NMEA Outputs from Scala
Scala can output data in the following formats.
Marport's proprietary sentence
Scala uses the following sentence to output sensor data:
- $MP: Talker identifier
- MSD: Sentence formatter (Marport Sensor Data)
- X, YY, ZZZ: location of the emitting sensor on the trawl gear
- TTT: type of sensor data
- u: acronym of the unit
- VV.VVV: decimal value
- *<chk>: checksum. The checksum is a security measure to ensure that the sentence is transmitted accurately. The checksum follows the NMEA specifications (IEC 61162-1 Ed.4).
The following sections give more details about the contents of the sentence.
Sensor location
- X: 1 or 2 letters indicating on which gear the sensor is installed. This is useful only for twin or triple trawl gears.
- YY: 2 letters indicating the part of the gear where the sensor is installed.
- ZZZ: numerical code that is a Marport sensor node identifier related to the Mx receiver configuration. It is used in Scala to position the sensors in the 3D views.
Type of gear | Gear position | X |
---|---|---|
Single | T | |
Twin trawl | Starboard | ST |
Twin trawl | Port | PT |
Triple trawl | Starboard | ST |
Triple trawl | Middle | MT |
Triple trawl | Port | PT |
Unknown | <Empty> |
Trawl gear part | YY |
---|---|
Port Door | PD |
Starboard Door | SD |
Port Wing | PW |
Starboard Wing | SW |
Headrope | HR |
Footrope | FR |
Body | BO |
Cod-end | CE |
Clumps in twin or triple gears are coded as a starboard door of the trawl:
Clump | X, YY | Description |
---|---|---|
Twin trawl | P, SD | Port trawl, starboard door |
Triple trawl, starboard clump | M, SD | Middle trawl, starboard door |
Triple trawl, port clump | P, SD | Port trawl, starboard door |
Sensor data types and values
- TTT: 3 letter code corresponding to the type of data.
- u: acronym of the unit.
- VV.VVV: decimal value.
Data type | TTT | Unit | u | Description |
---|---|---|---|---|
Depth | DPT | meters | m | Depth of sensor (distance from surface) |
Catch | CAT | % |
Currently 0 (sensor OFF) or 100 (sensor ON), unit field is empty |
|
Pitch | PIT | degrees | d |
From -90 to 90 |
Roll | ROL | degrees | d |
From -180 to 180 |
Temperature | TMP | Celsius degrees | c | |
Spread starboard | XST | meters | m |
Distance between the master spread sensor and the slave. If the field is empty, it means “slave lost”. |
Spread clump | XCL | |||
Spread port | XPT | |||
Battery | BAT | % |
From 0 to 100. Unit field is empty. |
|
Speed along | SPL | m/s | ms | |
Speed across | SPX | m/s | ms | |
Distance to bottom | DTB | meters | m |
Distance from the sensor to the sea floor |
Opening | OPN | meters | m |
Distance from the headrope to the footrope or from the top to the bottom of the trawl body |
Clearance | CLR | meters | m |
Distance from the footrope or the bottom of the trawl body to the sea floor |
Slant Distance | SLD | meters | m |
Distance from the sensor to the hydrophone |
Relative Bearing | RBR | degrees | d |
Angle from the ownship to the sensor relative to ownship heading |
True Bearing | TBR | degrees | d |
Angle from the ownship to the sensor relative to True North |
Spread data comes from the master sensor.
Type of gear | X, YY, ZZZ, TTT | |
---|---|---|
Single (the master is on the port door) |
P,PD,23,XST |
Distance between doors |
Twin trawl (the master is on the port door) |
P,PD,23,XST |
Distance between doors |
P,PD,23,XCL |
Distance between port door and clump |
|
Triple trawl (the masters are on the port doors) |
P,PD,23,XST |
Distance between port door and starboard clump |
P,PD,23,XCL |
Distance between port door and port clump |
|
S,SD,223,XST |
Distance between starboard door and starboard clump |
|
Triple trawl with port (the master is on the port clump) |
P,SD,78,XST |
Distance between port clump and starboard door |
P,SD,78,XCL |
Distance between port clump and starboard clump |
|
P,SD,78,XPT |
Distance between port clump and port door |
Positioning sentences
and later: $PSIMS (Olex), $PTSAL (MaxSea version 12), $PMPT (TimeZero)
and later: adding $IIGLL (MaxSea version 12, single position sentence), $IITPT (Simrad)
and later: adding $PTSAL (SeaPix)
These are examples of PSMIS, PTSAL and IITPT sentences:
- $PSIMS: talker identifier + sentence formatter
- n: 1 = Spread1 (port trawl door when Twin Rig) / 2 = Spread2 (starboard trawl door when Twin Rig).
- aaa,M: slant range to sensor, in meters (filtered values, no decimals).
- bbb,M: horizontal range to sensor, in meters (unfiltered values, no decimals). Transmits null fields if depth-sensor is not activated (will calculate horizontal range with manual set depth).
- ccc.c,T: true bearing (deg.rel.north) to sensor. Requires gyro input for reliable data.
- ddd.d,M: spread measurement in meters (door to door or door to clump). Transmits null fields if invalid values. Filtered values if sensor's filter is on.
- hhmmss: time of transmission (time of Spread interrogation). Requires ZDA input from GPS for accurate timestamp.
- *hh: checksum
- $PTSAL: talker identifier + sentence formatter
- aaa.a: horizontal range in meters to sensor 1
- bbb.b: horizontal range in meters to sensor 2
- ccc.c: bearing to sensor 1 relative to stern line
- ddd.d: bearing to sensor 2 relative to stern line
- eee.e: depth in meters of sensor 1
- fff.f: depth in meters of sensor 2
- *hh: checksum
- $PMPT: talker identifier + sentence formatter
- POS: position
- AA: 2 letters code that specifies the part of the gear (SD = starboard door / PD = port door / CL = clump on twin trawl / SC = starboard clump on triple trawl / PC = Port Clump on triple trawl).
- bbb.b,M: horizontal distance in meters
- ccc.c,T: true bearing (deg.rel.north) to sensor
- ddd.d,M: depth below surface distance in meters
- eee.e,M: distance to bottom in meters if available, or empty
- hhmmss: time of data (hour-minutes-seconds)
- *hh: checksum
- @IITPT: talker identifier + sentence formatter. (TPT = Trawl position true vessel)
- aaa,M: horizontal range in meters to the target (0 - 4000 m). Requires an active depth sensor on the trawl or manual set depth, if not the slant range will be presented.
- bbb,P: true bearing to the target (i.e. relative to north). Requires gyro input for reliable data.
- ccc.c,M is the depth in meters of trawl below the surface (0 -2000 m). Requires an active depth sensor on the trawl or manual set depth, if not the depth field will be empty