can cause medical problems if mishandled. BillWB6BNQ Dave M wrote: Great find, Arthur. I had already convinced myself to use fiberglass insulation to reinsulate my OXCOs, but I'm going to order 2 or 3 sheets of this to play with. Arthur Dent wrote: If you check the popular auction site you can find several listing for Aspen Aerogel SPACELOFT Insulation. One listing has a 10x14x.2 piece for $7 including shipping and another listing has 481 rolls for $1.8 million, in case you have several ovens you need to re-insulate. ;-) http://www.ebay.com/itm/171328843398? -- Take care. Thanks, Brian Inglis ___ 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] OXCO insulation
On 2015-02-22 17:42, Charles Steinmetz wrote: Brian wrote: Thought of trying aerogel insulation? Dust free varieties avoid handling issues. Be careful not to over-insulate the oven -- it depends on a certain amount of heat flow to ambient to balance the heater. The stability of the heater control loop depends on having the correct amount of thermal resistance from oven to ambient (also, on the thermal resistance being distributed similarly to the original scheme). R-value for commercial aerogel insulation is about double rigid polyurethane insulation, so half the thickness would be about right. -- Take care. Thanks, Brian Inglis ___ 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] Looking for advice to get a submillisecond setup
On 2015-02-24 03:48, Matt wrote: Thanks for all the advice received on and off list. My main doubt was about the quality of cheap receivers but you cleared that doubt. To answer a few questions, the antenna would be put on top of the building on top right corner of http://referentiel.nouvelobs.com/file/2458497.jpg (the only square with some kind of roof) in Paris. So I am confident we can receive a good signal here. I don't think the tower could be a problem. The tower could create multipath reflections, and electrical equipment on a roof, such as elevator motors, could add noise. On top of the tower or further away south west would reduce reflections. -- Take care. Thanks, Brian Inglis ___ 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] OXCO insulation
Thought of trying aerogel insulation? Dust free varieties avoid handling issues. -- Take care. Thanks, Brian Inglis On 2015-02-22 12:56, Dave M wrote: Yes, I'm aware that the newer OXCOs don't have any insulation other than air inside the package. I failed to mention that in my post. I am primarily interested in the older OXCOs that have foam insulation inside. I have a couple of them, including the crystal oven from an old HP 5245L counter that needs new insulation. The old foam was destroyed by a heater that ran wide open for a while, burning a large portion of it to a crispy mess. Bob Camp wrote: A lot of modern OCXO’s no longer use insulation…. the gaps inside are now so small that you get very little benefit from it. On the older parts that do use insulation 2 to 4 pound per cubic foot density urethane foam is a typical choice. You can buy it from most plastics suppliers. It can be machined with just about any tooling out there. The dust is a mess, but it’s not normally considered hazardous. On Feb 21, 2015, at 7:09 PM, Dave M dgmin...@mediacombb.net wrote: What kind of foam insulation is generally used inside an OXCO? Do all manufacturers use the same kind? Is it available in small (hobbyist) amounts? I've read that some folks have used Great Stuff polyurethane-based insulating foam to repair an OXCO. I've used it to fill gaps around pipes in my home, but it's nor subjected to the high heat encountered in an OXCO. According to Dow's web site, it could present a fire hazard if subjected to temperature of 240F (115C). There is a Fireblock variety, but it appears to have pretty much the same formulation as the other varieties, so I can't see any advantage to it. Has anyone experienced any long term problems with Great Stuff in an OXCO? ___ 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] PPS delay on rockwell
On 2015-02-16 02:57, Hal Murray wrote: francesco.messi...@gmail.com said: I can only suspect it was unlocked, but I need to setup all the test in another place closer to the window, since I don't have a splitter to use the same antenna of the thunderbolt. If one or both are unlocked, I'd expect them to drift, not rapidly, but I'll bet it's easy to measure if you wait a day. There is software to talk to TBolts so it should be easy to find out if it is locked. Have you tried any software on the Rockwell? It may even talk NMEA so all you have to do is connect it to a PC and guess the baud rate. Or maybe upload a picture and somebody will recognize the model so you can google for details. See http://gpskit.nl for Rockwell commercial GPS module info. Those modules have an MCX/OSX antenna connector to connect a passive ceramic patch or active GPS antenna. They talk NMEA @ 4800,N,8,1 or Rockwell Zodiac binary @ 9600,N,8,1, depending on jumper settings. Rockwell Zodiac binary may be like SiRF binary as those appear to originally have been designed as Zodiac/Jupiter replacements. PPS accuracy is stated as 1us. There are instructions on the web to make a dipole GPS antenna from a length of coax cable: remove the outer insulation, trim the outer shield and inner conductor to 46mm, and heat shrink tubing (or tape?) to form the T shape. You could stick that out of a gap in a window facing towards the equator with a clear view of the sky. -- Take care. Thanks, Brian Inglis ___ 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] How to adjust clock frequency in FreeBSD 10.1 ?
