Re: [time-nuts] lawnmower robots may be the end of VLF timekeeping
Bill Hawkins wrote: Did the pictures have to be in SVG format? SVG is extremely available, and extremely useful because it allows you to scale the picture to any size you like, and retain all of the detail. It provides a lot more functionality than just that, but I am sure that you can use google to discover what that might be as well as most anyone. To quote the wiki entry for Scalable Vector Graphics: All major modern web browsers—including Mozilla Firefox, Internet Explorer, Google Chrome, Opera, and Safari—have at least some degree of SVG rendering support. My Mozilla based browser came with full support out of the box, so to speak. I expect that whatever browser you are using either natively supports SVG, or can pull in a plugin. If not, prudence dictates that it might be time for an upgrade... if only to gain the benefit of the latest security patches. Is this only a problem for those who routinely use SVG? Maybe. I expect that the solver of this problem will be someone who is flexible enough to embrace a wide variety of new techniques, and processes. -Chuck Harris -Original Message- From: Poul-Henning Kamp Sent: Saturday, May 09, 2015 7:16 AM I spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html ___ 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] lawnmower robots may be the end of VLF timekeeping
In message 45C7C6B09BC548C19241E4E0673E9E9F@system072, Bill Hawkins writes: Did the pictures have to be in SVG format? Is this only a problem for those who routinely use SVG? A problem how ? I *like* SVG since you can zoom without pixellation effects, and spent an afternoon writing code to screen-dump the HP8568 into SVG format for the very same reason. -- 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] lawnmower robots may be the end of VLF timekeeping
Yes, flexibility is the key. Once upon a time I could hack hardware and software using Unix and C, starting in 1982. I can no longer keep up with the bright ideas of millions of programmers. Bought some Windows 7 machines a year ago before they gave way to 8. Still use XP because I can do what I need to do with it, and it has become more stable since MS stopped supporting it. But I can't go to each new browser with better customer tracking tools. Tried Chrome briefly. Hate to be told what I might like to buy. So when an intriguing new mystery is presented with good data from one of the best members of this group, and all I get is empty boxes with red Xs at the top left, I am annoyed. Chasing the file name reveals SVG type. Chasing that reveals its purpose and some possible download sites. But the sites are not known to me, and I do not want to install unknown software, let alone learn how to use it. I'm sorry I expressed my annoyance, but I'm fighting an unknown infection, and that makes me testy. If someone could send me a reliable link to download SVG, I could try it after a full system backup. That's all extra work, but there's got to be a pony in there somewhere. Bill Hawkins -Original Message- From: Chuck Harris Sent: Monday, May 11, 2015 12:09 AM Bill Hawkins wrote: Did the pictures have to be in SVG format? Is this only [should have been NOT] a problem for those who routinely use SVG? Maybe. I expect that the solver of this problem will be someone who is flexible enough to embrace a wide variety of new techniques, and processes. -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] lawnmower robots may be the end of VLF timekeeping
In practice it seems to be hard to fight interference issues at lower frequencies. A local 50,000 watt AM (medium wave) broadcaster, put up a FM (VHF) transmitter several years ago. One of the reasons they gave for going to FM were the interference issues on the AM band. I noticed the newer electric trolly busses were significant sources of interference on my drive home from work. I've largely stopped using my HF amateur radios in the city, and even at VHF the noise floor is noticeably lower in the country side. Reception for my WWVB clock is also rather hit or miss from south western Canada but it does work on occasion.I was however pleased that my 1.2 Ghz amateur radio activities don't seem to disrupt my own GPS reception despite less 15 feet of antenna separation. Sent from my iPad On 2015-05-09, at 12:48 PM, Bob Camp kb...@n1k.org wrote: Hi The real questions: 1) Are they breaking any laws with their pollution? 2) Is there a regulatory body that is charged with enforcing those laws? 3) Is the cost (hours / dollars / hassle) of taking action prohibitive? Often it’s a combination of more than one that gets you … This is fundamentally no different than the boys setting up their system right next to GPS. The main difference is that they had to go through the licensing process and not all these devices do that. I do know that when every radio clock within 1/2 Km goes dead, there are towns that will have a lot of people scratching their heads …. Bob On May 9, 2015, at 2:15 PM, Björn b...@lysator.liu.se wrote: The same has been observed by the lightning listeners at blitzortnung.org -- Björn div Originalmeddelande /divdivFrån: Poul-Henning Kamp p...@phk.freebsd.dk /divdivDatum:2015-05-09 14:15 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivRubrik: [time-nuts] lawnmower robots may be the end of VLF timekeeping /divdiv /divI spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html -- 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. ___ 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] lawnmower robots may be the end of VLF timekeeping
