Re: [time-nuts] How can I measure GPS Antenna quality?

From: Mark Sims Yes. It also works with GPSD so should be able to work with any device that GPSD supports. It also works with most common GPS receiver native binary languages and provides full device control. --- Thanks, Mark. I look forward to playing with a copy. I

Re: [time-nuts] How can I measure GPS Antenna quality?

The interpolation does not spread the data to where sats have not appeared... what it effectively does is intelligently make the dots bigger... but only along the azimuth "axis". For each elevation angle, it starts at azimuth 0 degrees and searches forward until it sees a point with signal.

Re: [time-nuts] How can I measure GPS Antenna quality?

> I'd like to try something like a Voronoi tessellation, but that gets rather nasty to implement.. There's a boost library... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

Re: [time-nuts] How can I measure GPS Antenna quality?

Mark wrote: The tricky bit is interpolating signal levels between logged points (there is a display options for showing the raw signal level data). Heather interpolates between adjacent azimuth points at each elevation angle. I always wondered about the "filled in" (interpolated) plot.

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/22/16 10:13 AM, Mark Sims wrote: Attached is a screen shot from Lady Heather showing various antenna signal displays. The antenna was a cheap GPS/GLONASS patch antenna (mounted on a 3 foot ground level tripod ) connected to a rather nice NVS-08 receiver tracking GPS, SBAS, and GLONASS

Re: [time-nuts] How can I measure GPS Antenna quality?

Mark, Was that screen invoked from the LH application or via command line? I don't see a mention of something similar on the LH help pop-up. 73/jeff/ac0c www.ac0c.com alpha-charlie-zero-charlie -Original Message- From: Mark Sims Sent: Tuesday, November 22, 2016 12:13 PM To:

Re: [time-nuts] How can I measure GPS Antenna quality?

Hi Atilla, Read the document below https://www.ngs.noaa.gov/ANTCAL/docs/NGSantcalprocedures.pdf And the reference within         antenna_README.pdf Antennas are generally not calibrated individually by the user. You make sure the antenna you buy are in the ANTCAL or Geo++ lists. Any use of a snow

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/21/16 10:10 AM, Tom Van Baak wrote: For the equipment hobbyists usually have, the phase center is not that important. Most antennas have a variation <5mm. Even 10mm would lead to just a ~33ps variation. I agree. And besides, for those of us here in Oregon/Washington, the very ground is

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/21/16 2:58 PM, Attila Kinali wrote: On Mon, 21 Nov 2016 08:22:50 -0800 jimlux wrote: I'm not sure about whether an anechoic (which is really "hypoechoic") chamber is going to get you the data you need. Calibrating the chamber to the needed level of accuracy might

Re: [time-nuts] How can I measure GPS Antenna quality?

On Mon, 21 Nov 2016 08:22:50 -0800 jimlux wrote: > I'm not sure about whether an anechoic (which is really "hypoechoic") > chamber is going to get you the data you need. Calibrating the chamber > to the needed level of accuracy might be harder than doing field >

Re: [time-nuts] How can I measure GPS Antenna quality?

> For the equipment hobbyists usually have, the phase center is not that > important. Most antennas have a variation <5mm. Even 10mm would lead to > just a ~33ps variation. I agree. And besides, for those of us here in Oregon/Washington, the very ground is moving northwest at several inches per

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/21/16 8:38 AM, Bob Camp wrote: Hi On Nov 21, 2016, at 9:54 AM, Attila Kinali wrote: On Sun, 20 Nov 2016 14:13:58 -0800 Hal Murray wrote: If I gave you a pile of data, how would you compute a quality number? Can I just sum up the S/N slots

Re: [time-nuts] How can I measure GPS Antenna quality?

When I was doing VHF and UHF direction finding antenna design, I would drive out to the highest readily accessible hilltop for testing. Once I came up with a low sidelobe design, I started picking up things like lamp posts, trees, and bushes in the parking lot, aircraft over LAX and John Wayne

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/21/16 6:54 AM, Attila Kinali wrote: On Sun, 20 Nov 2016 14:13:58 -0800 Hal Murray wrote: 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? There are multiple issues. As

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/21/16 4:15 AM, Bob Camp wrote: Hi At spectrum analyzer bandwidths, the GPS signals out of the antenna are more than 20 db below the noise floor. You can’t see them with an analyzer. You need to run things into the equivalent of a receiver to turn it into anything you can see above the

Re: [time-nuts] How can I measure GPS Antenna quality?

On Sun, 20 Nov 2016 14:13:58 -0800 Hal Murray wrote: > 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? There are multiple issues. As already mentioned, SNR is only a part of

Re: [time-nuts] How can I measure GPS Antenna quality?

In message <2974f356-3729-448e-a428-dc4d340ff...@n1k.org>, Bob Camp writes: >If I put up a handful of antennas on the back porch, I can indeed hook them >up to various receivers and cables. I actually had a chance to do that once: http://phk.freebsd.dk/raga/ I was very careful

Re: [time-nuts] How can I measure GPS Antenna quality?

On 11/20/16 7:41 PM, Mark Sims wrote: When I was developing the precision survey code for Lady Heather, I used a lot of antennas. My definition of antenna quality boiled down to how well the results of a 48 hour survey compared to the cm level survey point that I had for my antenna position

Re: [time-nuts] How can I measure GPS Antenna quality?

Hi At spectrum analyzer bandwidths, the GPS signals out of the antenna are more than 20 db below the noise floor. You can’t see them with an analyzer. You need to run things into the equivalent of a receiver to turn it into anything you can see above the noise. What you will see on an

Re: [time-nuts] How can I measure GPS Antenna quality?

Yo Hal! On Sun, 20 Nov 2016 14:13:58 -0800 Hal Murray wrote: > Is that even a sensible question? Yes, it is a good question. I have been buying a lot of cheap GPS antennas for testing on RasPis. I plug the antenna into a GPS, then just wait until the GPS gets a good

Re: [time-nuts] How can I measure GPS Antenna quality?

> Le 21 nov. 2016 à 02:57, Tom Van Baak a écrit : > > Hi Hal, > > That's a very sensible question. I've often wondered the same, but I'm > embarrassed to say I have never done a thorough job with it. You know the > constellation repeats approximately every 24 hours so

Re: [time-nuts] How can I measure GPS Antenna quality?

If you run two antenna simultaneously then... 1) they both can't be at the same location and 2) What if the two antenna interfere one with the other. I think maybe you need to collect data over a long enough period of tine that wether averages out. the satellite tracks repeate pretty much

Re: [time-nuts] How can I measure GPS Antenna quality?

Hi Hal, That's a very sensible question. I've often wondered the same, but I'm embarrassed to say I have never done a thorough job with it. You know the constellation repeats approximately every 24 hours so you want your X hours to be a multiple of days. Looking at SNR seems obvious and may

Re: [time-nuts] How can I measure GPS Antenna quality?

You need a definition of "Quality" to work with. One definition might be "does it meet published specs? under what conditions?" Another definition might be associated with reliability and ruggedness. Longevity in outdoor conditions. Another might be with the antenna supporting your use case.