Re: [time-nuts] Divider circuit for Rubidium Standard
On 4/26/2015 3:51 AM, Bryan _ wrote: All: P I was looking at the project from David partridges web site http://www.perdrix.co.uk/FrequencyDivider/index.html -=Bryan=- ___ This is a comparator based circuit. This will give you worse performance than just about anything else, but it may be good enough anyway. Rick Karlquist N6RK ___ 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] CM level GPS accuracy in a smartphone
Should be fun when it becomes available... they claim they can get accurate carrier phase info using a cheap antenna in the phone... and in real time. It should also be able to get accurate time. http://www.eurekalert.org/pub_releases/2015-05/uota-ncg050415.php ___ 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] TymServe 2100 1995 Issue - A Kludgy Fix
Hi, 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. Will the next time this problem reoccurs be another 20 years? Alan ___ 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] The low budget UT+ newbie time-nut project: FrequencyReference
HI For what you are doing, RG-6 Quad Shield is fine. Save the LMR-400 for other things. Get a pigtail that will connect to the GPS board. It needs to be pretty flexible. That connector is not very study. Don’t bother with an adapter. Been there / done that, not a good idea. You need the mechanical isolation a thin coax gives you. Get one with an SMA, N, or F connector on the other end. The auction sites have tons of them. Consider that the best way to get things lined up is to divide the time base down to 1 pps and use the counter to watch what it does vs the GPS. You can get good accuracy without a lot of hassle that way. Bob On May 5, 2015, at 7:35 PM, Tom Van Baak t...@leapsecond.com wrote: For reasons unknown to me, the body of the message was missing on the first attempt. Hi Bob, While we debug your mail problem, here is your post. /tvb - Original Message - From: Bob Fleming To: time-nuts@febo.com Sent: Tuesday, May 05, 2015 3:36 PM Subject: The low budget UT+ newbie time-nut project: Frequency Reference For reasons unknown to me, the body of the message was missing on the first attempt. The low budget UT+ newbie time-nut project: Frequency Reference Thanks to Bob Stewart’s generous offer I am now in possession of the heart of my first time-nut project. My first stage plan is to make something for screwdriver disciplining the 10Mhz reference on my frequency counter for work with ham radio. Bought on ebay for a ridiculous low bid my Fluke 1953A -20 is synced to WWV as well as propagation will allow. It was fading in and out over two minutes at one point and that is good enough for ham radio but just good enough is not what I desire and it took the better part of three days spare time fooling with it to get it that close. (fail) I have seen a reference to changing the 1PPS output of the UT+ to 100PPS but if that is not applicable to my UT+ I will divide the 10Mhz by 100. In either case my scope will be triggered with the UT+ to compare signals as discussed here a few weeks ago. First thing I noticed about the UT+ is that the power/control 10 pin connector headder on the UT+ looks just like internal USB headers on a computer motherboard. In fact, a pair of 5 pin of USB header plugs fit perfectly. Second there is the antenna connector, the OCX. Apparently an MCX is required and I have none. Then there is wire selection for the antenna. Before I can buy an MCX connector I better decide on the wire. I have plenty of RG6 quad shield, enough LMR-400 that I was saving for another project and several boxes of radio shack RG8 that I can’t find any use for. The rat shack RG8 is pretty much hopeless but I haven’t recycled it yet. LMR-400 is too stiff to plug directly in the tiny OCX without a pigtail of much more flexible wire and extra connectors. Input impedance of the UT+ is 50 ohms but I am tempted to use the RG6 because my 20’ run will only lose about 2 DB not including impedance mismatch on both ends. My limited experience with over 1GHz is that any connector will have losses so I suspect that using 75 ohm RG6 coax won’t be much worse than the LMR-400 with extra connectors, adapter and a pigtail. Critique of my plans and/or guidance will be greatly appreciated. I guess about a dozen of us will be building newbie time nut projects with these. Thanks, Bob Fleming N5TX time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] The low budget UT+ newbie time-nut project: FrequencyReference
