Re: [time-nuts] Anyone have experience with this antenna?

[Thomas Petig]

On Wed, Feb 07, 2018 at 03:07:24PM +, Poul-Henning Kamp wrote:
> 
> In message <875e4bc6-32c3-4724-afcd-086553ae5...@n1k.org>, Bob kb8tq writes:
>
> >Water wise, one might note the large piles of snow sitting on my antennas at 
> >the moment. Yes, I
> >could go knock it off, but somehow it just keeps coming back. Weird how 
> >winter works …. There
> >is no perfect solution.
>
> Somebody at BIPM told me that their antennas were heated and thermostatically
> kept at constant temperature.
This is how you (can) do it. Here a small picture and some info:
https://www.sp.se/en/index/resources/GNSS/Sidor/default.aspx

Thomas, SA6CID
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Re: [time-nuts] Anyone have experience with this antenna?

[Bob kb8tq]

Hi

They probably have a group of people on staff to go out and dry them off after 
it rains …. :)

Indeed, there are a lot of pictures of heated enclosures for antennas. The 
debate over the
dielectric properties of the coverings goes back a long way. There are notes in 
the standard
databases for the antennas that came with optional covers. They have a separate 
data file
for the “with cover” and “without cover” versions. The discussion here is 
pretty much an 
replay of how the conversation has gone over the years. There is indeed a group 
of people
who (quite rightly) suggest that it’s not a big deal in most cases. 

Bob

> On Feb 7, 2018, at 10:07 AM, Poul-Henning Kamp  wrote:
> 
> 
> In message <875e4bc6-32c3-4724-afcd-086553ae5...@n1k.org>, Bob kb8tq writes:
> 
>> Water wise, one might note the large piles of snow sitting on my antennas at 
>> the moment. Yes, I 
>> could go knock it off, but somehow it just keeps coming back. Weird how 
>> winter works …. There
>> is no perfect solution. 
> 
> Somebody at BIPM told me that their antennas were heated and thermostatically
> kept at constant temperature.
> 
> -- 
> 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.

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Re: [time-nuts] Anyone have experience with this antenna?

[Poul-Henning Kamp]

In message <875e4bc6-32c3-4724-afcd-086553ae5...@n1k.org>, Bob kb8tq writes:

>Water wise, one might note the large piles of snow sitting on my antennas at 
>the moment. Yes, I 
>could go knock it off, but somehow it just keeps coming back. Weird how winter 
>works …. There
>is no perfect solution. 

Somebody at BIPM told me that their antennas were heated and thermostatically
kept at constant temperature.

-- 
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.
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Re: [time-nuts] Anyone have experience with this antenna?

[Bob kb8tq]

Hi

It’s not the end stops that are the issue. It’s the wall of the pipe. If the 
dimensions in 
the sketch are roughly correct and you scale it to the dimensions of the eBay 
antenna,
that is a big tall pipe. Indeed “nothing overhead” would mitigate part of the 
issue. That magic
line runs roughly along Hadrian’s Wall in the UK. I’d bet that 80 degrees 
overhead would still be
an issue. 

Again, this is an extreme case and not the typical cover for a GPS antenna. 

Water wise, one might note the large piles of snow sitting on my antennas at 
the moment. Yes, I 
could go knock it off, but somehow it just keeps coming back. Weird how winter 
works …. There
is no perfect solution. 

Bob

> On Feb 7, 2018, at 3:59 AM, Poul-Henning Kamp  wrote:
> 
> 
> In message 
> 

Re: [time-nuts] Anyone have experience with this antenna?

[Dr. David Kirkby]

On 6 February 2018 at 03:33, John Green  wrote:

> https://www.ebay.com/itm/High-Precision-L1-L2-GNSS-GPS-GLONA
> SS-BeiDou-RTK-CORS-survey-antenna/162718512935?ssPageNam
> e=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649
>
> Listed on eBay as a L1/L2 antenna with decent specs.


I used to work in the antenna industry selling 'professional' antennas -
not aimed at the amateur radio market. Many specifications are invented to
be better than a competitor. The competitors do it too, so it is not just
one company. If you sell antennas with valid specifications, it would be
next to impossible to sell them, as competitors will have higher
specifications.

