Where's SVN63? What's up with recent satellites UNUSUFN? Here's some
insight from Allen Instruments:

'As of today, 29 satellites are in operation and set healthy. In
addition, SVN63/PRN01 and SVN27/PRN27 are transmitting L-band signals
but are not currently in service.

SVN63/PRN01, the second Block IIF satellite to be placed in orbit, is
still being commissioned and remains set unhealthy in the broadcast
almanacs. According to independent analyses, the satellite’s cesium
clock, the first of its three clocks to be activated, is not
performing according to specifications. SVN63/PRN01′s active clock
will likely be switched to one of its rubidiums, perhaps as early as
next week.

SVN27/PRN27, a Block IIA satellite launched in 1992, was
decommissioned on 10 August 2011. The satellite has been removed from
broadcast almanacs but continues to transmit L-band signals,
presumably for end-of-life testing.

SVN35 returned to active service, once again, this time as PRN30, on
16 August 2011, to replace SVN30/PRN30, which was decommissioned from
active service on 20 July 2011. SVN35 is being moved to the B1-F slot,
previously occupied by SVN30.

There are currently four backup or residual satellites: SVNs 30, 32,
37, and 49. However, SVN30 has been deemed no longer usable and there
are plans to dispose of it.

SVN24/PRN24, a Block IIA satellite launched in 1991 and the second
oldest active GPS satellite, reportedly experienced a reaction wheel
failure on 30 September 2011. It has stopped broadcasting L-band
signals'.

http://www.alleninstruments.com/blog/

Old equipment 'giving up the ghost', new equipment malfunctioning!

--- CHAS

On Oct 6, 7:46Â*pm, HIPAR <captc...@verizon.net> wrote:
> Where's SVN63? Â*What's up with recent satellites UNUSUFN? Â*Here's some
> insight from Allen Instruments:
>
> 'As of today, 29 satellites are in operation and set healthy. In
> addition, SVN63/PRN01 and SVN27/PRN27 are transmitting L-band signals
> but are not currently in service.
>
> SVN63/PRN01, the second Block IIF satellite to be placed in orbit, is
> still being commissioned and remains set unhealthy in the broadcast
> almanacs. According to independent analyses, the satellite’s cesium
> clock, the first of its three clocks to be activated, is not
> performing according to specifications. SVN63/PRN01′s active clock
> will likely be switched to one of its rubidiums, perhaps as early as
> next week.
>
> SVN27/PRN27, a Block IIA satellite launched in 1992, was
> decommissioned on 10 August 2011. The satellite has been removed from
> broadcast almanacs but continues to transmit L-band signals,
> presumably for end-of-life testing.
>
> SVN35 returned to active service, once again, this time as PRN30, on
> 16 August 2011, to replace SVN30/PRN30, which was decommissioned from
> active service on 20 July 2011. SVN35 is being moved to the B1-F slot,
> previously occupied by SVN30.
>
> There are currently four backup or residual satellites: SVNs 30, 32,
> 37, and 49. However, SVN30 has been deemed no longer usable and there
> are plans to dispose of it.
>
> SVN24/PRN24, a Block IIA satellite launched in 1991 and the second
> oldest active GPS satellite, reportedly experienced a reaction wheel
> failure on 30 September 2011. It has stopped broadcasting L-band
> signals'.
>
> http://www.alleninstruments.com/blog/
>
> Old equipment 'giving up the ghost', new equipment malfunctioning!
>
> --- Â*CHAS

The switch from Cs3 to Rb1 happened in the last 48 hrs, source: NGA
Current GPS Satellite data:
Clock swap, 05 October 2011, from Cs3 to Rb1...

On Oct 6, 10:09*pm, macpacheco <marc...@macp.eti.br> wrote:

> The switch from Cs3 to Rb1 happened in the last 48 hrs, source: NGA
> Current GPS Satellite data:
> Clock swap, 05 October 2011, from Cs3 to Rb1...

Notice there was also a clock swap from Cs to Rb for GPS IIF-1. so
there might be something deficient in the design of those Atomic
Frequency Standards that isn't evident during ground testing. That
investigation will keep the analysts busy before GPS IIF-3 takes
flight.

The Rb standard flying aboard GPS IIF-1 shows cyclic artifacts that
some suggest are thermal effects. Let's see if GPS IIF-2 exhibits
similar characteristics.

