UHDAS Serial Inputs

UHDAS data files have a specific directory and filename convention. During UHDAS data acquisition the serial data are timestamped and written to disk, and translated into a simple binary format. VmDAS ascii serial fiels (N1R, N2R, N3R) can also be translated into this binary format.

1. RAW

Serial data are logged into the raw directory

• each serial port gets its own subdirectory

• the file suffix is an indicator of the contents

• every line that is logged is timestamped by the computer

Example (for a POSMV): raw/posmv/km2011_202_07200.pmv

2. RBIN

Ascii serial data are translated into binary, in the rbin directory. Each ascii serial stream (eg POSMV, GPS,…) and each configured message inside it, are translated into a binary files which can be read (or written) by Python or Matlab.

• each serial port gets its own subdirectory (parallel to raw)

• the NMEA message determines the file suffix

Example (for a POSMV):

• rbin/posmv/km2011_202_07200.pmv.rbin (for $PASHR message)

• rbin/posmv/km2011_202_07200.gps.rbin (for $GPGGA message)

UHDAS file format

km = ship letters
2011 = year of data collection
202 = zero-based integer day of year
07200 = zero-based seconds of day
pmv 'message' (see below)
rbin = suffix for rbin data

RBIN message name

There is only one rbin message name for a given NMA string. Typical UHDAS directory names are used below. Given the NMEA message (left) and the presence or absence of a checksum, the message name is fixed.

NMEA string	typical UHDAS directory name	checksum?	message name
$GPGGA	gpsnav	yes	gps
$INGGA	gpsnav	yes	gps
$GPGGA	gpsnav	no	ggn
$INGGA	gpsnav	no	ggn
$HEHDT	gyro	yes	hdg
$HEHDG	gyro	yes	hdg
$HEHDT	gyro	no	hnc
$HEHDG	gyro	no	hnc
$PASHR,ATT	ashtech	yes	adu
$PASHR,AT2	ashtech	yes	at2
$PASHR,PAT	ashtech	yes	pat
$GPPAT	ashtech	yes	paq
$PASHR	posmv	yes	pmv
$PRDID	heading	yes	rdi
$PSXN,20+$PSXN,23	seapath	yes	sea
$GPGGA+$PSXN,20	seapath	yes	gps_sea
$PSAT,HPR	csi	yes	psathpr
: (tss1)	mahrs	yes	tss1
: (tss1)	mahrs	no	hnc_tss1

CODAS Python processing must be configured so it can find appropraite instrument+message pairs for position, reliable heading, and a heading correction device (if present).