A balloonist realized he was lost. He descended and spotted a man on the
ground. He shouted down:
Excuse me, can you help me? I promised a friend I would meet him half an
hour ago, but I don't know where I am.
The man on the ground replied, You're at 42° 24.5' North latitude, 71°
11.3' West
For those who wondered what the spectrum transmitted by a GPS satellite
looked like, see:
http://www.esa.int/SPECIALS/Galileo_IOV/SEM60KBX9WG_0.html
Cheers,
David
--
SatSignal software - quality software written to your requirements
Web: http://www.satsignal.eu
Email:
list
Subject: [time-nuts] OT: GPS satellite spectrum displayed...
For those who wondered what the spectrum transmitted by a GPS satellite
looked like, see:
http://www.esa.int/SPECIALS/Galileo_IOV/SEM60KBX9WG_0.html
Cheers,
David
--
SatSignal software - quality software written to your requirements
David,
Surely the signals displayed in the link below are those of the Galileo
satellites and not GPS.
Rob Kimberley
Of course, Rob. I was using GPS in its generic sense.
Cheers,
David
--
SatSignal software - quality software written to your requirements
Web: http://www.satsignal.eu
Email:
-nuts-boun...@febo.com] On
Behalf Of David J Taylor
Sent: 22 December 2011 18:56
To: Time-nuts mailing list
Subject: [time-nuts] OT: GPS satellite spectrum displayed...
For those who wondered what the spectrum transmitted by a GPS satellite
looked like, see:
http://www.esa.int/SPECIALS
At least that is how the graphic is labeled :).
Per Enge (Author/Contributor of many GPS text books) has some good
cartoons
on the current and future GPS Spectrum, and one power spectrum display,
on:
of precise time and frequency measurement
Cc: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] OT [GPS Survey grade RX]
Sure..
That's what all those geodesy folks do. Over sufficient time span, one can
relate gps measurements to an eci frame On Dec 5, 2010, at 5:43 PM
Hi Brian:
A friend has an Android cell phone with built in GPS. It has a
resolution of 0.0001 arc seconds as does the GPS I just got for my camera:
http://www.prc68.com/I/Nikon.shtml#GPS
I think it's a common feature of the newest SiRF chip set. What's not
know is how accurate they are.
When you start getting to less than a meter.. For absolute, you need to start
worrying about stuff like solid earth tides, plate movement, a whole host of
things are all contributors in that 10-100 cm range.
For relative work( most surveying) the effects are small over a distance of
tens of
b...@lysator.liu.se wrote:
When you start getting to less than a meter.. For absolute, you need to
start worrying about stuff like solid earth tides, plate movement, a whole
host of things are all contributors in that 10-100 cm range.
Absolute and relative... can be a word game. It depends
GPS surveying relative to astronomical reference? I don't think so.
-John
==
b...@lysator.liu.se wrote:
When you start getting to less than a meter.. For absolute, you need to
start worrying about stuff like solid earth tides, plate movement, a
whole
host of things are all
Sure..
That's what all those geodesy folks do. Over sufficient time span, one can
relate gps measurements to an eci frame
On Dec 5, 2010, at 5:43 PM, J. Forster j...@quik.com wrote:
GPS surveying relative to astronomical reference? I don't think so.
-John
==
time and frequency measurement
Cc: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] OT [GPS Survey grade RX]
Sure..
That's what all those geodesy folks do. Over sufficient time span, one can
relate gps measurements to an eci frame On Dec 5, 2010, at 5:43 PM, J.
Forster
I wish to survey some of my land here in the US. What used GPS
receivers out there might be good candidates?
I really don't want to haul a Z3801A out in the woods and run a self-
survey unless the cost is too high. :-)
-Brian, WA1ZMS
___
How accurate do you want the survey to be? What's your budget?
A handheld GPS can give you 3 meters for 200-300 bucks.
Bill Hawkins
-Original Message-
From: wa1...@att.net
Sent: Saturday, December 04, 2010 6:57 PM
I wish to survey some of my land here in the US. What used GPS
I'd like to get to 30cm. My hand-held GPS gets me to about 4m if the
constalation of birds is in my favor.
Budget would be about $1k.
-Brian, WA1ZMS
On Dec 4, 2010, at 9:11 PM, Bill Hawkins b...@iaxs.net wrote:
How accurate do you want the survey to be? What's your budget?
A handheld
wa1...@att.net wrote:
I wish to survey some of my land here in the US. What used GPS receivers
out there might be good candidates?
All of the usual survey instrument companies have GPS widgets of one
sort or another. Trimble, Topcon, etc.
However, if it's a one shot deal, just go rent
wa1...@att.net wrote:
I'd like to get to 30cm. My hand-held GPS gets me to about 4m if the
constalation of birds is in my favor.
Budget would be about $1k.
30 cm relative to yourself, or relative to some official point (state
plane grid, for instance).
Fellow time-nuts,
While this is off-topic, I just wanted to drop a few lines...
Spectracom/Pendulum (Pendulum Instruments is now parts of Spectracom)
has released a 8 channel GPS simulator. It's an L1 C/A only thing, but I
thought it may be useful for some of you guys to know about.
It's
You could (temporarily) install a structure that blocks reception in one
direction and then infer the meridian direction from the occultation of
SVs by the obstruction.
However the accuracy of the determination wont be high.
Bruce
Anyway, that's an idea.