On 2015-02-11 18:35, Rick Thomas wrote: I’ve got a machine with a really bad clock. When I run NTP on it, the freq goes straight to 500.0 (over a period of a few days) and stays there, while the offset grows and grows. I recently switched this machine from Debian Linux to FreeBSD (wanting to learn more about FreeBSD). Under Linux, I used adjtimex to modify the TICK value and (once I had converged on the right value) NTP was able to stabilize the clock. Is there an equivalent hack for FreeBSD? See http://lists.freebsd.org/pipermail/freebsd-stable/2010-February/055369.html and rest of thread. First check your BIOS and OS have spread spectrum frequency changes and sleep states disabled, as those will make all clock sources appear unreliable. Then check your clock sources as shown earlier in the quoted thread and see if changing the clock source gives lower frequency drift. If your frequency drift is still excessive, try doing the calculation as in the quoted post and change your clock source frequency to compensate. Stop ntpd and rm ntp.drift before applying any clock source change. Let ntpd run for a few hours; use ntpq -c rv to check frequency for convergence, and offset for convergence towards zero; once those values start changing in the opposite direction, ntpd is disciplining the clock, and the values should start oscillating around its best estimates. -- Take care. Thanks, Brian Inglis ___ 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] tyco electronics A1025
On 2014-12-14 10:29, Francesco Messineo wrote: On Sun, Dec 14, 2014 at 6:12 PM, Bob Camp kb...@n1k.org wrote: that's not meant as a time nut stratum 1. It's just a free gps module I would like to recycle as a needed stratum 1 server for a small network. Of course if I can find informations on it. I know there're better options, but in this case anything would do. … and NTP is not a GPSDO or a Cs replacement. My guess is that there is no PPS out of the device. It would be very unusual if there was. Finding the NEMA output pin should be possible with an oscilloscope. At that point, a simple serial connection to the server is about all you need. Bring up the NEMA driver and it is running. It is unlikely that any further optimization would be possible, even with the (maybe) 290 page data sheet on the part. I would not let the lack of a data sheet stop you in this case. Hook up the output to a PC with a terminal program and see what you get. The main problem would be if you need to find the serial input pin to change what it puts out, hopefully you do not. The A1029, which is a newer model, has indeed a PPS output and I've been able to find a datasheet for it but the pinout isn't anything like the A1025. I planned to reverse engineer the pinout, but I'd like at least not to be forced to try to guess the power pins. Maybe someone still has the data for this older module. One article mentions the A1029 as a drop in replacement for the A1025, as an early auto receiver with gyro and dead reckoning nav holdover, but that may refer to the complete module, and you may have just the GPS. The GPS could have provided PPS for DR nav, and some TE model specs offer TCXOs, which may also have been required for DR timing holdover, but may not have been part of the GPS. Those GPS seem to have been standard STMicroelectronics parts with firmware customization for functions and additions, and offered proprietary $PSTM NMEA sentences. If you can read off the STM part STA 2... (perhaps under a patch antenna) you may be able to search for more details. -- Take care. Thanks, Brian Inglis ___ 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] Did a member of time-nuts buy this?
On 2014-12-09 04:10, Mike Monett wrote: One very cute addition would be to pull down the NIST GPS data and use it to correct your system on an hourly / daily basis. If you do that with common view satellites, you most certainly will beat a surplus grade Cs standard. How can we do this? The NIST archives state The archive is only updated once every 24 hours, so data are not available for today's date. Data from the previous day are added to the archive at about 1600 UTC. http://www.nist.gov/pml/div688/grp40/gpsarchive.cfm Is there another page that has current data? If so, how do we incorporate it into the GPSDO? IGS http://igscb.jpl.nasa.gov/components/data.html has pointers to get 15 minute samples from high rate IGS stations around the world: http://cddis.gsfc.nasa.gov/Data_and_Derived_Products/GNSS/high-rate_data.html USNO info tells you which SVNs/PRNs have Cs (few) and Rb (most) clocks: might be interesting to compare accuracy of Cs vs Rb SVs in view. -- Take care. Thanks, Brian Inglis ___ 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] 1900kHz radiolcation testing on east coast US?
On 2014-12-07 16:28, Tim Shoppa wrote: Would any time-nuts know of radiolocation-type testing going on, on east coast of US, maybe around Maine? There is a very strong wideband signal on 1900-1920kHz, with a 120Hz substructure and a 4Hz rep-rate, likely megawatt power range. Sound sample (recorded with 2400Hz receiver bandwidth, although the whole signal is far far wider bandwidth) at http://www.trailing-edge.com/1910-intruder.wav Pics of the waveform at http://www.trailing-edge.com/1910-intruder-1.png and zoomed in at http://www.trailing-edge.com/1910-intruder-2.png Could it be an artifact of interference with NAA 1-1.8MW@24kHz which also uses ~3MW@60Hz for deicing on the inactive array, as it is now below freezing and fairly humid in coastal Maine http://en.wikipedia.org/wiki/VLF_Transmitter_Cutler -- Take care. Thanks, Brian Inglis ___ 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] 1900kHz radiolcation testing on east coast US?
On 2014-12-07 16:28, Tim Shoppa wrote: Would any time-nuts know of radiolocation-type testing going on, on east coast of US, maybe around Maine? There is a very strong wideband signal on 1900-1920kHz, with a 120Hz substructure and a 4Hz rep-rate, likely megawatt power range. Sound sample (recorded with 2400Hz receiver bandwidth, although the whole signal is far far wider bandwidth) at http://www.trailing-edge.com/__1910-intruder.wav http://www.trailing-edge.com/1910-intruder.wav Pics of the waveform at http://www.trailing-edge.com/__1910-intruder-1.png http://www.trailing-edge.com/1910-intruder-1.png and zoomed in at http://www.trailing-edge.com/__1910-intruder-2.png http://www.trailing-edge.com/1910-intruder-2.png On Mon, Dec 8, 2014 at 9:15 AM, Brian Inglis brian.ing...@systematicsw.ab.ca mailto:brian.ing...@systematicsw.ab.ca wrote: Could it be an artifact of interference with NAA 1-1.8MW@24kHz which also uses ~3MW@60Hz for deicing on the inactive array, as it is now below freezing and fairly humid in coastal Maine http://en.wikipedia.org/wiki/__VLF_Transmitter_Cutler http://en.wikipedia.org/wiki/VLF_Transmitter_Cutler On 2014-12-08 07:30, Tim Shoppa wrote: 80*24 = 1920. 80th harmonic seems quite a stretch unless there is some malfunction (as you point out maybe an interaction with 60Hz heating... hmm... maybe they thought they could use PWM on the heating circuit.). For sure they have enough power and enough wire in the air to do the damage being observed. Do you know what the normal 24kHz waveform looks like? (FSK, MSK?) Some of the locals think it is iceland and that is pretty much the same beam heading as Cutler Maine. OK beam is a little optimistic,but we do have directional antennas for 160M and we do know which way is NE :-) Articles about NAA VLF say MSK@24kHz, that the deicing power available is quadruple the 3MW@60Hz to meet time goals, and it is operated remotely from somewhere around DC! -- Take care. Thanks, Brian Inglis ___ 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] Z3805A: How to correct a 1024 week date error?
