Re: [time-nuts] Tbolt Damping setting
Good points, and You got 4 1/2 out of five correct, Not bad at all. Ha ha - thank you teacher! Fairy nuff, yes, your plots show the long-term effects. I would like to know what the best time-constant is to use. I appreciate that everyone's will be different, depending on individual characteristics of the Thunderbolts, and also (perhaps more importantly) the aerial and its position. However, I think it would be interesting to at least see the relative differences for one location. I recently learnt that our national mapping organisation (The Ordnance Survey) average the results from their L1/L2 Leica 1200 system receivers, for two hours. Is the oscillator in the Leica significantly worse than that in out Thunderbolts, or could we also benefit from a time-constant of longer than 1000 seconds? I will try to find a quiet rubidium, and do some comparisons against that - the results should, at least, be valid out to a few thousand seconds. I also plan to try reducing the signal level threshold (from the current 4AMU) as recently suggested, and try to see some quantifiable results. TTFN, Peter Vince (G8ZZR, London, England) ___ 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] Source for Trimble Bullet GPS antennas?
My Trimble Bullet antenna seems less sensitive than any other GPS antenna I have (a Symmetricom, a good-looking Trimble mag-mount and several cheap active antennas). I receive fewer sats with the Bullet, at any time that I have tried. Maybe it is defective, or maybe that's the way it is. I bought the Symmetricon HP 58532A new on eBay for a very reasonable price (forgot how much, but I think it was $45 or so). I would recommend it over the Bullet, it looks better made too (more metal). Didier KO4BB On Wed, Dec 16, 2009 at 1:54 AM, Robert Atkinson wrote: Try Flike I on ebay http://cgi.ebay.co.uk/lucent-GPS-Timing-Reference-Antenna-26db-Gain-N-connect_W0QQitemZ290369619357QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item439b60c59d Robert G8RPI. --- On Tue, 15/12/09, Charles P. Steinmetz charles_steinm...@lavabit.com wrote: From: Charles P. Steinmetz charles_steinm...@lavabit.com Subject: [time-nuts] Source for Trimble Bullet GPS antennas? To: Discussion of precise time and frequency measurement time-nuts@febo.com Date: Tuesday, 15 December, 2009, 22:33 For initial testing of my Thunderbolt I'll use a Garmin GA 29 marine antenna that's lying around, but for my permanent installation I'd like to find an actual Trimble Bullet. The web turns up mostly scam links (search services, etc.), and so far I've not found a source. Any suggestions? Probably best to reply direct to avoid wasted reflector bandwidth. Thank you, Charles ___ 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] Tbolt Damping setting
Peter PV) However, I think it would be interesting to at least see the relative differences for one location. The relative difference can be seen in the Green Dac plot, which shows the total PP noise at 50 Sec and slower. The Dac is scaled to 1e-11 per division, for RMS or ADEV, divide PP by about 5. As you pointed out the Tbolt and LH can NOT do 1 sec noise directly without an external reference, BUT by looking at the excess nose that is applied to the DAC, you can see what is happening at one sec, or 10 or 100. Ideally The Dac should not be forced to move at a freq below the TC setting, If it does that is added noise. By the way, To force a similar sort of 50 ns sawtooth phase error waveform when using an external reference, Use the Osc phase setting to invert the phase of the Tbolt OSC sync timing. PV) Is the oscillator in the Leica significantly worse than that in out Thunderbolts, or could we also benefit from a time-constant of longer than 1000 seconds? I know little about anything except Tbolts but If you show me a couple of good plots, with and without GPS control, I could probable answer that. PV) I will try to find a quiet rubidium Depending on what errors you are most concerned with, Phase short term or long term , Low tau ADV or High Tau ADV, (or hold over, yek) May not even be necessary for it to be a low noise quiet one Have fun ws (in central California) ***- Original Message - From: Peter Vince pvi...@theiet.org To: WarrenS warrensjmail-...@yahoo.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, December 16, 2009 4:54 AM Subject: Re: [time-nuts] Tbolt Damping setting Good points, and You got 4 1/2 out of five correct, Not bad at all. Ha ha - thank you teacher! Fairy nuff, yes, your plots show the long-term effects. I would like to know what the best time-constant is to use. I appreciate that everyone's will be different, depending on individual characteristics of the Thunderbolts, and also (perhaps more importantly) the aerial and its position. However, I think it would be interesting to at least see the relative differences for one location. I recently learnt that our national mapping organisation (The Ordnance Survey) average the results from their L1/L2 Leica 1200 system receivers, for two hours. Is the oscillator in the Leica significantly worse than that in out Thunderbolts, or could we also benefit from a time-constant of longer than 1000 seconds? I will try to find a quiet rubidium, and do some comparisons against that - the results should, at least, be valid out to a few thousand seconds. I also plan to try reducing the signal level threshold (from the current 4AMU) as recently suggested, and try to see some quantifiable results. TTFN, Peter Vince (G8ZZR, London, England) ___ 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] Loran C question