Bob, I'm sure much more qualified nuts will chime in, but a few thoughts of mine. Over the years, I've collected enough GPS antennas from hamfests, online vendors and who-knows-where, all for prices from free to tens of dollars. Most of them came with anywhere from 3' to 10+meters of cable. Most of those cables have been terminated in SMA connectors. Not sure how long you think your cable run will be (mine is 15', skylight to workbench) but I'd stay away from RG6 just as a matter of practice. The antennas are generally amplified, but still... MCX to SMA pigtails are cheap and plentiful. Once you are SMA, everything else is easy. To me, division is far better than trying to modify the UT+. Welcome to the asylum. The inmates all have good ideas! On Tue, May 5, 2015 at 7:35 PM, Tom Van Baak t...@leapsecond.com wrote: For reasons unknown to me, the body of the message was missing on the first attempt. Hi Bob, While we debug your mail problem, here is your post. /tvb - Original Message - From: Bob Fleming To: time-nuts@febo.com Sent: Tuesday, May 05, 2015 3:36 PM Subject: The low budget UT+ newbie time-nut project: Frequency Reference For reasons unknown to me, the body of the message was missing on the first attempt. The low budget UT+ newbie time-nut project: Frequency Reference Thanks to Bob Stewart’s generous offer I am now in possession of the heart of my first time-nut project. My first stage plan is to make something for screwdriver disciplining the 10Mhz reference on my frequency counter for work with ham radio. Bought on ebay for a ridiculous low bid my Fluke 1953A -20 is synced to WWV as well as propagation will allow. It was fading in and out over two minutes at one point and that is good enough for ham radio but just good enough is not what I desire and it took the better part of three days spare time fooling with it to get it that close. (fail) I have seen a reference to changing the 1PPS output of the UT+ to 100PPS but if that is not applicable to my UT+ I will divide the 10Mhz by 100. In either case my scope will be triggered with the UT+ to compare signals as discussed here a few weeks ago. First thing I noticed about the UT+ is that the power/control 10 pin connector headder on the UT+ looks just like internal USB headers on a computer motherboard. In fact, a pair of 5 pin of USB header plugs fit perfectly. Second there is the antenna connector, the OCX. Apparently an MCX is required and I have none. Then there is wire selection for the antenna. Before I can buy an MCX connector I better decide on the wire. I have plenty of RG6 quad shield, enough LMR-400 that I was saving for another project and several boxes of radio shack RG8 that I can’t find any use for. The rat shack RG8 is pretty much hopeless but I haven’t recycled it yet. LMR-400 is too stiff to plug directly in the tiny OCX without a pigtail of much more flexible wire and extra connectors. Input impedance of the UT+ is 50 ohms but I am tempted to use the RG6 because my 20’ run will only lose about 2 DB not including impedance mismatch on both ends. My limited experience with over 1GHz is that any connector will have losses so I suspect that using 75 ohm RG6 coax won’t be much worse than the LMR-400 with extra connectors, adapter and a pigtail. Critique of my plans and/or guidance will be greatly appreciated. I guess about a dozen of us will be building newbie time nut projects with these. Thanks, Bob Fleming N5TX time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent KS-24361/Thunderbolt antenna advice sought.
