Question on data specification for temperature

[jakobdalsgaard]

Hi there,

New user of SignalK -- in multiple places in the specification I read that the unit for temperature is Kelvin.

Such as here:

http://signalk.org/specification/1.5.0/doc/vesselsBranch.html#vesselsregexpenvironmentinsidetemperature

I'd just like to know if there is any rationale behind this choice? Is this a unit that commonly is used in instrumentation?

[sbender9]

We use SI units for everything. https://en.wikipedia.org/wiki/International_System_of_Units

[jakobdalsgaard]

While it's true that Kelvin is the primary unit for temperature in the SI system; then, very much unlike the SI system in general, they do define a secondary unit of temperature, Celcius.

https://www.npl.co.uk/si-units/kelvin

The kelvin is the SI unit of thermodynamic temperature, and one of the seven SI base units. Unusually in the SI, we also define another unit of temperature, called the degree Celsius (°C). Temperature in degrees Celsius is obtained by subtracting 273.15 from the numerical value of the temperature expressed in kelvin.

So Celcius could actually be used without violating a decision to use SI units. Just saying.

[sbender9]

The actual unit chosen doesn't really matter that much, IMHO. What matters is that we're consistent, end users will always have different preferences about what units they want to see. So clients that display data need to be able to convert data into the units the user prefers.

[jakobdalsgaard]

Off, consistency is important. The choice of Kelvin merely affects the databrowser. Thanks for the explanations.