README

******** ABOUT TRUE WIND ********

Truewind calculates true wind direction and speed given apparent wind direction,
apparent wind speed and boat speed.

Note that some call this "Boat Wind" and is different from the sort of true wind
that would be calculated using GPS speed and heading.

Truewind reads in NMEA strings and generates NMEA strings.

Supported input NMEA strings:
VHW, VWR and MWV (with Reference = R);

Supported output NMEA strings
MWV (Reference = T);

A basic shell script (test-input.sh) has been included to generate some NMEA
test data. Truewind can consume this directly, or you can feed it via KPlex.

Developed by: Tony Miller, tony.miller@eightyoptions.com



******** COMPILATION INSTRUCTIONS ********

Type the following command to compile typewind.

make




******** EXECUTION ********

Usage:
truewind -if=input_file_name -of=output_file_name

The output file will be created if it doesn't already exist.


******* INTEGRATION WITH KPLEX *******
KPlex is an NMEA multiplexer. truewind can be used to read apparent wind speed,
apparent wind direction and boat speed from KPlex and then write to a FIFO file
that KPlex will then consume.

Config such as the following should be added to the kplex config file.


#output data needed for process calculating true wind
[file]
filename=[truewind input file]
direction=out
persist=yes
ofilter=+**VWR:+**VHW:+**MWV:-all

#read back in the calculated true wind
[file]
filename=[truewind output file]
direction=in
persist=yes