Another RF engineer, who I don't know from working with antennas, said to
me that antennas are a still a charlatan's paradise.

With antennas, probably more than any other device, I would believe the
specifications if I could verify them. Unfortunately, for that sort of
antenna, I don't know how to verify them.

If nothing else, I would ask the seller for a copy of the test reports that
back up the specifications.

I got a couple of WiFi antennas free from eBay, after proving the gain
specifications were vastly exaggerated. Depending on the phase of the moon,
the numbers that came up in last months lottery, eBay policy changes with
reguard to who pays the return shipping fee on items that are not as
described. If you can show its the seller, then in many cases they will not
wish to pay the return cost.

Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3
6DT, United Kingdom
Registered in England and Wales as company number 08914892
http://www.kirkbymicrowave.co.uk/
Tel 01621'680100 / +44 1621-680100 <01621%20680100>
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Re: [time-nuts] Anyone have experience with this antenna?

[Poul-Henning Kamp]

In message 

Re: [time-nuts] Anyone have experience with this antenna?

[Michael Wouters]

That does represent a limiting case but it's a bit pessimistic. The longest
path is for very shallow incident angles eg a 3 mm thick and 150 mm radius
disk gives an angle of only about 1 degree. At 10 degrees, the path is
about 20 mm; with a refractive index of 1.5, the path is only 10 mm longer.
10 degrees might be what you set in the receiver's elevation mask.

A mm thick layer of dirt is just going to be roughly another mm of plastic;
worse if it's absorbed moisture, true.

You have a point about water. Water has about 10 times the refractive index
of plastic (real part of n)  so this is more of a worry. A 1 mm film will
have triple the path through a nominal 3 mm of plastic so at 10 degrees
incidence there is now about 40 mm extra path which you might see in
post-processing. But you're not going to see that in the 1 pps.

Cheers
Michael

On Wed, 7 Feb 2018 at 8:14 am, Bob kb8tq  wrote:

> Hi
>
> Since we are talking about an L1 / L2 antenna here, a reasonable assumption
> would be that the target is something better than an “average result”. If
> you construct
> a cover out of a piece of PVC pipe (as shown in the original drawing),
> your worst
> case path has a foot or so of PVC in it compared to a best case path with
> well under
> a tenth of an inch. That’s going to give you a bit of variation ….. Add
> some dirt or water
> or ice to the equation and who knows what the result might be.
>
> Bob
>
> > On Feb 6, 2018, at 3:45 PM, Michael Wouters 
> wrote:
> >
> > I can see why the geodetic community would worry about antenna phase
> centre
> > variation when a radome is installed but is it really an issue in timing
> > applications? The few papers I've read suggest PCVs of less than 10 mm,
> or
> > equivalently, 30 ps. This is at the level of precision available from
> > post-processed, carrier phase time-transfer but  invisible in the 1 pps
> > coming out of your receiver, even with a good sawtooth correction. Am I
> > missing something?
> >
> > Cheers
> > Michael
> >
> > On Wed, 7 Feb 2018 at 4:14 am, Bob kb8tq  wrote:
> >
> >> Hi
> >>
> >> There are “cell site” specific GPS antennas on the market. Panasonic has
> >> had one out
> >> for quite a while. I’m sure there are several others.
> >>
> >> One issue with doing any sort of “cover” for a precision antenna is
> >> distorting it’s pattern.
> >> Plastic (or whatever you use) will have different properties than air. A
> >> path through a blob
> >> of “not air” will change the effective path length. That impacts the
> >> timing and thus the
> >> navigation solution. If you are worried about 2mm sort of pattern
> >> accuracy, things get
> >> tricky. Early on, there was a big “throw out the radomes push when this
> >> was first noticed.
> >>
> >> Bob
> >>
> >>> On Feb 6, 2018, at 6:15 AM, Bo Hansen  wrote:
> >>>
> >>> Hi
> >>>
> >>> Besides the RF characteristics it may also be worth considering the
> >> quality of the plastics used. Over time water ingress may become an
> issue.
> >> Fours years after the installation of a CN brand antenna, sourced
> locally
> >> so probably not counterfeit either, we had to replace it at OZ7IGY
> >> www.oz7igy.dk
> >>>
> >>> RF wise 42 dB of gain IS an issue. Again at OZ7IGY, with 12 carriers in
> >> the air especially 13 cm and 23 cm, blocking and IMD were an issue
> before
> >> we mounted a BPF. I have taken apart the above mentioned antenna, a
> >> Motorola antenna and an eBay "hockey puck" antenna. The best design was
> >> clearly the Motorola one because it had a BPF after the pre-amp -
> probably
> >> because it was designed by RF competent people too. Each of the other
> ones
> >> had two FETs/MMICs in series and then a BPF. Of cause if no nearby
> carriers
> >> are in the air it may be less of an issue.
> >>>
> >>> So designing a really good antenna and pre-amp may be a business
> >> opportunity. There are many hi IP3 MMICs available designed for GPS and
> the
> >> like purposes. SAW BPFs with <1 dB loss are available fairly cheap so
> one
> >> before the FET/MMIC with a 1 dB NF is the way to go. A DIY radome using
> >> standard materials from any hardware shop is attached.
> >>>
> >>> Bo, OZ2M
> >>>
> >>> ___
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> >>
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> 

