Entity_and_Attribute_Overview:
The times recorded in the navigation file are in UTC. Keyword definitions and the information listed below are comprehensive and not found in every file. The definitions are as follows:
FTP: The first record located at the top of the header used to identify the file format.
VER: HYPACK version number.
INF: General survey information filled in by the data technician. This typically contains the survey participants, the vessel name, other agencies involved with the survey, and the location of the survey. The three numbers at the end refer to initial tide correction at start-of-line, initial draft correction at start-of-line and sound velocity from the navigation parameters. The wrong vessel is listed in files 001_2139.062, 001_2240.062, and 002_2146.062
FIL: Raw format file.
ELL: Ellipsoid information. The name of the ellipsoid followed by the semi-major axis in meters and the flattening ration.
PRO: Project information record where TME indicates Transverse Mercator and the central meridian of -81 indicates UTM, zone 17.
DTM: Datum transformation record
GEO: Geoid model. Blank if not present.
HVU: Horizontal and Vertical Units (meters).
TND: Survey time and date in UTC.
DEV 0: Indicates that the lines with device designation 0 are lines of DGPS data acquired with the Coda Octopus F180 motion reference unit antenae.
OFF: device offsets (none used during this data collection) The number following OFF indicates which device
DEV 1: Indicates that these are lines of device designation 1. However, there was no second GPS recever on this cruise (DEV 0 was the only receiver), this option was inadvertently left on when setting up HYPACK for this cruise.
OFF: device offsets (none used during this data collection) The number following OFF indicates which device
LIN: planned line data follows in the format "LIN nw" where nw=number of waypoints.
PTS: planned line waypoints; easting, northing in UTM zone 16N, meters.
LBP: planned line begin point; easting, northing in UTM zone 16N, meters.
LNN X: planned line name where X is the line name
EOL: end of planned line
EOH: end of header
The remaining elements have similar information in the first 3 columns. The first column will indicate the data type, the second column will indicate the device that recorded the information (e.g. 0 for Coda Octopus F180 receiver) and the third column is the time tag (seconds past midnight) that is also sometimes referred to as the latency. The remaining information on each line is specific to the data type.
POS: Position of the ship - in this case the antenna - in the format "POS dn t x y" where dn=device number; t=time tag (seconds past midnight); x=easting; y=northing. On this cruise these values are in UTM, Zone 16N, WGS84.
QUA: Position quality information in the format "QUA dn t n m h sat mode" where dn=device number; t=time tag (seconds past midnight); n=number of values to follow; m = 10 minus HDOP (horizontal dilution of precision); h=HDOP; sat=number of satellites; mode=GPS mode (NMEA 0183 standard values) where 2=Differential GPS fix.
RAW: Position information in the format "RAW dn t n lat long alt utc" where dn=device number; t=time tag (seconds past midnight); n=number of values to follow; lat=raw latitude X 100; long=raw longitude X 100; alt=antenna altitude above ellipsoid (meters); utc=GPS time in the format HHMM.
GYR: Gyro Data (heading) in the format "GYR dn t h" where dn=device number; t=time tag (seconds past midnight); h=shipheading angle.
MSG: Message string in the format "MSG dn t message" where dn=device number; t=time tag (seconds past midnight); message is the message sent from the device. On this cruise, three different messages were sent from the DGPS: $GPGGA $GPHDT $GPVTG. These will be defined later.
EC1: Echo Sounding (single frequency) in the format "EC1 dn t rd" where dn=device number; t=time tag (seconds past midnight); rd=raw depth.
FIX: events marked manually by the user in the format "FIX dn t event_number" where dn=device number (typically 99 as there is no device for manual events); t=time tag (seconds past midnight); event_number=event number such as 1,2,3,4.
The National Marine Electronics Association (NMEA) strings present in the HYPACK file are the $GPVTG, $GPZDA, $SDDPT, $GPGGA and $GPHDT. These are defined as follows:
$GPVTG is track made good and ground speed in the format "$GPVTG, t, T, m, M, n, N, k, K refcheck" where t=true course made good over ground, degrees; T indicates the previous number refers to true course; m=magnetic course made good over ground, dgrees; M indicates the previous number refers to magnetic course; n=ground speed; N indicates the previous number refers to Knots, k=ground speed; K indicates the previous number refers to Kilometers per hour, refcheck= checksum at the end of the string with the first character an *.
$GPGGA is GPS fix data in the format "$GPGGA, t, lat, lath, long, longh, q, sat, h, a, M, alt, M, t2, refcheck" where t=time in UTC in the format hhmmss.ss; lat=latitude in the format ddmm.mmmmmm; lath= N or S indicating the latitude hemisphere; long=longitude in the format dddmm.mmmmmm; longh=E or W indicating the longitude hemisphere; q=fix quality where 2 is a DGPS fix; sat=number of satellites; h=Horizontal Dilution of Precision (HDOP); a=Antenna altitude above mean sea level (geoid); M= units of antenna altitude in meters; alt=height of geoid above WGS84 ellipsoid; M=units of geoidal height in meters; t2=time since last DGPS update; refcheck=DGPS reference station id and the checksum.
$GPHDT is Actual vessel heading in degrees in format "$GPHDT,xxx.x,T" where xxx.x=heading in degrees and T indicates True Heading, checksum
Entity_and_Attribute_Detail_Citation:
