wiki:ShmDocMenuFileReadGse
Last modified 14 years ago Last modified on 02/05/2009 11:22:41 AM

Menu entry Read GSE

Reads in GSE formatted data files. A file selection box pops up to let the user select the data file. The default path in the selection box may be changed in Configure. After selecting the file, all traces of the file are read in. By default all previously read traces are deleted before reading a new GSE file. To keep traces when reading new ones switch on the Keep Traces button in the Read dialog box (this is not straightforward, I admit). This Read GSE command reads both formats, GSE1 and GSE2.

Please note that only a part of the header information is read into SHM (start time, number of samples, station name, channel name, component, sample rate, calibration gain). All other information (in particular station location and transfer function) is ignored and must be supplied separately via SH input files (station location file, filter files).

The relevant header entries in GSE files are in the lines starting with WID1 and the following line in GSE1 or the line starting with WID2 in GSE2. A brief listing of the content of these lines is appended at the end of this page. A complete description of the GSE2 format is found in http://orfeus.knmi.nl/manuals.

SHM reads the calibration information and multiplies a velocity calibration gain, given in (nm/s)/Count, to the samples. If the calibration gain is given as displacement constant in nm/Count, as it is required in GSE2 and possible in GSE1, it is rescaled to velocity using the calibration period information of the header:

cv = cd * 2 * pi / T

where cv = velocity calibration, cd = displacement calibration, T = calibration period. The advantage of multiplying cv to the data is, that when using broadband data the amplitude is given in nm/s in the passband, since broadband data are usually proportional to velocity. For narrowband data the above operation is meaningless, it just has to be taken into account for computation of absolute amplitudes.

Known bug: Open/read errors on the file are not notified, just nothing is read in.

Format entries of the GSE1 header lines WID1

*line 1 pos 01-04: must be WID1
*line 1 pos 06-13: start date yyyyddd, yyyy = year, ddd = julian date
*line 1 pos 15-16: start hour, format %2d (C-syntax) or i2 (Fortran)
*line 1 pos 18-19: start minute, format %2d (C-syntax) or i2 (Fortran)
*line 1 pos 21-22: start second, format %2d (C) or i2 (Fortran)
*line 1 pos 24-26: start millisecond, format %3d (C) or i3 (Fortran)
*line 1 pos 28-35: number of samples, format %8d (C) or i8 (Fortran)
*line 1 pos 37-42: station name, maximum 6 characters, unused must be blank
 line 1 pos 44-51: channel ID, maximum 8 characters, unused must be blank
*line 1 pos 53-54: channel name, 2 chars, e.g. SZ, LZ, LN, LE, ...
*line 1 pos 56-66: sample rate, format %11.7f (C) or f11.7 (Fortran)
 line 1 pos 68-73: system type, max. 6 chars, unused must be blank
*line 1 pos 75-78: data format type, 4 chars, e.g. INTV, CMP6, ...
*line 1 pos 80   : differencing flag, values 0,1 or 2, no of differences
*line 2 pos 01-09: calibration gain, format %9.6f (C) or f9.6 (Fortran)
*line 2 pos 10   : units of motion for cal. gain, 0=displ, 1=veloc, 2=accel
*line 2 pos 11-17: calibration period, format %7.4f (C) or f7.4 (Fortran)
 line 2 pos 19-27: station latitude, format %9.4f (C) or f9.4 (Fortran)
 line 2 pos 29-37: station longitude, format %9.4f (C) or f9.4 (Fortran)
 line 2 pos 39-47: station elevation, format %9.4f (C) or f9.4 (Fortran)
 line 2 pos 49-57: depth of sensor, format %9.4f or f9.4, -999 = unknown
 line 2 pos 59-65: beam azimuth, format %7.2f or f7.2, deg, -1 = unknown
 line 2 pos 67-73: beam slowness, format %7.2f, f7.2, s/deg, -1 = unknown
 line 2 pos 75-80: horizontal orientation, format %6.1f, 6.1f, -1 = unkown

(* = used by SH/SHM)

Format entries of the GSE2 header line WID2

*pos 001-004: must be WID2
*pos 006-015: start date yyyy/mm/dd
*pos 017-028: start time hh:mm:ss.sss
*pos 030-034: station name, max. 5 chars, unused must be blank
*pos 036-038: FDSN channel name, e.g. BHZ, BHN, LHZ, ...
 pos 040-043: auxiliary id code, max. 4 chars, unused must be blank
*pos 045-047: data type, INT, CMn, n=compression bits
*pos 049-056: number of samples, format %8d or i8
*pos 058-068: sampling rate (Hz), format %11.6f or f11.6
*pos 070-079: calibration gain in nm/count at cal. period, format %10.2e, e10.2
*pos 081-087: calibration period, format %7.3f, f7.3
 pos 089-094: instrument type, max. 6 chars, unused must be blank
 pos 096-100: horizontal orientation, %5.1f or f5.1, -1 if vertical
 pos 102-105: vertical orientation, %4.1f or f4.1, 90 if horizontal

(* = used by SH/SHM)


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