On 2014-12-02 19:46, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: On 3 Dec 2014 02:08, James Robbins jsrobb...@earthlink.net wrote: Another option would be to hack the ntp software so it gives out a correct date, assuming that you can determine what the It was sold to me as a Z3801A updated to 58503A . However: 1. The main board is labeled Z3805A (Not Z3801A) as are some of the chips. 8. It reports to the GPSCon program that it is a Z3801A! NTP driver 26 supports HP 58503A and HP Z3801A GPS Receivers http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver26.html but it does not handle GPS wrap - only supported by NMEA driver, where you can find example code for wrap handling. -- Take care. Thanks, Brian Inglis ___ 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 for ntp
On 2014-10-22 21:07, Joseph Gray wrote: Now I'm confused. Both the ebay listing and the linked specsheet clearly state that the Ublox Neo-7N is used. Is this true or not? On Wed, Oct 22, 2014 at 2:50 PM, Tom Van Baak t...@leapsecond.com wrote: The USB interface will give you unpredictable timing and you still have to hook up the PPS output somehow, so can only really be recommended for navigation uses. No, both versions of this board have a very nice 1PPS output pin. Use the serial or USB interface for NMEA sentences only; use 1PPS for timing. I managed to browse to N25 not 725 devices when I looked them up! -- Take care. Thanks, Brian Inglis ___ 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 for ntp
On 2014-10-20 19:39, Joseph Gray wrote: What does everyone think of this GPS module for ntp use? According to the specsheet, it uses a Ublox Neo-7N. http://www.ebay.com/itm/RY725AI-10Hz-UART-USB-interface-GPS-Glonass-QZSS-antenna-module-flash-memory-/181562403752 Does anyone want to take a wild guess as to the best/worst case UTC offset I might get with such a setup? I realize that I'd have to try it to really find out, but guesses and advice from those more knowledgeable is always appreciated. RYN25AI and RYN25DI actually use a MAX-7C (Crystal), with no RTC, designed for low cost, low power, a passive antenna, and for the AI, a USB interface. The USB interface will give you unpredictable timing and you still have to hook up the PPS output somehow, so can only really be recommended for navigation uses. http://www.ebay.com/itm/RYN25DI-10Hz-RS232-interface-high-performance-GPS-Glonass-antenna-module-battery-/181553452840?pt=LH_DefaultDomain_0hash=item2a456dd728 The DI has an RS-232 interface so you can at least hook that up with the PPS on DCD to the BB UART and get less jittery results, which will vary with temperature, as it uses only a regular crystal oscillator. -- Take care. Thanks, Brian Inglis ___ 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 jump
On 2014-10-11 00:49, Hal Murray wrote: gign...@gmail.com said: Is it actually possible to phase lock two oscillators together cross the distance from DC to Colorado Springs? (2400 kilometers or so). ? I think so - if your clocks are stable enough. There is probably a simple rule for PLL stability based on round-trip-time and bandwidth (and other factors). TWSTFT http://www.usno.navy.mil/USNO/time/twstt and http://tf.nist.gov/time/twoway.htm where NIST says stability is .1-1ns/day and better than GPS common view at 1-10ns accuracy http://tf.nist.gov/time/commonviewgps.htm -- Take care. Thanks, Brian Inglis ___ 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 jump
On Oct 9, 2014, at 7:43 PM, Jim Palfreyman jim77...@gmail.com wrote: We look after 5 separate hydrogen masers spread all over Australia and we collect tic phases between the masers and the GPS. On around ~Oct 7 we have noticed that the normal steady straight line (with standard daily noise) took a noticeable downward turn - on all 5 masers. On 2013-10-03 05:33, Jim Palfreyman wrote: Noticed an above average bump in our H-Maser vs GPS graphs - from sites all over Australia. Recent coronal mass ejection or US government shutdown not updating GPS? Anyone else seen it? drop out gap between about 04.21-04.26 UTC? clockstats.20131003: 56568 15684.876 127.127.20.4 $GPRMC 042124 A ... 56568 16004.862 127.127.20.4 $GPRMC 042644 A ... peerstats.20131003: 56568 15684.876 127.127.20.4 961a -0.02270 ... 0.05344 56568 16004.862 127.127.20.4 961a -0.13150 ... 