GAPS - User Guide
I.4 DATASTANDARD
The DATA Standard protocol is composed of the POSIDONIA positioning messages:
$PTSAG, $PTSAX, $PTSAY, $PTSAZ , $PTSAH, $PTASQ, $PIXOG, $PIXSE
I.4.1 PTSAG
Transponder Absolute Positioning Message (geographical coordinates and depth)
$PTSAG,#nnnnn,hhmmss.sss,dd,mm,yyyy,bbb,ddmm.mmmmm,h,dddmm.mmmmm,d,a,dddd.dd,a,ss
ss.ss*ck
$PTSAG,#16068,124544.449,18,12,2017,1,4305.25355,N,00631.76852,E,F,1013.10,1,9999.00*23
$PTSAG,#16071,124546.173,18,12,2017,0,4305.25123,N,00631.79102,E,F,0002.89,1,9999.00*25
#nnnnn
hhmmss.sss
dd
mm
yyyy
bbb
ddmm.mmmmm
h
dddmm.mmmmm
d
a
dddd.dd
a
ssss.ss
*ck
Recurrence frame number
Time in hours, minutes, seconds ,milliseconds
Day (jj = 0 to 31)
Month (mm =1 to 12)
Year
0: Ship, 1 to 128: Transponder ID
Latitude degrees, minutes and 1/100000
Hemisphere (N: North, S: South)
Longitude degrees, minutes and 1/100000
Longitude direction (E: East, W: West)
Validity of acoustic hydrophones: 0 to F (binary coding, see below)
Calculated depth in meters
Depth validity (0: None 1: Calculated 2: Sensor)
Sensor depth in meters
Hexadecimal checksum ('*' precedes the checksum value)
● Position validity: The value represents the acoustic hydrophone validity on 4 bits (from
0000 to 1111). 0 means channel not valid and 1 hydrophone operating properly. GAPS can
still output valid positions even if the validity is not 1111 (three channels are enough). All
output positions are valid.
> 1111 --> F (all 4 hydrophones OK)
> 1110 --> E (hydrophone #1 NOK)
> 1101 --> D (hydrophone #2 NOK)
> 1011 --> B (hydrophone #3 NOK)
> 0111 --> 7 (hydrophone #4 NOK)
● Calculated depth / Sensor depth: The antenna knows only one depth that is the fusion
of both depths (calculated and sensor). This “optimized” depth is in the “Calculated depth”
field.
● Sensor depth: if the Acoustic Transponder has no sensor, the value is 9999.
● In case of ship, the Calculated / Sensor depth is the depth of the acoustic center
(barycenter of the hydrophones). The GAPS Depth field in the INSTALLATION >
MECHANICAL PARAMETERS tab of the Web-based user interface is the depth of the
top flange of the GAPS unit. The distance between the top flange and the acoustic center
is approximately 0.6 m (589.3 mm).
186 MU-GAPS-AN-005-H - November 2019
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