Hi Ok, all of these receivers are designed to work with an amplified antenna. The typical antennas have between 20 and 30 db of gain. They allow a cable loss of ~ 10 db between the antenna and the receiver. A 3 db splitter would come out of the “cable loss” budget. The receivers put out 5V on the coax. You can find antennas that only work with 7V. You can also find 3.3V antennas that will be damaged by 5V. Most of the low cost antennas you come across will work at 5V. You want an outside / permanent antenna location. Magnetic mount “car style” antennas often do not survive well when kept outdoors for a long time. They also are a bit tough to mount solidly. You will spend weeks letting the GPSDO’s stabilize and many days doing surveys. Throwing that all away each time the antenna moves is no fun. The auction sites will sell you a “timing” antenna for $40 delivered. With some shopping, you can get a very good antenna for $150 delivered. You already have $300 to $500 invested. Skimping on the antenna does not make a lot of sense. There are a number of different antenna designs out there. You can make a good one any number of different ways. There is nothing magic about a quad helix style. Bob On May 5, 2015, at 11:35 AM, Oghma og...@live.co.uk wrote: Thanks to Vlad, Bob, and Chris for the responses so far - and for the helpful suggestions/advice. Since the focus of the answers to my (I suppose, dual-headed) question has been on the splitting/sharing aspect, rather than on actual antenna type/model, I'm guessing that the actual antenna used doesn't matter - would that be a fair assumption to make? So, does that mean that I could use a simple patch type antenna intended for use with in-car gps 'satnav' style units - such as the ones Garmin sell? I only ask because I have seen some discussion of quad-helix (and LHCP vs RHCP) antennas, and most of the pictures I have seen of the innards of antennas have been Q-H style. Also, given that dc feeds are provided by the receivers, it would suggest that some dirt of active/amplified antenna is expected to be connected. Foitnote: I'm in the UK, so I'm not sure that the 'cable TV splitters' referred to would be available here. We do have cable TV, but if I understand correctly, the signals (if not carried into the house on optical fibres) are all sent down the cable in the sub 500MHz range - perhaps someone on the list who is in the UK could comment further on that? Regards John Sent tomorrow from my time machine. ___ 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] Tymserve 2100 thinks it's 1995?
Hi The point is that the company likely has newer products that are based on the same code concepts. Not all software ideas are covered by copyright or a patent. Once you give away copies of the code, the world can base products off that code. You now have a competitor who has a *much* lower cost basis that you do. The next layer to the onion is selling the company. Many of these companies sell primarily for their IP and not for any other of their assets. You can watch them get sold, the IP stripped out, and then re-sold for a lot less money. Yes it’s a crazy world…. Bob On May 5, 2015, at 11:46 AM, Alan Ambrose alan.ambr...@anagram.net wrote: Hi, You can claim that software costs nothing once you write the first copy. In the next breath we all expect to get ongoing customer support for that software and (e ) patches for this and that. When a vendor charges us by the year for that support we are unhappy. Would I love to see all these 10 to 20 year old boxes running perfectly 20 years from now - sure. It's a noble goal. I have a *lot* of boxes. With all the GPS issues in the past, and likely in the future - not likely to happen. Of course, once the suppliers have decided they can't make any further money from it, it would be a nice goodwill gesture to make the software open source so that others can fix it if they want. Alan ___ 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] The low budget UT+ newbie time-nut project: FrequencyReference
For reasons unknown to me, the body of the message was missing on the first attempt. Hi Bob, While we debug your mail problem, here is your post. /tvb - Original Message - From: Bob Fleming To: time-nuts@febo.com Sent: Tuesday, May 05, 2015 3:36 PM Subject: The low budget UT+ newbie time-nut project: Frequency Reference For reasons unknown to me, the body of the message was missing on the first attempt. The low budget UT+ newbie time-nut project: Frequency Reference Thanks to Bob Stewart’s generous offer I am now in possession of the heart of my first time-nut project. My first stage plan is to make something for screwdriver disciplining the 10Mhz reference on my frequency counter for work with ham radio. Bought on ebay for a ridiculous low bid my Fluke 1953A -20 is synced to WWV as well as propagation will allow. It was fading in and out over two minutes at one point and that is good enough for ham radio but just good enough is not what I desire and it took the better part of three days spare time fooling with it to get it that close. (fail) I have seen a reference to changing the 1PPS