Re: [time-nuts] Anyone have experience with this antenna?

[Bob kb8tq]

Hi

Since we are talking about an L1 / L2 antenna here, a reasonable assumption 
would be that the target is something better than an “average result”. If you 
construct 
a cover out of a piece of PVC pipe (as shown in the original drawing), your 
worst 
case path has a foot or so of PVC in it compared to a best case path with well 
under
a tenth of an inch. That’s going to give you a bit of variation ….. Add some 
dirt or water
or ice to the equation and who knows what the result might be. 

Bob

> On Feb 6, 2018, at 3:45 PM, Michael Wouters  wrote:
> 
> I can see why the geodetic community would worry about antenna phase centre
> variation when a radome is installed but is it really an issue in timing
> applications? The few papers I've read suggest PCVs of less than 10 mm, or
> equivalently, 30 ps. This is at the level of precision available from
> post-processed, carrier phase time-transfer but  invisible in the 1 pps
> coming out of your receiver, even with a good sawtooth correction. Am I
> missing something?
> 
> Cheers
> Michael
> 
> On Wed, 7 Feb 2018 at 4:14 am, Bob kb8tq  wrote:
> 
>> Hi
>> 
>> There are “cell site” specific GPS antennas on the market. Panasonic has
>> had one out
>> for quite a while. I’m sure there are several others.
>> 
>> One issue with doing any sort of “cover” for a precision antenna is
>> distorting it’s pattern.
>> Plastic (or whatever you use) will have different properties than air. A
>> path through a blob
>> of “not air” will change the effective path length. That impacts the
>> timing and thus the
>> navigation solution. If you are worried about 2mm sort of pattern
>> accuracy, things get
>> tricky. Early on, there was a big “throw out the radomes push when this
>> was first noticed.
>> 
>> Bob
>> 
>>> On Feb 6, 2018, at 6:15 AM, Bo Hansen  wrote:
>>> 
>>> Hi
>>> 
>>> Besides the RF characteristics it may also be worth considering the
>> quality of the plastics used. Over time water ingress may become an issue.
>> Fours years after the installation of a CN brand antenna, sourced locally
>> so probably not counterfeit either, we had to replace it at OZ7IGY
>> www.oz7igy.dk
>>> 
>>> RF wise 42 dB of gain IS an issue. Again at OZ7IGY, with 12 carriers in
>> the air especially 13 cm and 23 cm, blocking and IMD were an issue before
>> we mounted a BPF. I have taken apart the above mentioned antenna, a
>> Motorola antenna and an eBay "hockey puck" antenna. The best design was
>> clearly the Motorola one because it had a BPF after the pre-amp - probably
>> because it was designed by RF competent people too. Each of the other ones
>> had two FETs/MMICs in series and then a BPF. Of cause if no nearby carriers
>> are in the air it may be less of an issue.
>>> 
>>> So designing a really good antenna and pre-amp may be a business
>> opportunity. There are many hi IP3 MMICs available designed for GPS and the
>> like purposes. SAW BPFs with <1 dB loss are available fairly cheap so one
>> before the FET/MMIC with a 1 dB NF is the way to go. A DIY radome using
>> standard materials from any hardware shop is attached.
>>> 
>>> Bo, OZ2M
>>> 
>>> ___
>>> 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.
>> 
>> ___
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>> 
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Re: [time-nuts] Anyone have experience with this antenna?

