Does a stationary (not in motion) GPS receiver know where the North is?
As far
as I can understand, it doesn't, isn't it?
Antonio I8IOV
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That is an interesting question.
It could be possible if it had two antennas or its antenna was
not omni-directional.
Mike - AA8K
iov...@inwind.it wrote:
Does a stationary (not in motion) GPS receiver know where the North is?
As far
as I can understand, it doesn't, isn't it?
iov...@inwind.it wrote:
Does a stationary (not in motion) GPS receiver know where the North is?
As far
as I can understand, it doesn't, isn't it?
Not one with a unidirectional antenna, which is the usual stuff.
If you have multiple antennas you can sort out the directions. But it is
an
It depends on the GPS receiver. The GPS chipset won't know (it knows where
it is and can remember where it was to know what direction it's moving), but
some consumer GPS receivers (Garmin, Magellan) have electronic compasses
built in. My Garmin eTrex Legend does NOT have a compass built in, but
Robert Darlington wrote:
It depends on the GPS receiver. The GPS chipset won't know (it knows where
it is and can remember where it was to know what direction it's moving), but
some consumer GPS receivers (Garmin, Magellan) have electronic compasses
built in. My Garmin eTrex Legend does NOT
Am Saturday 21 November 2009 15:05:12 schrieb iov...@inwind.it:
Does a stationary (not in motion) GPS receiver know where the North is?
As far
as I can understand, it doesn't, isn't it?
Umm, as far as i understand it, a single receiver with a single
omnidirectional antenna (at least with
Does a stationary (not in motion) GPS receiver know where the North is?
No, a stationary object is a point, not a line or a vector.
The notion of North (or any direction) has no meaning
to a point, by definition.
There are two exceptions. If during your long polar trek
the latitude is ±90º 00'
- Original Message -
From: Magnus Danielson mag...@rubidium.dyndns.org
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Saturday, November 21, 2009 4:05 PM
Subject: Re: [time-nuts] OT - GPS and North
Robert Darlington wrote:
It depends on the GPS
Agreed Magnus, but I dont think any gizmos are required. If the the
positions of the satellites are known, as they must be to enable the
antennas position to be calculated, I think just an extra set of
calculations is necessary to indicate the direction to anywhere else
on the planet (or
Tom Van Baak wrote:
Does a stationary (not in motion) GPS receiver know where the North is?
No, a stationary object is a point, not a line or a vector.
The notion of North (or any direction) has no meaning
to a point, by definition.
You are mixing things a litte too much here. There is no
mike cook wrote:
- Original Message - From: Magnus Danielson
mag...@rubidium.dyndns.org
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Saturday, November 21, 2009 4:05 PM
Subject: Re: [time-nuts] OT - GPS and North
Robert Darlington wrote:
It
Yes, but it is rather difficult to manufacture an
isotropic antenna. Unless the antenna is oriented
so as to present a normal hemisphere of same gain,
it might be theoretically possible to model the gain
versus direction, coupled with the knowledge of
location of satellites and received
If the
positions of the satellites are known, as they must be to enable the
antennas position to be calculated, I think just an extra set of
calculations is necessary to indicate the direction to anywhere else on the
planet (or elsewhere) including the geographic poles.
Mike,
The
Would Time Difference of Arrival techniques combined with an array of four
closely spaced antennas work with Gps signals as a means of determing the
orentation of the antenna array vs the gps satellites ? (I#39;m thinking
traditional TDOA techniques may not work with gps signals.)
Mike Naruta
OK. Sme GPS receivers have magnetic sensors. What do they do with/about
magnetic deviation.
-John
==
Tom Van Baak wrote:
Does a stationary (not in motion) GPS receiver know where the North is?
No, a stationary object is a point, not a line or a vector.
The notion of North (or
Clearly, two three antennas can tell you everything you need to know. I've
seen video of a model helicopter flying itself with three GPS antennas.
NASA, I think.
-John
===
Would Time Difference of Arrival techniques combined with an array of four
closely spaced antennas work with Gps
Tom, this would be taking advantage of the
irregularities of the GPS receive antenna
to determine the orientation of the antenna.
For example, if the GPS antenna were a Yagi,
and it was pointed with the major lobe in
an Easterly direction, when you listen to
a satellite in the East, you know
Apparently, I was goi9ng in the wrong direction...
Don
BTW, I do have a pinout for your tcxo, I think, if it is the same as the
5.11etc.
Don
EB4APL
No, EROS was an oscillator manufacturer named Electronic Research Co,
now INFICON EDC (www.electrodynamics.com).
I have a 10 MHz TCXO which is
Maybe something too basic many too say, but did you lower the Tbolts signal
level mask AMU setting?
Default is 3, set to 1 or 2 so that it will accept lower level signals
- Original Message -
From: saidj...@aol.com
To: time-nuts@febo.com
Sent: Saturday, November 21, 2009 11:40 AM
Hi Said,
As we talked about some weeks ago... your test is unfair to the Tbolt, but
that is perhaps intentional. The Tbolt will need more gain to work. You
are giving it a signal that is out of spec.
--
Björn
Hi guys,
some weeks ago we talked about reception problems on Trimble
Mark Spencer wrote:
Would Time Difference of Arrival techniques combined with an array of four closely
spaced antennas work with Gps signals as a means of determing the orentation of the
antenna array vs the gps satellites ? (I#39;m thinking traditional TDOA
techniques may not work with gps
Gary Chatters wrote:
Mark Spencer wrote:
Would Time Difference of Arrival techniques combined with an array of
four closely spaced antennas work with Gps signals as a means of
determing the orentation of the antenna array vs the gps satellites ?
