rinex211.txt

读取GPS的Rinex观测文件

* The time system identifier in the TIME OF LAST OBS header record has to
  be identical to the one in the TIME OF FIRST OBS record

* Clarification of Table A2 to be compatible with examples of Table A7:
  For event flags without significant epoch the epoch fields can be left blank.
  Table A6: Format for epoch contained obvious errors

* Clarification of the floating point exponent format in navigation message
  files (two digits, E,e,D,d letters)

0.6 Version 2.11                                                               |
                                                                               |
The modifications of 2.10 leading to Version 2.11 include:                     |
                                                                               |
- Definition of the Galileo satellite system code                              |
- Definition of the code for Galileo System Time (GAL)                         |
- Definition of the frequency numbers for Galileo and new GPS observables      |
- Observation code for L2C pseudorange (C2)                                    | 
- Some clarifications in the GEO NAV Message files:                            |
  - Transmission time of message                                               |
  - Health                                                                     |
  - URA                                                                        |
  - CORR TO SYSTEM TIME replaced by more general D-UTC A0,A1,T,W,S,U record    |
- Introduction of wind speed and direction, rain fall increment, hail indicator|
- Recommendation regarding unknown/undefined observation types and header      |
  records                                                                      |
- Recommendations for extended filenames for high-rate observation files       |


1. THE PHILOSOPHY OF RINEX

The first proposal for the "Receiver Independent Exchange Format" RINEX has
been developed by the Astronomical Institute of the University of Berne for
the easy exchange of the GPS data to be collected during the large European
GPS campaign EUREF 89, which involved more than 60 GPS receivers of 4
different manufacturers. The governing aspect during the development was
the following fact:

Most geodetic processing software for GPS data use a well-defined set of
observables:

- the carrier-phase measurement at one or both carriers (actually being a
measurement on the beat frequency between the received carrier of the
satellite signal and a receiver-generated reference frequency).

- the pseudorange (code) measurement, equivalent to the difference of the
time of reception (expressed in the time frame of the receiver) and the
time of transmission (expressed in the time frame of the satellite) of a
distinct satellite signal.

- the observation time being the reading of the receiver clock at the
instant of validity of the carrier-phase and/or the code measurements.

Usually the software assumes that the observation time is valid for both
the phase AND the code measurements, AND for all satellites observed.

Consequently all these programs do not need most of the information that is
usually stored by the receivers:  They need phase, code, and time in the
above mentioned definitions, and some station-related information like
station name, antenna height, etc.


2. GENERAL FORMAT DESCRIPTION

Currently the format consists of seven ASCII file types:

   1. Observation Data File
   2. Navigation Message File
   3. Meteorological Data File
   4. GLONASS Navigation Message File
   5. GEO Navigation Message File
   6. Satellite and Receiver Clock Date File
   7. SBAS Broadcast Data File

The format definition of the clock files has been published in 1998
in a separate document by Jim Ray and Werner Gurtner, available at the IGS
Central Bureau Information System:
  ftp://igscb.jpl.nasa.gov/igscb/data/format/rinex_clock.txt

The format definition of the Space-based augmentation system (SBAS) broadcast
data file has been published in 2004 by Norbert Suard, Werner Gurtner and Lou
Estey, available at the IGS Central Bureau Information System:
  ftp://igscb.jpl.nasa.gov/igscb/data/format/geo_sbas.txt

Each file type consists of a header section and a data section. The header
section contains global information for the entire file and is placed at
the beginning of the file. The header section contains header labels in
columns 61-80 for each line contained in the header section. These labels
are mandatory and must appear exactly as given in these descriptions and
examples.

The format has been optimized for minimum space requirements independent
from the number of different observation types of a specific receiver by
indicating in the header the types of observations to be stored. In
computer systems allowing variable record lengths the observation records
may be kept as short as possible. Trailing blanks can be removed from the
records. The maximum record length is 80 bytes per record.

Each Observation file and each Meteorological Data file basically contain
the data from one site and one session. RINEX Version 2 also allows to
include observation data from more than one site subsequently occupied by
a roving receiver in rapid static or kinematic applications. Although Version 2
allows to insert header records into the data field we do not recommend to
concatenate data of more than one receiver (or antenna) into the same file,
even if the data do not overlap in time.

If data from more than one receiver has to be exchanged it would not be
economical to include the identical satellite messages collected by the
different receivers several times. Therefore the Navigation Message File
from one receiver may be exchanged or a composite Navigation Message File
created containing non-redundant information from several receivers in
order to make the most complete file.

The format of the data records of the RINEX Version 1 Navigation Message
file is identical to the former NGS exchange format.

The actual format descriptions as well as examples are given in the Tables
at the end of the paper.


3. DEFINITION OF THE OBSERVABLES

GPS observables include three fundamental quantities that need to be defined:
Time, Phase, and Range.

