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Galileo ever come on stream?



 
 
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  #31  
Old February 22nd 18, 08:28 AM posted to uk.tech.digital-tv
Jim Lesurf[_2_]
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Posts: 4,326
Default Galileo ever come on stream?

In article , NY
wrote:


Ah, so the civilian signal was simply a full-precision signal with a
random value added to it? I'd thought that it was a value that was
truncated by masking off the more precise bits.


IIRC they pseudo-randomly 'jittered' the information to blur the time
accuracy. You needed to be able to decode the secret squirrel info to find
out the details of the jitter pattern and get a more accurate result. Or do
a long-term average, etc, as others have pointed out.

Jim

--
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  #32  
Old February 22nd 18, 08:31 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 2,448
Default Galileo ever come on stream?

On 22/02/2018 08:25, tim... wrote:


"Bill Wright" wrote in message
news
On 21/02/2018 09:33, tim... wrote:

Encryption on the more accurate service - cf eg Sky's charges for TV
packages.

So they can charge you for the "technology" in a chip that decrypts it

but how can they do that on anything other than a "one time fee" model.


Individually addressable receivers, same as Sky


Sky have a way of contacting the owners of their boxes

There is no realistic way to contact the owner of a GPS receiver, which
might be installed inside a boat or a car or a tank


A Sky box might be installed in a boat, barge, yacht, car, caravan,
motorhome, ocean-going ship, or hot air balloon.

Bill
  #33  
Old February 22nd 18, 09:10 AM posted to uk.tech.digital-tv
Tweed[_3_]
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Posts: 36
Default Galileo ever come on stream?

Jim Lesurf wrote:
In article , NY
wrote:


Ah, so the civilian signal was simply a full-precision signal with a
random value added to it? I'd thought that it was a value that was
truncated by masking off the more precise bits.


IIRC they pseudo-randomly 'jittered' the information to blur the time
accuracy. You needed to be able to decode the secret squirrel info to find
out the details of the jitter pattern and get a more accurate result. Or do
a long-term average, etc, as others have pointed out.

Jim


GPS carries two coded signals. The unencrypted signal was jittered to give
an accuracy of around 100 metres. This has since been removed and accuracy
is roughly 5 metres. The military have access to a second encrypted signal
which gives a much higher accuracy. This signal is also transmitted on a
second frequency, which allows ionospheric error to be cancelled out.
Ionospheric delays can cause offsets, as noted by an earlier poster.
(Offsets to road position can also be caused by poor road position data. OS
have had to do a huge amount of work to align the national grid to GPS
coordinates. Not all grid squares have turned out to be as square as they
had hoped owing to original survey errors.) The jitter on the civilian
signal can now be added back on a regional basis, so accuracy can be
reduced in a war zone whilst maintaining it elsewhere. The fact that the
system can be regionally made more inaccurate at the touch of a button is
probably one reason why Europe wanted to have its own separate system. With
so much now dependent on GPS positioning, suddenly returning to 100 metre
accuracy could have severe economic consequences.

http://geoconnect.com.au/gps-signals-l1-l2-l5/ has some interesting info on
the GPS signals, and improvements being made.

  #34  
Old February 22nd 18, 09:22 AM posted to uk.tech.digital-tv
R. Mark Clayton[_2_]
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Posts: 649
Default Galileo ever come on stream?

On Thursday, 22 February 2018 09:31:39 UTC, wrote:
On 22/02/2018 08:25, tim... wrote:


"Bill Wright" wrote in message
news
On 21/02/2018 09:33, tim... wrote:

Encryption on the more accurate service - cf eg Sky's charges for TV
packages.

So they can charge you for the "technology" in a chip that decrypts it

but how can they do that on anything other than a "one time fee" model.

Individually addressable receivers, same as Sky


Sky have a way of contacting the owners of their boxes

There is no realistic way to contact the owner of a GPS receiver, which
might be installed inside a boat or a car or a tank


A Sky box might be installed in a boat, barge, yacht, car, caravan,
motorhome, ocean-going ship, or hot air balloon.

Bill


Indeed, but you have to arrange for it to be able to phone home from time to time or it stops working.
  #35  
Old February 22nd 18, 09:33 AM posted to uk.tech.digital-tv
[email protected]
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Posts: 1,245
Default Galileo ever come on stream?

On Wed, 21 Feb 2018 12:16:03 +0000, Andy Burns
wrote:

R. Mark Clayton wrote:

I thought it odd that it was seeing more than 12 satellites at once.


I'm seeing 19 satellites now in gpsstatus
https://mobiwia.com/gpsstatus

But they're all circles (for GPS) and squares (for GLONASS) no crosses
(for BEIDOU) or plus symbols (for GALILEO) I guess a snapdragon 808
doesn't see chinese/european satellites?


Out in the open, with no screening by buildings or trees, I can
usually see about 24 satellites - GPS, Glonass, Beidou and Galileo.
  #36  
Old February 22nd 18, 09:34 AM posted to uk.tech.digital-tv
R. Mark Clayton[_2_]
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Posts: 649
Default Galileo ever come on stream?

On Wednesday, 21 February 2018 12:16:04 UTC, Andy Burns wrote:
R. Mark Clayton wrote:

I thought it odd that it was seeing more than 12 satellites at once.


I'm seeing 19 satellites now in gpsstatus
https://mobiwia.com/gpsstatus

But they're all circles (for GPS) and squares (for GLONASS) no crosses
(for BEIDOU) or plus symbols (for GALILEO) I guess a snapdragon 808
doesn't see chinese/european satellites?


There aren't very many of the last two.
  #37  
Old February 22nd 18, 09:43 AM posted to uk.tech.digital-tv
NY
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Posts: 1,329
Default Galileo ever come on stream?

wrote in message
...
On Wed, 21 Feb 2018 12:16:03 +0000, Andy Burns
wrote:

R. Mark Clayton wrote:

I thought it odd that it was seeing more than 12 satellites at once.


I'm seeing 19 satellites now in gpsstatus
https://mobiwia.com/gpsstatus

But they're all circles (for GPS) and squares (for GLONASS) no crosses
(for BEIDOU) or plus symbols (for GALILEO) I guess a snapdragon 808
doesn't see chinese/european satellites?


Out in the open, with no screening by buildings or trees, I can
usually see about 24 satellites - GPS, Glonass, Beidou and Galileo.


My old phone (Samsung Galaxy S2) could only see GPS satellites and the
maximum I saw was around 10. My new phone (Samsung Galaxy S7) can see
additional ones (solid squares as well as solid discs, in GPS Status) and I
think the maximum I've seen is around 18 or 19.

GPS tracks seem to be better in the sense of having fewer occasions when the
track drifts off the road that I'm driving on, though it still suffers total
loss of reception and lengthy periods trying to re-acquire a lock when I'm
on a cruise ship. All that metal gets in the way... Strangely, going out on
the top deck, where I then have unimpeded view to the horizon, doesn't
always help, even after I've updated the A-GPS almanac.

  #38  
Old February 22nd 18, 09:52 AM posted to uk.tech.digital-tv
[email protected]
external usenet poster
 
Posts: 1,245
Default Galileo ever come on stream?

On Thu, 22 Feb 2018 10:43:12 -0000, "NY" wrote:

wrote in message
.. .
On Wed, 21 Feb 2018 12:16:03 +0000, Andy Burns
wrote:

R. Mark Clayton wrote:

I thought it odd that it was seeing more than 12 satellites at once.

I'm seeing 19 satellites now in gpsstatus
https://mobiwia.com/gpsstatus

But they're all circles (for GPS) and squares (for GLONASS) no crosses
(for BEIDOU) or plus symbols (for GALILEO) I guess a snapdragon 808
doesn't see chinese/european satellites?


Out in the open, with no screening by buildings or trees, I can
usually see about 24 satellites - GPS, Glonass, Beidou and Galileo.


My old phone (Samsung Galaxy S2) could only see GPS satellites and the
maximum I saw was around 10. My new phone (Samsung Galaxy S7) can see
additional ones (solid squares as well as solid discs, in GPS Status) and I
think the maximum I've seen is around 18 or 19.

GPS tracks seem to be better in the sense of having fewer occasions when the
track drifts off the road that I'm driving on...


Depends whether you are checking the absolute location, or the
location shown by a driving app.
Road navigation apps try to fit the received location to the road you
are on, and move the displayed position accordingly.
  #39  
Old February 22nd 18, 10:21 AM posted to uk.tech.digital-tv
Andy Burns[_12_]
external usenet poster
 
Posts: 573
Default Galileo ever come on stream?

R. Mark Clayton wrote:

Andy Burns wrote:

I guess a snapdragon 808 doesn't see chinese/european satellites?

There aren't very many [...]


The chinese ones, I think they're filling the orbital slots that cover
asia first. For eu ones, over half the orbital slots are now populated,
so I'd expect to occasionally see some if the phone was capable.


  #40  
Old February 22nd 18, 10:31 AM posted to uk.tech.digital-tv
Alan White[_3_]
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Posts: 95
Default Galileo ever come on stream?

On Thu, 22 Feb 2018 10:10:16 +0000 (UTC), Tweed
wrote:

The jitter on the civilian
signal can now be added back on a regional basis,


As the 'footprint' for one satellite is slightly less than a
hemisphere of the earth and up to twelve of them can be received at
any particular locality it's a bit difficult to do that.

--
Alan White
Mozilla Firefox and Forte Agent.
In Helensburgh, Scotland.
Weather:- http://windycroft.co.uk/weather
 




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