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Revision 16 (changes since 15 are marked blue)
Note before reading any further: This file format is still in development. Not all features and intended usages are supported yet by this standard. New features will be added gradually and lead to new versions of this standard.
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The signal is a dataset containing the samples of the measurement or simulation or calculation or postprocessing step. A signal maps to an experiment variable.
Name: HDF Dataset name; must be unique in the set. It is the HDF-safe name of the signal. For reference the original potentially HDF-unsafe name is provided with the data in the 'signalSource' attribute.
Path: "/<set name>/<signal name>"
Datatype: float32, float64
Dimensions: 1 (time domain) to 7 (frequency domain)
Additional properties of the signal are added as attributes. Below are the common attributes. In sub sections domain or source specific attributes can be found.
Attibutes:
NameRole | Data type | Exists? | Description | Convention / example | Schema | ||||||||||||
rawName | i | utf8 | O | original signal name if this had to be reformatted to be used as hdf5 name. | |||||||||||||
unita | unit_str | A | name of the unit of the signal. This defines the quantity of the experiment variable. | “m/s”, “-“, “rad” | sp1, da1 | ||||||||||||
signalTypea | prop_str | NS | defines the experiment variable or simulation property or the kind of quantity. | “velocity”, etc “angular velocity” | sp1, da1 | ||||||||||||
descriptioni | utf8 | A | description of the signal. More detail than name. E.g. the kind of quantity or experiment variable; whether it is an absolute value or a delta. | (tbd) | |||||||||||||
timeOffset | a | float64 | NS | the time offset in seconds between real start time and the moment the timestamp is created. | da1 | ||||||||||||
ordera | int32 | O | In case of frequency data specifies whether it is a first or second order effect or otherwise. | 1: first order. 2: second order. -1: Not applicable.position | da1 | ||||||||||||
minimum | ds_type | O | lowest value in the dataset | sp1 | |||||||||||||
maximum | ds_type | O | highest value in the dataset | sp1 | |||||||||||||
mean | ds_type | O | mean or average value of the dataset (tbd: weighted arithmetic mean?) | sp1 | |||||||||||||
standardDeviation | ds_type | O | standard deviation of the values in the dataset | sp1 | |||||||||||||
position | float64[3] | NS | location of the variable in the specified Coordinate System. | a | float64[3] | NS | location of the variable in the specified Coordinate System. | [0.0, 0.0, 0.0] | direction | a | float64[3] | NS | direction of the signal c.q. experiment variable in the specified CS. In case of a rotation it is the direction of the axis of rotation. | Roll in ACK: [1.0,0.0,0.0] Sway in ACK: | [0.0, 10.0, 0.0]referenceSystem | da1 | a |
direction | float64[3]utf8 | NS | specifies in which Coordinate Sytem position and direction are given. | “ACK”, (todo: complete list) | direction of the signal c.q. experiment variable in the specified CS. In case of a rotation it is the direction of the axis of rotation. | Roll in ACK: [1.0,0.0,0.0] Sway in ACK: [0.0, 1.0, 0.0] | da1 | ||||||||||
referenceSystem | utf8 | NS | specifies in which Coordinate Sytem position and direction are given. | “ACK”, (todo: complete list) | da1 | ||||||||||||
signalSource | utf8 | O | holds information about the sensor. Depends on system used. | signalSource | I | utf8 | O | holds information about the sensor. Depends on system used. Also contains the original signal name from the measurement system. | (tbd) | ||||||||
channelNoi | int32 | O | if no sensor information is provided holds the channel number in case of measured data. | 123 | |||||||||||||
basess | obj_ref[] | O | List of object references to all datasets that are a master signal to this signal. | [objRef(“time”)] | h5m | ||||||||||||
baseNames | s | utf8[] | O | Names of the base signals (informational only. Not intended for rebuilding the datamodel) | h5m | ||||||||||||
notes | i | utf8 | A | Any additional information about this signal. | (free text) | ||||||||||||
writeErrors | i | utf8[] | O | Specifies any errors that occurred while writing the signal (dataset). Mostly value errors. |
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The obj_ref is an HDF Object Reference value. It is used to define relations between individual entries in the file.
Note: Most common HDF viewers will only render this type as "object reference" and not specify to which item it refers. If applicable such an attribute is accompanied by an attribute that specifies the name(s) of the referred object(s).
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Used for the datatype of attributes that are the same as the element type of the dataset. Denoted "ds_type" for scalar, "ds_type[1,2]" for a 1 x 2 array, "ds_type[,,]" for a 3D array of any size and so on.
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