GGTTS GPS Data Format, version 01 The NML GPS receivers used for common view now report data in the GGTTS format. This format provides more information than the old format, and some data is given to higher precision than before. The data preamble is shown below, along with a brief description of what some of the lines mean. The data header is then reproduced, with the meanings shown below that. Note that the data field is longer than 80 columns, and the heading has been "folded" for clarity. ----------------------------------------------------------------------------- GGTTS GPS DATA FORMAT VERSION = 01 REV DATE = 1995-10-31 /Revision date of data header RCVR = AOA TTR6 0267 1991 /Receiver type, S.N. etc CH = 01 /number of receiver channels IMS = 99999 /Ionospheric correction receiver, or LAB = NML 99999 if ionosphere modelled X = -4648204.01 m /Antenna co-ordinates Y = +2560474.76 m Z = -3526504.99 m FRAME = ITRF93 /frame of reference COMMENTS = NO COMMENTS INT DLY = 40.0 ns /internal receiver delay CAB DLY = 0292.0 ns /antenna to receiver cable delay REF DLY = 0000.0 ns /reference 1PPS delay REF = 36340 /Reference (NML Caesium HP5071,S.N.340) CKSUM = 66 /Checksum for header (see CK below) PRN CL MJD STTIME TRKL ELV AZTH REFSV SRSV REFGPS SRGPS DSG hhmmss s .1dg .1dg .1ns .1ps/s .1ns .1ps/s .1ns IOE MDTR SMDT MDIO SMDI CK .1ns.1ps/s.1ns.1ps/s ------------------------------------------------------------------------------ PRN Satellite vehicle PRN (pseudo random number). This identifies the code number used for the satellite's CA code. CL Common-view class byte (hexadecimal). STTIME Start time of the track in hours minutes and seconds. MJD is hhmmss the day on which the track occured. TRKL Length of the track in seconds. s ELV Elevation of spacecraft in tenths of degrees at the midpoint .1dg of the track. AZTH Azimuth of spacecraft in tenths of degrees at the midpoint .1dg of the track. REFSV Difference between the (NML) reference and the space .1ns vehicle clock in tenths of nanoseconds. SRSV Slope of best line of fit for REF-SV data in .1ps/s tenths of picoseconds/second. REFGPS Difference between the (NML) reference and the GPS .1ns time in tenths of nanoseconds. SRGPS Slope of best line of fit for REF-GPS in .1ps/s tenths of picoseconds/second. DSG [Data Sigma] Root mean square of residuals of best line .1ns of fit for REFGPS in tenths of nanoseconds. IOE Index of Ephemeris. Three digit code indicating the ephemeris used for computation. MDTR Modelled tropospheric delay in tenths of nanoseconds .1ns SMDT Slope of modeled tropospheric delay in .1ps/s tenths of picoseconds/second. MDIO Modelled Ionoshperic delay in tenths of nanoseconds. .1ns SMDI Slope of modelled ionospheric delay in .1ps/s tenths of picoseconds/second. CK Data line checksum. Hex sum, modulo 256 of ascii values of all characters in the data line up to CK.