sp3c.txt

包含三个M文件

Change Record.  This type of record always begins with the character 'V'. 
When the position/velocity mode flag is set to 'V' in line one, then each
Position and Clock Record for a satellite will be followed by a
corresponding Velocity and Clock Rate-of-Change Record (although in some
cases there may be a Position and Clock Correlation Record in between the
two).  The satellite velocity components are given in columns 5-46 in units
of decimeters/second and have a precision of 10**-4 millimeters/second. 
Columns 47-60 give the rate-of-change of the clock correction in units of
10**-4 microseconds/second.  The precision of this parameter is 10**-16
seconds/second.  Bad or absent velocity values are to be set to 0.000000.  
Bad or absent clock rate-of-change values are to be set to _999999.999999.  
The six integer nines are required, whereas the fractional part nines are 
optional.  In a manner similar to the Position and Clock Record,
columns 62-69 hold two-digit exponents for representing the standard
deviation of the X-, Y-, Z-velocities (e.g., 1.25**14 = 22.7374 or
approximately 0.0022 mm/sec).  Columns 71-73 hold a three-digit exponent for
representing the standard deviation of the clock correction rate-of-change
(e.g., 1.025**191 = 111.7528 or approximately 0.0112 psec/sec).  A value of
99 or 999 would mean that a standard deviation was too large to represent.
If a standard deviation is unknown, its field is left blank.  If one or more
fields in columns 61 through 73 are omitted, a Velocity and Clock Rate-of-
Change Record may contain less than 73 columns.


     Line 27 (in example 2) is the optional Velocity and Clock Rate-of-
Change Correlation Record.  This type of line always begins with the
characters 'EV'.  Columns 5-18 give the standard deviations for the X-, Y-,
Z-velocities in units of 10**-4 millimeters/second.  The standard deviations
of the velocity components are given to greater resolution than the
approximates values given in the Velocity and Clock Rate-of-Change Record. 
A value of 9999 would mean that a velocity standard deviation was too large
to be represented.  Columns 20-26 give the standard deviation of the clock
correction rate-of-change in units of 10**-4 psec/sec.  A value of 9999999
would mean that the clock correction rate-of-change was to large to be
represented. If a standard deviation is unknown, its field is left blank.
Columns 28-80 are used to store the correlation coefficients between the
velocity components and the clock correction rate-of-change (xy, xz, xc, yz,
yc, and zc).  Each 8-digit integer would be divided by 10,000,000 to produce
a correlation coefficient between -0.9999999 and +0.9999999.  If some of the
correlation coefficients are omitted, a Velocity and Clock Rate-of-Change
Correlation Record may contain less than 80 columns.

FINAL NOTE: Any software which reads SP3-c files must be prepared to read
the 'EP' and 'EV' correlation records if they are present. If the person or
agency using the file decides that the correlation information (and the more
accurate standard deviations) are not needed, then these 'EP' and 'EV'
records might be stripped out to save space, or simply ignored and skipped
over. There may be only a few EP and/or EV records placed in an SP3-c file,
i.e., it is not necessary to have EP and/or EV records for every satellite 
at every epoch (as shown in Example 2 below). The only rule is: since no 
satellite IDs are given in the optional EP and EV records, they must 
immediately follow their corresponding P or V record for that satellite.   
The satellite order of the P, EP, V, and EV records (or subset of these) 
must be the same as the order of the satellite IDs in lines 3 through 7 in
the header. Thus the order and the total number of satellites at each epoch
must always be the same. This serves as an integrity check on the file --
i.e., satellites must be designated as "bad" or "absent" by intentionally
setting their position (and velocity) values equal to zero.  There should 
never be any satellite's Position or Velocity records left out at an epoch.
Since not all SP3-c records will contain their maximum number of columns,
missing columns should be interpreted as blanks.  Any program reading an
SP3-c file must be prepared to deal with short records (either by padding
with blanks, or by some other method). 


Example 1. SP3-c file with Position and Clock Record used at each epoch.

