2022-07
file: spotwave_instructions_manual.docx
23 of 50
without external power. If the spotWave device is connected within this time period to a battery pack, it runs in
the Logging Mode with real time clock.
The measurement data can be retrieved from the spotWave device by connecting it to an end device and
downloading the data.
16.4.
Measurement Mode
A spotWave device measures features of an AE signal. The measured data is stored to a feature file that
meets the SQLite3 standard. The file extension of the feature file is *.pridb. Vallen AE Suite analysis software
can read and process this file.
The sampled signal is stored to a transient recorder file that meets the SQLite3 standard. The file extension of
the transient recorder file is *.tradb. Vallen AE Suite analysis- and feature extraction software can read and
process this file.
A list of measured features is found in the subsequent chapter 16.4.3, List of Time Domain Features.
16.4.1. Hit Based Measurement Mode
A measurement of an AE-signal is triggered when the AE signal exceeds a certain, user defined detection
threshold. An AE signal that exceeds the detection threshold is called a detected burst signal or hit. The
spotWave device detects hits and discriminates them from each other.
A set of features describing a hit are extracted by the spotWave processor’s feature extraction unit.
Intensity analysis of recorded data can be done based on the peak amplitude, energy and the number of
threshold crossings of a hit.
Activity analysis can be done for a single channel based on the number of hits measured within a certain time
period.
16.4.2. Long Duration Mode
The spotWave device switches into a long duration mode if its internal hit buffer is full. It stays in a long
duration mode until a hit data set can be written to the internal buffer again. As a result, the data set that is
written in long duration mode can include many hits.
The internal hit buffer can run full if more data is generated than transferred to the end device. Such a
situation can occur in the cases of (i) a high hit rate, (ii) wrong, i.e. too low, threshold setting and (iii) data is
not polled fast enough by a data acquisition program.
Intensity analysis of the recorded data can be done based on the peak amplitude, energy and the number of
threshold crossings.
An activity analysis can be done based on the number of threshold crossings of a certain time period.
Data sets that are generated in long duration mode receive a D flag.
16.4.3. List of Time Domain Features
The time domain features are extracted by the Feature Extraction unit of the signal processor of the spotWave
device. A list of time domain features follows in the table below.
Feature
Description
A
Burst signal peak amplitude in units of dB
AE
. Maximum voltage excursion within the duration
of a burst signal
