Re: [time-nuts] Practical Survey-In Accuracy?
On Sat, 23 Aug 2014 16:38:42 -0700 Bob Stewart b...@evoria.net wrote: Given that my antenna is just a puck at the peak of the attic (never got around to adding the DIY choke-ring) A choke ring will not help you much in the attic. You already have lots of reflecting and refracting surfaces/volumes above the antenna. Unless you get to the top of your roof, i wouldn't bother adding a choke ring. Attila Kinali -- I pity people who can't find laughter or at least some bit of amusement in the little doings of the day. I believe I could find something ridiculous even in the saddest moment, if necessary. It has nothing to do with being superficial. It's a matter of joy in life. -- Sophie Scholl ___ 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] Practical Survey-In Accuracy?
Hi Attila, Is wood, nails, and asphalt shingle really that big of a problem at these frequencies? The antenna is within 2 ft of the highest point of the roof. Bob From: Attila Kinali att...@kinali.ch To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, August 28, 2014 8:15 AM Subject: Re: [time-nuts] Practical Survey-In Accuracy? On Sat, 23 Aug 2014 16:38:42 -0700 Bob Stewart b...@evoria.net wrote: Given that my antenna is just a puck at the peak of the attic (never got around to adding the DIY choke-ring) A choke ring will not help you much in the attic. You already have lots of reflecting and refracting surfaces/volumes above the antenna. Unless you get to the top of your roof, i wouldn't bother adding a choke ring. Attila Kinali ___ 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] Practical Survey-In Accuracy?
On Thu, 28 Aug 2014 06:30:14 -0700 Bob Stewart b...@evoria.net wrote: Is wood, nails, and asphalt shingle really that big of a problem at these frequencies? The antenna is within 2 ft of the highest point of the roof. Consider this: A lot of people complain about the reflections caused by trees. But what is a tree? It's mostly air and a few leaves, with a branch here and there. Also: 60cm is less than 2λ. ie the roof is in the near field of the antenna, where everything causes a change of the antenna behaviour (resonance frequency, radiation pattern, phase centre etc) Depending on what you do with the GPS signal, you might or might not care about that. If you are a nutty time-nut and want to wring out ever last bit of jitter out of your PPS, then you will care about the effect of the roof. Attila Kinali -- I pity people who can't find laughter or at least some bit of amusement in the little doings of the day. I believe I could find something ridiculous even in the saddest moment, if necessary. It has nothing to do with being superficial. It's a matter of joy in life. -- Sophie Scholl ___ 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] Practical Survey-In Accuracy?
Attila Kinali wrote: On Thu, 28 Aug 2014 06:30:14 -0700 Bob Stewart b...@evoria.net wrote: Is wood, nails, and asphalt shingle really that big of a problem at these frequencies? The antenna is within 2 ft of the highest point of the roof. Consider this: A lot of people complain about the reflections caused by trees. But what is a tree? It's mostly air and a few leaves, with a branch here and there. Also: 60cm is less than 2λ. ie the roof is in the near field of the antenna, where everything causes a change of the antenna behaviour (resonance frequency, radiation pattern, phase centre etc) Depending on what you do with the GPS signal, you might or might not care about that. If you are a nutty time-nut and want to wring out ever last bit of jitter out of your PPS, then you will care about the effect of the roof. Attila Kinali In light of these posts about antennae and reflections, etc., I have a similar question. I'm planning to move my workbench out of my attached garage into a separate garage building. The new garage is about 24' x 36', and has a metal roof. My plan is to mount my GPS antenna atop a metal pipe mounted at the peak at the end of the gable roof. How far above the metal roof should I mount the antenna so reflections will be minimized, at least to the point of diminishing returns? The antenna will have a pretty good view of the sky from that location. Any other issues that I should be aware of when dealing with a metal roof? Thanks, Dave M ___ 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] Practical Survey-In Accuracy?
On Thu, 28 Aug 2014 09:21:51 -0500 Dave M dgmin...@mediacombb.net wrote: How far above the metal roof should I mount the antenna so reflections will be minimized, at least to the point of diminishing returns? I've been told, that 2m is ok. Sorry, i don't have any hard numbers. The antenna will have a pretty good view of the sky from that location. Any other issues that I should be aware of when dealing with a metal roof? Heating of the garage due to sun? Attila Kinali -- I pity people who can't find laughter or at least some bit of amusement in the little doings of the day. I believe I could find something ridiculous even in the saddest moment, if necessary. It has nothing to do with being superficial. It's a matter of joy in life. -- Sophie Scholl ___ 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] Practical Survey-In Accuracy?
