$PASSDIR/last_location
The last_location file contains the latest site location. This location may be set
by the command newsite if the system
is permanently fixed or is moved infrequently. The site location must be continually
updated by whereami or nmea_monitor if the system is mobile, such
as a ship board system or a portable land based system. Once the file has been updated,
other TeraScan commands access this file to determine the antenna location. The time
correction is calculated by sunclock .
The alititude, magentic declination and dip are calculated by whereami and nmea_monitor . The shipheading is stored on a the
completion of a pass by antenna and
may be not up to date with the current ship position. It is updated only if the
reading is good. Not all of the following records may be stored in the file.
The file contains the following records of the form:
*gps latitude longitude date time
*timeadj timeadjustment date time
*altitude elevation date time
*declination mag_declination
mag_dip date time
*shipheading heading
date time
*sst temperature date time
where
| *gps | is a constant string. |
| latitude | latitude, in degrees of the antenna site. North latitudes are positive, south latitudes are negative. This is a real number. |
| longitude | longitude, in degrees, of the antenna site. East longitudes are positive, west longitudes are negative. This is a real number. |
| date | is the date of the last reading (yy/mm/dd format). This field is optional on every record |
| time | is the time of day of the last reading (hh:mm:ss gmt format). This field is optional on every record. |
| *timeadj | is a constant string. |
| timeadjustment | is the time correction to the system time. This error should always be less than one second. It is the residual error between the system clock and real time that cannot be removed due to timing of the internal system clock. |
| *altitude | is a constant string. |
| elevation | is the altitude of the antenna site, in meters above sea level. |
| *declination | is a constant string. |
| mag_declination | is the magnetic declination of the antenna site, in degrees from true north. Positive value means the magnetic pole is EAST of true north. Negative value means the magnetic pole is WEST of true north. |
| mag_dip | is the magnetic dip of the antenna site, in degrees (0.0 to 90.0). |
| *shipheading | is a constant string. |
| heading | is the shipheading at the specified date and time. Degrees from true north ( 0.0 - 360.0). This is a real number. |
| *sst | is a constant string. |
| temperature | is the current local sea surface temperature stored in the file. Degrees C. This is a real number |
[1]cat $PASSDIR/last_location
*gps -77.849 166.660 97/5/6 18:3:22
*timeadj 0.017
*altitude 33.2
*declination 13.41 58.15
*shipheading 144.3 97/5/3 10:21:12
None
whereami, newsite, site location, sunclock, magnetic_model.
1. If a value is undefined ( BAD value), it will not be stored in
the file.
2. Time adjustment will be stored in the file even if the adjustment is
0.0 seconds.
Last Updated: $Date: 2000/07/21 21:30:03 $