Said,
Are those using the u-blox receivers? (I don't know of any other company with a
50 channel receiver.) If so, what's your overall
opinion of them?
Jason
one more product line: all of our Jackson Labs Technologies, Inc.
FireFly-1A and FireFly-IIA based GPSDO Timing products use WAAS by
Hi Jason,
yes, we use uBlox among others. We have a very high opinion of these in
mobile applications.
We add dynamic GPS filter parameter configuration in our software, the
units with default configuration are not really usable in mobile applications
above walking speed. We did numerous
Just curious, but which popular GPS timing receivers work with WAAS?
The only one I can think of off the top of my head is that Garmin hockey puck.
Jason
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Hi Jason,
one more product line: all of our Jackson Labs Technologies, Inc.
FireFly-1A and FireFly-IIA based GPSDO Timing products use WAAS by default.
Actually they use WAAS in the Americas, Egnos in Europe and other SBAS
signals around the world.
We have shown significantly better
On 10/08/2010 08:09 PM, Brooke Clarke wrote:
Hi John:
The WAAS birds may be too weak to receive with an omni antenna, hence
the desire to get some gain.
The normal GPS sats will pass through the beam and the GPS antenna will
pick up some sats directly so you do get some TRAIM.
Doppler is not an
On 10/8/2010 1:48 PM, Magnus Danielson wrote:
I would not be supprised if they had not considered such a threat.
This is a common threat for all bent-pipe birds. They have been jammed
before and we can expect them to be jammed again. However, I do not
think the WAAS or any similar is
Hi Magnus:
Stanford Telecom built GPS simulators to test their GPS ICs. It's made
where each wire wrap PCB is based on a page from ICD-200.
http://www.prc68.com/I/5001A.html
Have Fun,
Brooke Clarke
http://www.PRC68.com
Magnus Danielson wrote:
On 10/09/2010 04:47 PM, Matthew Kaufman
On 10/9/2010 8:00 AM, Magnus Danielson wrote:
Hmm. Yes. Creative! Once demonstrated essentially all WAAS/EGNOS/SBAS
sats need to develope some protective measure.
Unless, of course, such protective measures already exist. I can think
of several ways right off the top of my head... one would
Matthew Kaufman wrote:
On 10/9/2010 8:00 AM, Magnus Danielson wrote:
Hmm. Yes. Creative! Once demonstrated essentially all WAAS/EGNOS/SBAS
sats need to develope some protective measure.
Unless, of course, such protective measures already exist. I can think
of several ways right off the top
On 10/9/2010 8:22 AM, jimlux wrote:
Unlikely that this would be in the open literature. It's pretty
clearly one of those things that falls under export control.
Quite likely. The threat itself hasn't been mentioned as far as I can
tell, either... as someone who relies on GPS timing for
Hi
The Russians have been willing to sell GPS jammers for quite a while. They
aren't terribly expensive. Their export controls are a bit different than the
US's.
Bob
On Oct 9, 2010, at 12:00 PM, Matthew Kaufman wrote:
On 10/9/2010 8:22 AM, jimlux wrote:
Unlikely that this would be in
But unlike the threat I described, they're not pre-mounted in geo orbit over
the US... As far as we know.
Matthew Kaufman
(Sent from my iPhone)
On Oct 9, 2010, at 9:16 AM, Bob Camp li...@rtty.us wrote:
Hi
The Russians have been willing to sell GPS jammers for quite a while. They
aren't
Bob Camp wrote:
Hi
The Russians have been willing to sell GPS jammers for quite a while. They
aren't terribly expensive. Their export controls are a bit different than the
US's.
Bob
Simple GPS jammers are pretty easy, since consumer GPS is very
vulnerable to repeater jammers. Hmm I
On 10/09/2010 09:47 PM, jimlux wrote:
Bob Camp wrote:
Hi
The Russians have been willing to sell GPS jammers for quite a while.
They aren't terribly expensive. Their export controls are a bit
different than the US's.
Bob
Simple GPS jammers are pretty easy, since consumer GPS is very
On Oct 9, 2010, at 12:47 PM, jimlux wrote:
Simple GPS jammers are pretty easy, since consumer GPS is very vulnerable to
repeater jammers. Hmm I wonder if that would adversely affect a GPSDO?
Probably not, since the repeated signal is just as stable as the original one.
I would think that
The other thing is that something like a quad helix or patch doesn't have the
same cross-pol over the hemisphere. It could be real good in one direction and
not so good in others. Just like isotropic antennas, you can't physically
realize the same cp in all directions (cf hairy ball theorem)
Magnus Danielson wrote:
On 10/08/2010 03:35 AM, jmfranke wrote:
When I said the feed would work, I was meaning it would work if LHC.
The illustrations and text imply you could just place a normal GPS
receiver at the feed location, but the polarization would be wrong.
Which was what I reacted
Yep, a Cassegrain antenna would work.
John WA4WDL
--
From: Bill Janssen bi...@ieee.org
Sent: Friday, October 08, 2010 11:52 AM
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] GPS backup
Bill Janssen wrote:
Magnus Danielson wrote:
On 10/08/2010 03:35 AM, jmfranke wrote:
When I said the feed would work, I was meaning it would work if LHC.
The illustrations and text imply you could just place a normal GPS
receiver at the feed location, but the polarization would be wrong.
Hi Jim:
I've got a spare Ku band satellite dish and would like to use it for GPS.
In an ideal application the GPS antenna would be mounted in the normal
manner and above it would be a sub-reflector aimed at the Ku dish.