output of the UT+ to 100PPS but if that is not applicable to my UT+ I will divide the 10Mhz by 100. In either case my scope will be triggered with the UT+ to compare signals as discussed here a few weeks ago. First thing I noticed about the UT+ is that the power/control 10 pin connector headder on the UT+ looks just like internal USB headers on a computer motherboard. In fact, a pair of 5 pin of USB header plugs fit perfectly. Second there is the antenna connector, the OCX. Apparently an MCX is required and I have none. Then there is wire selection for the antenna. Before I can buy an MCX connector I better decide on the wire. I have plenty of RG6 quad shield, enough LMR-400 that I was saving for another project and several boxes of radio shack RG8 that I can’t find any use for. The rat shack RG8 is pretty much hopeless but I haven’t recycled it yet. LMR-400 is too stiff to plug directly in the tiny OCX without a pigtail of much more flexible wire and extra connectors. Input impedance of the UT+ is 50 ohms but I am tempted to use the RG6 because my 20’ run will only lose about 2 DB not including impedance mismatch on both ends. My limited experience with over 1GHz is that any connector will have losses so I suspect that using 75 ohm RG6 coax won’t be much worse than the LMR-400 with extra connectors, adapter and a pigtail. Critique of my plans and/or guidance will be greatly appreciated. I guess about a dozen of us will be building newbie time nut projects with these. Thanks, Bob Fleming N5TX 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] CM level GPS accuracy in a smartphone
Hi I think I’d bet on L1/L5 (with similar accuracy) showing up cheap on the market first. Bob On May 5, 2015, at 6:01 PM, Mark Sims hol...@hotmail.com wrote: Should be fun when it becomes available... they claim they can get accurate carrier phase info using a cheap antenna in the phone... and in real time. It should also be able to get accurate time. http://www.eurekalert.org/pub_releases/2015-05/uota-ncg050415.php ___ 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] 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] TymServe 2100 1995 Issue - A Kludgy Fix
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. Will the next time this problem reoccurs be another 20 years? Alan Hi Alan, Correct, the date conversion is trivial. See www.leapsecond.com/tools/gpsepoch.c or gpsweek.c for example. The hard part is understanding when the GPS receiver fails and when to apply the 1024 week correction, or not. This is made difficult or impossible if the receiver does not give you internal information or if you do not already have external information (like an alternative, independent GPS, or UTC date source). If you wanted to cheat you could keep an independent clock inside the Arduino and then add or subtract 1024 weeks until it looked right. But this is complicated by power failures in either the GPS receiver or the Arduino. Worse yet are cold starts where the receiver doesn't know what the UTC-GPS correction is. It gets messy at best. And without testing in a GPS simulator you can't be sure what will happen when epoch changes again on 2019-03-31 or some other random date in the future. With these epoch issues going on I also wouldn't trust the receiver to handle the upcoming leap second correctly either. I mean, 2015-06-30 is an accepted date for a leap second. But if you're 1024 weeks back in time the receiver will try to apply the leap on 1995-11-14, which is not a valid end of month date. What will it do? I don't know. So these are all things that would have to be tested and perhaps delegated to the Arduino to sort out. It's just not simple to get 100% reliable UTC from a sick GPS receiver. The receivers that fail right at the epoch (1999-08-15 or 2019-03-31 or 2038-11-14) are simple to work-around. Also receivers that allow user input of year, so that they can cache the GPS epoch number, are also simple to work-around. But this TymServe 2100 doesn't seem to fall into either of those categories. I hope this sheds light on why a simple, trustworthy fix is not likely. And with millions of GPS receivers out there that have no problems this week, because they were designed right in the first place, you have to ask yourself if a hack to this old make/model is worth it. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] The low budget UT+ newbie time-nut project: Frequency Reference
