| Textural File Header |
| Byte Number |
Field Description |
| 1-3200 |
single header written as ASCII, as opposed to EBCDIC, with no extensions |
| |
| Binary File Header |
| 3201-3204 |
Job Identification Number: left blank. |
| 3205-3208 |
Line Number: set to the array name, 1, 2, 3, etc. |
| 3209-3212 |
Reel Number: set to 1. |
| 3213-3214 |
Traces Per Ensemble: set to the number of traces in the gather. |
| 3215-3216 |
not used. |
| 3217-3218 |
Sample Interval: set to the sample interval in micro-seconds. All traces have the same sample interval. |
| 3219-3220 |
not used. |
| 3221-3222 |
Number of Samples Per Trace: set to the number of samples per trace. All traces in the gather have the same number of samples. The maximum allowed is 32767 samples. |
| 3223-3224 |
Field Samples Per Trace: set the same as the Number of Samples Per Trace. |
| 3225-3226 |
Data Format: set to 5 (4-byte IEEE floats). |
| 3227-3254 |
not used. |
| 3255-3256 |
Measurement System: set to 1 (meters). |
| 3257-3500 |
not used. |
| 3501-3502 |
SEG-Y Revision Number: set to 0x0100 (rev 1.0). |
| 3503-3504 |
Trace Length Flag: set to 1 (all traces the same length). |
| 3505-3506 |
Number of Extended Text Headers: set to 0 |
| |
|
| |
All unused fields in the binary file header are set to 0x00. |
| |
| Trace Header |
| 1-4 |
Line Trace Sequence Number: set to 1. |
| 5-8 |
not used. |
| 9-12 |
Field Record Number: set to the recording window number. |
| 13-16 |
Field Trace Number: set to the sequence number of the trace in the gather. |
| 17-20 |
Energy Source Point Number: set to the event ID. |
| 21-28 |
not used. |
| 29-30 |
Trace ID Code: set to 15 for the Z component, 16 for the N component, or 17 for the E component. If unknown it is set to 1 for seismic data. |
| 31-36 |
not used. |
| 37-40 |
Source to Receiver Distance: set to the distance from the source to the receiver in meters. The source to receiver distance sign is determined by calculating the least-squares linear regression of receiver locations of the array and the intersection of a line perpendicular to the linear regression which crosses through the shot location. Receiver locations to the left of this intersection have negative source to receiver distances. |
| 41-44 |
Receiver Group Elevation: set to the integer value of the station elevation in decimeters. |
| 45-48 |
Source Elevation: set to the surface elevation of the source in decimeters. |
| 49-52 |
Source Depth: the distance from the surface to the source in decimeters. |
| 53-68 |
not used. |
| 69-70 |
Elevation and Depth Scaler: set to -10, (divide by 10 to get meters). |
| 71-72 |
Coordinate Scaler: set to -10,000, (divide by 10,000 to get degrees). |
| 73-76, 77-80 |
X and Y Coordinates, respectively, of the source are set to the longitude and latitude in degrees multiplied by 10,000. Set to 0 if unknown. |
| 81-84, 85-88 |
X and Y Coordinates, respectively, of the receiver are set to longitude and latitude in degrees multiplied by 10,000. Set to 0 if unknown. |
| 89-90 |
Coordinate Units: set to 3, (decimal degrees). |
| 91-114 |
not used. |
| 115-116 |
Number of Samples: set to the number of samples in the trace. |
| 117-118 |
Sample Interval: set to the sample interval of the data in micro-seconds. |
| 119-120 |
Gain Type: set to 1 (fixed). |
| 121-122 |
Gain Constant: set to the gain set in the data logger. |
| 157-158, 159-160 |
Year and Day of Year, respectively of the trace start time. |
|
161-162, 163-164, 165-166
|
Hour, Minute and Seconds, respectively of the trace start time. |
| 167-168 |
Time Basis Code: set to 4 (UTC). |
| 169-170 |
Trace Weighting Factor: ln (bit_weight_in_volts) / ln (2). |
| 171-172 |
Geophone Group Number: set to the array ID. |
| 173-206 |
not used. |
| 207-208 |
Milli-seconds are set in the extended part of the header (non-standard). |
| |
|
| |
All unused fields in the trace header are set to 0x00. |
