Issue 6: Working with Measurements and Metadata
The m+p Analyzer is all about measuring vibration data and providing traceable results that, even years later, can be reviewed and put into context. In this 6th issue, we will have a look at the data structure of the measurement object with its properties and metadata. You will learn how to work with metadata tags during measurement, in reviewing data sets and post-processing data.
Data Structure of a Measurement
At first glance, acquiring data is mainly about sampling a voltage signal - may it be acceleration, pressure, temperature, etc. - and saving those sample values to the hard drive. But that is merely what is required in a production setup: One might want to save not only time sampled data but spectra, PSDs, FRFs, octaves, etc. and while the actual sample values are the most important, properties associated to the measurement process such as sample rate, channel names, references, etc. need to be traceable as well. In m+p Analyzer, we solve this by having a data structure for the measurement that consists of three main parts: data, properties and metadata.
- Data: real or complex valued arrays holding the measured/processes data in time/frequency/octave domain
- Properties: values directly associated to the data, e.g. as sample rate or channel name
- Metadata: additional user defined information, e.g. name of a specimen or calibration date of a sensor
Tag Measurements with User-Defined Metadata on the Fly
Many engineering tasks comprise repeated measurements of similar test specimen or measuring the same specimen in a slightly different test setup (ambient temperature, mounting, etc.). In these scenarios where repeated measurements need to be distinguishable, metadata and the auto-popup feature may come in handy. In fact, some of m+p Analyzer’s built-in measurement modes rely heavily on this feature, e.g. the shock capture which we will use as an example:
First open the “Configuration”, click on “Advanced” below and check “Meta-data”. Now you'll find a tab called "Meta-data". This tab allows the user to specify custom metadata tags suited for the given measurement task. It is specified by Name/Value pairs presented in a spread sheet. The Name field is how m+p Analyzer refers to a metadata, i.e. company, specimen no., operator and can later be used to filter data. The Value field is the actual content, which may be a text, a date or a predefined list of values. I.e. if only three specimens will be tested, one may specify a list and during the test campaign would just select the correct one from a dropdown menu instead of writing the name out every time.
The checkbox “Auto prompt metadata” enables the auto-popup feature, which will bring up a metadata screen when starting a measurement. The following example shows how to configure m+p Analyzer and enable the auto-popup metadata feature.
Review and Edit Data, Properties and Metadata in the Measurements Editor
You can review and edit all data, properties and metadata of a measurement in the Measurements Editor. Select multiple measurements to block-edit several values of different measurements at once.
Custom Columns and Filter Option of the Browser for Metadata
All metadata tags may be shown as column headers in the browser. The columns filters (see also Issue 5 in last Newsletter) can also be applied to metadata to filter for similar tagged measurements.