Probably about the only accurate way, really.
A GPS antenna is light weight enough that it could be
mounted to a suitable turntable clamped to the shaft of
a stepper motor. The assumed physical center of the
antenna could be mounted directly on the axis of
rotation. Then you would know accurate
Hi
At least according to:
ftp://geodesy.noaa.gov/pub/abilich/oldPC/Documents/antcal/calibPapers/Schmitz2002.pdf
There are others doing the same thing.
Bob
> On May 9, 2015, at 2:37 AM, Poul-Henning Kamp wrote:
>
>
> In message , Bob Camp writes:
>
>> The “put the antenna up and ro
On 5/8/15 11:37 PM, Poul-Henning Kamp wrote:
In message , Bob Camp writes:
The “put the antenna up and rotate it to see what happens” experiment
has indeed been done. The objective was not correcting the antenna’s
issues, but validating that their model of the antenna’s phase
center wa
In message , Bob Camp writes:
>The “put the antenna up and rotate it to see what happens” experiment
>has indeed been done. The objective was not correcting the antenna’s
>issues, but validating that their model of the antenna’s phase
>center was correct. They were trying to see if anecho
Hi
The “put the antenna up and rotate it to see what happens” experiment has
indeed been done. The
objective was not correcting the antenna’s issues, but validating that their
model of the antenna’s phase
center was correct. They were trying to see if anechoic chamber data really
gave correct a
In message <554bc3c3.7090...@earthlink.net>, Jim Lux writes:
>>> I wonder if anybody ever made a rotating GPS antenna to average out the
>>> X-Y phase-center offset ?
>>
>> There is a severe mechanical problem with that. Moving contacts
>> are very hard to keep electrically stable
You wo
On Thu, 7 May 2015 14:43:44 -0400
Tim Shoppa wrote:
> Gotcha with modulating the PPS onto a RF carrier, is that for time
> resolution of 1 nanosecond, you would end up using a Gigahertz of bandwidth.
Not really. You are not doing detection in frequency space
or of an infintely sharp pulse. As su
tsho...@gmail.com said:
> Gotcha with modulating the PPS onto a RF carrier, is that for time
> resolution of 1 nanosecond, you would end up using a Gigahertz of bandwidth.
You might be able to use near-field antennas. Picture 2 PCBs spaced a few mm
apart with circular antennas. It would be int
On Thu, 7 May 2015 08:18:05 -0700
"Tom Van Baak" wrote:
> Attila,
>
> My thought was to put PHK's proposed experiment entirely on the rotating
> table: antenna, receiver, local Cs standard, laptop, and battery.
Then you have to be carefull, that the rotation does not modulate
the reference. I
On 5/7/15 7:23 AM, Attila Kinali wrote:
On Sun, 03 May 2015 07:29:30 +
"Poul-Henning Kamp" wrote:
When you post-process raw GPS data you get to include antenna phase
center / gain / az/el corrections for free.
Speaking of which...
I wonder if anybody ever made a rotating GPS antenna to
time-nuts] Important parameters for a GPS/GNSS antenna
Personally I would be happy with PPS time resolution at 10 nanoseconds but
others would want better than a nanosecond.
Gotcha with modulating the PPS onto a RF carrier, is that for time
resolution of 1 nanosecond, you would end up using a Gig
Also consider phase wind up.
http://www.navipedia.net/index.php/Carrier_Phase_Wind-up_Effect
Sure there are also some papers on rotating antennas.
http://www.researchgate.net/profile/Simon_Banville/publication/257945217_Antenna_Rotation_and_Its_Effects_on_Kinematic_Precise_Point_Positioning/l
Personally I would be happy with PPS time resolution at 10 nanoseconds but
others would want better than a nanosecond.
Gotcha with modulating the PPS onto a RF carrier, is that for time
resolution of 1 nanosecond, you would end up using a Gigahertz of bandwidth.
Tim N3QE
On Thu, May 7, 2015 at
I'm curious whether it would need 360 degree rotation? Would simply cycling
about 120 degrees on the end of a short arm be just as good and could be done
without a rotary joint? I understand that now the RX is moving but within a
small radius would it be unbearable? Or would 300 degrees around t
Just put the GPS antenna, receiver, battery, and a low power RF
transmitter modulated by the PPS (wide bandwidth = fast edge time) on
the turntable, then use an appropriate receiver to demodulate the PPS
and feed it to the rest of the system. Put the RX antenna directly
above (or below) the tu
>> I wonder if anybody ever made a rotating GPS antenna to average out the
>> X-Y phase-center offset ?
> Of course, this does not really work with a gps antenna, unless you
> put the whole receiver onto the rotary table. But then you shift
> the problem onto the PPS output (note: amplitude noise
On Sun, 03 May 2015 07:29:30 +
"Poul-Henning Kamp" wrote:
> >When you post-process raw GPS data you get to include antenna phase
> >center / gain / az/el corrections for free.
>
> Speaking of which...
>
> I wonder if anybody ever made a rotating GPS antenna to average out the
> X-Y phase-ce
On Sat, 02 May 2015 18:36:30 +0200
Magnus Danielson wrote:
> On 04/29/2015 10:43 PM, Attila Kinali wrote:
> > Moin,
> >
> > I recently discovered openEMS[1], which is, very simply put, a fancy
> > antenna simulator. I played a little with it and thought about
> > trying to optimize an GPS patch a
On Sat, 2 May 2015 13:25:16 -0400
Bob Camp wrote:
> Phase / delay stability over temperature would be an interesting thing
> to look at. Probably not a big deal on
> a simple antenna. It might be an issue as the antenna interacts with the
> preamp and filter.
I've seen a couple of papers concer
> I wonder if anybody ever made a rotating GPS antenna to average out the
> X-Y phase-center offset ?
PHK,
I ran across this wonderful "shaker table" experiment and concluded that
post-processing would always be better than playing moving antenna games.
See pages 9-13 of:
http://www.nceo.ac.uk/
In message , "Tom Van Baak" writes:
>When you post-process raw GPS data you get to include antenna phase
>center / gain / az/el corrections for free.
Speaking of which...
I wonder if anybody ever made a rotating GPS antenna to average out the
X-Y phase-center offset ?
--
Poul-Henning
> A tri-band antenna design is... uh.. difficult.
> At the moment I am just playing with some software. Yes, I might
> end up with something that resembles an antenna design. But with my level of
> knowledge getting a good single band antenna would be already quite
> some feat. Designing a multi-ba
Hi
Obviously this becomes a “that depends” sort of question. For timing, you
probably can
do a fine job with an antenna that nukes everything below 20 degrees to the
horizon. That
*assumes* that you have a good enough view that it does not pull to many sat’s
out of your population
*and* that
Attila,
On 04/29/2015 10:43 PM, Attila Kinali wrote:
Moin,
I recently discovered openEMS[1], which is, very simply put, a fancy
antenna simulator. I played a little with it and thought about
trying to optimize an GPS patch antenna design for timing use.
Will take it for a test-drive to see ho
On Thu, 30 Apr 2015 17:19:22 +
Gregory Maxwell wrote:
> I have no experience in the subject, but one parameter I didn't see
> you mention is front/back ratio-- it should have the lowest gain
> possible for angles below whatever you would horizon mask in order to
> suppress multipath coming in
Moin,
I recently discovered openEMS[1], which is, very simply put, a fancy
antenna simulator. I played a little with it and thought about
trying to optimize an GPS patch antenna design for timing use.
But I had to discover that I actually do not know what to optimze for.
There are many paramters
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