Antonio
The
-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of iov...@inwind.it
Sent: Monday, 23 November 2009 8:08 AM
To: time-nuts
Subject: Re: [time-nuts] OT - GPS and North
Thanks all.
The conclusion seems to be that an ordinary and stationary GPS receiver
with
a single
-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of iov...@inwind.it
Sent: Monday, 23 November 2009 8:08 AM
To: time-nuts
Subject: Re: [time-nuts] OT - GPS and North
Thanks all.
The conclusion seems to be that an ordinary and stationary GPS receiver
Hi Florian,
That is basicly the way it is done. The source is a magnetic model - a
formula with lots of coefficients, you input your position and the
output is an approximation of your magnetic declination at that position.
It can be implemented by precomputing a lockup table (map) with the
Notice several of the eloran/GPS receivers advertise better than one degree
heading accuracy even when stationary. Wonder if this the result of the sensor
using an array of ferrite bar antennas or just a magnetic compass ?
The eLoran Heading output using Loran-C provides bearing accuracy better
Stanley Reynolds wrote:
Notice several of the eloran/GPS receivers advertise better than one degree
heading accuracy even when stationary. Wonder if this the result of the sensor
using an array of ferrite bar antennas or just a magnetic compass ?
The eLoran Heading output using Loran-C
;-)
Stanley
- Original Message
From: Magnus Danielson mag...@rubidium.dyndns.org
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sun, November 22, 2009 11:18:58 AM
Subject: Re: [time-nuts] OT - GPS and North
Stanley Reynolds wrote:
Notice several
Thanks all.
The conclusion seems to be that an ordinary and stationary GPS receiver with a
single
omnidiretional antenna knows very well where satellites are relative to the
true North,
and where the true North is relative to satellites, but doesn't know (more
precisely:
can't indicate, as
iov...@inwind.it wrote:
Thanks all.
The conclusion seems to be that an ordinary and stationary GPS receiver with a
single
omnidiretional antenna knows very well where satellites are relative to the
true North,
and where the true North is relative to satellites, but doesn't know (more
iov...@inwind.it wrote:
Thanks all.
The conclusion seems to be that an ordinary and stationary GPS receiver
with a single
omnidiretional antenna knows very well where satellites are relative to the
true North,
and where the true North is relative to satellites, but doesn't know
stanley_reyno...@yahoo.com said:
For example a CDMA cell site that is dependent on GPS would slowly
deteriorate if GPS was lost, but a large number of CDMA cell sites
would continue to work if they could be synced to another source.
Unless, of course, that other source was depending on GPS
Stanley Reynolds wrote:
Yes, found this patent :
http://www.freepatentsonline.com/y2008/0186232.html
A method and radio navigation system compass apparatus for determining true north
or azimuth or orientation of a vehicle or the like by the use of integrated Loran and
satellite radio
It's going to be hard to use LORAN C, if the system is shut down.
-John
=
Stanley Reynolds wrote:
Yes, found this patent :
http://www.freepatentsonline.com/y2008/0186232.html
A method and radio navigation system compass apparatus for determining
true north or azimuth or
Hi Antonio:
That's an interesting question.
It turns out that one of the key military applications of GPS, in addition to
position and time, is to find North to high accuracy. This is needed to be
known to better that one grad (1/6400 of a circle). In that past it was done
using a
Hi Antonio:
That's an interesting question.
It turns out that one of the key military applications of GPS, in addition to
position and time, is to find North to high accuracy. This is needed to be
known to better that one grad (1/6400 of a circle). In that past it was done
Hi Bruce:
Do you know where I might find connection information on the MD-1 star tracker
used in the B-52? See:
http://www.prc68.com/I/MD1.shtml
The system was good to 1 arc minute (including temperature, pressure, etc.) and
I've heard that the sensor was far better than that (into the arc
You could (temporarily) install a structure that blocks reception in one
direction and then infer the meridian direction from the occultation of
SVs by the obstruction.
However the accuracy of the determination wont be high.
Bruce
Anyway, that's an idea.
Antonio
The other way to find
than $2k)
73 Rex VK7MO
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of iov...@inwind.it
Sent: Monday, 23 November 2009 8:08 AM
To: time-nuts
Subject: Re: [time-nuts] OT - GPS and North
Thanks all.
The conclusion seems
-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of iov...@inwind.it
Sent: Monday, 23 November 2009 8:08 AM
To: time-nuts
Subject: Re: [time-nuts] OT - GPS and North
Thanks all.
The conclusion seems to be that an ordinary and stationary GPS receiver with
a single
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
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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
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
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
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
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
Date: Thu, 1 Oct 2009 23:13:33 -0400
From: David I. Emery d...@dieconsulting.com
Subject: Re: [time-nuts] GPS from a window seat
I never had anyone from the airline bother me about doing this
(discretely) UNTIL a recent flight this August from Boston to
London Heathrow on American ...
In message fad0f39d8fa7f440861941a74b1ae560364...@sbsserver.aremv.local, Dav
e Baxter writes:
Tests were done a few years ago at London Gatwick, LGW (on the ground)
to see what impact (if any) the use of a cellphone had when used inside
a commercial pasenger aircraft.
I think the only documented
Amen to your last paragraph.
Roy
- Original Message -
From: Poul-Henning Kamp p...@phk.freebsd.dk
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Friday, October 02, 2009 9:34 AM
Subject: Re: [time-nuts] [OT] GPS from a window seat
In message
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