Entity_and_Attribute_Overview:
Not all attributes are present in each navigation file. The following list explains the attributes that may be present in each HYPACK navigation file. GPS receivers were recorded as devices 0, 1 and 3. Tide correction values from device 3 (Novatel DL-V3 RTK GPS) were used to tide correct bathymetry data during post-processing. Device 0 (Ashtech Surveyor RTK GPS) data was not recorded to nav files during sediment sampling operations on julian days 320 and 321 (11/16/2009 and 11/17/2009).
The times recorded in the navigation file are in UTC (Coordinate Universal Time). Keywords and the information they provide 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.
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 -69 indicates UTM, zone 19.
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: RTK receiver (Ashtech Surveyor RTK GPS).
OFF 0: Device 0 offsets. Format for value is: OFF dn n1 n2 n3 n4 n5 n6 n7, where dn=device number; n1=starboard/port offset (starboard is positive, port is negative); n2=forward/aft offset (forward is positive, aft is negative); n3=height of antenna or depth of transducer draft (always positive); n4=yaw rotation angle (clockwise rotation is positive); n5=roll rotation angle (port side up is positive); n6=pitch rotation angle (bow up is positive); n7=device latency in seconds.
DEV 1: DGPS receiver (CSI LGBX Pro DGPS).
OFF 1: Device 1 offsets. Format for value is: OFF dn n1 n2 n3 n4 n5 n6 n7, where dn=device number; n1=starboard/port offset (starboard is positive, port is negative); n2=forward/aft offset (forward is positive, aft is negative); n3=height of antenna or depth of transducer draft (always positive); n4=yaw rotation angle (clockwise rotation is positive); n5=roll rotation angle (port side up is positive); n6=pitch rotation angle (bow up is positive); n7=device latency in seconds.
DEV 2: Disabled
DEV 3: RTK Tides (Novatel DL-V3 RTK GPS).
OFF 3: Device 3 offsets. Format for value is: OFF dn n1 n2 n3 n4 n5 n6 n7, where dn=device number; n1=starboard/port offset (starboard is positive, port is negative); n2=forward/aft offset (forward is positive, aft is negative); n3=height of antenna or depth of transducer draft (always positive); n4=yaw rotation angle (clockwise rotation is positive); n5=roll rotation angle (port side up is positive); n6=pitch rotation angle (bow up is positive); n7=device latency in seconds.
DEV 4: Disabled
DEV 5: Echosounder - NMEA string
LIN: Planned line data follows in the format "LIN nw" where nw=number of waypoints
PTS: Planned line waypoints in the format "PTS x y" where x=waypoint easting; y=waypoint northing (UTM zone 19N, meters, WGS84 for this survey)
LBP: Planned line begin point in the format "LBP x y" where x=x grid position; y=y grid position (UTM zone 19N, meters, WGS84 for this survey)
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 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.
GYR: Gyro Data (Heading). Format "GYR dn t h", where dn=device number, t=time tag (seconds past midnight), h=ship heading 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. These message strings are defined further down in the NMEA definition section.
EC1: echo sounding (singe frequency). Format "EC1 dn t rd", where dn=device number, t=time tag (seconds past midnight), rd=raw depth.
POS: Position of the ship 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 19, 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 0=fix not available or invalid; 1=GPS fix; 2=Differential GPS fix; 3=GPS PPS Mode fix; 4=RTK fix; 5=RTK float.
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.
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. These numbers are incremented by the software.
TID: Tide correction in the format "TID dn t dc" where dn=device number; t=time tag (seconds past midnight); dc=draft correction. TID 3 (from Novatel DL-V3 RTK GPS receiver) was applied to bathy in post-processing
The (National Marine Electronics Association) NMEA strings $GPGGA, $GPVTG, $GPZDA and $SDDPT are stored in the HYPACK file. These are defined as follows:
$GPGGA is GPS fix data in the format "$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 hemisphere; q=fix quality where 0=fix not available or invalid; 1=GPS fix; 2=Differential GPS fix; 3=GPS PPS Mode fix; 4=RTK fix; 5=RTK float; 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.
Example: $GPGGA,163052.00,4118.964217,N,07036.966471,W,4,10,00.9,00005.332,M,-030.544,M,01,*57
UTC Time = 163052
Latitude = 4118.964217 N
Longitude = 7036.966471 W
Fix Quality = 4
Number of satellites = 10
HDOP = 00.9 relative accuracy of horizontal position
Altitude = 5.332 meters above mean sea level
Height of geoid above WGS84 ellipsoid = -30.554 meters
Time since last update = 01
Checksum = *57.
$GPVTG is track made good and ground speed in the format "$GPCTG, true, T, mag, M, grsp, N, grdp, K, mode", where t=true course made good over ground in degrees, T= True, m=magnetic course made good over ground in degrees, M=magnetic, gdsp=ground speed, N=Knots, grsp=ground speed, K=Kilometers per hour, mode=Mode indicator (A=Autonomous, D=Differential, E=Estimated, N=Data not valid).
Example: $GPVTG,089.23,T,104.82,M,004.86,N,009.02,K,D*28
True course made good: 089.23
Magnetic course made good: 104.82
Ground speed (knots) = 4.86
Ground speed (kilometers) = 9.02
Mode=Differential
$GPZDA is UTC Date/Time and Local Time Zone Offset in the format "$GPZDA,hhmmss.ss,xx,xx,xxxx,xx,xx" where hhmmss.ss=UTC, xx=Day, 01 to 31, xx=month, 01 to 12, xxx=Year, xx=Local zone description, 00 to +/- 13 hours, xx=Local zone minutes description (same sign as hours), checksum.
Example: $GPZDA,163053.00,09,08,2007,,*60
UTC= 163053.00
UTC day = 09
UTC month = 08
UTC year = 2007
Local zone hours = null
Local zone minutes = null
Checksum = *60
$SDDPT is water depth relative to the transducer in meters in the format "$SDDPT, depth meters, offset *checksum"
Example: $SDDPT, 3.71, 0.50*57
Depth in meters = 3.71
Offset from transducer: Positive value is distance from transducer to water line; Negative value is distance from transducer to keel.
Entity_and_Attribute_Detail_Citation:
