The Instruments

The Velocity instrument

The Velocity instrument simulates NMEA sentences for water speed and traveled distance.

The value of some input fields can be changed with the up-down buttons located at the right side of the input boxes, or typed directly into the input boxes. Note that decimals are ignored when using up/down buttons.

Note that there is a choice of 2 sentence identifiers: $WI (Weather instruments) or $II (Integrated Instrumentation) in order to maintain compatibility between different manufacturers of this kind of instruments.

Operation

After clicking the "Start" button the Wind instrument simulation will start, and NMEA sentences will be sent to the selected serial port of the PC, until the "Hold" or "Exit and Save" buttons are pressed. Note that only NMEA sentences will be send that are checked in the "NMEA sentences" panel.

When the "Open Log file" option from the main "File" menu was selected, the sentences will also be written to the user selected file.

To view the sentences being sent select the "View trace window" option from the main menu.

Clicking the "Hold" button will suspend operation, until "Cont." is clicked. "Exit and Save" will exit the instrument and save all current values in the windows registry, so that next time the instrument is used it can continue where it stopped.

A short description of each field will follow below.

Water speed offset
Difference between the true speed (from the cockpit) and the speed through the water.

Water speed Longitudinal/Transverse
Only visible when $VDVBW sentence checkbox is ticked. The longitudinal water speed results from Cockpit (ground) speed compensated with Water speed offset. Negative Longitudinal speed means "astern", negative Transverse speed means "to port", positive "to starboard".

Ground speed Longitudinal/Transverse
Only visible when $VDVBW sentence checkbox is ticked. The longitudinal ground speed is copied from the Cockpit (ground) speed. Negative Longitudinal speed means "astern", negative Transverse speed means "to port", positive "to starboard".

Stern transverse speed Water/Ground
Only visible when $VDVBW sentence checkbox is ticked AND only in NMEA version 2.3/3.01. Negative Transverse speed means "to port", positive "to starboard".

Distance traveled
The distance traveled this trip and the total distance. 3 decimals precision.

NMEA sentences panel
Tick the sentences you want to send, select the interval (0-59) and if you want a checksum calculated and added to the sentences or not.