0.15721 loopstats.20131003: 56568 15684.876 -0.02270 0.899 0.07071 0.70 4 56568 16004.862 -0.13150 0.898 0.08830 0.000114 4 Did anyone else who tracks H-masers notice this as well? Is it JPL making corrections? Le 10 oct. 2014 à 03:09, Bob Camp a écrit : GPS is steered by the Air Force last time I checked. A really good place to check is the NIST Time and Frequency pages that show both real time and historical data for each GPS sat compared to NIST time: http://www.nist.gov/pml/div688/grp40/gpsarchive.cfm Hopefully it’s accessible via that link from a variety of locations. Since the NIST data is independent of the steering (two different outfits involved) it should not be vulnerable to a “our ground segment broke and we steered everything to match” sort of error. On 2014-10-09 23:06, mike cook wrote: I remember Jim reported a similar issue back in october last year: That dates are close enough to make you wonder if it is not part of some cycle. From: http://www.usno.navy.mil/USNO/time/gps/gps-info GPS SYSTEM TIME GPS system time is given by its Composite Clock (CC). The CC or paper clock consists of all operational Monitor Station and satellite frequency standards. GPS system time, in turn, is referenced to the Master Clock (MC) at the USNO and steered to UTC(USNO) from which system time will not deviate by more than one microsecond. The exact difference is contained in the navigation message in the form of two constants, A0 and A1, giving the time difference and rate of system time against UTC(USNO,MC). Page also gives links to GPS time data ftp://tycho.usno.navy.mil/pub/gps/utcgps30.dat which shows a 2ns jump in UTC(USNO)-GPS smoothed over 2 days from Oct 7-8, but that appears normal; the 1ns differences from Oct 2-7 appear anomalous. Looking at the NIST 10 min data, from Oct 3-8 the gap between GPS samples and NIST closed about 1.5ns/day, dropping now to about .5ns/day: the graph shows the values sliding down to the right, and now levelling off about zero. So are NIST and USNO steering each other? -- Take care. Thanks, Brian Inglis ___ 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] SMTP with Trimble Thunderbolt-E
On 2014-09-26 07:17, Luc Gaudin wrote: I need to have remotely access to Trimble Thunderbolt-E to manage it. I first sort out the physical (network) parts to get the Serial port out on the network (unit CSE-H53N from Sollae Systems). For management I am looking to use SNMP. Is there any system capable to convert the serial information from the Trimble Thunderbolt to SNMP ? Some people are talking about proxy agent. Is any can help ? You could also use retail serial to USB then USB to enet adapters which are probably a lot cheaper. Embedded Linux PCs such as Raspberry Pi and Beaglebone Black are cheap and can be configured with serial ports, but you may need hardware to stretch the PPS if you want to use it: FatPPS http://tapr.org/kits_fatpps.html and software to read or convert from Motorola binary TSIP, and the options seem to be: tboltd http://wa5znu.org/2011/08/tbolt to pass TSIP across TCP which would allow you to use LH on Windows or under Wine on PC Linux, gpsd http://www.catb.org/gpsd for Linux programs, or ntp http://ntp.org/downloads.html. Anything else requires you to decode the TSIP binary stream and make it available via SNMP. -- Take care. Thanks, Brian Inglis ___ 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] Anyone having a problem getting Bulletin B from maia.usno.navy.mil?
On 2014-07-11 07:54, mike cook wrote: Looks like my problem is back: /usr/local/bin/wget -O /tmp/finals-all http://maia.usno.navy.mil/ser7/finals.all 2 /dev/null gets --2014-07-11 15:35:27-- http://maia.usno.navy.mil/ser7/finals.all Resolving maia.usno.navy.mil (maia.usno.navy.mil)... 199.211.133.23 Connecting to maia.usno.navy.mil (maia.usno.navy.mil)|199.211.133.23|:80... failed: Operation timed out. Retrying. --2014-07-11 15:36:51-- (try: 2) http://maia.usno.navy.mil/ser7/finals.all Connecting to maia.usno.navy.mil (maia.usno.navy.mil)|199.211.133.23|:80... failed: Operation timed out. Retrying. Still no problems on primary maia (from outside US) but backup toshi not available right now. See note on http://maia.usno.navy.mil page about getusnoeop.ksh script and README. Customize and schedule to get your products from primary or backup servers as soon as they are posted (after 17.10UTC). The finals.all data does not seem to be available from iers, but just through usno. I use is to create graphs of UTC-UT1 delta. I was looking today as I wanted to add to my graph the difference between the observed and predicted values since the records started. Bulletin A is a USNO only product. IERS EOP PC data products are produced only weekly or end one month ago. Unfortunately it did not occur to me to backup the source data. I believe the above script may keep some backups. -- Take care. Thanks, Brian Inglis ___ 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] Anyone having a problem getting Bulletin B from maia.usno.navy.mil?
