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Drivers Manual

Nortek Vessel Mounted Current Profiler (ASCII) - 23

Description

This driver will decode current speed/direction information from a Nortek Vessel Mounted Current Profiler (VMCP).

A VMCP measures the current profile underneath your vessel, and outputs for each depth 'cell' the speed and direction of the current.
An average current speed and direction are calculated for the entire profile.
Typical application for the average current speed and direction would be to use it on a dredging vessel, when dumping rock material from the water surface onto the seabed, in order to estimate the final dump location.

A VMCP unit is normally installed on a vessel in combination with Nortek's SurveyVM™ software, which is interfaced straight to the VMCP unit.
It collects raw velocity data, and if the software is also interfaced to the vessel's GPS and gyro, it may output velocity data corrected for vessel motion to third party software, like QINSy.

Driver Information

Driver  Nortek - Vessel Mounted Current Profiler Interface Type Serial Driver Class Type Terminated <ETX> or <CR><LF>
UTC Driver (question) No Input / Output Input Executable

DrvQpsTerminated.exe

Related Systems
Related Pages  



Decoding Notes

The time in the datastring (available in ASCII telegram) is ignored. This means that data will be timestamped whenever it arrives at the serial comport, using the computer's system or PPS time.

Values decoded from the ASCII data are internally converted to meters/sec, degrees and dBar. Values decoded from the NMEA sentences are converted to survey units/sec and degrees.

A possible checksum at the end of each NMEA sentence is ignored by the driver.

Interfacing Notes

Because the driver is interfaced to the SurveyVM™ software, and not directly to the VMCP unit, it does not need to send request commands in order to receive data.
So a one-way wiring interface cable would be sufficient.
Use the following wiring diagram for a one-way cable:

DB-25

Sensor

or

DB-9

Sensor

 

DB-25

COM

or

DB-9

COM

Pin 2

TXD

Pin 3

TXD

-----

Pin 3

RXD

Pin 2

RXD

Pin 3

RXD

Pin 2

RXD

X

Pin 2

TXD

Pin 3

TXD

Pin 7

SG

Pin 5

SG

-----

Pin 7

SG

Pin 5

SG

Default baud rate will be 9600-8-1-none, but it is strongly recommended to increase the baud rate when outputting the ASCII Standard or Extended format, due to the vast amount of bytes sent per profile.

Database Setup

  • In order to decode the average current speed and direction, add a Miscellaneous System to your template database and select driver "Nortek - Vessel Mounted Current Profiler (ASCII)" or "Nortek - Vessel Mounted Current Profiler (NMEA)".
    On the second wizard page, add two observations, name one e.g. "CURRENT SPEED", and the other e.g. "CURRENT DIR".
    The important part is assigning the correct Slot 1:


    Slot 1 name for the average speed should be, in capitals, "SPD AVG".
    Slot 1 name for the average direction should be, in capitals, "DIR AVG".



    Notice that when the NMEA driver is selected, the average speed and direction are decoded directly from the VDR sentence (other sentences are ignored).
    No formulas are applied, except for converting knots to survey units/sec.
    The observations quality indicator (as seen in the Observation Physics Display) will be zero.

    When the ASCII driver is used, the average speed and direction are calculated using the mean for all corrected Veast and Vnorth values of all depth cells.
    The observation's quality indicator (as seen in the Observation Physics Display) will be the standard deviation of the mean value for each depth cell.
  • The VMCP can also be used for "bottom tracking", to obtain the vessel's ground speed (SOG) and course over ground (COG).
    These two observations can be used to enhance the Kalman filter of the Computation Setup.
    In that case the VCMP should be instructed to output the NMEA VTG sentence.

    In order to decode the speed- and course over ground, add a Speed Log System to your template database and select driver "Nortek - Vessel Mounted Current Profiler (NMEA)".
    On the second wizard page, add a 'Bearing (True)' observation, and add a 'Speed' observation.
  • The important part is assigning the correct Slot 1:

    Slot 1 name for the speed observation must be, in capitals, "SPD VTG".
    Slot 1 name for the bearing observation should be, in capitals, "DIR VTG".

