I don't wish to offend, but that is totally wrong. Even if every
satellite were on the exact same frequency, with the exact same
doppler, and the exact same direction, you would still have no problem
separating the carriers of the multiple satellites. The reason is
that the satellites do not
On 2/20/07, Peter Vince [EMAIL PROTECTED] wrote:
I don't wish to offend, but that is totally wrong. Even if every
satellite were on the exact same frequency, with the exact same
doppler, and the exact same direction, you would still have no problem
separating the carriers of the multiple
Hi Dave,
Try browsing chapter three here-
http://www.gmat.unsw.edu.au/snap/gps/gps_survey/principles_gps.htm
I have trouble getting my head round some of this stuff as well and
found it a useful read.
DaveB
That looks really excellent, I'll go off and study - thank you for the link.
And
[EMAIL PROTECTED] said:
The interfering signals to GPS are:
...
3) defective ground based equipment, like the active TV antenna on a
ship in Monterey bay.
I hadn't heard about the Monterey Bay GPS mess. Google found this writeup.
The Hunt for RFI - Unjamming a Coast Harbor
Magnus Danielson wrote:
However if all you have is a 10811 it will limit the short term
satbility of such a GPSDO.
The phase carrier measurements will have a lower noise floor than the
10811 for tau 10s or so.
A better oscillator (FTS1200, FTS100 Oscilloquartz OSA8607 etc.) will
have a
I sort of understand the idea of correlation in order to receive the
signals from several satellites all on the same frequency, but I
wonder if someone has a simple explanation of how the carrier phase
can be tracked when there are several carriers all at once? Does it
rely on the different
In message [EMAIL PROTECTED], Peter Vince writes:
Does it
rely on the different Doppler-shifts making them distinguishable?
It would have to, if they were not on different frequencies, they
would sum to a single sinewave and you couldn't tell them apart
(unless you have a direction sensitive
Layman explanation, be nice to me please...
The notion of carrier with a spread spectrum system is theoretical.
There is no carrier signal being sent continuously and modulation
sidebands that contain the information, as you would with an AM signal.
This is more like an FM signal, where the
In message [EMAIL PROTECTED], Didier Juges writes:
There are at most 12
visible satellites at the same time, so there is no need for more than
12 channels (at least for a single frequency L1 receiver)
That's only true for a nominal 24 sat constellation. With the
current 30+ constellation you
Hi
But... as marketing people thinks that 'more satellites, better' some
manufactures are commercializing small GPS receivers with 16 and even 20
channels... and obviously, no advantage over 12-channel ones. Perhaps
they expect the Navstar constellation to be so crowded in the near
future to
: Re: [time-nuts] Carrier phase tracking
Hi
But... as marketing people thinks that 'more satellites, better' some
manufactures are commercializing small GPS receivers with 16 and even 20
channels... and obviously, no advantage over 12-channel ones. Perhaps they
expect the Navstar constellation
From: Didier Juges [EMAIL PROTECTED]
Subject: Re: [time-nuts] carrier phase tracking GPS receiver
Date: Mon, 19 Feb 2007 06:37:35 -0600
Message-ID: [EMAIL PROTECTED]
Magnus Danielson wrote:
However if all you have is a 10811 it will limit the short term
satbility of such a GPSDO
But... as marketing people thinks that 'more satellites, better' some
manufactures are commercializing small GPS receivers with 16 and even
20 channels... and obviously, no advantage over 12-channel ones.
Perhaps they expect the Navstar constellation to be so crowded in the
near future to
Hi Hal:
The interfering signals to GPS are:
1) other satellites, they all transmit on the same frequency.
2) ground based transmitters, through harmonic radiation.
3) defective ground based equipment, like the active TV antenna on a
ship in Monterey bay.
There are now GPS+Glonass (spelling?)
From: Peter Vince [EMAIL PROTECTED]
Subject: [time-nuts] Carrier phase tracking
Date: Mon, 19 Feb 2007 16:30:04 +
Message-ID: [EMAIL PROTECTED]
I sort of understand the idea of correlation in order to receive the
signals from several satellites all on the same frequency, but I
wonder
Hal Murray wrote:
How many satellites are there in the Russian or European systems? Or will
there be if/when everything gets fully deployed?
The European Galileo system is planned with 30 satellites, with 27 actives
and 3 hot spares. Only one test bird is flying so far..
--Magne
From: Didier Juges [EMAIL PROTECTED]
Subject: Re: [time-nuts] Carrier phase tracking
Date: Mon, 19 Feb 2007 11:19:28 -0600
Message-ID: [EMAIL PROTECTED]
Layman explanation, be nice to me please...
The notion of carrier with a spread spectrum system is theoretical.
There is no carrier signal
From: Rob Kimberley [EMAIL PROTECTED]
Subject: Re: [time-nuts] Carrier phase tracking
Date: Mon, 19 Feb 2007 17:55:49 -
Message-ID: ![EMAIL PROTECTED]
There is an advantage in more channels...as in the main these are navigation
GPS receivers designed to work in all environments ( i.e. stuck
Rob Kimberley wrote:
Interestingly, no one has mentioned the Augmentation systems like WAAS or
EGNOS where wide area correction data is transmitted down from INMARSAT to
improve nav accuracy. Primarily aimed at improved aircraft navigation
systems, it has a benefit for timing users. Zyfer have
Several of you have mentioned the Russian GPS system
(Glonass) which has been in operation since the 1980's.
Several commercial (high-end) receivers work with both
GPS and Glonass. Google for details.
I borrowed one of Doug's (niceties.com) combined GPS
and Glonass Javad receivers in 2001 and
: [time-nuts] Carrier phase tracking
Rob Kimberley wrote:
Interestingly, no one has mentioned the Augmentation systems like WAAS
or EGNOS where wide area correction data is transmitted down from
INMARSAT to improve nav accuracy. Primarily aimed at improved aircraft
navigation systems, it has
Thank you Didier - it sounds horrendous, and I'm glad I am not trying
to design the equipment to do it :-)
Peter
Layman explanation, be nice to me please...
The notion of carrier with a spread spectrum system is theoretical.
There is no carrier signal being sent continuously and
From: Hal Murray [EMAIL PROTECTED]
Subject: Re: [time-nuts] Carrier phase tracking
Date: Mon, 19 Feb 2007 12:34:33 -0800
Message-ID: [EMAIL PROTECTED]
But... as marketing people thinks that 'more satellites, better' some
manufactures are commercializing small GPS receivers with 16 and even
On 2/19/07, Poul-Henning Kamp [EMAIL PROTECTED] wrote:
Does it
rely on the different Doppler-shifts making them distinguishable?
It would have to, if they were not on different frequencies, they
would sum to a single sinewave and you couldn't tell them apart
(unless you have a direction
Magnus Danielson wrote:
You can acheive much greater speedup by a combined frequency/phase approach.
You will get a very accurate frequency error estimate, so you will very
quickly be close enought to go into phase lock. At least if your clock isn't
too noisy. So, the lock-in time should not
Didier Juges wrote:
Magnus Danielson wrote:
You can acheive much greater speedup by a combined frequency/phase approach.
You will get a very accurate frequency error estimate, so you will very
quickly be close enought to go into phase lock. At least if your clock isn't
too noisy. So, the
In message [EMAIL PROTECTED], Matt
Ettus writes:
On 2/19/07, Poul-Henning Kamp [EMAIL PROTECTED] wrote:
Does it
rely on the different Doppler-shifts making them distinguishable?
It would have to, if they were not on different frequencies, they
would sum to a single sinewave and you couldn't
Dr Bruce Griffiths wrote:
Didier
Typically with a good local oscillator you can do even better than that,
around 1E-11 in 1 sec is achievable and has been achieved.
Even with the on board TCXO typically 3E-11 or so in 1s is achieved.
Bruce
I don't understand how such good variance can
From: Didier Juges [EMAIL PROTECTED]
Subject: Re: [time-nuts] carrier phase tracking GPS receiver
Date: Mon, 19 Feb 2007 17:50:04 -0600
Message-ID: [EMAIL PROTECTED]
Bon soir Didier,
Magnus Danielson wrote:
You can acheive much greater speedup by a combined frequency/phase approach.
You
From: Poul-Henning Kamp [EMAIL PROTECTED]
Subject: Re: [time-nuts] Carrier phase tracking
Date: Tue, 20 Feb 2007 00:11:59 +
Message-ID: [EMAIL PROTECTED]
In message [EMAIL PROTECTED], Matt
Ettus writes:
On 2/19/07, Poul-Henning Kamp [EMAIL PROTECTED] wrote:
Does it
rely
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Didier
Typically with a good local oscillator you can do even better than that,
around 1E-11 in 1 sec is achievable and has been achieved.
Even with the on board TCXO typically 3E-11 or so in 1s is achieved.
Bruce
I don't
Hi Bruce,
Dr Bruce Griffiths wrote:
Bon soir Didier
You are confusing the disciplining precision of the oscillator with
measurement of its short term stability via the GPS receiver in this case.
Bruce
Bon après midi to you, I believe, and if my Clock program is any good,
you just
Didier
Didier Juges wrote:
Hi Bruce,
Dr Bruce Griffiths wrote:
Bon soir Didier
You are confusing the disciplining precision of the oscillator with
measurement of its short term stability via the GPS receiver in this case.
Bruce
Bon après midi to you, I believe, and if my
More satellites IS better in downtowns all over the globe, and in forrests
etc. Modern high sensitivity receivers have the equivalent of many 10
thousands of classic correlators... Good for finding faint signals,
using long correlations times, and tracking many reflections of the same
signal.
--
Bruce,
Thanks a lot, I will wait until I get the unit and find out exactly
which model it is, then I'll let you know what the next questions will
be :-)
All applications I have seen referenced when searching google for
carrier phase tracking had to do with surveying or precise tracking.
I
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