[Michael Wouters]

I can see why the geodetic community would worry about antenna phase centre
variation when a radome is installed but is it really an issue in timing
applications? The few papers I've read suggest PCVs of less than 10 mm, or
equivalently, 30 ps. This is at the level of precision available from
post-processed, carrier phase time-transfer but  invisible in the 1 pps
coming out of your receiver, even with a good sawtooth correction. Am I
missing something?

Cheers
Michael

On Wed, 7 Feb 2018 at 4:14 am, Bob kb8tq  wrote:

> Hi
>
> There are “cell site” specific GPS antennas on the market. Panasonic has
> had one out
> for quite a while. I’m sure there are several others.
>
> One issue with doing any sort of “cover” for a precision antenna is
> distorting it’s pattern.
> Plastic (or whatever you use) will have different properties than air. A
> path through a blob
> of “not air” will change the effective path length. That impacts the
> timing and thus the
> navigation solution. If you are worried about 2mm sort of pattern
> accuracy, things get
> tricky. Early on, there was a big “throw out the radomes push when this
> was first noticed.
>
> Bob
>
> > On Feb 6, 2018, at 6:15 AM, Bo Hansen  wrote:
> >
> > Hi
> >
> > Besides the RF characteristics it may also be worth considering the
> quality of the plastics used. Over time water ingress may become an issue.
> Fours years after the installation of a CN brand antenna, sourced locally
> so probably not counterfeit either, we had to replace it at OZ7IGY
> www.oz7igy.dk
> >
> > RF wise 42 dB of gain IS an issue. Again at OZ7IGY, with 12 carriers in
> the air especially 13 cm and 23 cm, blocking and IMD were an issue before
> we mounted a BPF. I have taken apart the above mentioned antenna, a
> Motorola antenna and an eBay "hockey puck" antenna. The best design was
> clearly the Motorola one because it had a BPF after the pre-amp - probably
> because it was designed by RF competent people too. Each of the other ones
> had two FETs/MMICs in series and then a BPF. Of cause if no nearby carriers
> are in the air it may be less of an issue.
> >
> > So designing a really good antenna and pre-amp may be a business
> opportunity. There are many hi IP3 MMICs available designed for GPS and the
> like purposes. SAW BPFs with <1 dB loss are available fairly cheap so one
> before the FET/MMIC with a 1 dB NF is the way to go. A DIY radome using
> standard materials from any hardware shop is attached.
> >
> > Bo, OZ2M
> >
> > ___
> > 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.
>
> ___
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>
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Re: [time-nuts] Anyone have experience with this antenna?

[Bo Hansen]

Hi

Indeed a radome may distort the antenna pattern. In teh case of DIY projects 
the trick that most can apply is to take a piece of the radome material and put 
it into a microwave own. If it doesn't get hot it is OK for most DIY cases.

Infinion have some nice GNSS MMICs e.g. BGA924N6 


Bo

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Re: [time-nuts] Anyone have experience with this antenna?

[Bob kb8tq]

Hi

The microwave trick is fine for working out if it is a lossy material. 
Unfortunately 
what gets you in this case is more than just loss. A coax cable has core 
material 
that will (usually) do quite well in a microwave. None the less, the delay 
through 
the coax is different than through air ( = the coax has a velocity factor). 

Bob


> On Feb 6, 2018, at 12:25 PM, Bo Hansen  wrote:
> 
> Hi
> 
> Indeed a radome may distort the antenna pattern. In teh case of DIY projects 
> the trick that most can apply is to take a piece of the radome material and 
> put it into a microwave own.  If it doesn't get hot it is OK for most DIY 
> cases.
> 
> Infinion have some nice GNSS MMICs e.g. BGA924N6 
> http://demo.21dianyuan.com/infineon/download/download_down/id/40/type/cn 
> 
> 
> Bo

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Re: [time-nuts] Anyone have experience with this antenna?

[Van Horn, David]

In a previous job, I used plastics to "lens" antennas at 2.4 GHz, shaping the 
patterns for more desirable results. 
XFDTD is a great software package for this application but it is expensive.
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Re: [time-nuts] Anyone have experience with this antenna?

