PRE- AND INITIAL PROCESSING STEPS

7.3.2 Getting Started: Pre- & Initial Processing Steps

THE RINEX DATA EXCHANGE FORMAT

RINEX (Receiver INdependent EXchange) is an exchange format devised in 1989 for geodetic applications requiring the international exchange of GPS datasets, gathered during global campaigns, by different brands of receivers (GURTNER, 1 994). It has now been adopted as the standard exchange and storage format for GPS surveying and precise navigation applications as well. RINEX Version 2, which is able to handle kinematic GPS data, is now in common use.

The RINEX format has the following characteristics:

ASCII format, with a maximum of 80 characters per record.
Phase data recorded in cycles of L1 and L2 carrier frequencies, pseudo-range data in metres.
All receiver-dependent calibrations already applied to data.
Time-tag is the time of the observation in the receiver clock time frame (not necessarily in GPS Time).
Separate data (Table 1), Navigation Message (Table 2), and meteorological data files with header sections.

Table 1. Sample RINEX data file.

----|---1|0---|---2|0---|---3|0---|---4|0---|---5|0---
|---6|0---|---7|0---|---8|0

 PASADENA CA 91109 USA |       LOGOS::JPLGPS
COMMENT
TIDB                                                        MARKER
NAME
DSN                 JET PROPULSION LABORATORY               OBSERVER /
AGENCY
     2              DSN ROGUE           DSN ROGUE SOFTWARE  REC # /
TYPE / VERS
     2              D. AND M.   C146-6-1                    ANT
# / TYPE
 -4460853.8350  2682467.2310 -3674736.3630                  APPROX
POSITION XYZ
        0.0000        0.0000        0.0000
ANTENNA: DELTA H/E/N
     1     1
WAVELENGTH FACT L1/2
     5    C1    L1    L2    P1    P2
# / TYPES OF OBSERV
    30
INTERVAL
    92     7    26     6    52   30.000000                  TIME
OF FIRST OBS
    92     7    26    23    59   30.000000
TIME OF LAST OBS
 92  7 26  6 52 30.0000000  0  5  2 11 18 19 28

22333042.96600 -12176065.17700  -9487835.16600  22333025.72200
22333027.39100
  22934353.22700  -7227959.70200  -5632169.61500
22934338.21900  22934340.52000
  20485466.29600 -23339757.04000
-18186808.56800  20485447.35300  20485447.55500
  20609091.79300
-20568272.40900 -16027208.73300  20609081.52200  20609081.81200

23894196.98000    154816.73100    120640.79300  23894184.83300
23894185.36800
 92  7 26  6 53  0.0000000  0  6  2 11 16 18 19 28

22315737.73400 -12267004.73700  -9558697.09700  22315720.51000
22315722.15200
  22922104.35200  -7292336.30500  -5682333.14300
22922087.79100  22922090.05900
  23641617.41410  -3724083.52810
-2901879.61310  23641605.66310  23641608.09510
  20491946.68800
-23305701.79300 -18160272.01900  20491927.79600  20491927.80600

20609475.02700 -20566263.57700 -16025643.39900  20609463.71700
20609463.99400
  23903831.76500    205446.05300    160092.21000
23903819.21500
23903820.15300

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|---7|0---|---8|0

Table 2. Sample RINEX Navigation Message file.

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     1              NAVIGATIO
N DATA                         RINEX VERSION / TYPE
DMD_TO_RINEX v1.5   JET
PROPULSION LAB. 92-07-27 16:50:22   PGM / RUN BY / DATE
FILES OBTAINED FROM
THIRD PARTIES MAY NOT BE IDENTICAL TO   COMMENT
 THE LATEST AVAILABLE FROM
JPL. FOR INFORMATION CONTACT:    COMMENT
 THOMAS G. LOCKHART    | PHONE
(818)354-6102                COMMENT
 NASA/JPL M/S 238-625  | FAX
(818)393-4965                COMMENT
 4800 OAK GROVE DRIVE  | EMAIL
jplgps@logos.dnet.nasa.gov   COMMENT
 PASADENA CA 91109 USA |
LOGOS::JPLGPS                COMMENT

26 92  7 26  8 51 44.0
1.635868102312D-06-3.410605131648D-13 0.000000000000D+00

2.170000000000D+02 1.128125000000D+01 4.738768932810D-09
5.863412966114D-02
    4.898756742477D-07 8.141674217768D-03
9.039416909218D-06 5.153610269547D+03

3.190400000000D+04-7.636845111847D-08-1.371976967685D+00-4.470348358154D-08

9.603279283700D-01
2.067812500000D+02-1.491259472097D+00-8.059264366977D-09

-4.760912775126D-10 1.000000000000D+00 6.550000000000D+02
0.000000000000D+00
    3.200000000000D+01 0.000000000000D+00
0.000000000000D+00 2.170000000000D+02
15 92  7 26  8 51
44.0-2.961605787277D-07-4.547473508865D-13 0.000000000000D+00

3.000000000000D+01-5.693750000000D+01 4.155887189938D-09
1.478679355308D+00
   -2.870336174965D-06 7.184803485870D-03
1.033581793308D-05 5.153687067032D+03
    3.190400000000D+04
1.918524503708D-07 2.862619155647D+00 5.215406417847D-08

9.620121289009D-01 1.818437500000D+02
1.902453767716D+00-7.588887740440D-09
    4.989493818108D-10
1.000000000000D+00 6.550000000000D+02 0.000000000000D+00

3.200000000000D+01 0.000000000000D+00 0.000000000000D+00
3.000000000000D+01

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0---|---7|0---|---8|0

Most commercial GPS surveying packages will output RINEX formatted data files. Many commercial GPS surveying packages will also permit the input of RINEX formatted data files for processing. These have the following implications:

Data from one brand of receiver may be processed within another commercial software package.

Data from campaigns using a mixed set of GPS receivers can be processed within one software package.

In reality, the processing of data collected by a certain brand of GPS receiver using software not explicitly designed to process this data can be problematical. The main problem arises because of incompatible time-tags (see Figures in section 6.3.8).

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