Re: [time-nuts] ...Your thoughts on the Trimble Resolution T?
Hi, if I remember my statistics correctly: 1-Sigma is the standard deviation of all measurements. 6-Sigma is something like 99.997%(?) of all measurements, basically all relevant measurements. Keep in mind that the Motorola GPS need to be initialized by a binary string, they will not produce any output signal until initialized. Also, the Motorola parts have one drawback: they need a Lithium battery (or similar) to keep the most recent Almanac. I have found that the TTFF (first fix) can take quite long if the battery is weak (2V) and the RTC stops due to this, or if there is no Almanac in Memory. Don't know how the Trimble unit behaves. The Clock Granularity message is to be applied to the next following 1PPS pulse in Motorola speak. Typically, the 1PPS is captured by a Microcontroller, which can then add the granularity message data to the capture time, and thus improve the measurement over the long term. bye, SJ ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] ...Your thoughts on the Trimble Resolution T?
In message [EMAIL PROTECTED], [EMAIL PROTECTED] writes: Also, the Motorola parts have one drawback: they need a Lithium battery (or similar) to keep the most recent Almanac. I have found that the TTFF (first fix) can take quite long if the battery is weak (2V) and the RTC stops due to You can capture and store the almanac on your computer/microcontroller/whatever and initialize the receiver with it when you cold start. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] ...Your thoughts on the Trimble Resolution T?
[EMAIL PROTECTED] wrote: The Clock Granularity message is to be applied to the next following 1PPS pulse in Motorola speak. Typically, the 1PPS is captured by a Microcontroller, which can then add the granularity message data to the capture time, and thus improve the measurement over the long term. The hardware granularity message can be used to provide a hardware correction to the time of the next one-pulse-per-second pulse. Richard Hambly, who does business as CNS Systems http://www.cnssys.com/ will sell you his CNS Clock II) with a Precise PPS option that includes this hardware-corrected 1 PPS output. The $1500 price includes the M12+ timing receiver nicely packages, together with the hardware clock correction option, power supply, etc., and his SynTac32 software to control it from a PC. You supply (or purchase from him) the external antenna with 5 volt or 3 volt low noise amplifier (LNA) and the antenna cable. In recent correspondence with me, Hambly claims: Recent tests of the CNS Clock II with the precision PPS option shows short term noise of about ± 3 nsec pk-pk with drift over a 10-minute period, probably due to ionoshperic variations, creating an overall error of ± 10 nsec pk-pk (zero mean, 3.7 nsec 1-sigma) as referenced to an HP5065A Rubidium Standard, itself calibrated to GPS. (I presume he's using nsec to mean nanosecond -- even though the standard SI symbol for the nanosecond is ns rather than nsec.) -- James Maynard Salem, Oregon, USA ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] ...Your thoughts on the Trimble Resolution T?
You can find M12+ sawtooth information and plots at: http://www.leapsecond.com/pages/m12/sawtooth.htm Also, here is a nice graph comparing the 1 PPS error of 4 GPS receivers: http://www.leapsecond.com/pages/gps4/cns-1pps.gif Dark blue is a Motorola Oncore VP with approximately +/- 50 ns of jitter; 30 ns rms. Pink is a Motorola M12+, 10 ns rms. Yellow is a Motorola M12+ with hardware (or software) sawtooth correction; 6 ns rms. Green is an HP SmartClock (58503B) with 1.3 ns rms. Note however that although the short-term jitter is less there appears to be more wander of the phase mid-term (typical of a GPSDO). So in the end, for long-term 1 PPS timing use, I found the M12+ with sawtooth correction more stable than the other GPS receivers, including a GPSDO. /tvb http://www.LeapSecond.com ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] ...Your thoughts on the Trimble Resolution T?
Hi: I'm not sure if Trimble does it on the Resolution T, but on the Trimpack GPS receivers, http://www.pacificsites.com/~brooke/Trimpack.shtml#BUB have a Lithium battery soldered to one of the PCBs and a Dallas chip that turns all the RAM into non volatile memory (just like core memory in operation). This means that when powered up it not only has the almanac and ephemeris data for all the satellites it also has the fix information so the warm start time is very short. They say if the receiver is moved more than 100 km TTFT will be longer. My Trimpacks which were built in the 1990 (Gulf war) time period all have good batteries, so the current needed to do this must be very small. The sawtooth correction can be used with hardware to move the 1 PPS edge or it can be used in software where a computer does the math on the measured time interval. Have Fun, Brooke Clarke, N6GCE [EMAIL PROTECTED] wrote: . . . Also, the Motorola parts have one drawback: they need a Lithium battery (or similar) to keep the most recent Almanac. I have found that the TTFF (first fix) can take quite long if the battery is weak (2V) and the RTC stops due to this, or if there is no Almanac in Memory. Don't know how the Trimble unit behaves. . . . . ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Manual
TIA John! If i can do anything for you, tell me! Regards Ulrich -Ursprüngliche Nachricht- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von John Ackermann N8UR Gesendet: Freitag, 31. März 2006 16:08 An: Discussion of precise time and frequency measurement Betreff: Re: [time-nuts] Manual Ulrich, I think I have a manual for the 103. I'll see if I can get it scanned, though it may take a week or so. John Ulrich Bangert wrote: Folks, a good friend of mine got his hands on a surplus FLUKE 103 frequency phase comparator. Has anyone of you a manual of this device that he can share with him? Or a pointer to to a pdf on the web? Regards Ulrich Bangert [EMAIL PROTECTED] Ortholzer Weg 1 27243 Gross Ippener ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi- bin/mailman/listinfo/time-nuts ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
