NGA > Office of Geomatics > GPS > Documentation

 


NGA/GPS 5 Minute Ephemeris SP3 Format Description

Effective date February 26, 2012

 


NGA products use the format finalized by the National Geodetic Survey. 

The SP3 format provide ephemeris data in either position (P) mode or velocity (V) modes.

The SP3 format is precise to 1 mm and 1 picosecond.  Velocity, when included, is precise to 10-4 mm/sec and 10-4 picoseconds/s.

 

The following is the format for the "enhanced" SP3:

                1         2         3         4         5         6

       123456789012345678901234567890123456789012345678901234567890

 

1      #aV2012 10  1  0  0  0.00000000     288 DD+AD WGS84 FIT  NGA

2      ## 1708  86400.00000000   300.00000000 56201 0.0000000000000

3      +   31     1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17

4      +         18 19 20 21 22 23 25 26 27 28 29 30 31 32  0  0  0

5      +          0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0

6      +          0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0

7      +          0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0

8      ++         2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2

9      ++         2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  0  0

10     ++         0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0

11     ++         0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0

12     ++         0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0

13     %c cc cc ccc ccc cccc cccc cccc cccc ccccc ccccc ccccc ccccc

14     %c cc cc ccc ccc cccc cccc cccc cccc ccccc ccccc ccccc ccccc

15     %f  0.0000000  0.000000000  0.00000000000  0.000000000000000

16     %f  0.0000000  0.000000000  0.00000000000  0.000000000000000

17     %i    0    0    0    0      0      0      0      0         0

18     %i    0    0    0    0      0      0      0      0         0

19     /*      NGA, ST. LOUIS,MO.                                 

20     /*   EPHEMERIS COMPUTED FROM  1 DAYS OF DATA

21     /*   EPOCHA SMOOTHER 

22     /* CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

23     *  2012 10  1  0  0  0.00000000                                                

24     P  1  -1677.901589  16285.584053 -20920.350325    275.849218                   

25     V  1 -25096.728698   8665.572021   8818.525202      0.015870                   

26     P  2  20801.130436 -14268.541598   7587.240521    404.556632                   

27     V  2  10280.136019   -147.845949 -29536.235333      0.011634                   

28                .             .             .             .      

29                .             .             .             .

30                .             .             .             .

31                .             .             .             .

32                .             .             .             .

33                .             .             .             .

34     *  2012 10  1 23 55  0.00000000                                                

35     P  1  -1545.870613  16240.292187 -20966.016107    275.985617                   

36     V  1 -25177.862925   8604.994335   8581.662169      0.015774                   

37                .             .             .             .

38                .             .             .             .

39                .             .             .             .

40                .             .             .             .

41                .             .             .             .

42                .             .             .             .

43     P 32   -143.412125  18718.631715 -18837.924362   -493.864143                   

44     V 32 -18157.215193 -16024.551820 -15137.882157     -0.039374                   

45     EOF

SP3 (Enhanced) Format:

 

Line 1:  ('#aV',i4,4i3,f12.8,6x,'96 DD+AD WGS84 FIT  NGA')

Column

Description

Allowed or Sample value

1

Symbol

#

2

Version Identifier

a

3

Position/Velocity Mode Flag

P or V

4-7

Year Start

2012

8

Unused

 

9-10

Month Start

10

11

Unused

 

12-13

Day of Month Start

1

14

Unused

 

15-16

Hour Start

 0

17

Unused

 

18-19

Minute Start

 0

20

Unused

 

21-31

Second Start

0.00000000

32

Unused

 

33-39

Number of Epochs

   288

40

Unused

 

41-45

Data Used

DD+AD

46

Unused

 

47-51

Coordinate System

WGS84

52

Unused

 

53-55

Orbit Type

FIT

56

Unused

 

57-60

Agency

NGA

 

 

Line 2:   ('##',i5,f16.8,f15.8,i6,f16.13)

Column

Description

Allowed or Sample value

1-2

Symbol

##

3

Unused

 

4-7

GPS Week

1708

8

Unused

 

9-23

Seconds of Week

0.00000000

24

Unused

 

25-38

Epoch Interval

  300.0000000

39

Unused

 

40-44

Modified Julian Day Start

 56201

45

Unused

 

46-60

Fractional Day

0.00000000

 

Line 3:   ('+',i5,3x,17i3)

Column

Description

Allowed or Sample value

1-2

Symbol

+

3-4

Unused

 

5-6

Number of Satellites

31

7-9

Unused

 