On 2014-07-09 01:30, mike cook wrote: times out. Can I get it from anywhere else? http://maia.usno.navy.mil/ser7/bulb.dat works for me - the original is at ftp://hpiers.obspm.fr/iers/bul/bulb_new/bulletinb.dat -- Take care. Thanks, Brian Inglis ___ 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] Opinions on OpenNTPD
On 2014-06-27 00:14, Matthew Martin wrote: Greetings to the group! I just obtained a Rev C Beagleboard Black this week, and the standard distribution does not include ntpd. When I check for available ntpd related packages using the aptitude command, it offers OpenBSD's openntpd as the one available ntpd package. A little bit of research on the OpenNTPD project suggests to me that it is a lightweight ntpd implementation. They even suggest that if you are looking for the ultimate accuracy you may not want to use OpenNTPD. Has anyone here actually used OpenNTPD, and perhaps made a comparison with a more standard ntpd package? I get the feeling that I would be better off with a standard ntpd. Does OpenNTPD even support PPS or the variety of clock source drivers that standard ntpd supports? Reply by Harlan Stenn to a message on NTP list: e1w2tov-0002qs...@stenn.ntp.org last I checked openntpd was actually an SNTP implementation, not an NTP implementation. H and I saw some comments talking about adding support for leap seconds, so I wouldn't expect it to support any of the algorithms, only the protocol. -- Take care. Thanks, Brian Inglis ___ 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] National Standards labs worldwide - specifically Australia
On 2014-06-29 04:33, Dr. David Kirkby wrote: I know of NPL in the UK, and NIST in the USA, but is anyone aware of other standard labs. In particular I am looking for the Australian equivalent. A Google search came across Standards Australia http://www.standards.org.au/ but I don't know how authoritative this is. There is basically nothing stopping any body here setting up a web site claiming to be the countries leading non-government standards labs. I have a very healthy skepticism of calibration laboratories in general NIST for example does have a .gov domain, which gives it a bit more credibility than a typical .com. NPL does not have a .gov, despite we use it in the UK. I found the The National Measurement Institute (NMI) http://www.measurement.gov.au/ which is probably the one I am looking for. There are people on this list who I would trust to produce a list of national standards labs more than I would from a Google search or Wikipedia. There are a couple of things I am looking to find out - neither of which are very time-nut related, but both are to some extent as they they involve measuring the phase difference between two signals. 1) There was some work done somewhere (I believe an Australian lab), which showed that calibrating a VNA with 1/8 and 3/8 offset shorts is superior to a flush short and 1/4 spacer. Both give the desired 180 degree difference in reflected signal, so at first thought they are equivalent. I do know the reason the 1/8 and 3/8 are superior, but I'd like to find a reference. 2) Who in Australia would be best at measuring the reflection coefficient of a 50 Ohm termination? BIPM lookup for NMIs - practical information useful links metrology institutes http://www.bipm.org/en/practical_info/useful_links/nmi.html AU - NMIA http://www.measurement.gov.au -- Take care. Thanks, Brian Inglis ___ 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 puck?
US GS MR350P/S4 has PPS connected http://www.usglobalsat.com/store/download/713/mr350ps4_ds_ug.pdf On 2014-06-26 14:59, Tom Van Baak wrote: David, Also check the web/eBay for: GlobalSat GPS BU353 S4 Dirt cheap, well made, water proof, high performance, NMEA or binary. They come in both USB (if you want to use them with a PC or SBC) or RS232/serial (if you want to use them with microcontrollers or data loggers or PC or SBC). The 1PPS is available at the IC, which you can access by opening the case (screws, not glue). /tvb - Original Message - From: David C. Partridge david.partri...@perdrix.co.uk To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Thursday, June 26, 2014 1:01 PM Subject: Re: [time-nuts] GPS puck? Mark, Thank you that looks ideal, now all I need is a suitable weatherproof cover and I'm in business. Regards, David Partridge ___ 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. -- Take care. Thanks, Brian Inglis ___ 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] WWVB paper in May 2014 IEEE communications...
On 2014-05-31 12:22, Scott Newell wrote: At 08:01 AM 5/31/2014, Bob Camp wrote: Hi Well that's a bit more information. We seem to be missing the deployment schedule on the other new modulation formats. I kind of doubt that the watch and clock guys are going to start the fabs turning out millions of chips until they can test all the formats. http://www.eversetclocks.com/press http://www.eversetclocks.com/receivers They claim to have shipped samples back in 2013, with production slated for Q3. I can't find anyone selling them. Is anyone recording or decoding the new phase modulation? If so, what are you using? I'm trying to measure WWVB signal quality with an old radio clock tied to a PC parallel port. Maybe I should ask for a sample of the ES100 or ES200 to compare. Don't hold your breath waiting for a reply - XW LLC d/b/a XtendWave foreclosed by Grindstone Capital - was up for public auction or private sale on Valentine's day: http://www.txheadlines.com/index.php/public_notices/article/NOTICE-OF-PUBLIC-SALE-All-of-XW-LLCs-Accounts-commercial-tort-claims-chatte/ More modulation details: http://www.nist.gov/pml/div688/grp40/upload/NIST-Enhanced-WWVB-Broadcast-Format-1_01-2013-11-06.pdf -- Take care. Thanks, Brian Inglis ___ 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] NTP and Windows 7
On 2014-03-27 07:59, John Nelson wrote: Greetings from Wales. I'm not sure whether this august forum is the appropriate place to ask a question about PC timekeeping, but in the hope that someone can point me in the right direction I'll ask anyway ;-) I have just replaced Windows XP with Windows 7. The PC involved (a fairly elderly 2.4GHz Core2 machine) runs an application called 'PlanePlotter' which requires accurate timekeeping and mandates Meinberg's NTP software. Using the UK pool.ntp.org servers as a reference source this has worked very well under XP for several years and the clock was seldom more than a few milliseconds out. Under Windows 7, however, the clock can be anything up to 0.2s awry and the offset is very erratic. The daily loopstats graph looks like a section through a mountain range. I have carefully checked all settings and combed the internet for suggestions but can see no reason for the sharply degraded performance. Is there something about Windows 7 that degrades the performance of NTP? Or is there anything subtle I can check? NTP list - setup at http://lists.ntp.org/listinfo/questions - might be better. Search archives for relevant topics. Power saving is more ubiquitous with Win 7 and it defaults to Balanced, with high jitter, and system changes make it a less consistent timekeeper than XP - Windows 8 is better. Ensure your BIOS is set to as much as possible disable spread spectrum (reduces RFI) and sleep states (reduces power). Go to Control Panel/Power, ensure your Power profile is set to High Performance and Put the computer to sleep is set to Never, then go into Advanced settings and set more things to Maximum Performance, Never, Disabled, or 100% as appropriate. -- Take care. Thanks, Brian Inglis ___ 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] other ADEV tools (was GPSDO simulation tool)
