In message fc02a5e8-5396-4474-a307-546e10909...@n1k.org, 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
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 p...@phk.freebsd.dk wrote:
In message
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
On 5/8/15 11:37 PM, Poul-Henning Kamp wrote:
In message fc02a5e8-5396-4474-a307-546e10909...@n1k.org, 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
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 wouldn't need
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
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.
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
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
On Thu, 7 May 2015 08:18:05 -0700
Tom Van Baak t...@leapsecond.com 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
On Thu, 7 May 2015 14:43:44 -0400
Tim Shoppa tsho...@gmail.com 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
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
Subject: Re: [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
On 5/7/15 7:23 AM, Attila Kinali wrote:
On Sun, 03 May 2015 07:29:30 +
Poul-Henning Kamp p...@phk.freebsd.dk 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
On Sat, 2 May 2015 13:25:16 -0400
Bob Camp kb...@n1k.org 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
On Sun, 03 May 2015 07:29:30 +
Poul-Henning Kamp p...@phk.freebsd.dk 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
On Sat, 02 May 2015 18:36:30 +0200
Magnus Danielson mag...@rubidium.dyndns.org 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
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
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
In message B373DA32B0D748A9B45D90A7D38B2C32@pc52, 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
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:
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
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-band
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
On Thu, 30 Apr 2015 17:19:22 +
Gregory Maxwell gmaxw...@gmail.com 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
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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