rinex211.txt

读取GPS的Rinex观测文件

remaining differences during the post-processing.

8.1.2 Pseudorange Definition

The pseudorange (code) measurement is defined to be 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.

If a mixed-mode GPS/GLONASS receiver refers all pseudorange observations to
one receiver clock only,

- the raw GLONASS pseudoranges will show the current number of leap seconds
  between GPS time and GLONASS time if the receiver clock is running in the
  GPS time frame

- the raw GPS pseudoranges will show the negative number of leap seconds
  between GPS time and GLONASS time if the receiver clock is running in the
  GLONASS time frame

In order to avoid misunderstandings and to keep the code observations within
the format fields, the pseudoranges must be corrected in this case as follows:

  PR(GPS) := PR(GPS) + c * leap_seconds   if generated with a receiver clock
                                          running in the GLONASS time frame

  PR(GLO) := PR(GLO) - c * leap_seconds   if generated with a receiver clock
                                          running in the GPS time frame

to remove the contributions of the leap seconds from the pseudoranges.

"leap_seconds" is the actual number of leap seconds between GPS and GLONASS
(UTC) time, as broadcast in the GPS almanac and distributed in Circular T
of BIPM.

8.1.3 More Than 12 Satellites per Epoch

The format of the epoch / satellite line in the observation record part of
the RINEX Observation files has only been defined for up to 12 satellites
per epoch. We explicitly define now the format of the continuation lines,
see Table A2.


8.2 RINEX Navigation Files for GLONASS

As the GLONASS navigation message differs in contents from the GPS message
too much, a special GLONASS navigation message file format has been defined.

The header section and the first data record (epoch, satellite clock
information) is similar to the GPS navigation file. The following records
contain the satellite position, velocity and acceleration, the clock and
frequency biases as well as auxiliary information as health, satellite
frequency (channel), age of the information.

The corrections of the satellite time to UTC are as follows:

  GPS    : Tutc = Tsv - af0  -  af1  *(Tsv-Toc) - ... -  A0  - ... - leap_sec
  GLONASS: Tutc = Tsv + TauN - GammaN*(Tsv-Tb)        + TauC

***  In order to use the same sign conventions for the GLONASS corrections
     as in the GPS navigation files,  the broadcast GLONASS values are
     stored as:
                  -TauN, +GammaN, -TauC.

The time tags in the GLONASS navigation files are given in UTC (i.e. _not_
Moscow time or GPS time).

File naming convention: See above.


9.  RINEX Extensions for Geostationary Satellites (GPS Signal Payloads)

With the implementation of GNSS programs, GPS-like ranging measurements can be
performed on geostationary navigation payloads.

RINEX Version 2.10 defines the necessary extensions to handle such data in
RINEX files for data exchange and postprocessing purposes.


9.1 RINEX Observation Files for GEO Satellites

A new satellite system identifier has been defined for the geostationary
GPS signal payloads: "S", to be used in the RINEX VERSION / TYPE header line
and in the satellite identifier 'snn', nn being the GEO PRN number minus 100.

                   e.g.: PRN = 120 --> 'snn' = "S20"

In mixed dual frequency GPS satellite / single frequency GEO payload
observation files the fields for the second frequency observations of GEO
satellites remain blank, are set to zero values or (if last in the record)
can be truncated.

The time system identifier of GEO satellites generating GPS signals defaults
to GPS time.


9.2 RINEX Navigation Message Files for GEO Satellites

As the GEO broadcast orbit format differs from the GPS message a special GEO
navigation message file format has been defined which is nearly identical with
the GLONASS nav mess file format.

The header section contains informations about the generating program,
comments, and the difference between the GEO system time and UTC.

The first data record contains the epoch and satellite clock information,
the following records contain the satellite position, velocity and
acceleration and auxiliary information such as health, age of the data, etc.

The time tags in the GEO navigation files are given in the GPS time frame,
i.e. not UTC.

The corrections of the satellite time to UTC are as follows:

  GEO    : Tutc = Tsv - aGf0  -  aGf1 *(Tsv-Toe) -  W0  - leap_sec

W0 being the correction to transform the GEO system time to UTC. Toe, aGf0,
aGf1 see below in the format definition tables.

The "Transmission Time of Message" (PRN / EPOCH / SV CLK header record) is     |
expressed in GPS seconds of the week. It marks the beginning of the message    |
transmission. It has to refer to the same GPS week as the "Epoch of            |
Ephemerides". It has to be adjusted by - or + 604800 seconds, if necessary     |
(which would make it lower than zero or larger than 604800, respectively).     |
It is a redefinition of the Version 2.10 "Message frame time".                 |
                                                                               |
"Health" shall be defined as follows:                                          |
                                                                               |
  - Bits 0 to 3 equal to Health in Message Type 17 (MT17)                      |
  - bit 4 is set to 1 if MT17 health is unavailable                            |
  - bit 5 is set to 1 if the URA index is equal to 15                          |
                                                                               |
  In the SBAS message definitions bit 3 of the health is currently marked as   |
  'reserved'.                                                                  |                                                                                                               |
  In case of bit 4 set to 1, it is recommended to set bits 0,1,2,3 to 1, too.  |
                                                                               |
"User Range Accuracy" (URA):                                                   |
                                                                               |
  The same convention for converting the URA index to meters is used as        |
  with GPS. Set URA = 32767 meters if URA index = 15.                          |
                                                                               |
"IODN" (Issue Of Data Navigation)                                              |
                                                                               |
  The IODN is defined as the 8 first bits after the message type 9,            |
  called IODN in RTCA DO229, Annex A and Annex B and called "spare" in Annex C.|
                                                                               |
The "CORR TO SYSTEM" TIME header record has been replaced by the more general  |
record "D-UTC A0,A1,T,W,S,U" in Version 2.11.                                  |
                                                                               |
                                                                               |
10. Version 2.11 Modifications                                                 |
                                                                               |
The main driver for version 2.11 was the easy inclusion of Galileo and new GPS |
observables into the RINEX format. As these modifications are VERY MINOR (no   |
changes in the actual formats) many RINEX readers will not have to be          |
modified at all or to a small amount (accept version number 2.11), only.       |
                                                                               |
After the first introduction of the "GEO navigation message file" in Version   |
2.10 feedback from the SBAS community lead to a number of clarifications/      |
redefinitions that were included in the Version 2.11 modifications.            |
                                                                               |
10.1 Galileo and New GPS Observables                                           |
                                                                               |
10.1.1 New Observation Codes                                                   |
                                                                               |
In Version 2.10 only the observation codes for two frequencies were define     |
(Table A1).                                                                    |
                                                                               |
The new codes for GPS L2C/L5 and Galileo codes are introduced as follows:      |
                                                                               |
 +---------------------------------------------------------------------------+ |
 | System  Freq.Band  Frequency           RINEX 2-character Code             | |
 |                              Ps.Range  Carr.Phase  Doppler  Sign.Strength | |
 +---------------------------------------------------------------------------+ |
 | GPS     L1         1575.42     C1,P1       L1         D1         S1       | |
 |         L2         1227.60     C2,P2       L2         D2         S2       | |
 |         L5         1176.45      C5         L5         D5         S5       | |
 |                                                                           | |
 | Glonass G1         1602+k*9/16 C1,P1       L1         D1         S1       | |
 |         G2         1246+k*7/16 C2,P2       L2         D2         S2       | |
 |                                                                           | |
 | Galileo E2-L1-E1   1575.42      C1         L1         D1         S1       | |
 |         E5a        1176.45      C5         L5         D5         S5       | |
 |         E5b        1207.140     C7         L7         D7         S7       | |
 |         E5a+b      1191.795     C8         L8         D8         S8       | |
 |         E6         1278.75      C6         L6         D6         S6       | |
 |                                                                           | |
 | SBAS    L1         1575.42      C1         L1         D1         S1       | |
 |         L5         1176.45      C5         L5         D5         S5       | |
 +---------------------------------------------------------------------------+ |
                                                                               |
The current two-character observation code does not easily allow a further     |
refinement of the code to account for the different possibilities how to       |
generate a specific observable, e.g., with respect to the underlying           |
code (P,Y,M code in GPS) or the channels (I,Q, A,B,C in Galileo, I,Q in the    |
new GPS L5 frequency, GPS L2C). The next RINEX version (3.0) will increase the |
length of the observation codes to allow a more detailed definition.           |
                                                                               |
The definition of observations for Transit Doppler is obsolete and has been    |
removed from Version 2.11                                                      |
                                                                               |
10.1.2 Wavelength Factors                                                      |
                                                                               |
The WAVELENGTH FACT L1/2 header record defining the factor, the carrier        |
wavelength has to be divided with for ambiguity resolution, has been           |
introduced because of receivers generating GPS phase observations under        |
antispoofing with one cycle corresponding to half the carrier wavelength       |
only (squaring technique). Galileo observables will not be generated by        |
squaring. We therefore define the WAVELENGTH FACT L1/2 header record to be     |
valid for L1 and L2 GPS phase observables only. All wavelength factors default |
to 1. This header record can therefore be declared to be optional.             |
                                                                               |
10.1.3 Code for Galileo Satellite System                                       |
                                                                               |
Use "E" to indicate the Galileo Satellite System in the header of RINEX        |
observation files.                                                             |
                                                                               |
10.1.4 Galileo System Time                                                     |
                                                                               |
Include GAL as Galileo System Time into TIME OF FIRST OBS and TIME OF LAST OBS |
header records.                                                                |
                                                                               |
10.2 Clarifications in the GEO Navigation Message File                         |
                                                                               |
The following clarifications/modifications were introduced (see chapter 9.2):  |
                                                                               |
- Health word                                                                  |
- Issue of Data (Navigation) IODN                                              |
- Correction to system time                                                    |
- Transmission time of message                                                 |
                                                                               |
10.3 New observables for RINEX met files                                       |
                                                                               |
Wind speed (ms), wind direction (from where the wind blows), and an            |
incremental rain fall value (1/10 mm): rain accumulation since the last        |
recording, hail indicator                                                      |


REFERENCES

Evans, A. (1989): "Summary of the Workshop on GPS Exchange Formats."
Proceedings of the Fifth International Geodetic Symposium on Satellite
Systems, pp. 917ff, Las Cruces.

Gurtner, W., G. Mader, D. Arthur (1989):  "A Common Exchange Format for
GPS Data." CSTG GPS Bulletin Vol.2 No.3, May/June 1989, National Geodetic