--- CHAS

On Oct 7, 1:16*pm, HIPAR <captc...@verizon.net> wrote:
> On Oct 6, 10:09*pm, macpacheco <marc...@macp.eti.br> wrote:
>
> > The switch from Cs3 to Rb1 happened in the last 48 hrs, source: NGA
> > Current GPS Satellite data:
> > Clock swap, 05 October 2011, from Cs3 to Rb1...
>
> Notice there was also a clock swap from Cs to Rb for GPS IIF-1. *so
> there might be something deficient in the design of those Atomic
> Frequency Standards that isn't evident during ground testing. *That
> investigation will keep the analysts busy before GPS IIF-3 takes
> flight.
>
> The Rb standard flying aboard GPS IIF-1 shows cyclic artifacts that
> some suggest are thermal effects. *Let's see if GPS IIF-2 exhibits
> similar characteristics.
>
> --- *CHAS

My impression is that still, SVN25 have better performance than brand
new IIRs had in all aspects, is there any opinion to the contrary ?
SVN25 clock / ephemeris / URE performance seems to be among the best
of the whole constellation.

Marcelo

On Oct 8, 10:42*am, macpacheco <marc...@macp.eti.br> wrote:

> My impression is that still, SVN25 have better performance than brand
> new IIRs had in all aspects, is there any opinion to the contrary ?
> SVN25 clock / ephemeris / URE performance seems to be among the best
> of the whole constellation.
>
> Marcelo

I just being overly critical. According to the USAF, GPS IIF-1 is
working well within specifications. It consistently exhibits signal
in space error of 0.5 meters or less.

Last year, I came across a report concerning the orbital stability of
GPS IIF-1:

http://igscb.jpl.nasa.gov/pipermail/...10/006313.html

I haven't seen any follow-ups on that so, either the analyst was
overly critical or the system operators were able to 'fine tune' the
system to eliminate the problem.

The Air Force runs around telling the world NAVSTAR is the 'Gold
Standard'. Well, that's easy to defend when you're the 'only game in
town'. But, Glonass will soon be fully capable and two Galileo
satellites will soon be in orbit transmitting hydrogen maser quality
signals. Maybe these developments aren't important in the overall
scheme of things but if the USAF wants to retain its 'bragging
rights', they are going to need perfection. The world GNSS community
is watching critically.

--- CHAS

On 2011-10-08 13:49 , HIPAR wrote:

> The Air Force runs around telling the world NAVSTAR is the 'Gold
> Standard'. Well, that's easy to defend when you're the 'only game in
> town'. But, Glonass will soon be fully capable and two Galileo
> satellites will soon be in orbit transmitting hydrogen maser quality
> signals. Maybe these developments aren't important in the overall
> scheme of things but if the USAF wants to retain its 'bragging
> rights', they are going to need perfection. The world GNSS community
> is watching critically.

The tendency is to polyglot receivers. You can order an etrex 10/20/30
from Garmin that uses GPS and GLONASS concurrently in the nav solution.

As Galileo and Compass establish their constellations they'll just
become additional range sources.

Smart receivers could even be programmed to exclude the least desirable
(range error or otherwise) sats from any system and use the best from
all systems according to user needs. (would need some form of
control/input method to keep it up to date). With 90 - 120 satellites
up there (by 2020 or so) and diminishing returns on over-determined
solutions when there are more than 10 - 12 satellites in the solution,
the least accurate satellites could normally be ignored and relegated to
hot backup.

Add in SBAS aiding for each system for additional ranging, accuracy and
integrity in most areas.

In the end it won't matter which space system claims "best" or "gold" as
the receivers and users will determine the best sources.

--
gmail originated posts filtered due to spam.

On Oct 8, 2:19*pm, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:

> In the end it won't matter which space system claims "best" or "gold" as
> the receivers and users will determine the best sources.

I agree with that assessment.

Furthermore, with sub-meter signal in space errors the ionospheric
timing induced errors dominate.

It's a nationalistic thing.

--- CHAS

On 2011-10-08 14:51 , HIPAR wrote:
> On Oct 8, 2:19 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca>
> wrote:
>
>> In the end it won't matter which space system claims "best" or "gold" as
>> the receivers and users will determine the best sources.
>
> I agree with that assessment.
>
> Furthermore, with sub-meter signal in space errors the ionospheric
> timing induced errors dominate.

True, but like all things, the foundation is important.

> It's a nationalistic thing.

Of course. When the Chinese get traction with Compass you can be sure
it will be the best system in the known universe - at least according to
the Chinese government. We'll see how the government influences or
affects non-Compass receiver sales in China once it's viable. (The
current "Compass" system used their is a two-way system).

Per the set of slides that Ed. M linked to, the GLONASS system appears
to be the forthcoming "mandatory" GNSS for government use in Russia.
Will no doubt be similar in China and most European governments that
have an iron in the Galileo fire.

US agencies will use whatever gets the job done.


