Posted by: Ger Rietman | February 2, 2011

NemaStudio NMEA 0183 simulator, new release V1.10

HeadingExample

New version of NemaStudio

Just released Version 1.10 of NemaStudio. In this new version many important updates in the Heading and the AIS sections have been implemented.

As usual, registered users can download and install the new version from the download section of the Sailsoft website www.sailsoft.nl or by clicking the following direct link: http://www.sailsoft.nl/downloads/NemaStudio110Setup.msi. Of course you can keep your current license for this updated version. No need to re-enter, your current codes will automatically be applied to the new version.

Not a registered user? You can use the link above to download a trial copy of this version of NemaStudio. The trial is fully functional but is limited to output a maximum of 500 NMEA 0183 and AIS sentences.

Changes and corrections in this version

•  AIS Class B targets: Position Device and Position Accuracy were not saved. Corrected.
•  GPS: UTC Date was not automatically advancing to the next day. Corrected. 
•  GPS: Introduced a new option choice in the NMEA settings: "User-tweaked UTC Date/Time" vs "Realistic UTC Date/Time".
With this new option the user can either choose to use the "real" UTC date and time or choose to fake UTC data and time to his needs. In the latter case the position update timer can have no decimals in its value, because this value is used to increment the UTC timeseconds field in this case. 
•  AIS message 21 (Aid to Navigation position report) corrected   is implemented       
•  AIS message 4 (Base Station position report) adjusted to ITU-R M.1371 version 4: Transmission Control bit included
•  AIS message 4 (Base Station position report) did not correctly include Type of Electronic Fixing Device. Corrected. 
•  AIS message 1 (Class A Vessel position report) extended with a checkbox to indicate that no Turn Indicator is present, resulting in ROTais=-128.
The ROT value in the ROT up/down control now gives the actual Rate Of Turn in degrees/min instead of ROTais. The actual ROT in deg/min as shown now in the up/down control is converted to the ROTais value (+/- 126) and stored in the ROT field in message 1. When the "No TI"(no Turn Information) checkbox is checked the ROTais value -128 is stored in the ROT field in message 1.
When the value in the ROT up/down control > 708 or < -708 then the ROT ais value is set to 127 or -127. 
•  Heading: now different up/down controls for Magnetic and True heading for better interpretation of HDT and HDM.
$HEHDM now gives the magnetic course calculated from the magnetic sensor compensated by variation and deviation.
$HEHDT now gives the True course straight from the True course sensor. w now
•  Heading: Rate Of Turn up/down control added.
The value in the ROT up/down control gives the actual Rate Of Turn in degrees/min instead of rudder angle as before.  The ROT in degrees/minute in the up/down control can either be adjusted with the up/down buttons of the control or is taken proportionally from the Rudder control, and is in the range of +708 degrees/min (turn to starboard) to -708 degrees/min (turn to port).

Important changes in the Heading Instrument

There are two major changes in the Heading Instrument in Version 1.10 of NemaStudio you may want to take notice of.

In earlier versions of NemaStudio the True Course value for the HDT sentence was derived from the Magnetic Course by applying Variation and Deviation from the Magnetic Course. This was because there was no field available for a True Course sensor, e.g. Gyro. This was kind of confusing for many people, since the Magnetic Course was taken straight from the Magnetic Course sensor to the HDM sentence, without compensation for Variation and Deviation.

Changes in Version 1.10 re heading sensor readings:

  1. An up/down control was added for simulating a True Course sensor. When there is a GPS running, the value can optionally be taken from the GPS course.
  2. The True Heading sensor reading now goes uncompensated straight into the HDT sentence.
  3. The value in the HDM sentence is now taken from the Magnetic Heading sensor compensated by the given Variation and Deviation.

The HDG sentence has not been changed.

Changes in Version 1.10 re Rate Of Turn:

The second major update in the Heading Instrument concerns the Rate Of Turn handling.
In previous versions, ROT was handled rather primitively by NemaStudio by just taking the Rudder Control value to the NMEA 0183 ROT sentence.

In Version 1.10 this is considerably improved by adding a Rate Of Turn control to the Heading Instrument. The value in this control can of course be adjusted by the up/down arrow buttons of the control, but also by using the main Rudder Control. When using the main Rudder Control, the the ROT value is calculated by dividing 708 by the maximum rudder setting and multiplying this by the value in the Rudder Control.

Why the value of 708? The value 708 is used for consistency with the maximum ROT value possible in AIS message 1.

Please notice you can change the maximum range for the main Rudder Control in the General Settings. It is set to 30 degrees by default.

AIS message 1: Rate Of Turn changes

As in the Heading Instrument, the ROT handling was also considerably changed from earlier versions of NemaStudio.

  1. The GUI has been extended with a checkbox to indicate that a Turn Indicator is not present. Checking this box will result in ROTais=-128. (ROTais is the value as stored in the AIS message 1 according to ITU-R M.1371-4)
  2. The ROT value in the ROT up/down control now gives the actual Rate Of Turn in degrees/minute instead of ROTais.
  3. The actual ROT in degrees/minute as shown now in the up/down control is converted to the ROTais value (+/- 126) and stored in the ROTais field in message 1.
  4. When the value in the ROT up/down control > 708 or < -708 then the ROTais value is set to 127 or -127.
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