Re: [time-nuts] GPS Weekly Rollover Fail
This will be my Z3801A's second rollover and its third 1024-week epoch. Is there any pre-1980 GPS equipment still out there that will be undergoing a third rollover and fourth 1024-week epoch? Was the 1978-1979 Block 1 GPS usage, using a different base date, or were there more fundamental changes in 1980? The Block 1 birds were still in use in the 1990's. Tim N3QE On Wed, Feb 6, 2019 at 8:18 AM Bob kb8tq wrote: > Hi > > One would *hope* that everybody making multi GNSS modules would be cross > checking > and taking care of GPS rollover that way. It’s always nice to see them > explicitly stating > that they are doing it. > > Bob > > > On Feb 6, 2019, at 12:57 AM, Michael Wouters > wrote: > > > > BeiDou, Galileo and GLONASS all broadcast UTC time of day (or thereabouts > > for GLONASS - it's offset by the timezone for Moscow) so any multi-GNSS > > receiver has a sanity check on UTC calculated from GPS. > > > > Michael > > > > On Wed, 6 Feb 2019 at 11:03 am, Bob kb8tq wrote: > > > >> Hi > >> > >> From what I can see, you can send it a command that puts a new “oldest > >> date” > >> number into flash. Since it also tracks Glonass and Galileo, that will > >> stretch out the > >> time before you *need* to do something (like into the next century). > They > >> also have > >> the “no dates before the firmware was issued” check. There may be other > >> date > >> checks in there. Those are just what I’ve found so far. > >> > >> It also is likely that the “new” GPS sats will be flying within 19 > years. > >> That will add > >> more bits to the GPS time fields. Who knows if the “modern” modules > >> already handle > >> those bits or not …. > >> > >> Bob > >> > >>> On Feb 5, 2019, at 5:23 PM, Hal Murray > wrote: > >>> > >>> > >>> kb...@n1k.org said: > The F9P has multiple cross checks, traps, and even a user configurable > “oldest possible date” entry. > >>> > >>> Neat/thanks. > >>> > >>> Is that stored in flash, or lost on power cycle? > >>> > >>> If it's in flash, I can "fix" things for another 20 years by extracting > >> the > >>> device from its box, taking it to a bench setup, running a flash-update > >>> program, then reassembling things. As ugly as that is, it may be > >> simpler than > >>> updating the firmware in the box. > >>> > >>> > >>> -- > >>> These are my opinions. I hate spam. > >>> > >>> > >>> > >>> > >>> ___ > >>> time-nuts mailing list -- time-nuts@lists.febo.com > >>> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >>> and follow the instructions there. > >> > >> > >> ___ > >> time-nuts mailing list -- time-nuts@lists.febo.com > >> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> and follow the instructions there. > >> > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] GPS Weekly Rollover Fail
Hi One would *hope* that everybody making multi GNSS modules would be cross checking and taking care of GPS rollover that way. It’s always nice to see them explicitly stating that they are doing it. Bob > On Feb 6, 2019, at 12:57 AM, Michael Wouters > wrote: > > BeiDou, Galileo and GLONASS all broadcast UTC time of day (or thereabouts > for GLONASS - it's offset by the timezone for Moscow) so any multi-GNSS > receiver has a sanity check on UTC calculated from GPS. > > Michael > > On Wed, 6 Feb 2019 at 11:03 am, Bob kb8tq wrote: > >> Hi >> >> From what I can see, you can send it a command that puts a new “oldest >> date” >> number into flash. Since it also tracks Glonass and Galileo, that will >> stretch out the >> time before you *need* to do something (like into the next century). They >> also have >> the “no dates before the firmware was issued” check. There may be other >> date >> checks in there. Those are just what I’ve found so far. >> >> It also is likely that the “new” GPS sats will be flying within 19 years. >> That will add >> more bits to the GPS time fields. Who knows if the “modern” modules >> already handle >> those bits or not …. >> >> Bob >> >>> On Feb 5, 2019, at 5:23 PM, Hal Murray wrote: >>> >>> >>> kb...@n1k.org said: The F9P has multiple cross checks, traps, and even a user configurable “oldest possible date” entry. >>> >>> Neat/thanks. >>> >>> Is that stored in flash, or lost on power cycle? >>> >>> If it's in flash, I can "fix" things for another 20 years by extracting >> the >>> device from its box, taking it to a bench setup, running a flash-update >>> program, then reassembling things. As ugly as that is, it may be >> simpler than >>> updating the firmware in the box. >>> >>> >>> -- >>> These are my opinions. I hate spam. >>> >>> >>> >>> >>> ___ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] GPS Weekly Rollover Fail
BeiDou, Galileo and GLONASS all broadcast UTC time of day (or thereabouts for GLONASS - it's offset by the timezone for Moscow) so any multi-GNSS receiver has a sanity check on UTC calculated from GPS. Michael On Wed, 6 Feb 2019 at 11:03 am, Bob kb8tq wrote: > Hi > > From what I can see, you can send it a command that puts a new “oldest > date” > number into flash. Since it also tracks Glonass and Galileo, that will > stretch out the > time before you *need* to do something (like into the next century). They > also have > the “no dates before the firmware was issued” check. There may be other > date > checks in there. Those are just what I’ve found so far. > > It also is likely that the “new” GPS sats will be flying within 19 years. > That will add > more bits to the GPS time fields. Who knows if the “modern” modules > already handle > those bits or not …. > > Bob > > > On Feb 5, 2019, at 5:23 PM, Hal Murray wrote: > > > > > > kb...@n1k.org said: > >> The F9P has multiple cross checks, traps, and even a user configurable > >> “oldest possible date” entry. > > > > Neat/thanks. > > > > Is that stored in flash, or lost on power cycle? > > > > If it's in flash, I can "fix" things for another 20 years by extracting > the > > device from its box, taking it to a bench setup, running a flash-update > > program, then reassembling things. As ugly as that is, it may be > simpler than > > updating the firmware in the box. > > > > > > -- > > These are my opinions. I hate spam. > > > > > > > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] GPS Weekly Rollover Fail
Hi From what I can see, you can send it a command that puts a new “oldest date” number into flash. Since it also tracks Glonass and Galileo, that will stretch out the time before you *need* to do something (like into the next century). They also have the “no dates before the firmware was issued” check. There may be other date checks in there. Those are just what I’ve found so far. It also is likely that the “new” GPS sats will be flying within 19 years. That will add more bits to the GPS time fields. Who knows if the “modern” modules already handle those bits or not …. Bob > On Feb 5, 2019, at 5:23 PM, Hal Murray wrote: > > > kb...@n1k.org said: >> The F9P has multiple cross checks, traps, and even a user configurable >> “oldest possible date” entry. > > Neat/thanks. > > Is that stored in flash, or lost on power cycle? > > If it's in flash, I can "fix" things for another 20 years by extracting the > device from its box, taking it to a bench setup, running a flash-update > program, then reassembling things. As ugly as that is, it may be simpler > than > updating the firmware in the box. > > > -- > These are my opinions. I hate spam. > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] GPS Weekly Rollover Fail
kb...@n1k.org said: > The F9P has multiple cross checks, traps, and even a user configurable > âoldest possible dateâ entry. Neat/thanks. Is that stored in flash, or lost on power cycle? If it's in flash, I can "fix" things for another 20 years by extracting the device from its box, taking it to a bench setup, running a flash-update program, then reassembling things. As ugly as that is, it may be simpler than updating the firmware in the box. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] GPS Weekly Rollover Fail
On Tue 2019-02-05T13:02:47-0800 Tom Van Baak hath writ: > GPS time began Jan-1980 and the first rollover occurred in Aug-1999. > The next one is April-2019 and Nov-2038 after that. > We time nuts will be on full alert Saturday evening April 6 to > Sunday morning April 7 to find and record any anomalies. The actual GPS 1023 to 0 is not the only date when these events happen. About a dozen buses in the county fleet are currently displaying dates in mid 1999 presumably because their GPS firmware adds some constant to the GPS week number. Previous rollovers happened last year and have been fixed; new rollovers happened around the beginning of this year. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] GPS Weekly Rollover Fail
Hi If you take a look at some of the modules that have come out in the last few years, they now have much better protection for rollover issues than the older parts did. The F9P has multiple cross checks, traps, and even a user configurable “oldest possible date” entry. Bob > On Feb 5, 2019, at 4:02 PM, Tom Van Baak wrote: > > Bob, > >> is this just a known routine bug > > Yes, known. Yes, routine. No, not a bug. > > GPS system time is kept as a 10-bit week number and 20-bit second number. The > seconds count from 0 to 604799 and the week counts from 0 to 1023. What this > means is that every 1024 weeks (approx 19.62 years) there is a rollover. [1] > > GPS time began Jan-1980 and the first rollover occurred in Aug-1999. The next > one is April-2019 and Nov-2038 after that. > > These rollovers tend to have zero impact on position and navigation, but it > can affect the calculated UTC time in some receivers. This is not due to a > flaw in GPS but a lack of rigorous design and testing by the authors of the > receiver firmware. Even with simulation it's hard to fully test something > that occurs only once every 20 years under all conditions. > > We time nuts will be on full alert Saturday evening April 6 to Sunday morning > April 7 to find and record any anomalies. > > /tvb > > [1] https://www.gps.gov/cgsic/meetings/2017/powers.pdf > > > - Original Message ----- > From: "Bob Betts" > To: > Sent: Tuesday, February 05, 2019 10:11 AM > Subject: [time-nuts] GPS Weekly Rollover Fail > > >> Hello All: >> Just curious, but is this just a known routine bug that is methodically >> dealt with or is there a more serious problem in the system(s)? >> >> Here's the quote from a notice at www.gps.gov >> >> Thanks, >> Bob, N1KPR >> >> <https://www.gps.gov/governance/advisory/meetings/2017-11/powers.pdf> >> -- >> >> Failure: April 6/7, 2019 >> >> •UTC timing displayed and/or time tags of receiver data containing PNT >> information could jump by 19.7 years, resulting in system failures >> •Any month/year conversion could also fail•Navigation solution should be OK >> since GPS time is internally self consistent, but associated time tags could >> be incorrect thus corrupting navigation data at the system level•And the >> failure is not limited to April 6/7 2019 >> •A common fix for week number ambiguity was to hard code new pivot date, >> which shifts event to unknown date/time in future. >> >> –December 2014, older legacy USNO monitor receiver failed >> –Feb 14, 2016 Endruntechnology receivers using a Trimble GPS engine failed >> –Aug 14, 2016 Motorola OncoreUT+ older firmware failed >> –July 22, 2017 older Novatel GPS engine failed, notice was posted in Spring >> 2017 to upgrade firmware, but many did not check >> >> >> >> >> NOTE Pls add backup address to your phone book: rwbe...@yahoo.com >> >> http://www.bobsamerica.com http://www.youtube.com/n1kpr >> >> Engineering: Where Enigma meets Paradox >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] GPS Weekly Rollover Fail
Bob, > is this just a known routine bug Yes, known. Yes, routine. No, not a bug. GPS system time is kept as a 10-bit week number and 20-bit second number. The seconds count from 0 to 604799 and the week counts from 0 to 1023. What this means is that every 1024 weeks (approx 19.62 years) there is a rollover. [1] GPS time began Jan-1980 and the first rollover occurred in Aug-1999. The next one is April-2019 and Nov-2038 after that. These rollovers tend to have zero impact on position and navigation, but it can affect the calculated UTC time in some receivers. This is not due to a flaw in GPS but a lack of rigorous design and testing by the authors of the receiver firmware. Even with simulation it's hard to fully test something that occurs only once every 20 years under all conditions. We time nuts will be on full alert Saturday evening April 6 to Sunday morning April 7 to find and record any anomalies. /tvb [1] https://www.gps.gov/cgsic/meetings/2017/powers.pdf - Original Message - From: "Bob Betts" To: Sent: Tuesday, February 05, 2019 10:11 AM Subject: [time-nuts] GPS Weekly Rollover Fail > Hello All: > Just curious, but is this just a known routine bug that is methodically dealt > with or is there a more serious problem in the system(s)? > > Here's the quote from a notice at www.gps.gov > > Thanks, > Bob, N1KPR > > <https://www.gps.gov/governance/advisory/meetings/2017-11/powers.pdf> > -- > > Failure: April 6/7, 2019 > > •UTC timing displayed and/or time tags of receiver data containing PNT > information could jump by 19.7 years, resulting in system failures > •Any month/year conversion could also fail•Navigation solution should be OK > since GPS time is internally self consistent, but associated time tags could > be incorrect thus corrupting navigation data at the system level•And the > failure is not limited to April 6/7 2019 > •A common fix for week number ambiguity was to hard code new pivot date, > which shifts event to unknown date/time in future. > > –December 2014, older legacy USNO monitor receiver failed > –Feb 14, 2016 Endruntechnology receivers using a Trimble GPS engine failed > –Aug 14, 2016 Motorola OncoreUT+ older firmware failed > –July 22, 2017 older Novatel GPS engine failed, notice was posted in Spring > 2017 to upgrade firmware, but many did not check > > > > > NOTE Pls add backup address to your phone book: rwbe...@yahoo.com > > http://www.bobsamerica.com http://www.youtube.com/n1kpr > > Engineering: Where Enigma meets Paradox > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
