[time-nuts] Health of GPS constellation questioned -- "recently there have been more satellite outages than ever before"

Normand Martel martelno at yahoo.com
Wed Sep 6 12:16:10 EDT 2006


I've got this today from

http://tycho.usno.navy.mil/gpscurr.html
====================================================
        UNITED STATES NAVAL OBSERVATORY (USNO)
  
                        GPS CONSTELLATION STATUS
  
************************************************************************
     Information in this file is retained for
approximately seven 
     days or until completion of the event; be aware
that the  
     information provided below may change.
************************************************************************

A.  BLOCK II/IIA/IIR/IIR-M INDIVIDUAL SATELLITE STATUS

SVN  PRN
15   15  Launched 01 OCT 1990; usable 15 OCT 1990;
operating on Cs std
          Unusable 21 Aug 1358 UT and will remain
unusable until 
           further notice (NANU 2006079)
24   24  Launched 04 JUL 1991; usable 30 AUG 1991;
operating on Cs std
25   25  Launched 23 FEB 1992; usable 24 MAR 1992;
operating on Rb std
26   26  Launched 07 JUL 1992; usable 23 JUL 1992;
operating on Rb std
27   27  Launched 09 SEP 1992; usable 30 SEP 1992;
operating on Cs std
29   29  Launched 18 DEC 1992; usable 05 JAN 1993;
operating on Rb std
          Unusable 26 Aug 0147 UT and will remain
unusable until
           further notice (NANU 2006082)
30   30  Launched 12 SEP 1996; usable 01 OCT 1996;
operating on Cs std
32   01  Launched 22 NOV 1992; usable 11 DEC 1992;
operating on Cs std
33   03  Launched 28 MAR 1996; usable 09 APR 1996;
operating on Rb std
          Unusable 24 Aug 1502 UT and will remain
unusable until
           further notice (NANU 2006081)
34   04  Launched 26 OCT 1993; usable 22 NOV 1993;
operating on Rb std
35   05  Launched 30 AUG 1993; usable 28 SEP 1993;
operating on Rb std
36   06  Launched 10 MAR 1994; usable 28 MAR 1994;
operating on Rb std
37   07  Launched 13 MAY 1993; usable 12 JUN 1993;
operating on Rb std
38   08  Launched 06 NOV 1997; usable 18 DEC 1997;
operating on Cs std
39   09  Launched 26 JUN 1993; usable 20 JUL 1993;
operating on Rb std
40   10  Launched 16 JUL 1996; usable 15 AUG 1996;
operating on Cs std
41   14  Launched 10 NOV 2000; usable 10 DEC 2000;
operating on Rb std
43   13  Launched 23 JUL 1997; usable 31 JAN 1998;
operating on Rb std
44   28  Launched 16 JUL 2000; usable 17 AUG 2000;
operating on Rb std
45   21  Launched 31 MAR 2003; usable 12 APR 2003;
operating on Rb std
46   11  Launched 07 OCT 1999; usable 03 JAN 2000;
operating on Rb std
47   22  Launched 21 DEC 2003; usable 12 JAN 2004;
operating on Rb std
51   20  Launched 11 MAY 2000; usable 01 JUN 2000;
operating on Rb std
53   17  Launched 26 SEP 2005; usable 16 DEC 2005;
operating on Rb std
54   18  Launched 30 JAN 2001; usable 15 FEB 2001;
operating on Rb std
          Unusable 05 Sep 0053 to 0535 UT (NANUs
2006084, 2006085/05 SEP)
56   16  Launched 29 JAN 2003; usable 18 FEB 2003;
operating on Rb std
59   19  Launched 20 MAR 2004; usable 05 APR 2004;
operating on Rb std
60   23  Launched 23 JUN 2004; usable 09 JUL 2004;
operating on Rb std
61   02  Launched 06 NOV 2004; usable 22 NOV 2004;
operating on Rb std



B.  GPS ACTIVITIES
 1. Coordinated Universal Time (UTC) Time Step (Leap
Second)
     As of January 1, 2006, 0H 0M 0S, GPS is AHEAD of
UTC by FOURTEEN (+14) seconds.
 2.  On 16 Dec 2005 at approximately 2330 UT, the
L2-Band Civil Signal (L2C)
     was turned on for PRN17/SVN53, the first IIR-M
satellite. The following
     conditions of use apply:
     a.  The Air Force shall not guarantee the
availability or quality of L2C
         signals until Initial Operational Capability
(IOC).
     b.  Users are cautioned that the new signal is
under development and may
         be used for a variety of test applications
until achievement of IOC.
         Prior to IOC, signal availability and quality
of the L2C signal may be
         subject to change without prior notice. 
Therefore, any use of the L2C
         signal prior to being declared operational is
at the user's own risk.
     Please contact the USCG Navigation Center (Comm
703-313-5900) or the 
     GPS Operations Center (DSN 560-2541/Comm
719-567-2541) if you encounter
     problems.
 3. Selective Availablility (SA) levels set to zero.
     On May 2, 2000 at 0400 UT, SA levels were set to
zero.  For more
      details, check the Interagency GPS Executive
Board (IGEB) web
      site at http://www.igeb.gov. 
 4. GPS Automatic Time Steering
     In effect 18 Mar 1994 at 1415 UT and will remain
in effect until
      further notice at rate +/-1.0E-19 seconds per
second squared.
 5. Activation of Anti-Spoof (A-S)
     A-S was activated January 31, 1994 at 0000 UTC. 
Due to the
     December 8, 1993 declaration of Initial
Operational Capability
     (IOC), the P-code will not normally be available
to users who
      do not have valid cryptographic keys (iaw
Federal Radionavigation
      Plan (FRP) 1992).  (NANU 050-94042/DTG 112045Z
FEB 94)
 6. Implementation of Selective Availability (SA)
  a. SA was reactivated on July 1, 1991 at 0400 UT and
will remain in
      effect until further notice.  Civil users will
receive Standard
      Positioning Service (SPS) accuracy as specified
in the Federal
      Radionavigation Plan (FRP).  POC for policy: 
CDR Jackson at
      DSN 692-2634 or (719) 554-2634. (NANU
121-91182/DTG 011354Z JUL 91)
  b. According to the 2nd Satellite Operations
Squadron (2SOPS)
      Operational Advisory Bulletin:  SA was
implemented on November 15,
      1991 to the SPS level.
 

For information concerning:   BLOCK II       see file
. . . . . GPSB2
                              GPS SYSTEM     see file
. . . . . GPSSY
                              TIME TRANSFER  see file
. . . . . GPSTT

--  
File GPSTD
last updated
Tue Sep  5 11:35:09 UTC 2006
====================================================
SUMMARY

PRN 03 (Unusable 24 Aug 1502 UT and will remain
unusable until further notice)

PRN 12 non orbiting

PRN 15 (Unusable 21 Aug 1358 UT and will remain
unusable until further notice)

PRN 29  (Unusable 26 Aug 0147 UT and will remain
unusable until further notice)
PRN's 31 & 32 non orbiting

6 out of 32 birds being KO, it is nor critical (the
constellation is supposed to have at least 24 live
sats), but when you look ar PRN's 15, 03 & 29, (all
three being shut down within a week) no, it is not
normal...

BTW, on all the 26 live stellites, only six (01, 08,
10, 24, 27 and 30) run on Cesium standards, all other
rely on Rubidium.

73 de Normand Martel VE2UM
Montreal, Qc. Canada.


 
--- Christopher Hoover <ch at murgatroid.com> wrote:

> 
> [ the story seems overblown to me, but still worth
> sharing.  follow the
> last link for some real data. - ch ]
> 
> 
> GPS World: Current GPS constellation
> Aug 30, 2006
>  
>
<http://sidt.gpsworld.com/gpssidt/article/articleDetail.jsp?id=368448>
> 	
> 
> The current GPS constellation - its health and
> viability - continues in
> question and under scrutiny, despite reassurances
> from the Air Force. 
> 
> Last month's GPS World Survey & Construction
> e-newsletter relayed user
> plaints that there aren't enough healthy GPS
> satellites. Surveyors say
> they can't use RTK a full day with the current
> constellation even with
> every satellite healthy - and that recently there
> have been more
> satellite outages than ever before. They've resorted
> to filling GPS gaps
> with GLONASS. 
> 
> The online story drew immediate affirmation. "While
> most of the time we
> get good coverage, for the last couple months we
> have had a 4 to 6-hour
> gap where we 'float' a lot and our precision goes
> down. Unfortunately
> this gap is usually between 10 am and 2 pm, which
> creates some
> interesting scheduling problems." 
> 
> For years only three companies offered combined
> GPS/GLONASS receivers;
> that number recently doubled and now includes all
> major survey
> manufacturers. The market speaks. It would be ironic
> if GPS troubles
> helped revive GLONASS, just as perceived GPS
> shortcomings helped launch
> Galileo.
> 
> Others have written to ask what the JPO has been
> doing that has kept
> them occupied and unable to carry on GPS
> modernization or effective
> sustainment. In our September print issue of GPS
> World, We invited the
> GPS Joint Program Office to give their view
>
<http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=368240>
> ,
> and we asked an independent consultant for his
> perspective
>
<http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=367591>
> as well.
> 
> 
> 
> _______________________________________________
> time-nuts mailing list
> time-nuts at febo.com
>
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> 


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