Subject: [IGSMAIL-97] JPL analysis report
From: James F. Zumberge
Date: 17 SEP 1992 12:06:14

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IGS Electronic Mail       17-SEP-1992 12:06:14       Message Number 97
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From:    James F. Zumberge
Subject: JPL analysis report
         -------------------

Submitted by

J F Zumberge, G Blewitt, M B Heflin, D C Jefferson, F H Webb

all at the Jet Propulsion Laboratory, California Institute of Technology, 
Pasadena, CA  91109.

The following files have been posted on BODHI (for access to BODHI contact
[email-masked]):

______________________________________________________________________________
filename               contents
______________________________________________________________________________
jpl06607.sum           This text file.
jpl06607.erp           Earth rotation parameters for GPS week 660.
jpl06607.sp1           GPS ephemerides for GPS week 660, sp1 format.
jpl06607.sp3            "       "       "   "   "    " , sp3   "   .
______________________________________________________________________________

Beginning with the August 30 analysis, we have modified our estimation
strategy by modeling the deviation from nominal of each polar motion
component (x and y) as an independent linear function of time for each
UTC day. Pole values are still reported at noon each day. Prior to Aug 30,
we had estimated only a constant offset from a smooth interpolation of
the IERS Bulletin B predicts. The new strategy allows us to (i) quote
the value of the pole at noon even if we have an uneven distribution of
data during the day and (ii) be less sensitive to a priori rates. Because
most days have an even distribution of data and the a priori rates are
generally good, this new strategy will give almost identical results to
the old one except in unusual cases (e.g., if we have only a partial day
of data).

Also, we begin modeling 

           [UT1R-UTC](T) = nominal(T) + newparam*(T-To),

where nominal(T) is the value obtained by smooth interpolation of 
IERS Bulletin B predicts, To is noon of the day analyzed, and newparam is
a new estimated parameter. (UT1R is UT1 regularized by subtracting out
the sum of 41 short-period tidal terms.) This allows a daily estimate
of length of day (LODR):
 
           LODR == - [UT1R-UTC]'(To)             [by definition]
                =  - {nominal'(To) + newparam}   [our model]
                =~ -{[nominal(To+Td/2) - nominal(To-Td/2)]/Td + newparam}, 

where Td == 86400 sec and ' denotes differentiation with respect to time.
LODR is a rate and we report it in msec/day.

Because GPS is not sensitive to absolute UT1R (except through second order
effects on the satellite force model), our estimates of LODR are
insensitive to errors in the UT1R predicts.

We now include a 'JPL LODR TABLE' with the result of the above calculation.
The formal error in the table is strongly dependent on the validity of the
satellite model. It may be optimistic by as much as a factor of ~4.

In addition, our JPL UTPM TABLE now contains the value of nominal(To)
in the 'UT1R-UTC' column.

As indicated in the STATION INCLUSION table, we are beginning to get
Mas Palomas data soon enough to include it in our routine processing.

Also, for Sep 3 and 5 and continuing indefinitely, we have reduced our
data interval from 6 minutes to 5 minutes. As in our original strategy,
carrier phase data are decimated so that we are immune to S/A (the Rogue
internally does a quadratic fit over 10 s), and the pseudorange data are
smoothed over the interval using the carrier phase data.

Near the beginning of the week, the behavior of GPS20 returned to normal.

A-S was not on during this week.

WARNING: GPS20 is poorly modeled on August 30.

JPL LODR TABLE                               GPS week 660 (1992 Aug 30 - Sep 05)
  MJD       LODR     +/-
          (ms/day)
 48864.5    1.93     0.02
 48865.5    2.03     0.02
 48866.5    1.99     0.02
 48867.5    2.04     0.02
 48868.5    1.85     0.01
 48869.5    1.77     0.01
 48870.5    1.78     0.02
END LODR TABLE

NOTE: In the following table, UT1R-UTC are the assumed nominal values from
IERS Bulletin-B predicts; estimated LODR values are given in the previous
table.

JPL UTPM TABLE                               GPS week 660 (1992 Aug 30 - Sep 05)
  MJD       X        Y       UT1R-UTC XSIG    YSIG   UTSIG  RMS  XYC  XUC  YUC STA SAT PASS    
           ''        ''        sec     ''     ''      sec
 48864.5  -.01589   .50052   .34916  .00009  .00010  .00000  .0  .00  .00  .00  26 18  0
 48865.5  -.01367   .50202   .34731  .00008  .00009  .00000  .0  .02  .00  .00  23 18  0
 48866.5  -.01171   .50319   .34547  .00009  .00011  .00000  .0 -.01  .00  .00  25 18  0
 48867.5  -.00967   .50261   .34361  .00009  .00011  .00000  .0 -.03  .00  .00  25 18  0
 48868.5  -.00701   .50206   .34176  .00007  .00008  .00000  .0  .05  .00  .00  26 18  0
 48869.5  -.00491   .50188   .33988  .00007  .00008  .00000  .0 -.03  .00  .00  25 18  0
 48870.5  -.00262   .50278   .33800  .00008  .00009  .00000  .0  .07  .00  .00  27 18  0
END UTPM TABLE

The following table indicates the "3-dimensional orbit repeatability", as 
defined in IGS Mail Message 37, for GPS week 660:

JPL ORBIT REPEATABILITY TABLE                GPS week 660 (1992 Aug 30 - Sep 05)
      92  8 30   92  8 31   92  9  1   92  9  2   92  9  3   92  9  4   92  9  5
prn    rms (m)
  2       0.78       0.62       0.71       0.65       0.84       0.67       1.07
  3       0.80       0.57       0.45       0.61       0.38       1.48       0.77
 11       0.63       0.28       0.69       0.98       0.35       0.40       0.37
 12       0.75       0.66       0.74       0.55       0.73       0.71       0.82
 13       0.40       0.37       0.39       0.44       0.77       0.84       0.44
 14       1.03       1.28       1.24       0.98       1.29       0.98       1.24
 15       1.39       0.73       0.49       0.87       0.65       0.50       0.65
 16       0.97       0.89       0.90       0.94       0.35       1.19       1.36
 17       1.18       0.48       0.62       0.70       0.49       0.56       1.11
 18       0.92       0.73       0.65       0.87       0.73       0.82       0.87
 19       0.83       0.43       0.53       0.65       0.53       0.71       0.66
 20     649.27     317.05       1.32       1.66       1.77       1.80       2.26
 21       1.33       1.04       1.01       1.33       1.03       1.21       1.39
 23       0.95       0.31       0.50       0.48       0.78       0.94       2.01
 24       0.76       0.66       0.40       0.55       0.40       0.41       0.52
 25       0.60       0.40       0.50       0.61       0.57       0.80       0.69
 26       0.93       1.00       0.62       0.88       0.62       0.98       1.73
 28       0.69       0.42       0.68       0.34       0.66       0.88       0.64
END ORBIT REPEATABILITY TABLE

As described in IGS Mail Message 37, the following table compares the JPL
precise ephemerides with those from the broadcast ephemeris:

JPL COMPARISON OF BROADCAST NAVIGATION MESSAGE WITH PRECISE EPHEMERIDES
      92  8 30   92  8 31   92  9  1   92  9  2   92  9  3   92  9  4   92  9  5
prn    rms (m)
  2       9.8       12.5       12.1       13.7       10.5        9.8       13.5 
  3      11.7       18.1       11.8       12.21      10.9       14.6       15.5 
 11      10.3        5.9        6.8        9.0        4.2        4.3        3.2 
 12       5.9       17.2        5.5        8.1        7.2        8.9        7.4 
 13       5.1        6.1        9.3       10.8       10.4        8.1        8.7 
 14       7.8       13.5        8.5        9.4       10.0        9.9        9.7 
 15       5.1        8.4        8.3        6.9        6.3        4.9        4.9 
 16       8.1        7.3        7.9        8.6       10.1       11.3        9.1 
 17       5.5        7.9        7.5        7.0        8.4        6.2        7.1 
 18       7.1        6.0        6.8        8.8       10.1        9.5        6.8 
 19       3.5        5.2        4.5        4.5        4.2        4.0        4.5 
 20     360.8       16.2       11.3       11.0       10.9       10.7       10.1 
 21       4.7        5.1        7.3        8.0        5.7        6.3        8.3 
 23       7.6        6.9        4.1        4.4        5.6        9.9       14.0 
 24      12.8       12.6       11.9       11.8        9.9       15.2       14.4 
 25       6.0        5.9        9.2        9.7        8.4        8.7        7.1 
 26      10.0        9.3       11.9        8.7       11.1       11.8       11.0 
 28       2.9        3.9        5.6        4.4        3.0        2.9        3.1 
END COMPARISON OF BROADCAST NAVIGATION MESSAGE WITH PRECISE EPHEMERIDES

The following table, as explained in IGS Mail Message 91, indicates which 
tracking sites were used in this week's analysis:

JPL GROUND STATION INCLUSION TABLE           GPS week 660 (1992 Aug 30 - Sep 05)
         92  8 30  92  8 31  92  9 01  92  9 02  92  9 03  92  9 04  92  9 05

ALBH         X         X         X         X         X         X         X
ALGO*        X         X         X         X         X         X         X
FAIR*        X         X         X         X         X         X         X
GOLD         X         X         X         X         X         X         X
HART*        X         X         X         X         X         X         X
HERS         X         X         X         X         X         X         X
JPLM         X         X         X         X         X         X         X
KOKB*        X         X         X         X         X         X         X
KOSG         X         X         X         X         X         X         X
MADR*        X         X         X         X         X         X         X
MASP                                                 X                   X
MATE         X         X         X         X                   X         X
MCMU         X         X         X         X         X         X         X
METS         X                   X         X         X         X         X
NYAL         X         X         X         X         X         X         X
ONSA         X         X         X         X         X         X         X
PAMA         X         X         X         X         X         X         X
PENT         X         X         X         X         X         X         X
SANT*        X         X         X         X         X         X         X
STJO         X         X         X         X         X         X         X
TAIW         X         X         X         X         X         X         X
TIDB         X         X         X         X         X         X         X
TROM*        X         X         X         X         X         X         X
USUD         X                                       X         X         X
WETT         X                   X         X         X                   X
YAR1*        X         X         X         X         X         X         X
YELL         X         X         X         X         X         X         X
_______________________
*Indicates fiducial site.
END GROUND STATION INCLUSION TABLE