(I#39;m thinking traditional TDOA techniques
J. Forster wrote:
OK. Sme GPS receivers have magnetic sensors. What do they do with/about
magnetic deviation.
There is a field in one of the NMEA messages for magnetic deviation
which some GPS receivers fill in.
I do not know where they get the values. There is a mathematical model
Gary Chatters wrote:
I have no idea of how the math works for computing heading.
Checkout FORWARD and INVERSE (and their 3d equivalents) at
http://www.ngs.noaa.gov/TOOLS/Inv_Fwd/Inv_Fwd.html
While these are hosted on a NOAA site, I'm sure I've seen
it on a NASA site as well. IIRC, there is
Mark Spencer wrote:
Would Time Difference of Arrival techniques combined with an array of
four closely spaced antennas work with Gps signals as a means of
determing the orentation of the antenna array vs the gps satellites ?
(I#39;m thinking traditional TDOA techniques may not work with gps
J. Forster wrote:
OK. Sme GPS receivers have magnetic sensors. What do they do with/about
magnetic deviation.
There is a field in one of the NMEA messages for magnetic deviation
which some GPS receivers fill in.
I do not know where they get the values. There is a mathematical model
Iain Young wrote:
Gary Chatters wrote:
I have no idea of how the math works for computing heading.
Checkout FORWARD and INVERSE (and their 3d equivalents) at
http://www.ngs.noaa.gov/TOOLS/Inv_Fwd/Inv_Fwd.html
While these are hosted on a NOAA site, I'm sure I've seen
it on a NASA site as
b...@lysator.liu.se wrote:
J. Forster wrote:
OK. Sme GPS receivers have magnetic sensors. What do they do with/about
magnetic deviation.
There is a field in one of the NMEA messages for magnetic deviation
which some GPS receivers fill in.
I do not know where they get the values. There is a
When you think of time specifications from GPS, the GPS system is a
poor way to find north.
Even with a base line of 1000 metres you only have a fraction of a
degree.
The GPS system may be useful to get accurate time to simplify a star
observation, from a known (GPS)
position on this
Interesting thanks !
- Original Message
From: Gary Chatters gcarlis...@garychatters.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sat, November 21, 2009 2:57:15 PM
Subject: Re: [time-nuts] OT - GPS and North
Mark Spencer wrote:
Would Time
b...@lysator.liu.se wrote:
Mark Spencer wrote:
Would Time Difference of Arrival techniques combined with an array of
four closely spaced antennas work with Gps signals as a means of
determing the orentation of the antenna array vs the gps satellites ?
(I#39;m thinking traditional TDOA
Hi Neville
When you think of time specifications from GPS, the GPS system is a
poor way to find north.
I do not understand. Please elaborate. A baseline of 10 meter will often
give better than 1mrad accuracy.
Even with a base line of 1000 metres you only have a fraction of a
degree.
This
Neville Michie wrote:
When you think of time specifications from GPS, the GPS system is a
poor way to find north.
Even with a base line of 1000 metres you only have a fraction of a
degree.
The GPS system may be useful to get accurate time to simplify a star
observation, from a known (GPS)
Hi
If you only have one antenna and one receiver, the answer is fairly simple.
Swing it around you head on the end of a long string. Plot the position reading
vs time. Correlate the readings to the phase of the rotation.
It does indeed work (it's a doppler scanner ...). You could easily argue
Don,
Send me the pin out, please.
TIA
Ignacio, EB4APL
...
Don Latham wrote:
Apparently, I was goi9ng in the wrong direction...
Don
BTW, I do have a pinout for your tcxo, I think, if it is the same as the
Bob Camp wrote:
Hi
If you only have one antenna and one receiver, the answer is fairly simple. Swing it around you head on the end of a long string. Plot the position reading vs time. Correlate the readings to the phase of the rotation.
It does indeed work (it's a doppler scanner ...). You
Not so. I'm very familiar with laying in accurate North lines for gyro
testing. To get anything close to accurate (1 arc second or better) takes
many hours of stellar observation with a Wild T-3 class instrument.
-John
===
Neville Michie wrote:
When you think of time
When a star tracker is used as a stellar compass in effect takes
simultaneous fixes on several stars and the better ones are capable of
an rms error of a few arc seconds, largely limited by atmospheric
instability.
These are usually used for determining space vehicle attitude, in which
case
I once went through the exercise of finding North from a station at
home.
A gps fix would give me +- - 1metre northing and + - 1 metre
easting, another
fix 1000m away would be the same, a lousy base for an accurate azimuth.
Using an ephemeris for constants, a theodolite fix on a circumpolar
Hi Bjoern,
I respectfully disagree. I measured the loss through the GPS amp and Mini
Circuits splitter at only 10.1dB. That's really not a lot. I couldn't find
a loss-spec in the Thunderbolts' specification.
The Agilent amp has GPS filters in it that improve signal quality by
filtering
I think I was the one that started this.
My problem was the Tbolt did not work when connected to the Symmetricom
splitter alone (except for the antenna of course) but worked great when the
splitter was also connected to a Z3816A. I think it must have to do with
lack of appropriate power from the
Hi Said,
With your background, I assumed you would know better...
What is your antenna gain? What is your antenna cable loss? Does the Tbolt
work correctly connected directly to the GPS antenna? Do you have an
inline LNA to add close to the antenna? Do you have a higher gain antenna
available?
Am Saturday 21 November 2009 20:32:11 schrieb J. Forster:
OK. Sme GPS receivers have magnetic sensors. What do they do with/about
magnetic deviation.
Just a wild guess: The GPS receiver also knows its location, and magnetic
deviation is known to some degree in its variation over earth's
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