On 2014-03-21 20:50, Chris Albertson wrote: What's the best way to make an ADEV plot, other then using time lab? Timelab appears to be an MS Windows .exe file.I could write a script based on the definition of adev but I bet someone has already done this. Look for recent and some earlier posts by TVB about ADEV toolsavailable as source code on leapsecond.com. IIRC compiling is as easy as: gcc -o adev# adev#.c; run adev# /h to get instructions; then run adev# with options and an input data filename to get various *DEVs at as many tau as you could want. You can redirect output to a file, which you can load into Libre-/OpenOffice or similar spreadsheet to chart, or use gnuplot, R, or your favourite chart/graph/plot program. -- Take care. Thanks, Brian Inglis ___ 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] 3.0GHz Channel 3 installation in Agilent 53132A Counter
On 2014-03-19 16:00, James Robbins wrote: I think I may need to clarify my prior posting. Both old and new Channel 3 boards work fine (and read correctly) in my older 53132A counter. Both old and new Channel 3 boards fail to work properly in (and read 4x actual) the newer 53132A counter. So I think the problem is in the newer main 53132A box. As far as my understanding of the division ratios, I understand my error now. Thank you Dave (and some others). I have done some further testing and discovered one of HP/Agilent's little tricks. The main counter board channel 3 ribbon cable socket pin numbering does not conform to the channel 3 board ribbon cable socket numbering (they are crisscrossed). (I can supply the shifted numbers if anyone is interested.) However, my search for suspected unwanted zero ohm resistors left in the new box (to set the counter up for a 5 or 12.5GHz channel 3) has resulted in no joy and only a large headache and sore eyes:( Thanks everyone for trying to help here. It was supposed to be a plug and play addition to my counter. So much for the plan. Presumably you looked for obvious changes between the main boards? Have you checked the FW ROM markings or could you dump and compare the ROM contents? Thought of trying a straight (uncrossed) ribbon cable between the channel 3 board and the newer counter? That's the kind of change that might be done to reduce costs on newer model upgrades requiring a factory mod. -- Take care. Thanks, Brian Inglis ___ 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] 3.0GHz Channel 3 installation in Agilent 53132A counter
On 2014-03-18 12:19, James Robbins wrote: I hope this is not too OT. I have acquired a 3.0GHz original Channel 3 board for my Agilent 53132A counter. When installed, it reads four times (4x) the actual frequency. I'm wondering if anyone has any experience with such an installation and can point me to some setup item or zero ohm resistor I'm supposed to install. All that the manual says is to have it done by the factory. That will cost me more than the board itself. Many thanks. Jim Robbins N1JR According to: http://cp.literature.agilent.com/litweb/pdf/53132A-04A.pdf early serial numbers may need updated firmware. -- Take care. Thanks, Brian Inglis ___ 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] Trimble Thunderbolt 1pps
On 2014-01-27 23:32, Don Latham wrote: Mike S On 1/27/2014 1:33 PM, Robert Atkinson wrote: I looked at this a while ago. The spec only defines transmission levels, it does NOT specify receive thresholds. It certainly does... 2.1.3 For data interchange circuits, the signal shall be considered in the marking condition when the voltage on the interchange circuit, measured at the interface point, is more negative than -3 volts with respect to Circuit AB (Signal Common). The signal shall be considered in the spacing condition when the voltage is more positive than +3 volts with respect to Circuit AB (see 6.2). The region between +- 3 volts is defined as the transition region. The signal state is undefined when the voltage is in this transition region. - ANSI TIA/EIA-232-F (1997) we, maybe needed if you're running an ASR-33 teletype. . . Except ASR-33s came with a 20ma current loop interface. Later models added RS232 after it became popular. ISTR TWX terminals required one and Telex terminals the other. -- Take care. Thanks, Brian Inglis ___ 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] Trimble Thunderbolt 1pps
On 2014-01-27 12:43, Javier Herrero wrote: On 27.01.2014 19:33, Robert Atkinson wrote: All the receiver chips I've looked at, ancient and modern, have only positive thresholds. Most have single supplies and clamp the input at 1 diode drop negative WRT common after an input current limiting resistor, see the MC1489 datasheet. Not exactly. If you check the MC1489 datasheet from On Semiconductor, the thresholds can be programmed with the response control resistor and can in fact be negative. (Figures 6 and 7 in the datasheet). The serial input resistor forms part of a resistive divider with the feedback resistor and the external resistor - not simply a current limiter to the diode. Recent device app notes state the spec is more or less the same, with TIA-232-F making some changes to conform to current versions of ITU V.24, V.28, and ISO 2110, restating the old speed/distance curves in terms of load capacitance 2500pF; output is still max +/-25V @ 100mA, rise/fall time 4% of bit time, up to 30V/us slew out of 300ohm impedance, input min +/-3V into 3k-7kohm 2500pF. Most recent adapters will work with only 0/3.3V over short cables at low speeds: higher speeds up to 115,200bpps require more drive and are limited to 3m, low speeds may work over 10m. Good luck finding any docs for these interface boards nowadays. YMMV should have been stamped on these specs since day one ;^ -- Take care. Thanks, Brian Inglis ___ 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] Looking for Dual-Time Atomic Clock
On 2014-01-21 22:53, Andy wrote: Dick asked, What I am looking for is a way to display Local Time (MST) and Zulu (GMT) time in a small (6 X 8 or similar) package. There must be two displays and both lock up to NBS. Has anyone seen such a thing ? Might not meet all your specs, but MFJ may have something: http://www.mfjenterprises.com/Product.php?productid=MFJ-121B (too big?) http://www.mfjenterprises.com/Product.php?productid=MFJ-133RC (shows only one zone at a time?) Looks like MFJ-108B http://www.mfjenterprises.com/Product.php?productid=MFJ-108B fits your specs at a quarter the price, and it says it can be synced to WWV, although their product manual (single page setting guide) does not mention that feature. -- Take care. Thanks, Brian Inglis ___ 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] WAAS.....