That way the antenna might pickup sats near the horizon directly and
from
I've been half following this thread and can't make out the reason for a
less than hemispheric antenna pattern. GPS needs several birds to lock up,
and if you look at a single bird, Dopplar will make the signal useless as
a frequency reference.
Best,
-John
=
Hi Jim:
I've got a
@febo.com
Subject: Re: [time-nuts] GPS backup for the stationary time and
frequencyuser
I've been half following this thread and can't make out the reason for a
less than hemispheric antenna pattern. GPS needs several birds to lock up,
and if you look at a single bird, Dopplar will make the signal
On Oct 8, 2010, at 10:27 AM, J. Forster wrote:
GPS needs several birds to lock up,
To get a position fix, this is true; 3 birds minimum for a 2D fix, 4 birds
minimum for a 3D fix.
and if you look at a single bird, Dopplar will make the signal useless as
a frequency reference.
Only if you
KISS. This seems like a lot of work for not particularily good results.
Among other things, you have no closure so no measure of how good your
measuremwent is.
FWIW,
-John
On Oct 8, 2010, at 10:27 AM, J. Forster wrote:
GPS needs several birds to lock up,
To get a
On 10/8/2010 10:44 AM, J. Forster wrote:
KISS. This seems like a lot of work for not particularily good results.
I think the point is that the results are amazingly better than the
alternative if the medium-orbit GPS sats are all destroyed and/or
there's jamming coming from all over the
Brooke Clarke wrote:
Hi Jim:
I've got a spare Ku band satellite dish and would like to use it for GPS.
In an ideal application the GPS antenna would be mounted in the normal
manner and above it would be a sub-reflector aimed at the Ku dish.
That way the antenna might pickup sats near the
J. Forster wrote:
I've been half following this thread and can't make out the reason for a
less than hemispheric antenna pattern. GPS needs several birds to lock up,
and if you look at a single bird, Dopplar will make the signal useless as
a frequency reference.
If you're looking at boosting
Matthew Kaufman wrote:
On 10/8/2010 10:44 AM, J. Forster wrote:
KISS. This seems like a lot of work for not particularily good results.
I think the point is that the results are amazingly better than the
alternative if the medium-orbit GPS sats are all destroyed and/or
there's jamming
On Oct 8, 2010, at 10:44 AM, J. Forster wrote:
KISS. This seems like a lot of work for not particularily good results.
Among other things, you have no closure so no measure of how good your
measuremwent is.
Single-satellite timing mode is already commonly implemented in timing
receivers;
On 10/08/2010 07:27 PM, J. Forster wrote:
I've been half following this thread and can't make out the reason for a
less than hemispheric antenna pattern. GPS needs several birds to lock up,
and if you look at a single bird, Dopplar will make the signal useless as
a frequency reference.
If you
On 10/08/2010 08:07 PM, Matthew Kaufman wrote:
On 10/8/2010 10:44 AM, J. Forster wrote:
KISS. This seems like a lot of work for not particularily good results.
I think the point is that the results are amazingly better than the
alternative if the medium-orbit GPS sats are all destroyed and/or
On 10/08/2010 08:22 PM, jimlux wrote:
Brooke Clarke wrote:
Hi Jim:
I've got a spare Ku band satellite dish and would like to use it for GPS.
In an ideal application the GPS antenna would be mounted in the normal
manner and above it would be a sub-reflector aimed at the Ku dish.
That way the
Magnus Danielson wrote:
On 10/08/2010 08:22 PM, jimlux wrote:
B
You might do just as well with a flat cookie sheet.
Well, a 1 m dish gives you 48 dB gain at L1 if I calculate correctly.
I don't think so..48dBi would be huge...A numerical gain of 48 I can
believe:
let's say we have
48dBi is way way too big
18 I might go for
Look at aperture. Say it's six square wavelengths(40x60 cm). A dipole is about
1/8th square wave lengths..so the gain is 48 times that of a dipole. Say about
17dB +2dB or 19 dBi
On Oct 8, 2010, at 3:05 PM, Magnus Danielson
20 log(base10) (diameter in meters) + 20log(frequency in ghz) +17.8 = dbi
On 10/8/2010 8:39 PM, jimlux wrote:
Magnus Danielson wrote:
On 10/08/2010 08:22 PM, jimlux wrote:
B
You might do just as well with a flat cookie sheet.
Well, a 1 m dish gives you 48 dB gain at L1 if I calculate
Hi John:
The WAAS birds may be too weak to receive with an omni antenna, hence
the desire to get some gain.
The normal GPS sats will pass through the beam and the GPS antenna will
pick up some sats directly so you do get some TRAIM.
Doppler is not an issue in timing mode (i.e. position is
Brian Kirby wrote:
20 log(base10) (diameter in meters) + 20log(frequency in ghz) +17.8 = dbi
That assumes some nominal efficiency?
I'll have to remember that one.. 17.8
It's like the 32.44 dB for free space loss between isotropes 1 km apart
at 1 MHz
(+20log10(dist in km) + 20log10(freq
; Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] GPS backup for the stationary time and
frequencyuser
Hi John:
The WAAS birds may be too weak to receive with an omni antenna, hence the
desire to get some gain.
The normal GPS sats will pass
These were formulas I had written in my notes about 30 years ago, when I
worked in Satcom for the military and NASA.
I think they used an efficiency of 55 percent
another was 20log D(feet) + 20log F(mhz) - 52.4 = dbi
and the main formula of gain in db = k(pi*D/wave)squared showing
...@cox.net
Sent: Thursday, October 07, 2010 9:32 PM
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] GPS backup for the stationary time and
frequencyuser
You are correct. The dish feed should be LHC. The feed would work for
WAAS or other GPS
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