___ 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
Seems to me that the obvious simple answer works this way: Since the GPS must use an RS232 connection to communicate its information to the other devices in the telescope, all that need be done is to write a fairly trivial program to run on a PIC, or Arduino, that when presented with the date, adds 20 to the year, and then sends it on to the rest of the system. Everything that is not a date gets passed through unmolested. -Chuck Harris Pete Stephenson wrote: On Tue, May 5, 2015 at 2:42 AM, Andrew Cooper acoo...@keck.hawaii.edu wrote: We also ran into the TS2100 1995 bug this weekend. For us the consequences are a bit more severe... The telescopes will not point to the right location in the sky without accurate time! Ouch. I have some friends who work at the Subaru telescope. I'll check in to see if they're affected. For now we have configured a temporary fix... We set up two units, previously our primary and hot spare. The first unit is set to use GPS, which of course has the correct time but the wrong date. The first unit is sending a 1PPS signal to a second unit which is set to 1PPS input mode with a manually set date and time. We now have all of the IRIG and NTP capability we need and the correct date. Out of curiosity, is there no way to prime the device with the current date/time (e.g. from a wristwatch) so it can interpret the GPS week information correctly? I recall that several other devices have that ability. Is there a list of other common time-nut devices that are susceptible to similar issues? Lots of time-nuts use surplus equipment that's no longer supported and it'd not be fun to have them stop working. Cheers! -Pete ___ 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
p...@heypete.com said: Is there a list of other common time-nut devices that are susceptible to similar issues? Lots of time-nuts use surplus equipment that's no longer supported and it'd not be fun to have them stop working. We should make a list of good/bad units. The Z3801A does the right thing if you tell it the date. (I had one that was off by 1024 weeks and it's working correctly now.) -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TymServe 2100 1995 Issue - A Kludgy Fix
Hi Chuck, 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). So you have to convert the incorrect UTC date and time back to GPS date and time, then apply the 1024 GPS week correction, and then convert back to UTC. This requires knowledge of all leap seconds during the past 1024 week cycle and this information is not present in the GPS signal or in the binary or NMEA messages that come out of a GPS receiver. Don't forget to account for all the leap years during that period too: 1024 weeks is 19.638 normal years but 19.585 leap years. And when you power-on the GPS receiver it may have the wrong leap second count as well, wrong for both 1995 and wrong for 2015. You have to wait up to 12.5 minutes for that information to come down at 50 baud. Not saying it isn't possible, but it's not easy. And then you need to test it against last week and this week, and the week before and after June 30 of this year when the next leap second occurs. I realize the TymServe 2100 issue is unrelated to leap seconds. But leap seconds severely complicate any simple conversion between time scales, especially if you are interested in second or sub-second accuracy. /tvb - Original Message - From: Chuck Harris cfhar...@erols.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, May 05, 2015 6:33 AM Subject: Re: [time-nuts] TymServe 2100 1995 Issue - A Kludgy Fix Seems to me that the obvious simple answer works this way: Since the GPS must use an RS232 connection to communicate its information to the other devices in the telescope, all that need be done is to write a fairly trivial program to run on a PIC, or Arduino, that when presented with the date, adds 20 to the year, and then sends it on to the rest of the system. Everything that is not a date gets passed through unmolested. -Chuck Harris ___ 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
Hi The simple list of devices susceptible to this problem is: Almost all of them from before 1998, many of them after that. The issue is inherent in the design of the GPS coding and un-aided recovery of that coding. The need to address it only was apparent to most marketing departments after the first batch of gear started failing in the late 90’s. Bob On May 5, 2015, at 3:30 AM, Pete Stephenson p...@heypete.com wrote: On Tue, May 5, 2015 at 2:42 AM, Andrew Cooper acoo...@keck.hawaii.edu wrote: We also ran into the TS2100 1995 bug this weekend. For us the consequences are a bit more severe... The telescopes will not point to the right location in the sky without accurate time! Ouch. I have some friends who work at the Subaru telescope. I'll check in to see if they're affected. For now we have configured a temporary fix... We set up two units, previously our primary and hot spare. The first unit is set to use GPS, which of course has the correct time but the wrong date. The first unit is sending a 1PPS signal to a second unit which is set to 1PPS input mode with a manually set date and time. We now have all of the IRIG and NTP capability we need and the correct date. Out of curiosity, is there no way to prime the device with the current date/time (e.g. from a wristwatch) so it can interpret the GPS week information correctly? I recall that several other devices have that ability. Is there a list of other common time-nut devices that are susceptible to similar issues? Lots of time-nuts use surplus equipment that's no longer supported and it'd not be fun to have them stop working. Cheers! -Pete -- Pete Stephenson ___ 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] Lucent KS-24361/Thunderbolt antenna advice sought.