10-12

Satellite ID for the 1st satellite

  1

13-15

Satellite ID for the 2nd satellite

  2

*

*

*

*

*

*

*

*

*

58-60

Satellite ID for the 17th satellite

 18

 

Lines 4 to 7:   ('+',8x,17i3)

Column

Description

Allowed or Sample value

1-2

Symbol

+

3-9

Unused

 

10-12

Satellite ID for the next satellite

  19

*

*

*

*

*

*

*

*

*

58-60

Satellite ID for the last satellite

  0

 

Line 8 to 12:   ('++',7x,17i3)

Column

Description

Allowed or Sample value

1-2

Symbol

++

3-9                                     

Unused

 

10-12

Satellite Accuracy for the 1st satellite

  0

13-15

Satellite ID for the next satellite

  0

*

*

*

*

*

*

*

*

*

58-60

Satellite ID for the last satellite

  0

 

Lines 13 to 14:   ('%c cc cc ccc ccc cccc cccc cccc cccc ccccc ccccc ccccc ccccc')

Column

Description

Allowed or Sample value

1-2

Symbol

%c

3           

Unused

 

4-5

Characters

cc

6

Unused

 

7-8

Characters

cc

9

Unused

 

10-12

Characters

ccc

13

Unused

 

14-16

Characters

ccc

17

Unused

 

18-21

Characters

cccc

22

Unused

 

23-26

Characters

cccc

27

Unused

 

28-31

Characters

cccc

32

Unused

 

33-36

Characters

cccc

37

Unused

 

38-42

Characters

ccccc

43

Unused

 

44-48

Characters

ccccc

49

Unused

 

50-54

Characters

ccccc

55

Unused

 

56-60

Characters

ccccc

 

Lines 15 and 16:   ('%f  0.0000000  0.000000000  0.00000000000  0.000000000000000')

Column

Description

Allowed or Sample value

1-2

Symbol

%f

3           

Unused

 

4-13

Common Float

 0.0000000

14

Unused

 

15-26

Common Float

 0.000000000

27

Unused

 

28-41

Common Float

 0.00000000000

42

Unused

 

43-60

Common Float

 0.000000000000000

 

Lines 17 and 18:   ('%i    0    0    0    0      0      0      0      0         0')

Column

Description

Allowed or Sample value

1-2

Symbol

%i

3           

Unused

 

4-7

Integer

   0

8

Unused

 

9-12

Integer

   0

13

Unused

 

14-17

Integer

   0

18

Unused

 

19-22

Integer

   0

23

Unused

 

24-29

Integer

     0

30

Unused

 

31-36

Integer

     0

37

Unused

 

38-43

Integer

     0

44

Unused

 

45-50

Integer

     0

51

Unused

 

52-60

Integer

     0

 

Lines 19 to 22:   ('/* CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC')

 

Line 23 (The Epoch Header Record):   ('*',i6,4i3,f12.8)

Column

Description

Allowed or Sample value

1-2

Symbol

*

3           

Unused

 

4-7

Year Start

2012

8

Unused

 

9-10

Month Start

10

11

Unused

 

12-13

Day of Month Start

  1

14

Unused

 

15-16

Hour Start

  0

17

Unused

 

18-19

Integer

  0

20

Unused

 

21-31

Integer

     0

32-60

Unused

 

Epoch Headers in Line Twenty-three repeat for each new epoch with vehicle position and velocity records following.

 

Line 24 (The Position and Clock Record):   ('P',i3,4f14.6)

Column

Description

Allowed or Sample value

1

Position

P

2-4

Vehicle ID

  1

5-18

x coordinate (km)

   -1577.901589

19-32

y coordinate (km)     

  16285.584053

33-46

z coordinate (km)     

 -20920.350325

47-60

Clock time (μs)

       275.849218

Line Twenty-four will include an 'E' in column 75 to designate an Event in the Position and Clock Record.  ('P',i3,4f14.6,14x,'E')

 

Line 25 (The Velocity Record):   ('V',i3,4f14.6)

Column

Description

Allowed or Sample value

1

Velocity

V

2-4

Vehicle ID

  1

5-18

x coordinate (dm/s)

-25096.728698

19-32

y coordinate (dm/s)     

    8665.572021

33-46

z coordinate (dm/s)     

    8818.525202

47-60

Clock correction rate of change (10-4μs/s)

           0.015870

 Lines Twenty-four and Twenty-five repeat for each vehicle in the epoch.