[Bob kb8tq]

Hi

There are “cell site” specific GPS antennas on the market. Panasonic has had 
one out 
for quite a while. I’m sure there are several others. 

One issue with doing any sort of “cover” for a precision antenna is distorting 
it’s pattern. 
Plastic (or whatever you use) will have different properties than air. A path 
through a blob
of “not air” will change the effective path length. That impacts the timing and 
thus the 
navigation solution. If you are worried about 2mm sort of pattern accuracy, 
things get 
tricky. Early on, there was a big “throw out the radomes push when this was 
first noticed.

Bob

> On Feb 6, 2018, at 6:15 AM, Bo Hansen  wrote:
> 
> Hi
> 
> Besides the RF characteristics it may also be worth considering the quality 
> of the plastics used. Over time water ingress may become an issue. Fours 
> years after the installation of a CN brand antenna, sourced locally so 
> probably not counterfeit either, we had to replace it at OZ7IGY www.oz7igy.dk
> 
> RF wise 42 dB of gain IS an issue. Again at OZ7IGY, with 12 carriers in the 
> air especially 13 cm and 23 cm, blocking and IMD were an issue before we 
> mounted a BPF. I have taken apart the above mentioned antenna, a Motorola 
> antenna and an eBay "hockey puck" antenna. The best design was clearly the 
> Motorola one because it had a BPF after the pre-amp - probably because it was 
> designed by RF competent people too. Each of the other ones had two 
> FETs/MMICs in series and then a BPF. Of cause if no nearby carriers are in 
> the air it may be less of an issue.
> 
> So designing a really good antenna and pre-amp may be a business opportunity. 
> There are many hi IP3 MMICs available designed for GPS and the like purposes. 
> SAW BPFs with <1 dB loss are available fairly cheap so one before the 
> FET/MMIC with a 1 dB NF is the way to go. A DIY radome using standard 
> materials from any hardware shop is attached.
> 
> Bo, OZ2M
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Re: [time-nuts] Anyone have experience with this antenna?

[Attila Kinali]

On Tue, 6 Feb 2018 08:54:23 -0500
Bob kb8tq  wrote:

> One gotcha (if the data sheets are correct) is going to be the supply voltage.
> We normally stay away from 12V antennas because TBolt’s put out 5V. In the
> case of a survey antenna, 12V is what most of the gear puts out. I don’t know
> of any L1 / L2 gear that puts out 5 rather than 12V ….

Well, that's at least a very easy modification. Just open up the connection
between the bias-T and the LNA and insert some LM1117 or better an TPS7A45xx.

Attila Kinali

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Anyone have experience with this antenna?

[Bob kb8tq]

Hi

One gotcha (if the data sheets are correct) is going to be the supply voltage.
We normally stay away from 12V antennas because TBolt’s put out 5V. In the
case of a survey antenna, 12V is what most of the gear puts out. I don’t know
of any L1 / L2 gear that puts out 5 rather than 12V ….