Thanks to Vlad, Bob, and Chris for the responses so far - and for the helpful suggestions/advice. Since the focus of the answers to my (I suppose, dual-headed) question has been on the splitting/sharing aspect, rather than on actual antenna type/model, I'm guessing that the actual antenna used doesn't matter - would that be a fair assumption to make? So, does that mean that I could use a simple patch type antenna intended for use with in-car gps 'satnav' style units - such as the ones Garmin sell? I only ask because I have seen some discussion of quad-helix (and LHCP vs RHCP) antennas, and most of the pictures I have seen of the innards of antennas have been Q-H style. Also, given that dc feeds are provided by the receivers, it would suggest that some dirt of active/amplified antenna is expected to be connected. Foitnote: I'm in the UK, so I'm not sure that the 'cable TV splitters' referred to would be available here. We do have cable TV, but if I understand correctly, the signals (if not carried into the house on optical fibres) are all sent down the cable in the sub 500MHz range - perhaps someone on the list who is in the UK could comment further on that? Regards John Sent tomorrow from my time machine. ___ 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] Ultra High Stability Time Base Options for 53132A
Joe and I discovered some component value errors in the schematic I posted yesterday. I uploaded a corrected schematic to Didier's site. The filename of the corrected schematic is: HP_53132-60011_Timebase_Support_Board_schematic_redrawn.pdf When it comes off quarantine, you will be able to search for it at http://www.ko4bb.com/manuals/. Changes: R5, R6, R7, R8, and R9 changed from 5.6k to 56.2 ohms. For those who are wondering, the circuitry Joe drew in, which is present on the 60011 Timebase Support Board but not on the 60016 support board, is a buffer amplifier for the output of the 10811 OCXO in counters with Option 010 or 012. Best regards, Charles I am attaching a file with the capacitor values added. I have also uploaded it to Didier's site (filename is HP_53132-60011_Timebase_Support_Board_redrawn.pdf). ___ 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?
Hi all, The problem is not the 2100. It is the Trimble Ace III receivers inside of it. There is a company in France, Heol Design, that makes what is essentially a replacement for the Ace III, they call it an N024 model. I am currently in contact with them to see if their units will correct this issue. I first noticed the problem in the Datum BC635 cards and when I tried to go back to a 2100 is when it was confirmed for me. The French units are about $100 apiece and I'll keep you updated on if they work or not. In other 2100 news if you revert the firmware back to it's oldest version (2.something) that is embedded in the 2100 it gets rid of the 1 second leap issue. You'll lose quite a few options and functionality like the NIST ACTS connection, which I don't think works anyway, but your time will finally be right again. I did this by beginning the firmware update process and power cycling my machine during it. Basically by screwing it up you can make it better. Sean Gallagher On 5/4/2015 10:09 PM, Robert Watzlavick wrote: Mine was fine until I power cycled it :( I can confirm that even with the v4.1 firmware, power cycling it causes the date to revert back to 1995. A software restart as listed below seems to restore the correct date for awhile but it eventually reverts back to the wrong year. Maybe some smart guy can reverse engineer the binary and patch it. It must have already been patched once by the vendor since it seems unlikely the GPS firmware would have been updated. Luckily I have an ET-6000 so I can always feed IRIG-B from it into the TS-2100 until it too exhibits the rollover bug. After that runs out, I can use the 1 PPS input. -Bob On 05/04/2015 01:23 PM, Mark Strovink wrote: Bob Martink6rtm@... writes: Additional information -- Power cycling (leaving it off for about 5 minutes) didn't do any good. Once at the correct time/date, it bounces back to 1995 at about 30 seconds after the hour (now to Sep 18, 1995). My Tymserve 2100 gps unit (Rev 4.1) thinks it's 1995 -- September 17, 1995. But a restart (connect via telnet and give the commands util restart) brings it back to the correct time and date -- for a while? I haven't caught it dropping back, so i don't know if it's doing this on the hour, after an hour, or what, but I noticed it last night, and I've restarted it a few times today. Any clues? I know about the off-by-a-second issue with the pending leap second. This one is more interesting! So far I've just been issuing software restarts. The next time I'll power cycle the sucker and see if that does any good. GPS signal isn't the issue; the 2100 shares an external GPS antenna with my Thunderbolts through a Symmetricom 58536A GPS splitter, and the Thunderbolts are as happy as a Thunderbolt can be. cheers bob k6rtm What a great way to start a Monday: phone call that the entire domain was back in 1995. The good news: Tymserve units will keep the correct date in Free mode. GPS handling, not the GPS signail, is the problem. The GPS unit is rolling the date over to its initial date once the date is past May 2 or 3, 2015. The bad news: Tech support said the company will not be providing a fix for a product 5 years past end of support. ___ time-nuts mailing list --time-nuts@febo.com To unsubscribe, go tohttps://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. -- Respectfully, Sean Gallagher Malware Analyst 571-340-3475 ___ 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
