FTP: The first record located at the top of the header used to identify the file format.
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. ***In this case, the information recorded in at least some of the files was from another survey. This affects files in the MadSwan folder (001*.DAT through 006_0422.DAT). More files could be affected.
FIL: Raw format file.
ELL: Ellipsoid information. The name of the ellipsoid followed by the semi-major axis in meters and the flattening ratio.
PRO: Projection information record where TME indicates Transverse Mercator and the central meridian of -87 indicates UTM, zone 16.
TND: Survey time and date in UTC.
DEV 0: Indicates that the lines with device designation 0 are lines of DGPS data collected with the Ashtech system.
OFF 0: device offsets for device 0. Format of the value is OFF dn n1 n2 n3 n4 n5 n6 n7 where dn=device number; n1=starboard, port offsets where positive is starboard; n2=forward, aft offset where positive is forward; n3=height (antenna) or depth (transducer draft) offset - always positive; n4=yaw rotation angle where positive for clockwise rotation; n5=roll rotation angle where port side up is positive; n6=pitch rotation angle where bow up is positive; n7=device latency in seconds. No offset for device 0 during this data collection.
DEV 1: Indicates that the lines with device designation 1 are lines of range to fish.
OFF 1: device offsets for device 1 - see description above.
DEV 2: Indicates that the lines with device designation 2 are lines of depth collected by the Furuno echosounder.
OFF 2: device offsets for device 2 - see description above.
DEV 3: Indicates that the lines with device designation 3 are related to navigation values for the towfish taking into account the range to fish. This is the assumption being made based on the information provided.
OFF 3: device offsets for device 3 - see description above.
DEV 4: Indicates that the lines with device designation 4 are related to values sent to the ISIS system which records the SIS1000 data. This is the assumption being made based on the information provided.
OFF 4: device offsets for device 4 - see description above.
DDT 3: unknown HYPACK header element. Found in HYPACK drive documentation for device driver setup under YSI_6600.dll (version 220.127.116.11) with no further explanation. Seems to be some kind of place holder for a custom device driver of a "SMI" (Special Marine Instrument). And the assumption is that the 3 represents the device associated with this element.
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. ***In this case, easting and northing UTM zone 19N, meters.
LBP: planned line begin point in the format "LBP x y" where x=x grid position; y=y grid position. ***In this case I believe the values represent easting and northing, 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 (0 for Ashtech) 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 location - in the format "POS dn t x y" where dn=device number; t=time tag (seconds past midnight); x=easting; y=northing. During this survey these values are in UTM, Zone 16, WGS84.
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.
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.
DFT: No defined, but assumed to be either the depth to the towfish or elevation of the towfish above the sea floor in the format "DFT dn t rd" where dn=device number; t=time tag (seconds past midnight); rd=raw depth or elevation.
TOW: Uncertain as to the meaning of this tag but can make some assumptions. I believe it's the position of the tow fish as calculated using the range to fish. The format is assumed to be TOW dn t n x y ? ? ? where dn=device number; t=time tag (seconds past midnight); n=number of values to follow; x=easting; y=northing. The 3 values represented by ? ? ? are unknown. During this survey the easting and northing values are in UTM, Zone 16N, WGS84.
GYR: Gyro Data (heading) in the format "GYR dn t h" where dn=device number; t=time tag (seconds past midnight); h=shipheading angle.
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 HYPACK files do not contain any NMEA strings.