[time-nuts] ! PPS Source
I have been using 1 PPS from a Motorola M-12 timing module to steer a SRS PRS-10. I recently heard that a U-Blox ZED F9P module receives both L1 and L2 and can provide much improved positional accuracy. Would better positions translate into a smoother 1 PPS? Does anyone have experience with this U-Blox module? Can this be set up with a fixed position as a timing module? Is there a better source of 1 PPS at a reasonable cost? The U-Blox is about $200. Thanks, Joe, W7LUX --- This email has been checked for viruses by AVG. https://www.avg.com ___ 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] HP-105B Battery
Hello Roy, I replaced the original batteries with two 12 Volt 3.3 Ah SLA batteries and a string of diodes between the batteries to compensate for the different battery voltages. This is not perfect, but it works for about 3 years before the batteries need replacing. I used 7 1N4004 diodes in series to prevent overcharge and a MBRF1045 diode across the diode string to allow discharge. The SLA batteries float at 13.7 volts each. Be careful to not let the metal battery box touch and short the meter terminals. I used some of the original battery box plastic strips between the now loose battery box and the meter. Best, Joe, W7LUX --- This email has been checked for viruses by AVG. https://www.avg.com ___ 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] Portable Time Standard
Hello Petr and others, Thank you for the suggestions. I have several DS3231 modules running. I was able to adjust one to 0.04 PPM fast, which is more than good enough for my requirement of one second a month (this is at a constant temperature, but these RTC chips are supposed to be temperature compensated). I can read and write the DS3231 registers with a Raspberry Pi. Unfortunately, the RPi kernel sends time to the RTC every 11 1/2 minutes. This time is usually moderately accurate, but I have measured errors of up to 0.264 second, which is unacceptable. Does anyone have suggestions for a very low power controller and display for this RTC integrated circuit? The DS3231 has a 1 Hz square wave output that could signal the controller to read and display the time and date from the DS3231. The controller could sleep between updates, which would conserve batteries. Thanks again for all the suggestions, Joe By the way, the manufacturer of the high accuracy marine chronometer I was considering will not send specifications for other than 22 +/- 1 degree C. These DS3231 modules are a complete clock On 2/17/2019 3:46 PM, Petr Titěra wrote: > Hello, > > as I've said these are quite new, cheap RTC modules. There is DS3231SN > on them. Based on markings they were manufactured somewhere in 2008 but > I've bought them recently. > > I have two those modules. Both connected using I2C. > > First module is connected to Orange Pi sitting on my table. Pi is > running NTP and is controlled by NEO-6M GPS module (not timing, I know > butat this level accuracy of PPS signal should be enough). > > I measure in 10 seconds intervals difference between system time (which > I consider stable in long term) and time reported by RTC chip as > reported by adjtimex in compare mode. > > This is a little bit naive setup because timing from RTC is noisy but in > long run (its running for 25 days now) it should give me reasonable results. > > I did modify offset register. Again using naive approach. I've let run > unmodified module for one day and from that I did compute offset required. > > For second module I'm meassuring just now I don't care about time > reported and meassure only interval between rising edge of its PPS > pulses and PPS pulses from another GPS. Again for this measurement I > consider GPS PPS signal as stable. > > This second one is a little bit worse (or may be wrongly calibrated) but > I still get about 0.3PPM from my measurements. > > Petr Titera > > > > > Dne 17. 2. 2019 v 19:00 Joe Hobart napsal(a): >> Hello Petr, >> >> Your accuracy results are impressive. I have questions: >> >>What manufacture or brand DS3231 do you have? >> >>What do you use to communicate with the DS3231 and display time? >> >>How long has your DS3231 been running? >> >>Have you changed the crystal aging offset register(s) to compensate for >> crystal aging? >> >> Thank you, >> Joe >> >> >> On 2/15/2019 12:51 PM, Petr Titěra wrote: >>> Hello, >>> >>> sorry to reopen this old thread but it took me some time to measure. As >>> I've said I have one RTC module sitting right on my desk in my room >>> where temperatures can go anywhere between 3C and 20C. >>> >>> Using naive method of comparison of time difference between system time >>> and RTC module I get time difference only about 4.487869e-02 seconds in >>> 22 days. >>> >>> Petr Titera >>> >>> Dne 14. 1. 2019 v 16:11 Joe Hobart napsal(a): >>>> Hello Petr, >>>> >>>> I have not found a low power RTC chip that will keep 1 second a month with >>>> changes in temperature. This clock will be used to synchronize a portable >>>> communications system. >>>> >>>> Thank you, >>>> Joe >>>> >>>> >>>> On 1/13/2019 2:23 PM, Petr Titěra wrote: >>>>> I will probably sound dumb but did you consider cheap RTC chips? I have >>>>> one based on DS3231 currently on my table and although its is specified >>>>> to have precision +/-2PPM my seems to be in range about 0.5PPM right >>>>> from package with possibility to do some corrections. >>>>> >>>>> Petr Titera >>>>> >>>>> Dne 11. 1. 2019 v 20:57 Joe Hobart napsal(a): >>>>>> I need a relatively lightweight, self powered, portable clock accurate >>>>>> to 1 >>>>>> second per month. Temperatures may range from 10 to 35 C; altitude from >>>>>> 1000
Re: [time-nuts] Portable Time Standard
Hello Petr, Your accuracy results are impressive. I have questions: What manufacture or brand DS3231 do you have? What do you use to communicate with the DS3231 and display time? How long has your DS3231 been running? Have you changed the crystal aging offset register(s) to compensate for crystal aging? Thank you, Joe On 2/15/2019 12:51 PM, Petr Titěra wrote: > Hello, > > sorry to reopen this old thread but it took me some time to measure. As > I've said I have one RTC module sitting right on my desk in my room > where temperatures can go anywhere between 3C and 20C. > > Using naive method of comparison of time difference between system time > and RTC module I get time difference only about 4.487869e-02 seconds in > 22 days. > > Petr Titera > > Dne 14. 1. 2019 v 16:11 Joe Hobart napsal(a): >> Hello Petr, >> >> I have not found a low power RTC chip that will keep 1 second a month with >> changes in temperature. This clock will be used to synchronize a portable >> communications system. >> >> Thank you, >> Joe >> >> >> On 1/13/2019 2:23 PM, Petr Titěra wrote: >>> I will probably sound dumb but did you consider cheap RTC chips? I have >>> one based on DS3231 currently on my table and although its is specified >>> to have precision +/-2PPM my seems to be in range about 0.5PPM right >>> from package with possibility to do some corrections. >>> >>> Petr Titera >>> >>> Dne 11. 1. 2019 v 20:57 Joe Hobart napsal(a): >>>> I need a relatively lightweight, self powered, portable clock accurate to 1 >>>> second per month. Temperatures may range from 10 to 35 C; altitude from >>>> 1000 to >>>> 7000 feet. Although expensive, some of the marine quartz chronometers >>>> appear to >>>> meet this requirement. ~0.3 PPM. >>>> >>>> Does anyone have any experience with these devices? >>>> >>>> If so, has anyone tried to detect the probably weak magnetic field >>>> generated by >>>> the clock mechanism for time comparison purposes? >>>> >>>> Thanks, >>>> Joe, W7LUX >>>> >>>> --- >>>> This email has been checked for viruses by AVG. >>>> https://www.avg.com >>>> >>>> >>>> ___ >>>> 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] Portable Time Standard - Additional Clarification
Here is more explanation: I need a stand-alone, easily portable unit with display; the unit may be used where GPS, cell phone, or WWVB are not available. Low power consumption is highly desirable. I have seen advertisements of marine quartz chronometers listing an accuracy as good as <0.01 second/day at a constant temperature of 22 C. Has anyone had experience with a marine quartz chronometers? If so, how much did the accuracy vary with temperature? Thanks for the suggestions about pickup coils; I had hoped a coil would detect the clock movement well enough to compare to a standard 1 PPS. I have a Motorola GPS timing module and a storage oscilloscope for comparison. Joe --- This email has been checked for viruses by AVG. https://www.avg.com ___ 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] Portable Time Standard
I need a relatively lightweight, self powered, portable clock accurate to 1 second per month. Temperatures may range from 10 to 35 C; altitude from 1000 to 7000 feet. Although expensive, some of the marine quartz chronometers appear to meet this requirement. ~0.3 PPM. Does anyone have any experience with these devices? If so, has anyone tried to detect the probably weak magnetic field generated by the clock mechanism for time comparison purposes? Thanks, Joe, W7LUX --- This email has been checked for viruses by AVG. https://www.avg.com ___ 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] Lots of Off Topic discussion,
Scott McGrath I am an amateur radio operator (62 years), and I have accurate 1 PPS and 10 MHz available. I also coordinate emergency communications for this very large county. I use WWV: To judge propagation during normal and other than normal times To set clocks after a power outage To calibrate relatively new amateur radio transceivers (not Collins) To set my computer clock to better than 1/10 second for FT8 digital mode and when I was recovering faint asteroids that were in danger of being lost It is easy to set clocks within 1/10 second while watching the digital display and listening to the WWV/WWVH tics. I tend to get the wrong second when I use a GPS clock. Best, Joe Hobart ___ 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.