Hi Tom, One of the first words I taught my precocious kid when he was less than a year old was balderdash. It seemed appropriate for him to know that word if I was going to be his father. Hard for me to believe that little boy graduates from CMU with his BS in physics this month The currently buggy GPS receiver is outputting UTC time that is offset by 1024 weeks, and some number of seconds from reality. The past is irrelevant if we know the present offset. Add in that offset, reformat the UTC data frame and send it out when asked. An Arduino can do that in a very small number of milliseconds. And, the Arduino's time burden can be well known and applied to the data, if it is significant. 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? Seems way simpler to me than all of that code I had to wade through and cleanse of Y2K bugs. Since the OP was talking about a multi million dollar research telescope, which presumably matters to a lot of people, I will refrain from commenting about the wisdom of ignoring the well publicized 1024 week roll over bug, and not replacing/reflashing the GPS receiver years ago. -Chuck Harris Tom Van Baak wrote: Hi Chuck, 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). So you have to convert the incorrect UTC date and time back to GPS date and time, then apply the 1024 GPS week correction, and then convert back to UTC. This requires knowledge of all leap seconds during the past 1024 week cycle and this information is not present in the GPS signal or in the binary or NMEA messages that come out of a GPS receiver. Don't forget to account for all the leap years during that period too: 1024 weeks is 19.638 normal years but 19.585 leap years. And when you power-on the GPS receiver it may have the wrong leap second count as well, wrong for both 1995 and wrong for 2015. You have to wait up to 12.5 minutes for that information to come down at 50 baud. Not saying it isn't possible, but it's not easy. And then you need to test it against last week and this week, and the week before and after June 30 of this year when the next leap second occurs. I realize the TymServe 2100 issue is unrelated to leap seconds. But leap seconds severely complicate any simple conversion between time scales, especially if you are interested in second or sub-second accuracy. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tymserve 2100 thinks it's 1995?
Hi Sean, Thanks much for that information. 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. Note GPS Week Numbers system, as defined by the ICD200 GPS Specification, occupy a range from zero to 1023. The Week Number Roll Over (WNRO) occurs every 1024 weeks, or approximately every 19 years 8 months. August 1999 was the first roll-over for the GPS system since the beginning of GPS time on 06 January 1980. 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. Does anyone on the list know how well the http://www.heoldesign.com replacement works? Thanks, /tvb [1] http://trl.trimble.com/dscgi/ds.py/Get/File-1883/ace%20iii.pdf - Original Message - From: Sean Gallagher s...@wetstonetech.com To: time-nuts@febo.com Sent: Tuesday, May 05, 2015 10:06 AM Subject: Re: [time-nuts] Tymserve 2100 thinks it's 1995? Hi all, The problem is not the 2100. It is the Trimble Ace III receivers inside of it. There is a company in France, Heol Design, that makes what is essentially a replacement for the Ace III, they call it an N024 model. I am currently in contact with them to see if their units will correct this issue. I first noticed the problem in the Datum BC635 cards and when I tried to go back to a 2100 is when it was confirmed for me. The French units are about $100 apiece and I'll keep you updated on if they work or not. In other 2100 news if you revert the firmware back to it's oldest version (2.something) that is embedded in the 2100 it gets rid of the 1 second leap issue. You'll lose quite a few options and functionality like the NIST ACTS connection, which I don't think works anyway, but your time will finally be right again. I did this by beginning the firmware update process and power cycling my machine during it. Basically by screwing it up you can make it better. Sean Gallagher ___ 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?
