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database

A three file set containing all basic information and data needed for GPS processing

Overview

mergedb acts as a translator, taking the various possible source files and creating the database, a three file set containing all basic information and data needed for GPS processing. This simplifies the I/O for all subsequent program. Each of these three database files has a specific purpose and naming convention.

Data File

The data file contains all "common view" phase and pseudorange observations from all sites. The data from these sites have been time synchronized and output at a standard interval. If no data were available, an "edit" flag is inserted signalling that this data is unusable. In addition to the data, a line-of-site tropo correction, and space for an L1 and L2 editting instruction is included. The data file is binary to reduce size and speed I/O.

The data file uses the naming convention DBID + dt.dat where DBID is a database identification name or string. The most common DBID's are:

The former is the historical naming convention; the latter, standard for the two station databases created by run_survey.

Orbit File

The orbit file contains the Earth-centered, Earth-fixed (XYZ) coordinates for each satellite in each epoch in the data file.

The orbit file uses the naming convention DBID + or.dat

Header File

The header file contains the most basic information for all satellites and stations in the database. Note that the station information is taken from the POM files only.

The header file uses the naming convention DBID + hd.dat

Example 

* TSTRT: 1994   5   0  0   .00  TSTOP: 1994   5  23 45   .00
* mergedb versn:9608.14
$
  TOTAL # STATIONS:  2
TOTAL # SATELLITES: 26
 
18
19
22
28
29
31
17
25
27
15
 2
 7
26
14
13
 9
12
 4
 5
24
16
20
 3
23
21
 1
 
gode                  gode  1  1
             X,Y,Z (m):  1130773.922 -4831253.697  3994200.496
          TEMP(t)  (C):       25.751
          PRES(t) (mB):     1011.551
          RELH(t)  (%):       50.000
          CLOCK (usec):
 ANT - N,E,U,L1-L2 (m):         .000         .000         .000        -.018    4
brmu                  brmu  1  1
             X,Y,Z (m):  2304703.628 -4874817.240  3395186.957
          TEMP(t)  (C):       27.852
          PRES(t) (mB):     1014.576
          RELH(t)  (%):       50.000
          CLOCK (usec):
 ANT - N,E,U,L1-L2 (m):         .000         .000         .000        -.018    4
where:

line 1 is the start and stop times of the database.

line 2 is the mergedb version number.

line 3 signals the end of descriptive information. The user can put additional comments after line 2 but before this line if necessary.

line 4 is the total number of stations.

line 5 is the total number of satellites.

lines 7-32 (in this case) are the satellite PRN numbers in no particular order.

line 34 is the station name, the station four character ID and the L1 and L2 half integer flags. A half integer flag value of "1" means only whole cycle slips can occur; a value of "2" means half cycle slips are possible.

line 35 station coordintes in meters.

line 36-38 is the surface temperature, pressure and relative humidity in degrees Celsius, millibar and percentage of saturation respectively.

line 39 is the north, east and up offsets, in meters, of the L1 phase center from a convenient or required reference point. These values are followed by the L1 - L2 up offset, also in meters, and the antenna type identifier.

The station block (lines 34-39) is repeated for all other sites. 

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database.html
September 13, 1996
Steve Hilla