Did the pictures have to be in SVG format? Is this only a problem for those who routinely use SVG? -Original Message- From: Poul-Henning Kamp Sent: Saturday, May 09, 2015 7:16 AM I spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html ___ 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] lawnmower robots may be the end of VLF timekeeping
http://forum.blitzortung.org/showthread.php?tid=705highlight=lawn+mower Working url. Sorry for the mistake in previous post. -- Björn div Originalmeddelande /divdivFrån: Björn b...@lysator.liu.se /divdivDatum:2015-05-09 20:15 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] lawnmower robots may be the end of VLF timekeeping /divdiv /divThe same has been observed by the lightning listeners at blitzortnung.org -- Björn div Originalmeddelande /divdivFrån: Poul-Henning Kamp p...@phk.freebsd.dk /divdivDatum:2015-05-09 14:15 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivRubrik: [time-nuts] lawnmower robots may be the end of VLF timekeeping /divdiv /divI spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html -- 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. ___ 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] lawnmower robots may be the end of VLF timekeeping
They too emit radiation, prodominantly in the infrared region, but so do we all, even black (body) sheeps. Cheers, Magnus On 05/10/2015 03:12 AM, Alexander Pummer wrote: Bob Widlar -- yes the designer of the 741 -- of National Semiconductor had a better idea, he bought a few sheep 73 KJ6UHN Alex On 5/9/2015 2:02 PM, Mark Sims wrote: iRobot (the Roomba vacuum cleaner people) have applied for an exemption to allow them to send beacon signals in a 6-7 GHz band to fence in their new lawnmower. The band they want to operate in is apparently for indoor only low power applications. The easy solution is to just buy some goats... the emit very little in the way of EMI... but do emit other, u, signals. -- Clearly, you need a better nav system for the robot based on precision time of flight measurements from a network of transmitters around the property linked to your hydrogen maser. ___ 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] lawnmower robots may be the end of VLF timekeeping
While OT, in the interest of accuracy, it was linear guru Dave Fullagar, then at Fairchild, who designed the 741. Yes, it was Bob Widlar who pulled the wool over your eyes :-) Peter -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Feher Sent: Sunday, 10 May 2015 2:36 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] lawnmower robots may be the end of VLF timekeeping I remember that. It was when National was too cheap to cut their lawn. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Alexander Pummer Sent: Saturday, May 09, 2015 9:13 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] lawnmower robots may be the end of VLF timekeeping Bob Widlar -- yes the designer of the 741 -- of National Semiconductor had a better idea, he bought a few sheep 73 KJ6UHN Alex On 5/9/2015 2:02 PM, Mark Sims wrote: iRobot (the Roomba vacuum cleaner people) have applied for an exemption to allow them to send beacon signals in a 6-7 GHz band to fence in their new lawnmower. The band they want to operate in is apparently for indoor only low power applications. The easy solution is to just buy some goats... the emit very little in the way of EMI... but do emit other, u, signals. ___ 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] lawnmower robots may be the end of VLF timekeeping
I remember that. It was when National was too cheap to cut their lawn. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Alexander Pummer Sent: Saturday, May 09, 2015 9:13 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] lawnmower robots may be the end of VLF timekeeping Bob Widlar -- yes the designer of the 741 -- of National Semiconductor had a better idea, he bought a few sheep 73 KJ6UHN Alex On 5/9/2015 2:02 PM, Mark Sims wrote: iRobot (the Roomba vacuum cleaner people) have applied for an exemption to allow them to send beacon signals in a 6-7 GHz band to fence in their new lawnmower. The band they want to operate in is apparently for indoor only low power applications. The easy solution is to just buy some goats... the emit very little in the way of EMI... but do emit other, u, signals. -- Clearly, you need a better nav system for the robot based on precision time of flight measurements from a network of transmitters around the property linked to your hydrogen maser. ___ 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] lawnmower robots may be the end of VLF timekeeping
Moikka moi! I first thought about taking this off-list, but then decided against it because i think this topic is of general interest, not only to ham radios (who are the first one to notice) and time-nuts, but also to other, non-technical people. On Sat, 09 May 2015 22:10:51 +0300 Esa Heikkinen tn1...@nic.fi wrote: Poul-Henning Kamp kirjoitti: I spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html In the Finland that problem is even worse! For me it's called Savon Voima, our local power company (but also many other power companies around the Finland). They are using PLC based remote readable utility meters. These meters communicate with power lines, using ancient 1200 bps. FSK using 83.2/93.6 kHz frequencies. Because the power grid is not designed for this kind of communication, those frequencies will of course leak all over the places. [...] When this was reported to Finnish authority called Viestintävirasto (it's Finnish version of FCC), they say that this doesn't matter - the DCF77 is not protected in Finland (even when you can buy radio controlled clocks from the shop). This is outrageous! Someone in Finnland is not doing his job! The frequency regulations do not protect single frequencies, but frequency ranges and their use. The CEPT[1] reserves the 72-84kHz range for radio navigation (beside others) and explicitly mentiones DCF77 as a big user. I am not sure where the according allowed emission levels are (and currently i don't have access to the standard documents) and it might very well be that the standards stop at 100kHz or 150kHz... BUT! Devices are still not allowed to interfere with legitimate users in any radio bands. If they do, then they are violating the EMI/EMC laws[2]. I have seen quite a few regulation authorities not enforcing the established rules in recent years. Partially because it costs money to make a device compliant (and thus getting pressure from industry) and partially, because the times of crackling radio and TV sets are over (and thus the imediate need isn't as obvious as it used to). Yet, with the ever increasing number it becomes more and more important that emissions are kept at the lowest level possible. If your regulation authority does stupid things like the Finnish one, then you should talk to your political reprentatives and tell them about it. This is not a minor issue of just someone not being able to use his weird toy, but an issue of whole cities not being able to use their alarm clocks anymore! Not to talk about what happens when someones lawn mowner starts interfering with his neighbors pacemaker... Attila Kinali [1] http://www.erodocdb.dk/Docs/doc98/official/pdf/ercrep025.pdf [2] 'electromagnetic compatibility'means the ability of equipment to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances to other equipment in that environment; from European Directive 2004/108/EC -- _av500_ phd is easy _av500_ getting dsl is hard ___ 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] lawnmower robots may be the end of VLF timekeeping
Bob Widlar -- yes the designer of the 741 -- of National Semiconductor had a better idea, he bought a few sheep 73 KJ6UHN Alex On 5/9/2015 2:02 PM, Mark Sims wrote: iRobot (the Roomba vacuum cleaner people) have applied for an exemption to allow them to send beacon signals in a 6-7 GHz band to fence in their new lawnmower. The band they want to operate in is apparently for indoor only low power applications. The easy solution is to just buy some goats... the emit very little in the way of EMI... but do emit other, u, signals. -- Clearly, you need a better nav system for the robot based on precision time of flight measurements from a network of transmitters around the property linked to your hydrogen maser. ___ 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] lawnmower robots may be the end of VLF timekeeping
http://www.blitzortung.org/Webpages/index.php?lang=en typo correction. John -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Björn Sent: Saturday, May 09, 2015 2:15 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] lawnmower robots may be the end of VLF timekeeping The same has been observed by the lightning listeners at blitzortnung.org -- Björn div Originalmeddelande /divdivFrån: Poul-Henning Kamp p...@phk.freebsd.dk /divdivDatum:2015-05-09 14:15 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivRubrik: [time-nuts] lawnmower robots may be the end of VLF timekeeping /divdiv /divI spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html -- 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. --- This email has been checked for viruses by Avast antivirus software. http://www.avast.com ___ 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] lawnmower robots may be the end of VLF timekeeping
Poul-Henning Kamp kirjoitti: I spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html In the Finland that problem is even worse! For me it's called Savon Voima, our local power company (but also many other power companies around the Finland). They are using PLC based remote readable utility meters. These meters communicate with power lines, using ancient 1200 bps. FSK using 83.2/93.6 kHz frequencies. Because the power grid is not designed for this kind of communication, those frequencies will of course leak all over the places. Because the metering hardware is cheap crap made by Slovenian company, those frequencies are not very accurate/narrow and so they block the DCF77 77,5 kHz band totally! Because all in-house wiring act as an transmitter antennas, the field strenghts inside the houses can be as high as 120 dBuV/m. The system is so stupid that it need to communicate 24h to transfer less than six digits (the reading of the utility meter), which is basicly needed once per month for elecricity billing. Every meter can act as repeater to other meters. The DCF77 problem was verified when there was large blackout. During this blackout the DCF77 clocks was syncronized at moments, when they never synchronize normally. When this was reported to Finnish authority called Viestintävirasto (it's Finnish version of FCC), they say that this doesn't matter - the DCF77 is not protected in Finland (even when you can buy radio controlled clocks from the shop). The whole idea about PLC is so stupid and the universal stupidity factor of the people designing these is so high that there's nothing to do anymore. Even the power company said that this is not reliable system, having much of interferences, the readings are not transferred succesfully all the times. But still they buy this kind of crap, even when knowing it weaknesses. Clearly the marketing guys of PLC systems knows their business and they can even cope with local auhorities so that there's no problems to install these everywhere. I think that we have lost the game! Only way to set the clock is to build your own DCF77 transmitter - like the local authority said: the DCF77 band is not protected - at least here in Finland... -- 73s! Esa OH4KJU ___ 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] lawnmower robots may be the end of VLF timekeeping