Hi, You can claim that software costs nothing once you write the first copy. In the next breath we all expect to get ongoing customer support for that software and (e ) patches for this and that. When a vendor charges us by the year for that support we are unhappy. Would I love to see all these 10 to 20 year old boxes running perfectly 20 years from now - sure. It's a noble goal. I have a *lot* of boxes. With all the GPS issues in the past, and likely in the future - not likely to happen. Of course, once the suppliers have decided they can't make any further money from it, it would be a nice goodwill gesture to make the software open source so that others can fix it if they want. Alan ___ 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] TimeLab + sr620
Hello Magnus, It was a baud rate issue. Time Monitor defaults to 9600 and Time Lab uses 19200. Changed the counter and time monitor to use 19.2k and every body is happy. Now I have to figure out how to use time lab. My TIE plots just show as a strait line, I can zoom in to show detail but the y scale will go form +1.00E0 to +1.00E0 . I'm sure its a setting. Thank you On May 4, 2015, at 10:40 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Lincoln, Did you configure the coulder to use RS232 rather than GPIB? It's in the manual. Cheers, Magnus On 05/04/2015 07:28 AM, lincoln wrote: Hello, I've taken a first pass at using TimeLab over the weekend. I wasn't able to get it to work with my SRS sr 620 over RS232. I know that the com port / serial cable and counter are working. I can open terminal, talk to the counter, and make a measurement. When I setup a measurement in TimeLab If I hit the monitor button I don't see any activity. If I start the measurement, Time lab never gets past trying to establish communication with the counter. I'm sure its my fault. Any thoughs? thanks Lincoln ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TymServe 2100 1995 Issue - A Kludgy Fix
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. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] The low budget UT+ newbie time-nut project: Frequency Reference
I think the lowest cost GPSDO frequency reference has to be one made from these parts. You can get up and running for under $50. 1) the UT+ 2) a patch antenna 2) the Lars Walenius Arduino based controller, using the $3 version of the Arduino 3) An eBay OCXO for about $20. (this is the most expensive part) I built the above and at every decision point did what was both simplest and lowest cost. I just wanted to see what would happen. I ran it for a few months. I kept the output of this and the output from a Thunderbolt on each channel of my dual channel scope. Visually they kept in phase. One would drift right of left then be corrected. I could not see it drift, I'd have to come back and check now and then.Yes I know not a good characterization but in keeping with the simplest thing that can still work idea. On Mon, May 4, 2015 at 5:19 PM, Bob Fleming bob.flem...@usa.com wrote: ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TimeLab + sr620
Lincoln, Did you configure the coulder to use RS232 rather than GPIB? It's in the manual. Cheers, Magnus On 05/04/2015 07:28 AM, lincoln wrote: Hello, I've taken a first pass at using TimeLab over the weekend. I wasn't able to get it to work with my SRS sr 620 over RS232. I know that the com port / serial cable and counter are working. I can open terminal, talk to the counter, and make a measurement. When I setup a measurement in TimeLab If I hit the monitor button I don't see any activity. If I start the measurement, Time lab never gets past trying to establish communication with the counter. I'm sure its my fault. Any thoughs? thanks Lincoln ___ 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] TymServe 2100 1995 Issue - A Kludgy Fix
On Tue, May 5, 2015 at 2:42 AM, Andrew Cooper acoo...@keck.hawaii.edu wrote: We also ran into the TS2100 1995 bug this weekend. For us the consequences are a bit more severe... The telescopes will not point to the right location in the sky without accurate time! Ouch. I have some friends who work at the Subaru telescope. I'll check in to see if they're affected. For now we have configured a temporary fix... We set up two units, previously our primary and hot spare. The first unit is set to use GPS, which of course has the correct time but the wrong date. The first unit is sending a 1PPS signal to a second unit which is set to 1PPS input mode with a manually set date and time. We now have all of the IRIG and NTP capability we need and the correct date. Out of curiosity, is there no way to prime the device with the current date/time (e.g. from a wristwatch) so it can interpret the GPS week information correctly? I recall that several other devices have that ability. Is there a list of other common time-nut devices that are susceptible to similar issues? Lots of time-nuts use surplus equipment that's no longer supported and it'd not be fun to have them stop working. Cheers! -Pete -- Pete Stephenson ___ 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 splitter (was antenna advice sought)
The 58535A splitter has been spoken for. ___ 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.
