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
b...@lysator.liu.se wrote:
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
Using two Bullet II, Trimble p/n 4155600, antennas with all my receivers for
now. They feed two cheap TV satellite splitters 4 receiver ports each, DC power
diode steered to the antenna port from each receiver port. Feed line is RG6 50
to 75 feet in length. Never had less than one less than 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
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 navigation receivers employing
Hi Guys,
changing the AMU thresholds to 2.0 as suggested by Warren fixed the
problem, the unit is now working properly, thanks much for the hint. And no,
this
was not obvious to me.
It is always great to get constructive help rather than the you should
know better type of comments.
In
In a message dated 22/11/2009 19:45:35 GMT Standard Time, saidj...@aol.com
writes:
changing the AMU thresholds to 2.0 as suggested by Warren fixed the
problem, the unit is now working properly, thanks much for the hint. And
no, this
was not obvious to me.
Hi Said
Just out of
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
Said
changing the AMU thresholds to 2.0 fixed the problem,
If 3 was not working, you should be able to go lower than 2, likely 1.0 to 1.5
will be better yet.
The way I tell is using Lady Heather, if there are satellites signals with
levels between 20 and 30 dBc
with good ACCUs that are
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
Yes if the GPS outage is wide spread would need to eliminate the sources in the
same situation.
Guess another common view atomic clock would be needed. Some of the cesium
clocks were used to provide wire-line timing, don't know if these would be
still available and how to distribute this
I am using a Tbolt with a Symmetricom 58432A antenna, half sky view,
and a HP 58515A distribution amplifier without any problems, using the
default parameters.
Geraldo Lino de Campos
gera...@decampos.net
___
Hockey puck (or mouse) type GPS receivers are available for under $100.
What can I get in that price range that doesn't depend on GPS? I'm
interested in millisecond accuracy as well as nanosecond.
Has anybody built a WWVB-DO? (Time to dust off my WWVB toys.)
Is there some good WWV setup?
Further if at least one cell site has a accurate clock how far could it be
repeated before it lost it's useful accuracy using the CDMA signal as in :
http://www.endruntechnologies.com/frequency-standard-rackmount.htm
As cdma is not available everywhere:
Dear Said,
saidj...@aol.com wrote:
Hi Guys,
changing the AMU thresholds to 2.0 as suggested by Warren fixed the
problem, the unit is now working properly, thanks much for the hint. And no, this
was not obvious to me.
It is always great to get constructive help rather than the you should
b...@lysator.liu.se wrote:
Hi Nigel,
AMU and SNR are two different scales. I do not have a translation. A
Kepler award recepient once explained Trimbles AMU as a meaningless
unit. That said, SNR or C/N0 values cannot be directly compared between
different receivers since the measures might be
Hockey puck (or mouse) type GPS receivers are available for under $100.
What can I get in that price range that doesn't depend on GPS? I'm
interested in millisecond accuracy as well as nanosecond.
Has anybody built a WWVB-DO? (Time to dust off my WWVB toys.)
Is there some good WWV setup?
In a message dated 22/11/2009 21:23:49 GMT Standard Time, b...@lysator.liu.se
writes:
AMU and SNR are two different scales. I do not have a translation. A
Kepler award recepient once explained Trimbles AMU as a meaningless
unit. That said, SNR or C/N0 values cannot be directly compared
In a message dated 22/11/2009 21:48:14 GMT Standard Time,
warrensjmail-...@yahoo.com writes:
Concerning the relation of AMU to dBc, what I've seen is:
AMU of 4 is in the high 30, AMU of 3 is in the mid 30, AMU of 2 is in
the high 20, AMU of 1 is in the mid 20,
A good outdoor antenna
stanley_reyno...@yahoo.com said:
Further if at least one cell site has a accurate clock how far could
it be repeated before it lost it's useful accuracy using the CDMA
signal as in :
I think there are two cases.
The first is if the GPS receiver on a single site breaks, I think it would be
The lack of low cost options to GPS is the point, loran as a backup is not as
good or cheap, it is just the next best. WWVB is good if you are close that is
you are in ground wave range. Loran depends on ground wave and can reject
skywave some of this is made better via loran pulse nature.
J. Forster wrote:
Somebody mentioned TV and radio stations recently. (I think it was part
of the North discussion.)
What sort of frequency source is at the root of the local TV or radio
stations?
Is the sync timing for TV stations derived from the same source as the
carrier? Or are there two
Hal Murray wrote:
stanley_reyno...@yahoo.com said:
Further if at least one cell site has a accurate clock how far could
it be repeated before it lost it's useful accuracy using the CDMA
signal as in :
I think there are two cases.
The first is if the GPS receiver on a single site breaks, I
I'm not sure, but when satellite links go down, the picture freezes.
That implies a frame store which is likely bad news for timing.
I'm not sure that bad news is the right term.
If you have frame buffers (and they were a big breakthrough many years ago),
then you get timing from the output
gandal...@aol.com wrote:
In a message dated 22/11/2009 21:23:49 GMT Standard Time, b...@lysator.liu.se
writes:
AMU and SNR are two different scales. I do not have a translation. A
Kepler award recepient once explained Trimbles AMU as a meaningless
unit. That said, SNR or C/N0 values
In a message dated 23/11/2009 00:06:52 GMT Standard Time,
mag...@rubidium.dyndns.org writes:
The Thunderbolt Monitor does have it, I just ticked the box and had my
C/N measures instead. In the Setup menu, select Packet Masks and
Options... where you in the Packer 35 Options frame, the
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
If you needed to lower your AMU limit from 4 to 2, you are feeding the
Thunderbolt a signal level below the intended levels.
True, You MAY be feeding it a signal that is below what the cell site
recommended High gain outdoor antenna will give it.
But any conclusion past that sounds like pure
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
Warren,
WarrenS wrote:
If you needed to lower your AMU limit from 4 to 2, you are feeding the
Thunderbolt a signal level below the intended levels.
True, You MAY be feeding it a signal that is below what the cell site
recommended High gain outdoor antenna will give it.
But any conclusion
I cant remember the detail now but my converstaion with a BBC engineer at
the NPL meeting a few years back suggested along the lines of yes there
would be a stable frequency available on a digital TV signal but no it would
not be related (tracable) to any given standard because it didnt need to
IIRC, NTP turns a computer clock into a DO with millisecond accuracy.
Accuracy is stratified, with a number of Stratum 1 sources available.
Don't know if anyone has designed a collection of differentiated silicon
and stored programs that hooks to the internet and delivers a disciplined
10 MHz at
Given that we cannot do it with one GPS in a fixed position I would like to
get people's ideas on whether there is a reasonable cost way (say less than
$2K) to do it with two GPSs to get within a say half a degree.
The application is to find azimuth headings for Amateur radio microwave or
Hi Nigel, et. al.,
I just changed the setting to C/No with the help of the instructions posted
here; learned yet something else.
With that I now get between 30 and 36dBc/Hz C/No (at night, which usually
results in higher values than during daylight).
I am impatient, and expect my
Hi Rex:
You can do it with a single GPS (DAGR or PLGR96 or higher) with a 100 meter
baseline. See:
http://www.prc68.com/I/DAGR.shtml#GLS
http://www.prc68.com/I/DAGR.shtml#AzD
Have Fun,
Brooke Clarke
http://www.prc68.com
Rex Moncur wrote:
Given that we cannot do it with one GPS in a fixed
Well we are looking at alternates these days and indeed the tv signal ain't
what it used to be. Though even though network blackburst was cesium derived
local station butchered it..
But the good news is this the new dtv indeed does contain some pretty good
clocks and in theory things like the pcr
Something in the last post got cut off...
Anything you can do to minimize satellite constellation changes is good. If
reducing the signal level cutoff threshold or changing the elevation mask angle
works for your installation, go for it. It appears that the effects of
constellation
Mark
Sounds like the same problem I had when I had the AMU set TOO high. ( I don't
think it can be set with LH, Need Tboltmon to change it)
I have not seen the condition that you describe where the Tbolt will switch
satellites just because it has found a better one. (I don't think that
Some of the disagreement has to do with the fact that Two similar topics, each
with a different answer are being mixed together here.
Magnus's point:
1) How to make the Tbolt the best that it can be?
Answer: Start with a good strong signal and a quiet environment.
Said's situation:
2) How
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