Thought of or tried ground plane antennas like Trimble choke ring, Zephyr or similar to attenuate below horizon interference? On 2014-01-08 01:25, Brian, WA1ZMS wrote: In this case the timing rcvrs are located all with in a 20km radius with fixed known surveyed locations. The problem is GPS jamming that happens at random times. So one what if idea is to use a WAAS enabled rcvr and a yet to be selected parabolic antenna to point at a given WAAS sat. The concept is to give all rcvrs a single common view for critcal timing use in a comm system. The ultimate goal is to try and reduce the number of times when full sky view GPS antennas are victims of GPS band interference. This is only a half-baked idea of mine (in my day-job) but wanted Time Nuts feedback to see if it has any merit at all. BTW, the system has Rb for hold-over when there are problems but the frequent system error alarms indicating hold-over events is what I/we would like to reduce. New SNMP traps could mask off the events, but being an RF guy.I was thinking about a HW solution. :- ) -Brian, WA1ZMS/4 iPhone On Jan 7, 2014, at 11:05 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Brian, On 2014-01-08 02:25, Brian, WA1ZMS wrote: Hypothetical question For a given set of GPS timing grade receivers at multiple locations, is there any advantage by limiting allowable SVN numbers to only be the WAAS satellites? Well, if you do common view GPS comparision and is not into monitoring observables separately (which is recommended), then there is some use for it, as you configure the WAAS acceptance statically and only need to update it once a new bird becomes available or one disappears. However, I wonder if they are any good for that purpose anyway. So, in a more general way, I'd say no. More importantly, what are you trying to achieve? -- Take care. Thanks, Brian Inglis ___ 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] Using a UBlox NEO-6 GPS module for calibrating a PIC microprocessor based timer.
On 2013-12-01 15:52, Attila Kinali wrote: On Sun, 1 Dec 2013 13:57:56 -0500 Dale J. Robertson d...@nap-us.com wrote: A unidirectional error of 1/100th of a second would accumulate around a minute and a half per day. It's been a long time since I laid eyes on a mechanical pendulum clock. I remember the clock in my childhood home kept better time than that. ( I became odd very early. I compulsively compared the clock time to WWV time at least once a day. I had been using the time service from the phone company. I felt defrauded when I discovered (via WWV) that the time from the local telco's dialup time service was just a rough (very rough) approximation of the time. IIRC 10^-6 was easily acheivable with mechanical clocks, with the best going to 10^-8 or so (timescale IIRC 1 day). Hi, Many clocks and watches were tuned for years before being submitted for rating. Astronomical regulators (accurate pendulum clocks) kept time within .01s/day, and were improved down to about 1s/year, with the help of electromagnets, before being replaced by quartz oscillators in the 1930s; regulators in other areas were replaced by electric clocks timed from the grid during that same period. The best of these had Q ~110,000, with variations in the hundreds of us/day, better than network synced NTP servers which vary in the low ms. Mechanical marine chronometer movements are expected to vary only about 0.1s/day. Quartz wristwatch COSC certified chronometer movements are rated within .2s/day. Railroad chronometer movements were expected to stay within 30s/week or ~4s/day. Mechanical wristwatch COSC certified chronometer movements are rated within +6/-4s/day. The Geneva Standard certifies movements stay within 60s/week or ~8s/day. The certifications and standards (including ISO 3159) also require drift in multiple orientations and across a range of temperatures ~0-~40C should remain constant. So with 1 PPM ~ 1 s/11.5 day about 1-10 PPM or 10^-5 to 10^-6 range is expected. Most modern quartz wristwatches will be in this range and be more accurate than all but the best, custom mechanical timepieces. -- Take care. Thanks, Brian Inglis ___ 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] Morion MV89 and LTC6957
On 2013-11-11 05:32, Attila Kinali wrote: Moin Bernd, On Mon, 11 Nov 2013 12:47:15 +0100 Bernd Neubig bneu...@t-online.de wrote: Unfortunately, since they redesigned their webpages, i cannot find the OCXOs listed anywhere anymore (only the 8607 shows up). Oscilloquartz has discontinued their OCXO line. The only exception is the BVA OCXO. Oh..kay? Did Oscilloquartz at least sell their OCXO business to someone else? Or did they just close it? (I googled, but didn't get any results) Looks like Swatch Group Electronic Systems may have rationalized their company product lines this year and all the crystal and OCXO business is now done thru MicroCrystal - see http://www.oscilloquartz.com/textes-swatch-group-858 -- Take care. Thanks, Brian Inglis ___ 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 to H-Maser comparison
On 2013-10-03 05:33, Jim Palfreyman wrote: Noticed an above average bump in our H-Maser vs GPS graphs - from sites all over Australia. Recent coronal mass ejection or US government shutdown not updating GPS? Anyone else seen it? drop out gap between about 04.21-04.26 UTC? clockstats.20131003: 56568 15684.876 127.127.20.4 $GPRMC 042124 A ... 56568 16004.862 127.127.20.4 $GPRMC 042644 A ... peerstats.20131003: 56568 15684.876 127.127.20.4 961a -0.02270 ... 0.05344 56568 16004.862 127.127.20.4 961a -0.13150 ... 0.15721 loopstats.20131003: 56568 15684.876 -0.02270 0.899 0.07071 0.70 4 56568 16004.862 -0.13150 0.898 0.08830 0.000114 4 ___ 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] NIST off-line
It could well if the electrical utility bills are not paid for a few months! On 2013-10-01 12:09, paul swed wrote: Yes but wwvb is on a AA battery it will run out. :-) On Tue, Oct 1, 2013 at 1:45 PM, Tom Minnis tom_min...@att.net wrote: WWV is still ticking Tom On 10/1/2013 10:13 AM, David McGaw wrote: NIST is off-line due to the shutdown. http://www.nist.gov/pml/div688 __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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-nutshttps://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] refclock - NTP server settings/tuning?
