Site Information Files

These are binary files containing the history of coordinate, velocity, hardware and ocean loading information for GPS tracking sites.

Information Types

Hereafter, a single grouping of information comprising one of these types will be referred to as a record.  The information contained in a record are defined by C style data structures.  There are definitions, and routines for reading and writing these records defined for both C/C++ and Fortran.  General information on the record sturcture, the info common to all record types, defined standard size parameters, and the C, A, R, G/T, O and M record types is available.

Information Organization

General Information About Site Information Data Structures

The site information file is formatted to be read as an unformatted sequential file from (HP) FORTRAN.  The structure of
binary FORTRAN input/output (I/O) is:

SIZE<--------INFO------->SIZE

where:

• "INFO" is all variables, constants, arrays, etc. that are listed in the FORTRAN I/O command and
• "SIZE" is an integer set equal to the total number of bytes of "INFO".

The "INFO" is broken into two general categories in the site information records,

• information "common" to all records and
• information specific to that record type.

RECORD = <-common-><-----info-------->
or
RECORD = SIZE<--------INFO------->SIZE

Note that the leading "SIZE" integer begins the common data structure, the trailing "SIZE" integer concludes the type specific data structure.
 
 

The structures delineating the common and other information data types, and other relatined definitions are stored in the sidata.h header file.

Global Size Definitions

#define DATA_FORMAT     ((long)1)
#define FORMAT_99MAR15  ((long)2)

#define EPS_MINUTE      ((double)30.0/(double)86000.0)
#define EPS_SECOND      ((double)0.5/(double)86000.0)

#define MAX_record      256

#define MAX_altname     40
#define MAX_comment     60
#define MAX_domes       9
#define MAX_frame       7
#define MAX_from        16
#define MAX_fw          16
#define MAX_id          6
#define MAX_key         1
#define MAX_name_m1     16
#define MAX_name        20
#define MAX_plate       4
#define MAX_seq         1
#define MAX_sitename    24
#define MAX_sn          16
#define MAX_to          16

#define STR_altname     (MAX_altname+1)
#define STR_comment     (MAX_comment+1)
#define STR_domes       (MAX_domes+1)
#define STR_frame       (MAX_frame+1)
#define STR_from        (MAX_from+1)
#define STR_fw          (MAX_fw+1)
#define STR_id          (MAX_id+1)
#define STR_key         (MAX_key+1)
#define STR_name        (MAX_name+1)
#define STR_plate       (MAX_plate+1)
#define STR_seq         (MAX_seq+1)
#define STR_sitename    (MAX_sitename+1)
#define STR_sn          (MAX_sn+1)
#define STR_to          (MAX_to+1)

The Common Information Structure

The "common" structure has the following items:

size	total size in bytes minus leading/trailing 4 byte integers	4 byte long
modmjd	modification time high part [MJD]	4 byte long
modday	modification time low part [day]	8 byte double
type	"type" appears in this structure to fulfill the 8 byte boundary requirement of HP hardware. To minimize wasted space, "type" has meanings dependent upon the record type: A   = corresponding numeric antenna type ID C   = no use M   = no use O   = G/T = additive offsets OLT = no use R   = corresponding numeric receiver type ID	4 byte long
valmjd	first valid epoch high part [MJD]	4 byte long
valday	first valid epoch low part [day]	8 byte double
key	record type, i.e. A, C, M, ...	1 byte char
id	site ID	6 byte char
seq	site point code character	1 byte char
Total size		40 bytes

struct common_data_info {
        long   size;
        long   modmjd;
        double modday;
        long   type;
        long   valmjd;
        double valday;
        char   key;
        char   id[MAX_id];
        char   seq;
};

The Antenna Data Structure

The eccentricity is a local topocentric vector.  The "from" and "to" strings are provided to hold short reminders of the beginning and ending points of the eccentricity.  In almost every conceivable case, these should be "from" MON, "to" ARP.

struct antenna {
        double n;
        double e;
        double u;
        char   from[MAX_from];
        char   to[MAX_to];
        char   name[MAX_name];
        char   sn[MAX_sn];
        char   comment[MAX_comment];
        char   dummy[4];
        long   size;
};

The Coordinate/Velocity Data Structure

The coordinates are in the Earth-centered, fixed (ECF) frame which should be identified using the "frame" string, e.g. "ITRF97" or "IGS97".    The current list of tectonic plates recognized by this software is held in the xsites program header file, plate.h.

struct coordinates {
        double x;
        double y;
        double z;
        double xsig;
        double ysig;
        double zsig;
        double vx;
        double vy;
        double vz;
        double vxsig;
        double vysig;
        double vzsig;
        double refday;
        long   refmjd;
        char   frame[MAX_frame];
        char   domes[MAX_domes];
        char   plate[MAX_plate];
        char   sitename[MAX_sitename];
        char   altname[MAX_altname];
        char   comment[MAX_comment];
        long   size;
};

The Met Sensor Data Structure

struct met {
        double pru;
        char   pr[MAX_name];
        char   prsn[MAX_sn];
        char   rh[MAX_name];
        char   rhsn[MAX_sn];
        char   tm[MAX_name];
        char   tmsn[MAX_sn];
        char   comment[MAX_comment];
        char   dummy[4];
        long   size;
};

The Offset (G/T) Data Structure

The offset structure can contain a local topocentric or ECF vector offset.  Given the evolution of the global geodetic community, the use of the offset structure should be avoided.

struct offset {
        double offset[3];
        char   from[MAX_from];
        char   to[MAX_to];
        char   comment[MAX_comment];
        long   size;
};

The Ocean-loading Data Structure

Each pair of tidal harmonic variables is named with its Darwinian designation, e.g. m2 = M2 = principal lunar semidiurnal tide.  The phase is relative to the driving potential, i.e. the Moon or Sun.

struct oceanloading {
        double m2amp;
        double m2phs;
        double s2amp;
        double s2phs;
        double n2amp;
        double n2phs;
        double k2amp;
        double k2phs;
        double o1amp;
        double o1phs;
        double k1amp;
        double k1phs;
        double p1amp;
        double p1phs;
        double q1amp;
        double q1phs;
        double mfamp;
        double mfphs;
        double mmamp;
        double mmphs;
        double ssaamp;
        double ssaphs;
        char   comment[MAX_comment];
        long   size;
};

The Receiver Data Structure

struct receiver {
        char   name[MAX_name];
        char   sn[MAX_sn];
        char   fw[MAX_fw];
        char   comment[MAX_comment];
        long   size;
};