Hello! Someone on this list can tell me, please, the exact geographical position of the Yankee/Lessay 6731 Loran C station ? At my position (+41.353; -8.384)I am measuring an average delay of 32,495.87 microsec. along the day and IMHO this can't be the under construction (and apparently never operational) LOOP HEAD station. Thanks. Antonio CT1TE - A FCUP utiliza o sistema open source de webmail Horde/IMP (www.horde.org) Visite: http://www.fc.up.pt/ http://info.fc.up.pt/ ___ 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 question
In message 20091216235548.oer392im80gg8...@webmail.fc.up.pt, asma...@fc.up.pt writes: Hello! Someone on this list can tell me, please, the exact geographical position of the Yankee/Lessay 6731 Loran C station ? At my position (+41.353; -8.384)I am measuring an average delay of 32,495.87 microsec. along the day and IMHO this can't be the under construction (and apparently never operational) LOOP HEAD station. Loop Head never happened, but the British are transmitting at least a 7499 slave from somewhere in the UK. Not sure if the dual-rate ton 6731 also. Megapulse.com used to have the most up to date list of Loran data but it seems to be out of date with respect to European stuff now. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | 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 To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Loran C question
a quick Google shows it at 54°54′41.949″N 3°16′42.587″W On Wed, Dec 16, 2009 at 2:55 PM, asma...@fc.up.pt wrote: Hello! Someone on this list can tell me, please, the exact geographical position of the Yankee/Lessay 6731 Loran C station ? At my position (+41.353; -8.384)I am measuring an average delay of 32,495.87 microsec. along the day and IMHO this can't be the under construction (and apparently never operational) LOOP HEAD station. Thanks. Antonio CT1TE - A FCUP utiliza o sistema open source de webmail Horde/IMP (www.horde.org) Visite: http://www.fc.up.pt/ http://info.fc.up.pt/ ___ 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. -- --Eric _ Eric Garner ___ 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 question
asma...@fc.up.pt wrote: Hello! Someone on this list can tell me, please, the exact geographical position of the Yankee/Lessay 6731 Loran C station ? At my position (+41.353; -8.384)I am measuring an average delay of 32,495.87 microsec. along the day and IMHO this can't be the under construction (and apparently never operational) LOOP HEAD station. Anthorn UK Lessay (GRI 6731) 54°54?41.949?N 3°16?42.587?W From Wikipedia. Cheers, Magnus ___ 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] Source for Trimble Bullet GPS antennas?
Hi The Lucent Bullet is rated as a 26 +/-3 db LNA device. The Trimble Bullet is rated as 30 +/-3 db at 3.3 volts ( for the III model) The Trimble Bullet II is rated as 35 db at 5 volts A lot of the simple antennas are up around 45 db at 3.3 volts. The less specified parameter is noise figure. The Bullet II has a 2.75 db nf, the III at 3.3 db. I haven't seen a number on the Lucent part. These days a 1.5 db noise figure is not all that expensive at GPS frequencies. I suspect that none of that really helps straighten out any of this Bob On Dec 16, 2009, at 9:50 AM, Didier Juges wrote: My Trimble Bullet antenna seems less sensitive than any other GPS antenna I have (a Symmetricom, a good-looking Trimble mag-mount and several cheap active antennas). I receive fewer sats with the Bullet, at any time that I have tried. Maybe it is defective, or maybe that's the way it is. I bought the Symmetricon HP 58532A new on eBay for a very reasonable price (forgot how much, but I think it was $45 or so). I would recommend it over the Bullet, it looks better made too (more metal). Didier KO4BB On Wed, Dec 16, 2009 at 1:54 AM, Robert Atkinson wrote: Try Flike I on ebay http://cgi.ebay.co.uk/lucent-GPS-Timing-Reference-Antenna-26db-Gain-N-connect_W0QQitemZ290369619357QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item439b60c59d Robert G8RPI. --- On Tue, 15/12/09, Charles P. Steinmetz charles_steinm...@lavabit.com wrote: From: Charles P. Steinmetz charles_steinm...@lavabit.com Subject: [time-nuts] Source for Trimble Bullet GPS antennas? To: Discussion of precise time and frequency measurement time-nuts@febo.com Date: Tuesday, 15 December, 2009, 22:33 For initial testing of my Thunderbolt I'll use a Garmin GA 29 marine antenna that's lying around, but for my permanent installation I'd like to find an actual Trimble Bullet. The web turns up mostly scam links (search services, etc.), and so far I've not found a source. Any suggestions? Probably best to reply direct to avoid wasted reflector bandwidth. Thank you, Charles ___ 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. ___ 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 question
Thanks to Eric,Poul and Magnus the Yankee Mystery is solved very quickly: -That's the eLoran C station at HMS Nuthacht. The distances, indirectly observed is 1557.68 Km, and roughly measured with Google is 1557.43 km. That makes sense to me. I would like to report that I can receive clearly at night the Canadian and the East Coast US stations (at least until the anounced requien...) Best regards, Antonio CT1TE. Quoting Eric Garner garn...@gmail.com: a quick Google shows it at 54°54?41.949?N 3°16?42.587?W On Wed, Dec 16, 2009 at 2:55 PM, asma...@fc.up.pt wrote: Hello! Someone on this list can tell me, please, the exact geographical position of the Yankee/Lessay 6731 Loran C station ? At my position (+41.353; -8.384)I am measuring an average delay of 32,495.87 microsec. along the day and IMHO this can't be the under construction (and apparently never operational) LOOP HEAD station. Thanks. Antonio CT1TE - A FCUP utiliza o sistema open source de webmail Horde/IMP (www.horde.org) Visite: http://www.fc.up.pt/ http://info.fc.up.pt/ ___ 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. -- --Eric _ Eric Garner ___ 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. - A FCUP utiliza o sistema open source de webmail Horde/IMP (www.horde.org) Visite: http://www.fc.up.pt/ http://info.fc.up.pt/ ___ 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 question
The Loop Head transmitter is I think (It may be a new one) running from Anthorn (after being shipped up from Rugby) on the south bank of the Solway Firth. Dont forget there is a slave near Bordeau, Susstons (??)on the St Malo peninsula. The Megapulse web site data should be OK for the Lessay chain but perhaps not for the Anthorn slave. Lessay is a dual rate with the Sylt Chain. I dont think Anthorn is dual rate. Alan G3NYK --- On Wed, 16/12/09, Poul-Henning Kamp p...@phk.freebsd.dk wrote: From: Poul-Henning Kamp p...@phk.freebsd.dk Subject: Re: [time-nuts] Loran C question To: Discussion of precise time and frequency measurement time-nuts@febo.com Date: Wednesday, 16 December, 2009, 23:04 In message 20091216235548.oer392im80gg8...@webmail.fc.up.pt, asma...@fc.up.pt writes: Hello! Someone on this list can tell me, please, the exact geographical position of the Yankee/Lessay 6731 Loran C station ? At my position (+41.353; -8.384)I am measuring an average delay of 32,495.87 microsec. along the day and IMHO this can't be the under construction (and apparently never operational) LOOP HEAD station. Loop Head never happened, but the British are transmitting at least a 7499 slave from somewhere in the UK. Not sure if the dual-rate ton 6731 also. Megapulse.com used to have the most up to date list of Loran data but it seems to be out of date with respect to European stuff now. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | 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 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] Source for Trimble Bullet GPS antennas?
Bob wrote: The Lucent Bullet is rated as a 26 +/-3 db LNA device. The Trimble Bullet is rated as 30 +/-3 db at 3.3 volts ( for the III model) The Trimble Bullet II is rated as 35 db at 5 volts A lot of the simple antennas are up around 45 db at 3.3 volts. The less specified parameter is noise figure. The Bullet II has a 2.75 db nf, the III at 3.3 db. I haven't seen a number on the Lucent part. These days a 1.5 db noise figure is not all that expensive at GPS frequencies. I suspect that none of that really helps straighten out any of this As another Time Nut pointed out in an offlist e-mail, like any other radio system, it's not the LNA that does the serious work, but rather the physical antenna. In the case of GPS antennas, the LNA primarily compensates for losses in the feed coax. Higher gain can lead to overload of the LNA, so it's not necessarily a panacea -- particularly in high-density VHF/UHF environments. Reportedly, much better performance can be had from larger and more sophisticated antenna structures. I have RF design experience, based on which I wouldn't put any faith in noise figure specs from any but the most reputable suppliers. I assume Trimble is one such, and I know that Andrew (the apparent OEM supplier to Lucent) is. But most others should probably be taken with a large rocks of salt. Best regards, Charles ___ 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] Source for Trimble Bullet GPS antennas?
At 09:28 PM 12/16/2009, Charles P. Steinmetz wrote... it's not the LNA that does the serious work, but rather the physical antenna...I have RF design experience, based on which I wouldn't put any faith in noise figure specs from any but the most reputable suppliers. I assume Trimble is one such, and I know that Andrew (the apparent OEM supplier to Lucent) is. I use an Andrew GPS-QBW-26N. 4.5 db quadrifilar antenna, 26 +-3 db LNA, 2.5 db noise. Works well. ___ 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] 60Hz mains clocking in computers
In 1984 we had a QBUS-based 68000 (dual 68K, due to the paging flaw) that ran 9-track tapes off the end and gained about a good fraction of an hour a day on its clock. We complained to the vendor and they swapped CPU boards for us. Tapes worked fine, and the clock was more accurate, but programs ran slower. Hmmm. Leigh. At 1:44 AM + 12/13/09, time-nuts-requ...@febo.com wrote: Date: Sat, 12 Dec 2009 17:29:17 -0800 From: Colby Gutierrez-Kraybill co...@astro.berkeley.edu Subject: [time-nuts] 60Hz mains clocking in computers To: time-nuts@febo.com Message-ID: 3058527a-cc99-4174-be75-21dd92334...@astro.berkeley.edu Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes I'm trying to get to the bottom of whether or not any computing equipment made around the advent of UNIX systems (or any time-slicing system) used the mains cycles of 60Hz as phase lock for the internal system clock. My guess is that perhaps they did not as the computing logic is DC based, but, I have memories of using an 68000 based UNIX system that I thought had its internal clock based off of the 60Hz mains... Not sure the vendor anymore. ___ 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.