From what I've seen on the NTP groups, others' sites, and my own systems,
refclocks must be polled frequently (maxpoll 4).
You will get a more jittery trace but much lower offset and jitter.
The current stable NTP GPS NMEA driver has added user mode PPS support for
systems where a kernel PPS driver is unsupported, and how it does so may be
worth a look, to get similar results from your PTP packets.
Help is available by subscribing to questi...@lists.ntp.org.
You may also want to see whether you can use what the Linux PTP project offers.
On 2013-09-29 06:11, Anders Wallin wrote:
Thanks for all replies,
I can try changing maxpoll to a larger value and see if the trace is
smoother.
The refclock driver is a userspace C-program (daemon) that essentially does:
while(1) {
gettimeofday(tv,NULL) // system time, for NTP receiveTimeStamp
get_wr_time(wr_tv); // WR time, for NTP clockTimeStamp
// write tv and wr_tv to shared memory where NTP expects to see them
sleep(8);
}
This may be the cause of a constant negative offset I see, since one
time-stamp is always read before the other. Perhaps this could be improved
by reading system time both before and after get_wr_time() and reporting
the average of the two readings as receiveTimeStamp? Or measure the offset
and put it as a time1 offset-value in ntp.conf
If the driver was written as a kernel module, would that run with higher
priority and less variable delay?
I use the same piece of code to log how well system time tracks WR-time.
Here I sometimes see sudden spikes of 100s of microseconds. Could this be
caused by the OS context switching in the middle of my program between the
two timestamp-reading functions? Again, would this improve if the
time-logger was written as a kernel module, or is there some other way of
coding it that avoids context switches and keeps the two time-stamp reading
functions atomic?
Standard Ubuntu nowadays has a pre-packaged lowlatency kernel which I
think is RT-Preempt with some modifications. But I assume both the
refclock-driver and the logger would need a re-write to take advantage of
the RT-kernel. Does anyone have experienced with that?
thanks,
Anders
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Re: [time-nuts] Jackson Labs' Web-Site
nslookup fails and whois shows their domain registration expired yesterday On 2013-09-03 01:42, John C. Westmoreland, P.E. wrote: Hello All, A little off topic maybe - is it just me or is the Jackson-Labs.com site down/offline? http://www.jackson-labs.com http://jackson-labs.com Regards, John Westmoreland ___ 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-18, Windows, NTP Lat Lon
This question might be more appropriate for the NTP list at questi...@lists.ntp.org. Assuming you are using GPS 18 NMEA output and NMEA driver 20, set the statsdir either using the startup command line option -s or the conf command statsdir, as shown below, and enable clockstats: appends the $GPRMC message every poll interval e.g. minpoll 4 maxpoll 4 = 16s ~ 5400 lines/day. For example: ntpd ... -s c:/etc/ntp/stats -c c:/etc/ntp.conf ... OR in c:/etc/ntp.conf statsdir c:/etc/ntp/stats AND enable stats statistics clockstats loopstats peerstats # ref-clock drivers server 127.127.20.n prefer minpoll 4 maxpoll 4 ... On 2013-09-03 18:42, Jim Lux wrote: On 9/3/13 5:35 PM, Jim Lux wrote: I'm looking for an easy way to get current lat lon, when you've got a GPS-18 hooked up for NTP. That is, the GPS receiver is there doing it's NTP thing, so presumably it knows where it is. If NTP is decoding the GPRMC message, it has the lat/lon in it, so how can I get that info out (in a command line utility, into a file, or some such) I don't need millisecond time accuracy.. For now the GPS is just to make sure that the time is right. The GPGGA sentence would also do. And, I only need the GPS position once within a 30 second interval (it's not moving, I just want to know where it is). It's not like ntpd or ntpq have some handy switch that says display current lat/lon (which makes sense, because NTP is fundamentally time source agnostic). All of this with Windows 7. I suppose one way is to turn off NTP (releasing the com port), grab some data from the com port, parse it, then turn NTP back on. But that seems mighty clunky... I was hoping for some log file/debug feature that says give me the last sentence from the GPS. ___ 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] NTP/1-PPS/RS232 question
On 2013-08-20 02:45, Björn wrote: b...@lysator.liu.se said: The PTTI 1PPS is defined in http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf It is 20us long and common in some applications. However the voltage levels are a bit high... The section I saw said 10 V nominal, +1, -2. That's 8-11 V. I think that would work fine with a RS-232 receiver. Yes, but driving 10V into _50ohms_ is a lot of power for a modern receiver... /Björn RS-232 transmitter output impedance is 50 ohms, and that may be what the PPS timing info diagram shows the PPS signal being driven into. That PTTI spec Electrical Characteristics states receiver input impedance is 5kohms, so the diagram could also have a typo. Those levels are compatible with RS-232 3k-7k receiver input impedance range, *BUT* the transmitter output should be able to drive 10 receiver inputs, which may be possible with some RS-232 transmitters, but is not required with RS-232. ___ 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.
