Not all files contain the same HYPACK strings, but this list represents all the HYPACK strings represented in the files. These are the original files, no corrections have been made to these files.
The times recorded in the navigation file are in UTC. The EC1 messages, although present in many of the HYPACK files, are not verified. 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 vessel name, agencies involved with the survey, and the location of the survey.
ELL: Ellipsoid information. The name of the ellipsoid followed by the semi-major axis in meters and the flattening ratio.
PRO: Project information record where TME indicates Transverse Mercator and the central meridian of -75 indicates UTM, zone 18N.
DTM: Datum transformation record.
GEO: Geoid model. Blank if not present. Note: During survey 2012-024-FA, GEOID09 grid #4 for CONUS (g2009u4.geo) was used.
HVU: Horizontal and Vertical Units (meters).
TND: Survey time and date in UTC.
DEV [#]: [Insert data about cruise device #]
DEV 0: For survey 2012-024-FA: Indicates that lines collected with device designation 0 are lines of Differential Global Positioning System (DGPS) collected with the Hemisphere DGPS.
DEV 1: No usable lines of data from Device 1 occur in these HYPACK navigation files. This device is labeled as "bathy" however this is a dummy echosounder value and does not represent valid, corrected or verified data. See EC1 and SDDPT note below.
DEV 2: For survey 2012-024-FA: Indicates that lines collected with device designation 2 are lines of Real Time Kinematic GPS data collected from the Novatel Dl-V3.
DEV 3: For survey 2012-024-FA: Indicates that lines collected with device designation 3 are the NMEA string GPGGA lines of Real Time Kinematic GPS data collected from the Coda F180. ***Note: this is mislabeled in the header as "F190".***
OFF: Device Offsets in the format: OFF dn n1 n2 n3 n4 n5 n6 n7, where dn = device number; n1 = starboard or port offset (positive starboard); n2 = forward or aft offset (positive forward); n3 = height (antenna) or depth (transducer draft) offset; n4 = yaw rotation angle (positive for clockwise rotation); n5 = roll rotation angle (port side up is positive); n6 = pitch rotation angle (bow up is positive); n7 = device latency in seconds.
DDT: identifies the device that the computer clock is being synchronized to.
LIN 2: planned line data follows.
PTS: planned line waypoints (easting and northing, UTM, zone 18N, meters).
LBP: planned line begin point (easting and northing, UTM, zone 18N, meters).
LNN: planned line name.
USR: user information.
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 (0 for [Device 0] and 1 for [Device 1]) 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. Not all data types were recorded in each HYPACK file.
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 18N, WGS84.
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; and 5 = RTK Float. The last 3 values are decoded from GST message: standard deviation of latitude error (meters); standard deviation of longitude error (meters); Standard deviation of semi-major axis of error ellipsis (meters).
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 in the format ddmmmm.mmmm. To convert to ddmm.mmmmm multiply by 100; long=raw longitude in the format ddmmmm.mmmm. To convert to ddmm.mmmmm multiply by 100; alt=antenna altitude above ellipsoid (meters); utc=GPS time in the format HHMM.
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. During survey 2012-024-FA there were several different messages were sent from the GPS systems: $GPGGA, $GPRMC, $GPZDA and $GPVTG were standard throughout the survey. These message strings will be defined below.
TID: Tide correction in the format: TID dn t dc, where dn=device number, t=time tag (seconds past midnight), dc = draft correction.
EC1: Echo sounding (singe frequency) in the format: EC1 dn t rd, where dn=device number, t=time tag (seconds past midnight), rd=raw depth. Note: this message appears to be invalid throughout this survey as this was a dummy depth feed possibly used to plot survey history in the HYPACK real-time display.
GYR: Gyro data (heading) in the format: GYR dn t h, where dn=device number, t=time tag (seconds past midnight), h=heading.
HCP: Heave Compensation in the format: HCP dn t h r p, where dn=device number, t=time tag (seconds past midnight), h=heave in meters, r=roll in degrees (+ port side up), p=pitch in degrees (+ bow up).
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.
KTC: Describes how HYPACK records water levels (tide corrections) when using RTK in the format: KTC dn t nv eh lh u kval offset draft final, where dn = device number, t=time tag (seconds past midnight, matches GPS position), nv=number of values, eh= WGS84ellipsoidal height (from GPS), lh= local ellipsoidal height (on local ellipsoid), u=undulation, kval= K value, offset= antenna offset, draft=draft correction, final=final tide.
$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,123946.00,4117.1324,N,07220.9706,W,4,08,0.9,3.62,M,-31.40,M,01,0019*5C UTC Time = 123946.00 Latitude Deg = 41 Latitude Min = 17.1324 N Longitude Deg = 072 Longitude Min = 20.9706 W Fix Quality = 4 (indicates RTK) Number of satellites = 08 HDOP = 0.9 relative accuracy of horizontal position Altitude = 3.62 meters above mean sea level Height of geoid above WGS84 ellipsoid = -31.40 meters Time since last update = 01 Checksum = 0019*5C.
$GPVTG is track made good and ground speed in the format: $GPVTG, true, T, mag, M, grsp1, N, grsp2, 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, grsp1=ground speed, N=Knots, grsp2=ground speed, K=Kilometers per hour, mode=Mode indicator (A=Autonomous, D=Differential, E=Estimated, N=Data not valid).
Example: $GPVTG,177.258,T,,M,4.801,N,8.891,K,D*03 True course made good: 340.39 Magnetic course made good: 177.258 Ground speed (knots) = 4.801 Ground speed (kilometers) = 8.891 Mode=Differential.
$GPRMC is the recommended minimum specific GPS/TRANSIT data in the format "$GPRMC, hhmmss.ss, A, llll.ll, a, yyyyy.yy, a,x.x, x.x, ddmmyy, x.x, a, m*hh" where hhmmss.ss=UTC time fix, A=data staus (A=valid position, V=navigation receiver warning), llll.ll=latitude in the format ddmm.mmm, a=North/South, yyyyy.yy=longitude in the format dddmm.mmm, a=East/West, x.x=speed over ground in knots, x.x=track angle in degrees true, ddmmyy=UTC date of fix, x.x=magnetic variation degrees (Easterly variation subtracts from true course), a= E or W of magnetic variation, m= mode indicate (A=autonomous, D=Differential, E=Estimate, N=Data not valid), *hh=checksum.
Example: $GPRMC,123952.00,A,4117.124897,N,07220.969238,W,4.801,177.258,160912,,,D*43 UTC time = 123952.00 Navigation receiver warning = A Latitude 41 deg. 17.124897 min North Longitude 072 deg. 20.969238 min West Speed over ground = 4.801 (kts) Course Made Good = 177.258 (deg True) Date of fix = 160912 (DDMMYY) mandatory checksum = D*43
$GPZDA is UTC Date/Time and Local Time Zone Offset in the format "$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,123952.000,16,09,2012,,*57 UTC= 123952.00 UTC day = 16 UTC month = 09 UTM year = 2012 Local zone hours = null Local zone minutes = null Checksum = *57
$SDDPT is water depth relative to the transducer in meters in the format "$SDDPT, data_meters, offset_meters, checksum. Note: This data string only appears associated with DEV1 which was a dummy device labeled "Bathy" - data from this device is not valid, not corrected, and not verified.