#cP2001  8  8  0  0  0.00000000     192 ORBIT IGS97 HLM  IGS
## 1126 259200.00000000   900.00000000 52129 0.0000000000000
+   26   G01G02G03G04G05G06G07G08G09G10G11G13G14G17G18G20G21
+        G23G24G25G26G27G28G29G30G31  0  0  0  0  0  0  0  0
+          0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
+          0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
+          0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
++         7  8  7  8  6  7  7  7  7  7  7  7  7  8  8  7  9
++         9  8  6  8  7  7  6  7  7  0  0  0  0  0  0  0  0
++         0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
++         0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
++         0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
%c G  cc GPS ccc cccc cccc cccc cccc ccccc ccccc ccccc ccccc
%c cc cc ccc ccc cccc cccc cccc cccc ccccc ccccc ccccc ccccc
%f  1.2500000  1.025000000  0.00000000000  0.000000000000000
%f  0.0000000  0.000000000  0.00000000000  0.000000000000000
%i    0    0    0    0      0      0      0      0         0
%i    0    0    0    0      0      0      0      0         0
/* ULTRA ORBIT COMBINATION FROM WEIGHTED AVERAGE OF:
/* cou esu gfu jpu siu usu
/* REFERENCED TO cou CLOCK AND TO WEIGHTED MEAN POLE:
/* CLK ANT Z-OFFSET (M): II/IIA 1.023; IIR 0.000
*  2001  8  8  0  0  0.00000000
PG01 -11044.805800 -10475.672350  21929.418200    189.163300 18 18 18 219
PG02 -12593.593500  10170.327650 -20354.534400    -55.976000 18 18 18 219     M
PG03   9335.606450 -21952.990750 -11624.350150     54.756700 18 18 18 219
PG04 -16148.976900   8606.630600  19407.845050    617.997800 18 18 18 219
PG05  13454.631450  20956.333700   9376.994100    308.956400 18 18 18 219
PG06  18821.523100   1138.155450  18958.305500     -2.406900 18 18 18 219
 .
 .
 .

*  2001  8  9 23 45  0.00000000
PG01 -11044.805800 -10475.672350  21929.418200    189.163300 18 18 18 219  P   P
PG02 -12593.593500  10170.327650 -20354.534400    -55.976000 18 18 18 219  P   P
PG03   9335.606450 -21952.990750 -11624.350150     54.756700 18 18 18 219  P   P
PG04 -16148.976900   8606.630600  19407.845050    617.997800 18 18 18 219 EP   P
 .
 .
 .
PG30 -20393.814200  16198.067550  -4138.151700    428.892900 18 18 18 219  P   P
PG31 -23592.378250   1395.049800 -12524.037100    461.972900 18 18 18 219  P   P
EOF



Example 2. SP3-c file with all record types (P, EP, V, EV) used at each epoch.

#cV2001  8  8  0  0  0.00000000     192 ORBIT IGS97 HLM  IGS
## 1126 259200.00000000   900.00000000 52129 0.0000000000000
+   26   G01G02G03G04G05G06G07G08G09G10G11G13G14G17G18G20G21
+        G23G24G25G26G27G28G29G30G31  0  0  0  0  0  0  0  0
+          0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
+          0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
+          0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
++         7  8  7  8  6  7  7  7  7  7  7  7  7  8  8  7  9
++         9  8  6  8  7  7  6  7  7  0  0  0  0  0  0  0  0
++         0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
++         0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
++         0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
%c G  cc GPS ccc cccc cccc cccc cccc ccccc ccccc ccccc ccccc
%c cc cc ccc ccc cccc cccc cccc cccc ccccc ccccc ccccc ccccc
%f  1.2500000  1.025000000  0.00000000000  0.000000000000000
%f  0.0000000  0.000000000  0.00000000000  0.000000000000000
%i    0    0    0    0      0      0      0      0         0
%i    0    0    0    0      0      0      0      0         0
/* ULTRA ORBIT COMBINATION FROM WEIGHTED AVERAGE OF:
/* cou esu gfu jpu siu usu
/* REFERENCED TO cou CLOCK AND TO WEIGHTED MEAN POLE:
/* CLK ANT Z-OFFSET (M): II/IIA 1.023; IIR 0.000
*  2001  8  8  0  0  0.00000000
PG01 -11044.805800 -10475.672350  21929.418200    189.163300 18 18 18 219
EP    55   55   55     222  1234567 -1234567  5999999      -30       21 -1230000
VG01  20298.880364 -18462.044804   1381.387685     -4.534317 14 14 14 191
EV    22   22   22     111  1234567  1234567  1234567  1234567  1234567  1234567
PG02 -12593.593500  10170.327650 -20354.534400    -55.976000 18 18 18 219     M
EP    55   55   55     222  1234567 -1234567  5999999      -30       21 -1230000
VG02  -9481.923808 -25832.652567  -7277.160056      8.801258 14 14 14 191
EV    22   22   22     111  1234567  1234567  1234567  1234567  1234567  1234567
PG03   9335.606450 -21952.990750 -11624.350150     54.756700 18 18 18 219
EP    55   55   55     222  1234567 -1234567  5999999      -30       21 -1230000
VG03  12497.392894  -8482.260298  26230.348459      5.620682 14 14 14 191
EV    22   22   22     111  1234567  1234567  1234567  1234567  1234567  1234567
PG04 -16148.976900   8606.630600  19407.845050    617.997800 18 18 18 219
EP    55   55   55     222  1234567 -1234567  5999999      -30       21 -1230000
VG04 -22859.768469  -8524.538983 -15063.229095     -3.292980 14 14 14 191
EV    22   22   22     111  1234567  1234567  1234567  1234567  1234567  1234567
PG05  13454.631450  20956.333700   9376.994100    308.956400 18 18 18 219
EP    55   55   55     222  1234567 -1234567  5999999      -30       21 -1230000
VG05    392.255680  12367.086937 -27955.768747    -13.600595 14 14 14 191
EV    22   22   22     111  1234567  1234567  1234567  1234567  1234567  1234567
 .
 .
 .

*  2001  8  9 23 45  0.00000000
PG01 -11044.805800 -10475.672350  21929.418200    189.163300 18 18 18 219  P   P
EP    55   55   55     222  1234567 -1234567  5999999      -30       21 -1230000
VG01  20298.880364 -18462.044804   1381.387685     -4.534317 14 14 14 191
EV    22   22   22     111  1234567  1234567  1234567  1234567  1234567  1234567
PG02 -12593.593500  10170.327650 -20354.534400    -55.976000 18 18 18 219  P   P
EP    55   55   55     222  1234567 -1234567  5999999      -30       21 -1230000
VG02  -9481.923808 -25832.652567  -7277.160056      8.801258 14 14 14 191
EV    22   22   22     111  1234567  1234567  1234567  1234567  1234567  1234567
 .
 .
 .
PG30 -23592.378250   1395.049800 -12524.037100    461.972900 18 18 18 219  P   P
EP    55   55   55     222  1234567 -1234567  5999999      -30       21 -1230000
VG30 -13996.847785  -6945.665482  25908.199568      0.364488 14 14 14 191
EV    22   22   22     111  1234567  1234567  1234567  1234567  1234567  1234567
PG31  17353.533200  15151.105700 -13851.534050     -1.841700 18 18 18 219  P   P
EP    55   55   55     222  1234567 -1234567  5999999      -30       21 -1230000
VG31 -16984.306646  -2424.913336 -23969.277677    -14.371692 14 14 14 191
EV    22   22   22     111  1234567  1234567  1234567  1234567  1234567  1234567
EOF




                         ACKNOWLEDGMENTS

The idea for using floating-point base numbers (1.25**nn and 1.025**nnn,
rather than 2**nn) to improve the resolution of the standard deviations was
suggested by Benjamin Remondi.  The author would also like to thank the
several members of the IGS community who offered comments and suggestions on
the design of the SP3-c format: Henno Boomkamp, Gerd Gendt, Werner Gurtner, Urs
Hugentobler, Jan Kouba, Stephen Malys, Tomas Martin Mur, Jim Ray, Ignacio
Romero, Markus Rothacher, Mark Schenewerk, Victor Slabinski, Tim Springer,
Everett Swift, and Robert Weber. 
          


                           REFERENCES


1.  Remondi, B. W. 1985: Distribution of Global Positioning System
Ephemerides by the National Geodetic Survey, Presented at the First
Conference on Civil Applications of GPS - Institute of Navigation, September
12, 1985, 8 pp.

2.  Remondi, B. W. 1989: Extending the National Geodetic Survey Geodetic
Orbit Formats, NOAA Technical Report 133 NGS 46, 85 pp.

3.  Remondi, B. W., 1991: NGS Second Generation ASCII and Binary Orbit
Formats and Associated Interpolated Studies, Proceedings of the Twentieth
General Assembly, International Union of Geodesy and Geophysics, Vienna,
Austria, August 11-24, 1991, 28 pp.

4.  Gurtner, W., 2000: RINEX: The Receiver-Independent Exchange Format, GPS
World, Volume 5, Number 7, 48-52. Also available from:
ftp://igscb.jpl.nasa.gov/igscb/data/format/rinex210.txt

5.  Hilla, S., 2002: Extending the Standard Product 3 (SP3) Orbit Format,
Proceedings of the International GPS Service Network, Data, and Analysis
Center Workshop, Ottawa, Canada, April 8-11, 2002.     


6. Spofford, P. R. and Remondi, B. W., 1994: The National Geodetic Survey
Standard GPS Format SP3. (SP3-a format) available from the IGS website:
 http://igscb.jpl.nasa.gov/igscb/data/format/sp3_docu.txt


7. The NIMA SP3 format can be viewed at
 http://164.214.2.59/GandG/sathtml/sp3format.html


8. The IGEX98 SP3-b format [IGEX Mail-0042, SP3 Modifications (corrigenda)]
can be viewed at  http://igscb.jpl.nasa.gov/mail/igexmail/1998/msg00041.html
 

9. A list of identifiers for Low-Earth Orbiting satellites can be viewed at
http://cddis.gsfc.nasa.gov/sp3c_satlist.html