Slot Id Summary

Output Format

Decoding

System

Driver

Observation Type

Slot 1 Name

Comment

ASCII

Average current speed

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

SPD AVG

Calculated from mean for all corrected Veast and Vnorth values of all depth cells [in m/sec]

ASCII

Average current direction

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

DIR AVG

Calculated from mean for all corrected Veast and Vnorth values of all depth cells [in deg]

NMEA $--VDR

Average current speed

Miscellaneous

Nortek - Vessel Mounted Current Profiler (NMEA)

Generic

SPD AVG

VDR Field 6 (CurrentSpeedKnots) is used and converted to [survey units /sec]

NMEA $--VDR

Average current direction

Miscellaneous

Nortek - Vessel Mounted Current Profiler (NMEA)

Generic

DIR AVG

VDR Field 2 (DirectionTrue) is used [deg]

ASCII

Mean Heading

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

HEADING

Field 1 of Header Line 3 is used, and converted to [deg]

ASCII

Mean Pitch

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

PITCH

Field 2 of Header Line 3 is used, and converted to [deg]

ASCII

Mean Roll

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

ROLL

Field 3 of Header Line 3 is used, and converted to [deg]

ASCII

Mean Temperature

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

TEMP

Field 4 of Header Line 3 is used, and converted to [deg °C]

ASCII

Mean Pressure

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

PRESSURE

Field 5 of Header Line 3 is used, and converted to [dBar]

ASCII

Range Beam 1

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

RNG BEAM1

Field 4 of Header Line 5 is used, and converted to [survey units]

ASCII

Range Beam 2

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

RNG BEAM2

Field 5 of Header Line 5 is used, and converted to [survey units]

ASCII

Range Beam 3

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

RNG BEAM3

Field 6 of Header Line 5 is used, and converted to [survey units]

ASCII

Quality Beam 1

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

QTY BEAM1

Field 7 of Header Line 5 is used

ASCII

Quality Beam 2

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

QTY BEAM2

Field 7 of Header Line 5 is used

ASCII

Quality Beam 3

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

QTY BEAM3

Field 7 of Header Line 5 is used

NMEA $--VHW

Ship's along speed through water

Miscellaneous

Nortek - Vessel Mounted Current Profiler (NMEA)

Generic

SPD VHW

VHW Field 6 (SpeedKnots) is used and converted to [survey units /sec]

NMEA $--VHW

Ship's gyro heading

Miscellaneous

Nortek - Vessel Mounted Current Profiler (NMEA)

Generic

DIR VHW

VHW Field 2 (Heading) is used [deg]

NMEA $--VTG

Ship's speed over ground

Miscellaneous

Nortek - Vessel Mounted Current Profiler (NMEA)

Generic

SPD VTG

VTG Field 7 (SpeedKnots) is used and converted to [survey units /sec]

NMEA $--VTG

Ship's course over ground

Miscellaneous

Nortek - Vessel Mounted Current Profiler (NMEA)

Generic

DIR VTG

VHW Field 2 (GroundCourse) is used [deg]

NMEA $--VDR

Corrected current speed

Miscellaneous

Nortek - Vessel Mounted Current Profiler (NMEA)

Generic

SPD VDR

VDR Field 6 (CurrentSpeedKnots) is used and converted to [survey units /sec]

NMEA $--VDR

Corrected current direction

Miscellaneous

Nortek - Vessel Mounted Current Profiler (NMEA)

Generic

DIR VDR

VDR Field 2 (DirectionTrue) is used [deg]

NMEA $--VTG

Ship's speed over ground

Speed Log

Nortek - Vessel Mounted Current Profiler (NMEA)

Speed

SPD VTG

VTG Field 7 (SpeedKnots) is used and converted to [survey units /sec]

NMEA $--VTG

Ship's course over ground

Speed Log

Nortek - Vessel Mounted Current Profiler (NMEA)

Bearing (True)

DIR VTG

VHW Field 2 (GroundCourse) is used [deg]

ASCII

Current speed for individual depth cell 1

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

SPD 1

Speed in [m/sec], calculated from corrected Veast and Vnorth for the first Depth Cell

ASCII

Current direction for individual depth cell 1

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

DIR 1

Direction in [deg], calculated from corrected Veast and Vnorth for the first Depth Cell

ASCII

Current speed for individual depth cell 2

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

SPD 2

Speed in [m/sec], calculated from corrected Veast and Vnorth for the 2nd Depth Cell

ASCII

Current direction for individual depth cell 2

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

DIR 2

Direction in [deg], calculated from corrected Veast and Vnorth for the 2nd Depth Cell

...

...

...

...

   ...

...

...

ASCII

Current speed for individual depth cell 'n'

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

SPD n

Speed in [m/sec], calculated from corrected Veast and Vnorth for the nth Depth Cell

ASCII

Current direction for individual depth cell number 'n'

Miscellaneous

Nortek - Vessel Mounted Current Profiler (ASCII)

Generic

DIR n

Direction in [deg], calculated from corrected Veast and Vnorth for the nth Depth Cell

Additional Information

References: Nortek AS publications .