--
gmail originated posts filtered due to spam.

On Oct 8, 5:30*pm, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:
> On 2011-10-08 14:51 , HIPAR wrote:
>
> > On Oct 8, 2:19 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca>
> > wrote:
>
> >> In the end it won't matter which space system claims "best" or "gold" as
> >> the receivers and users will determine the best sources.
>
> > I agree with that assessment.
>
> > Furthermore, with sub-meter signal in space errors the ionospheric
> > timing induced errors dominate.
>
> True, but like all things, the foundation is important.
>
> > It's a nationalistic thing.
>
> Of course. *When the Chinese get traction with Compass you can be sure
> it will be the best system in the known universe - at least according to
> the Chinese government. *We'll see how the government influences or
> affects non-Compass receiver sales in China once it's viable. *(The
> current "Compass" system used their is a two-way system).
>
> Per the set of slides that Ed. M linked to, the GLONASS system appears
> to be the forthcoming "mandatory" GNSS for government use in Russia.
> Will no doubt be similar in China and most European governments that
> have an iron in the Galileo fire.
>
> US agencies will use whatever gets the job done.
>
> --
> gmail originated posts filtered due to spam.

One additional angle... Can GLONASS ever be better than GPS, given all
the investment in space atomic clock technology made by the US, and
although they have budget for launch and maintenance of their
constellation, Russia isn't know for having the best electronics for
anything.

Galileo should easily beat GPS as far as signal in space, but as I
understand, the availability of triple frequency that GPS can be use
for ultra accurate iono free measurements, while Galileo essentially
will have only L1 and E5/L5 (it has two E5 bands, but it seems those
are too close to be used for iono corrections).
So its entirely conceivable that triple frequency GPS might yield
better results that Galileo, specially with Galileo deployment so far
funded only for 18 SVs.

Silicon is cheap and will get cheaper, and the trend is for having at
least a couple of OEM suppliers of common multi frequency, multi
constellation GNSS receiver chip, so having 60-100 channel receiver
will become norm, at least for the high end market (for 36 birds in
view, with at least 2 signals from each bird tracked simultaneously).
Today there are plenty of cheap GPS receivers claiming 40+ channels
anyways (I assume those are for multipath elimination) look for
external USB GPS receivers and you shall find a bunch of them (likely
same receive chip from a single OEM).

Marcelo Pacheco

On 2011-10-09 09:02 , macpacheco wrote:
> On Oct 8, 5:30 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca>
> wrote:
>> On 2011-10-08 14:51 , HIPAR wrote:
>>
>>> On Oct 8, 2:19 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca>
>>> wrote:
>>
>>>> In the end it won't matter which space system claims "best" or "gold" as
>>>> the receivers and users will determine the best sources.
>>
>>> I agree with that assessment.
>>
>>> Furthermore, with sub-meter signal in space errors the ionospheric
>>> timing induced errors dominate.
>>
>> True, but like all things, the foundation is important.
>>
>>> It's a nationalistic thing.
>>
>> Of course. When the Chinese get traction with Compass you can be sure
>> it will be the best system in the known universe - at least according to
>> the Chinese government. We'll see how the government influences or
>> affects non-Compass receiver sales in China once it's viable. (The
>> current "Compass" system used their is a two-way system).
>>
>> Per the set of slides that Ed. M linked to, the GLONASS system appears
>> to be the forthcoming "mandatory" GNSS for government use in Russia.
>> Will no doubt be similar in China and most European governments that
>> have an iron in the Galileo fire.
>>
>> US agencies will use whatever gets the job done.
>>
>> --
>> gmail originated posts filtered due to spam.
>
> One additional angle... Can GLONASS ever be better than GPS, given all
> the investment in space atomic clock technology made by the US, and
> although they have budget for launch and maintenance of their
> constellation, Russia isn't know for having the best electronics for
> anything.

Look at the slides that Ed M. put up. GLONASS precision has increased
by steady effort since its inception and is close to GPS in system
accuracy. The orbital insertion dony by the Russians was said to be
more accurate ("rounder") that GPS. "Electronics" isn't the point but
rather engineering and physics. I'd give a longevity edge to the
Americans but the Russians are no slouches at all in getting things done.

Of course as I said earlier, the real point of all of it is that smart
programming of receivers could allow for selection of best only
satellites regardless of space system. The receiver will have 90 - 120
satellites or so to choose from by about 2020 with about 1/3 of them
visible at any given time - and various sources for range correction.
Who cares who built and launched it.

Note that the only way for Americans to get astronauts into space at
present is by hitching a ride with Russians. No US solution is in sight
despite much rhetoric.

--
gmail originated posts filtered due to spam.