TIME:

  The time of the measurement is the receiver time of the received signals.
  It is identical for the phase and range measurements and is identical for
  all satellites observed at that epoch. It is expressed in GPS time (not
  Universal Time).

PSEUDO-RANGE:

  The pseudo-range (PR) is the distance from the receiver antenna to the
  satellite antenna including receiver and satellite clock offsets (and
  other biases, such as atmospheric delays):

    PR  =  distance +
           c * (receiver clock offset - satellite clock offset +
                other biases)

  so that the pseudo-range reflects the actual behavior of the receiver
  and satellite clocks. The pseudo-range is stored in units of meters.

  See also clarifications for pseudoranges in mixed GPS/GLONASS files in
  chapter 8.1.

PHASE:

  The phase is the carrier-phase measured in whole cycles. The half-cycles     |
  measured by squaring-type receivers must be converted to whole cycles and    |
  flagged by the wavelength factor in the header section (GPS only).           |

  The phase changes in the same sense as the range (negative doppler). The
  phase observations between epochs must be connected by including the
  integer number of cycles. The phase observations will not contain any
  systematic drifts from intentional offsets of the reference oscillators.

The observables are not corrected for external effects like atmospheric
refraction, satellite clock offsets, etc.

If the receiver or the converter software adjusts the measurements using
the real-time-derived receiver clock offsets dT(r), the consistency of the
3 quantities phase / pseudo-range / epoch must be maintained, i.e. the
receiver clock correction should be applied to all 3 observables:

  Time(corr)  = Time(r)  -  dT(r)
  PR(corr)    =  PR(r)   -  dT(r)*c
  phase(corr) = phase(r) -  dT(r)*freq

DOPPLER:

The sign of the doppler shift as additional observable is defined as usual:
Positive for approaching satellites.


4. THE EXCHANGE OF RINEX FILES:

We recommend using the following naming convention for RINEX files:

   ssssdddf.yyt

   |   |  | | |
   |   |  | | +--  t:  file type:
   |   |  | |          O: Observation file
   |   |  | |          N: GPS Navigation file
   |   |  | |          M: Meteorological data file
   |   |  | |          G: GLONASS Navigation file 
   |   |  | |          L: Future Galileo Navigation file                       |
   |   |  | |          H: Geostationary GPS payload nav mess file
   |   |  | |          B: Geo SBAS broadcast data file
   |   |  | |                        (separate documentation)
   |   |  | |          C: Clock file (separate documentation)
   |   |  | |          S: Summary file (used e.g., by IGS, not a standard!)    |
   |   |  | |
   |   |  | +---  yy:  two-digit year
   |   |  |
   |   |  +-----   f:  file sequence number/character within day
   |   |               daily file: f = 0
   |   |               hourly files:
   |   |               f = a:  1st hour 00h-01h; f = b: 2nd hour 01h-02h; ... ;|
   |   |               f = x: 24th hour 23h-24h                                |
   |   |
   |   +-------  ddd:  day of the year of first record
   |
   +----------- ssss:  4-character station name designator


For 15-minutes high-rate tracking data we recommend the following extended     |
filenames:                                                                     |
                                                                               |
   ssssdddhmm.yyo                                                              |
                                                                               |
   |   |  ||  | |                                                              |
   |   |  ||  | +-  o: observation file                                        |
   |   |  ||  |                                                                |
   |   |  ||  +--- yy: two-digit year                                          |
   |   |  ||                                                                   |
   |   |  |+------ mm: starting minute within the hour (00, 15, 30, 45)        |
   |   |  |                                                                    |
   |   |  +-------  h: character for the n-th hour in the day                  |
   |   |               (a= 1st hour: 00h-01h, b= 2nd hour: 1h to 2h,...,       |
   |   |               x=24th hour: 23h-24h. 0= one-day file)                  |
   |   |                                                                       |
   |   +--------- ddd: day of the year                                         |
   |                                                                           |
   +------------ ssss: 4-character ID for the LEO receiver/antenna             |


When data transmission times or storage volumes are critical we recommend
compressing the files prior to storage or transmission using the UNIX
"compress" und "uncompress" programs. Compatible routines are available on
VAX/VMS and PC/DOS systems, as well.

Proposed file name extensions for the compressed files:

  +----------------------------------------------------------------------+     |
  | File Types                      All platforms    UNIX    VMS     DOS |     |
  |                                 uncompressed         compressed      |     |
  +----------------------------------------------------------------------+     |
  | Obs Files                            .yyO       .yyO.Z  .yyO_Z  .yyY |     |
  | Obs Files (Hatanaka compressed)      .yyD       .yyD.Z  .yyD_Z  .yyE |     |
  | GPS Nav Files                        .yyN       .yyN.Z  .yyN_Z  .yyX |     |
  | GLONASS Nav File                     .yyG       .yyG.Z  .yyG_Z  .yyV |     |