Hi The real questions: 1) Are they breaking any laws with their pollution? 2) Is there a regulatory body that is charged with enforcing those laws? 3) Is the cost (hours / dollars / hassle) of taking action prohibitive? Often it’s a combination of more than one that gets you … This is fundamentally no different than the boys setting up their system right next to GPS. The main difference is that they had to go through the licensing process and not all these devices do that. I do know that when every radio clock within 1/2 Km goes dead, there are towns that will have a lot of people scratching their heads …. Bob On May 9, 2015, at 2:15 PM, Björn b...@lysator.liu.se wrote: The same has been observed by the lightning listeners at blitzortnung.org -- Björn div Originalmeddelande /divdivFrån: Poul-Henning Kamp p...@phk.freebsd.dk /divdivDatum:2015-05-09 14:15 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivRubrik: [time-nuts] lawnmower robots may be the end of VLF timekeeping /divdiv /divI spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html -- 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. ___ 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] lawnmower robots may be the end of VLF timekeeping
iRobot (the Roomba vacuum cleaner people) have applied for an exemption to allow them to send beacon signals in a 6-7 GHz band to fence in their new lawnmower. The band they want to operate in is apparently for indoor only low power applications. The easy solution is to just buy some goats... the emit very little in the way of EMI... but do emit other, u, signals. -- Clearly, you need a better nav system for the robot based on precision time of flight measurements from a network of transmitters around the property linked to your hydrogen maser. ___ 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] lawnmower robots may be the end of VLF timekeeping
I spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html -- 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] lawnmower robots may be the end of VLF timekeeping
On 5/9/15 5:15 AM, Poul-Henning Kamp wrote: I spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html Clearly, you need a better nav system for the robot based on precision time of flight measurements from a network of transmitters around the property linked to your hydrogen maser. More practically, what about some sort of canceller.. This is low frequency, so if you put a pickup loop near the wire, you can collect a sample of the transmitted signal, and then adjust the mag and phase to cancel at your timing receiver antenna. I suspect the variation in mag and phase will be quite small over time/temperature/weather/volume occupancy. ___ 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] lawnmower robots may be the end of VLF timekeeping
Hi There are dog collar systems that work the same way as well as low speed data over power line systems. For what ever reason - they really like to create RFI. My guess is that it’s easy to generate a pulse with logic gates than it is to properly filter that pulse. The first question I’d have about the gizmo is: does it really *need* that awful looking square wave? I’d bet that the “antenna” in the lawnmower is a tuned loop of some sort. It probably would be happy with a much less wide band signal. I’ve had good luck with the buried dog fence setups and some pretty basic filtering. Of course this all works ok for your system. You have to be on very good terms with the neighbors to fix the problem from their system …. Bob On May 9, 2015, at 8:15 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: I spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html -- 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] lawnmower robots may be the end of VLF timekeeping
Hi, On 05/09/2015 02:15 PM, Poul-Henning Kamp wrote: I spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html As a ham-operator who just got my license and started to listen to what I have outside the door, I have been increasingly aware of the man-made noise (QRM as we say) poluting in my neighborhood. Working to replace my shitty antenna (Shield of a RG-58 as mounted 2,5 m up between a pair of trees) with a proper OCF-dipole, in hope of at least get some good signals in and out. 73 de Magnus SA0MAD ___ 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] lawnmower robots may be the end of VLF timekeeping
The same has been observed by the lightning listeners at blitzortnung.org -- Björn div Originalmeddelande /divdivFrån: Poul-Henning Kamp p...@phk.freebsd.dk /divdivDatum:2015-05-09 14:15 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivRubrik: [time-nuts] lawnmower robots may be the end of VLF timekeeping /divdiv /divI spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html -- 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.
