Schema Definition Questions

[jhs0402]

I have the following questions ;

• Is it okay to add units other than those specified in the ‘Measurement Units’ schema? (e.g. use by adding cm/s that is not specified in the schema)

• Similarly, is it okay to use additional definitions other than those specified in the schema, such as Statistic Type, Sensor Type, etc.?
  thank you

[stephenholleran]

Hi @jhs0402,

Thanks for asking some questions. I'll try and answer.

Is it okay to add units other than those specified in the ‘Measurement Units’ schema? (e.g. use by adding cm/s that is not specified in the schema)

I'm afraid we have set the measurement_units to be an 'enum'. That is, we have created a list of predefined units and the user must choose from this list. 'null' or 'other' are also options. The reason we have specified this list is to make sure everyone uses the same string to represent a unit. For example 'm/s' could also be 'ms-1', 'meters/sec', etc. One of the reasons for the data model is to standardize (in a way) these types of things so everyone knows what everyone is talking about and more importantly a machine will understand what is meant. This enables automation/digitalization to be built on top of it which is the powerful part of all of this. If there is a unit you want included please let us know and we can add it.

Similarly, is it okay to use additional definitions other than those specified in the schema, such as Statistic Type, Sensor Type, etc.?

Again, sensor_type and statistic_type are also enum's.

Sounds like you have a specific sensor you wish the data model to accommodate? If you do, please let us know what this sensor is and the use case for it and we can go about implementing it. Other people may be experiencing the same issue that we haven't thought of.

As this is an open-source project it is impossible to know who is using it and how much traction it is getting in the wind/solar industry or even how useful it is. Therefore, it is great to get these questions. Are you able to give us some background, either here or a DM, as to your experience of this data model and how you intend to use it?

Thanks,

[jhs0402]

How are you? @stephenholleran

Thank you for your detailed answer to my question. Also, please understand that my reply is late.

There are requests and inquiries as below.

1. Please add cm/s unit.

• This is to specify the unit of current speed among FLS data.

2. About GPS, Compass (roll, pitch, heading) data

Equipment model currently in use :

• GPS: Airmar-200WX, OTRONIX-AquaCompass
• roll, pitch: OTRONIX-AquaCompass
• heading: KVH-C100

I think that GPS and Compass data are 'instantaneous' values. However, there is currently no type called ‘instantaneous’ in statistical types.

What is your opinions? Also, do you have any examples of these?

(Even if it is not GPS or Compass, I think the statistical type of 'instantaneous' is necessary.)

Please let me know if you need additional information.

[stephenholleran]

Hi @jhs0402,

If cm/s is used commonly in the industry then absolutely we should add it. If we add cm/s, would any ADCP OEMs also may use mm/s. Should we add that too?

Adding instantaneous I think is a good suggestion. The sensor just records whatever the measurement is at that particular timestamp and doesn't do any ongoing sampling that then needs to be averaged. I could imagine other sensors do this too with records that do not change much over long periods of time.

For your scenario using it with pitch and roll, are you taking much faster samples at say 1 Hz and recording that? Just to note that the intention of the WRA Data Model is to capture the metadata that is useful for an analyst to work with the derived data. What I mean by that is the WRA Data Model isn't really built for capturing the lidar line of sight data, for example, but to capture the derived 10-min wind speed averages. I don't fully understand your scenario with the compass but I just want to highlight that it isn't really built to capturing the metadata that accelerometers produce at 1 Hz but more for the derived 10-min values that can be derived from it. I am not saying that the WRA Data Model couldn't do that, just the it may not currently capture everything you would need.

Getting back to adding instantaneous, would this be the best term to use? I can't actually think of an alternative but just putting the question out there. Would instant mean the same thing? Is it like a real time measurement?

cc @abohara, @kersting

[stephenholleran]

Thinking about the instantaneous question a bit more. Aren't all measurements avg anyway? For example with pressure measurements, the pressure doesn't change very fast over time so some pressure sensors don't sample every second but just take an instantaneous reading at the end of the 10-min period. Because the pressure doesn't change very fast, this "instantaneous" measurement is assumed to be the "average" measurement for that 10-min period. Therefore, there is an argument that instantaneous is actually an average since the previous measurement.

[jhs0402]

@stephenholleran

I will think about it some more and give you my opinion as soon as possible.
Please understand that my response may be slow due to frequent business trips.