Bob

> On Feb 6, 2018, at 6:48 AM, Attila Kinali  wrote:
> 
> Moin,
> 
> On Mon, 5 Feb 2018 21:33:59 -0600
> John Green  wrote:
> 
>> https://www.ebay.com/itm/High-Precision-L1-L2-GNSS-GPS-GLONASS-BeiDou-RTK-CORS-survey-antenna/162718512935?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649
>> 
>> Listed on eBay as a L1/L2 antenna with decent specs. They seem to indicate
>> it is as good as a choke ring antenna. I suspect it is just a patch in a
>> fancy package. 
> 
> It actually is. The fourth picture in the ebay listing shows that it's
> a dual, stacked patch antenna with a 4 point (0°, 90°, 180°, 270°)
> excitation using fiberglass as substrate. I am not sure I would trust
> the +/-2mm phase center error, but it's probably quite decent.
> But advertising it as "high precision" or even "chocke ring antenna
> functionality without out the size or weight" is an outright lie. 
> For one, they are too cheap to use nylon screws instead of
> metal screws in the antenna, which will lead to distortions in the
> radiation pattern. For another the fiberglass/epoxy substrate is going
> to change its dielectric constant with humidity, which will inevitably
> lead to changes in its resonance and radiation pattern. Third, the
> choke ring is to minimize influence of reflections close to or below
> the antenna horizon. This antenna does not have anything that comes even
> close to provide this feature.
> 
> Judging from the meager information on the ebay lsting, it's most likely
> a Shenzen Beitan 7151[1] or a 7201[2] ("data"sheets attached).
> 
> BTW: You can get the 7151 for 75USD and free sheeping on aliexpress.
> 
>> That is what the Leica and Trimble survey grade antennas I
>> have contain anyway. I bought one but haven't had the chance to do any
>> testing. I couldn't figure out how to get to the insides to take a peek
>> without damaging it. My antenna testing abilities are pretty feeble.
>> Mostly, I will just compare it to the Leica and Trimble to see how many
>> satellites it sees and look at position wander of the uBlox. Is there any
>> simple way to judge the quality of a GPS antenna?
> 
> If you have a known-good reference antenna and two receivers that can
> record the carrier phase data of the two antennas, then it's relatively
> easy to compare them (although there is quite a bit of math involved
> and you probably eed to write the software yourself, as i am not aware
> of any publicly, for hobbyists available software package).
> 
>   Attila Kinali
> 
> [1] http://www.sz-beitian.com/ProductsDetail?product_id=53
> [2] http://www.sz-beitian.com/ProductsDetail?product_id=52
> 
> -- 
> It is upon moral qualities that a society is ultimately founded. All 
> the prosperity and technological sophistication in the world is of no 
> use without that foundation.
> -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Anyone have experience with this antenna?

[djl]

There's a picture of the guts in the ebay description...it's a dual 
patch antenna!

the patches seem to be trimmed to get a pattern.

On 2018-02-05 20:33, John Green wrote:

https://www.ebay.com/itm/High-Precision-L1-L2-GNSS-GPS-GLONASS-BeiDou-RTK-CORS-survey-antenna/162718512935?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

Listed on eBay as a L1/L2 antenna with decent specs. They seem to 
indicate
it is as good as a choke ring antenna. I suspect it is just a patch in 
a
fancy package. That is what the Leica and Trimble survey grade antennas 
I

have contain anyway. I bought one but haven't had the chance to do any
testing. I couldn't figure out how to get to the insides to take a peek
without damaging it. My antenna testing abilities are pretty feeble.
Mostly, I will just compare it to the Leica and Trimble to see how many
satellites it sees and look at position wander of the uBlox. Is there 
any

simple way to judge the quality of a GPS antenna?
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Re: [time-nuts] Anyone have experience with this antenna?

[Tom Van Baak]

oops, sorry for the misfire.

> I couldn't figure out how to get to the insides to take a peek
> without damaging it.

For $99 I would take the risk to damage it... Or find someone with x-ray gear 
and have a peak inside. Or take it with you on your next plane flight and grab 
a photo of the TSA monitor as you pass through.

> My antenna testing abilities are pretty feeble.
> Mostly, I will just compare it to the Leica and Trimble to see how many
> satellites it sees and look at position wander of the uBlox. Is there any
> simple way to judge the quality of a GPS antenna?

That's a good question. It all depends on what you're using it for. If you're a 
mm survey kind of guy then mix that antenna with half a dozen name-brand 
antennae that you already own and trust. See how it stacks up in real-time or 
post-processing benchmarks. I'm a fan of measurement more than specs, so 
collect as much data as you can and share with us.

If you're a time-nut it's more complicated. It's possible you don't have 
anywhere near the kind of equipment that can detect sub-10 ns sort of bias or 
wander or noise. And then there are issues of orientation, elevation, 
linearity, thermal stability, etc. If it's not in the NGS database be 
suspicious. Ref:

https://www.febo.com/pipermail/time-nuts/2018-January/108519.html

/tvb

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Re: [time-nuts] Anyone have experience with this antenna?

[Tom Van Baak]

> testing. I couldn't figure out how to get to the insides to take a peek
> without damaging it. My antenna testing abilities are pretty feeble.
> Mostly, I will just compare it to the Leica and Trimble to see how many
> satellites it sees and look at position wander of the uBlox. Is there any
> simple way to judge the quality of a GPS antenna?
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