How to get True Wind Direction instead of apparent using Signal K.

[dreeas]

Hi folks,

Please bear with me here since I am a complete novice when it comes to boating and navigational equipment.

I have a project to setup a weather station at home using a decommissioned Gill ultrasonic windsensor I got from where I work.
My plan was to just get environmental data and log it to a database. 

After extensive googling I found that using Signal K on a Raspberry Pi was a good way to decode the iiMWV nmea sentence coming from the sensor. 
Especially since there also was a plugin to write to a influx database.

I thought I had it all figured out until I see that the wind angle is "apparent" and not true direction. 
I see the sensor nmea sentence is sending true direction 0-360 degrees but that is changed to environment.wind.angleApparent in the data browser in Signal K.

Could anyone please point me in the right direction on how to just pass through the "True ground wind direction" that is sent from the sensor??

Andreas