Hi Simple answer - yes. My observation over the years is that your typical roof absorbs quite a bit of RF starting way below GPS frequencies. My *guess* is that shingles are a bit lossy. Shingles + moisture more so. Shingles + dirt + moisture even worse. I also believe that plywood suffers the same way. Also consider that you have things like flashing, ridge vents, and gutters involved. Somewhere below 2 MHz or so things begin to get less crazy. I’ve spent a lot of time putting antennas up in a lot of attics and then moving them outdoors. Bob On Aug 28, 2014, at 9:30 AM, Bob Stewart b...@evoria.net wrote: Hi Attila, Is wood, nails, and asphalt shingle really that big of a problem at these frequencies? The antenna is within 2 ft of the highest point of the roof. Bob From: Attila Kinali att...@kinali.ch To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, August 28, 2014 8:15 AM Subject: Re: [time-nuts] Practical Survey-In Accuracy? On Sat, 23 Aug 2014 16:38:42 -0700 Bob Stewart b...@evoria.net wrote: Given that my antenna is just a puck at the peak of the attic (never got around to adding the DIY choke-ring) A choke ring will not help you much in the attic. You already have lots of reflecting and refracting surfaces/volumes above the antenna. Unless you get to the top of your roof, i wouldn't bother adding a choke ring. Attila Kinali ___ 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] Practical Survey-In Accuracy?
On Thu, Aug 28, 2014 at 6:30 AM, Bob Stewart b...@evoria.net wrote: Hi Attila, Is wood, nails, and asphalt shingle really that big of a problem at these frequencies? The antenna is within 2 ft of the highest point of the roof. Depends on what you call a problem. If you are getting a usable signal then some people would not call it a problem. When I moved my GPS antenna from user the roof to a pole mounted above the roof the signal improved greatly. The most notable improvements was the signal to noise ration of satellites near the horizon. Bob From: Attila Kinali att...@kinali.ch To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, August 28, 2014 8:15 AM Subject: Re: [time-nuts] Practical Survey-In Accuracy? On Sat, 23 Aug 2014 16:38:42 -0700 Bob Stewart b...@evoria.net wrote: Given that my antenna is just a puck at the peak of the attic (never got around to adding the DIY choke-ring) A choke ring will not help you much in the attic. You already have lots of reflecting and refracting surfaces/volumes above the antenna. Unless you get to the top of your roof, i wouldn't bother adding a choke ring. Attila Kinali ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] Practical Survey-In Accuracy?
I would call that done. Henry On Sat, Aug 23, 2014 at 4:38 PM, Bob Stewart b...@evoria.net wrote: I've had the LEA-6T sitting in survey-in mode for about 17 hours, and at this point, the u-center software says that the Mean 3D Std Dev is 0.109 meters. Given that my antenna is just a puck at the peak of the attic (never got around to adding the DIY choke-ring), has this reached the silly number phase, or should I let is simmer overnight before calling it done? Bob - AE6RV ___ 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] Practical Survey-In Accuracy?
Hi There are some periodic errors in GPS that only get averaged in after a = 48 hour survey. It’s not so much a specific error level in meters as much as averaging in all the “issues”. Bob On Aug 23, 2014, at 7:38 PM, Bob Stewart b...@evoria.net wrote: I've had the LEA-6T sitting in survey-in mode for about 17 hours, and at this point, the u-center software says that the Mean 3D Std Dev is 0.109 meters. Given that my antenna is just a puck at the peak of the attic (never got around to adding the DIY choke-ring), has this reached the silly number phase, or should I let is simmer overnight before calling it done? Bob - AE6RV ___ 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] Practical Survey-In Accuracy?
Hi Bob, Thanks for the info. I'll have to run a long test to see what the difference is. Maybe I can capture the XYZ coordinates to the PC during the run. Bob From: Bob Camp kb...@n1k.org To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, August 25, 2014 4:54 PM Subject: Re: [time-nuts] Practical Survey-In Accuracy? Hi There are some periodic errors in GPS that only get averaged in after a = 48 hour survey. It’s not so much a specific error level in meters as much as averaging in all the “issues”. Bob On Aug 23, 2014, at 7:38 PM, Bob Stewart b...@evoria.net wrote: I've had the LEA-6T sitting in survey-in mode for about 17 hours, and at this point, the u-center software says that the Mean 3D Std Dev is 0.109 meters. Given that my antenna is just a puck at the peak of the attic (never got around to adding the DIY choke-ring), has this reached the silly number phase, or should I let is simmer overnight before calling it done? Bob - AE6RV ___ 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] Practical Survey-In Accuracy?
I've had the LEA-6T sitting in survey-in mode for about 17 hours, and at this point, the u-center software says that the Mean 3D Std Dev is 0.109 meters. Given that my antenna is just a puck at the peak of the attic (never got around to adding the DIY choke-ring), has this reached the silly number phase, or should I let is simmer overnight before calling it done? Bob - AE6RV ___ 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.
