Re: [time-nuts] How phase stable is rg59 or alternate coax
Note that partial air core (9913) and foam dielectric is better than solid polyethylene. David N1HAC On 11/21/16 5:39 PM, Mark Spencer wrote: At one point I contemplated running Andrews "Heliax" for my GPS antenna. Part of the rationale was due to the data presented in page 2 of the following paper. http://ivs.nict.go.jp/mirror/meetings/v2c_wm1/phase_stability.pdf I subsequently decided to stay with my existing run of plenum rated RG58. The bulk of my cable run is indoors where the temperature is fairly stable. Regards Mark Spencer On Nov 21, 2016, at 12:59 PM, Scott Stobbe wrote: When I first took a look at some of the coax datasheets I couldn't find anything. I was able to find the following paper "phase stability of typical navy radio frequency coaxial cables" http://www.dtic.mil/dtic/tr/fulltext/u2/628682.pdf I attached the table from the last page. They estimate RG59 to have a tempCo of -330 PPM/degC for electrical length. They also estimated RG-58 at -480 PPM/degC. On Mon, Nov 21, 2016 at 2:44 PM, John Ackermann N8UR wrote: I can't find the data right now, but will keep digging. There's also a short paper from the early 2000s from Haystack on their measurement of LMR400 in an environmental chamber. They came to the same conclusion, but I can't find that paper either. :- John, many thanks for the Haystack tip! That is a wonderful paper, I believe the one you are quoting is "Dispersion and temperature effects in coax cables" http://www.haystack.mit.edu/tech/vlbi/mark5/mark5_memos/067.pdf ___ 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] How phase stable is rg59 or alternate coax
At one point I contemplated running Andrews "Heliax" for my GPS antenna. Part of the rationale was due to the data presented in page 2 of the following paper. http://ivs.nict.go.jp/mirror/meetings/v2c_wm1/phase_stability.pdf I subsequently decided to stay with my existing run of plenum rated RG58. The bulk of my cable run is indoors where the temperature is fairly stable. Regards Mark Spencer > On Nov 21, 2016, at 12:59 PM, Scott Stobbe wrote: > > When I first took a look at some of the coax datasheets I couldn't find > anything. I was able to find the following paper "phase stability of > typical navy radio frequency coaxial cables" > http://www.dtic.mil/dtic/tr/fulltext/u2/628682.pdf I attached the table > from the last page. They estimate RG59 to have a tempCo of -330 PPM/degC > for electrical length. They also estimated RG-58 at -480 PPM/degC. > >> On Mon, Nov 21, 2016 at 2:44 PM, John Ackermann N8UR wrote: >> >> I can't find the data right now, but will keep digging. There's also a >> short paper from the early 2000s from Haystack on their measurement of >> LMR400 in an environmental chamber. They came to the same conclusion, but >> I can't find that paper either. :- > > > John, many thanks for the Haystack tip! That is a wonderful paper, I > believe the one you are quoting is "Dispersion and temperature effects in > coax cables" http://www.haystack.mit.edu/tech/vlbi/mark5/mark5_memos/067.pdf > > ___ > 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] How phase stable is rg59 or alternate coax
When I first took a look at some of the coax datasheets I couldn't find anything. I was able to find the following paper "phase stability of typical navy radio frequency coaxial cables" http://www.dtic.mil/dtic/tr/fulltext/u2/628682.pdf I attached the table from the last page. They estimate RG59 to have a tempCo of -330 PPM/degC for electrical length. They also estimated RG-58 at -480 PPM/degC. On Mon, Nov 21, 2016 at 2:44 PM, John Ackermann N8UR wrote: > > I can't find the data right now, but will keep digging. There's also a > short paper from the early 2000s from Haystack on their measurement of > LMR400 in an environmental chamber. They came to the same conclusion, but > I can't find that paper either. :- John, many thanks for the Haystack tip! That is a wonderful paper, I believe the one you are quoting is "Dispersion and temperature effects in coax cables" http://www.haystack.mit.edu/tech/vlbi/mark5/mark5_memos/067.pdf ___ 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] How phase stable is rg59 or alternate coax
Several years ago I measured the delay of about 80 feet of LMR400 feeding a GPS antenna, much of which was lying on a black shingle roof in the Georgia sun. I checked in early afternoon when the sun was beating, and in the wee hours of the morning, to get the greatest temperature delta. My recollection is that the tempco was surprisingly small -- maybe a couple of nanoseconds. It was much less than the other elements of the GPS timing error budget. I can't find the data right now, but will keep digging. There's also a short paper from the early 2000s from Haystack on their measurement of LMR400 in an environmental chamber. They came to the same conclusion, but I can't find that paper either. :-( I don't know how much different RG58 results would be. John On 11/21/2016 09:38 AM, Scott Stobbe wrote: If you had 30 ft of rg59 outdoors seeing maybe 10 degC swings everyday, would the propagation time be stable to ps? ns? On Sun, Nov 20, 2016 at 7:04 PM Hal Murray wrote: Is that even a sensible question? Is there a better way to phrase it? The problem I'm trying to avoid is that the weather and the satellite geometry change over time so I can't just collect data for X hours, switch to the other antenna or move the antenna to another location, collect more data, then compare the two chunks of data. The best I can think of would be to setup a reference system so I can collect data from 2 antennas and 2 receivers at the same time. It would probably require some preliminary work to calibrate the receivers. I think I can do that by swapping the antenna cables. If I gave you a pile of data, how would you compute a quality number? Can I just sum up the S/N slots for each visible/working satellite? -- These are my opinions. I hate spam. ___ 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] How phase stable is rg59 or alternate coax
On 11/21/16 6:38 AM, Scott Stobbe wrote: If you had 30 ft of rg59 outdoors seeing maybe 10 degC swings everyday, would the propagation time be stable to ps? ns? Figure it's copper, so 16 ppm/deg C. velocity factor is about 2/3, so 30 ft is about 45 nanoseconds. about 1ps/degree Really, you also need to look at the effect on the propagation velocity of the radial expansion of the coax, too, and the change in epsilon. You can look up a "phase vs frequency" curve for most coax which factors all of this in. On Sun, Nov 20, 2016 at 7:04 PM Hal Murray wrote: Is that even a sensible question? Is there a better way to phrase it? ___ 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] How phase stable is rg59 or alternate coax
In message , Scott Stobbe writes: >If you had 30 ft of rg59 outdoors seeing maybe 10 degC swings everyday, >would the propagation time be stable to ps? ns? ps ? No way - *ever* ns ? Probably, but it depends a lot on the exact materials and manufacturing. -- 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] How phase stable is rg59 or alternate coax
If you had 30 ft of rg59 outdoors seeing maybe 10 degC swings everyday, would the propagation time be stable to ps? ns? On Sun, Nov 20, 2016 at 7:04 PM Hal Murray wrote: > > Is that even a sensible question? Is there a better way to phrase it? > > > The problem I'm trying to avoid is that the weather and the satellite > geometry change over time so I can't just collect data for X hours, switch > to > the other antenna or move the antenna to another location, collect more > data, > then compare the two chunks of data. > > The best I can think of would be to setup a reference system so I can > collect > data from 2 antennas and 2 receivers at the same time. It would probably > require some preliminary work to calibrate the receivers. I think I can do > that by swapping the antenna cables. > > > If I gave you a pile of data, how would you compute a quality number? Can > I > just sum up the S/N slots for each visible/working satellite? > > > -- > These are my opinions. I hate spam. > > > > ___ > 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.
