2. Preparation for examination, setting the operation mode parameters of the system
Connect the “leading” device to the computer and connect together all other devices with patch cables of required length. Turn on the power supplies and check at online mode of the system that all devices are working in a pre-designed manner. At the time of setting up the measurement and during the measurement, the status of cables and AE sensors as well as the acoustic activity on AE channels can be monitored continuously with color light signals. LED indicators for each AE channel appear on the front of the instrument as well as on the computer’s screen. When an enabled AE channel detects an AE Hit, its LED will light up. The tear or short circuit of the sensor cable, as well as the test run state of the AE channel, are marked by a different color.
During the measurement preparation, at first turn off the AE channels that will not be needed. Choose the right LC bandpass filter or set the digital filter for the main amplifiers. Determine the Hit detection Dead Time. Set the amplification mode and Hit Threshold mode and level for each AE channel individually – the optimum value for threshold levels can be set automatically, too. Enter the coordinates of each sensor and the waveguide parameters that may be applied. Select the type and sampling frequency of the environmental parameters, and provide a linear transformation of the analogue channels (that is, the correlation between the measured voltage or current signal and the measured physical quantity) to facilitate their subsequent interpretation. Either manually or automatically, in the test mode of AE sensors, the measurement-relevant properties of the object can be studied, such as the direction-dependent propagation speed and attenuation. It is possible to check the correctness and flawless operation of the entire system, including the sensitivity of the sensors installed on the object under inspection, the wiring and the external preamplifiers.
An “Automatic Serial Measurements” feature is available, which allows for continuous monitoring of objects.
During preparation of real-time evaluation during measurement, parameter groups can be compiled to list the measured or calculated AE parameters. For graphical representations of the distribution of parameters or relationships between them, X / Y1, Y2 functions can be defined. To localize AE sources, you can sort the AE channels into groups (Array), or use a general algorithm for the entire object under inspection. You can choose between linear, ring-like, plane, cylindrical or spherical localizing algorithms. You can specify the map parameters for the representation of localized sources.
Using almost any of the measured or calculated AE parameters, complex parametric filters can be defined so the evaluation is performed only on the measurement data corresponding to the conditions of the selected filters. Similarly, using almost any of the measured or calculated parameters, digital alarm conditions and alarm signals can be defined.
The instrument settings and all other data specified during the preparation of the measurement are stored in setup files.
- For setting parameters of the operating mode of the equipment, it is necessary to have an online mode between the computer and the entire AE system. Changing the parameters that determine the operating conditions of the equipment and receiving AE Hits and Events are impossible in the absence of communication between the AE system and the computer.
- Upon entering the online mode, the access path and the file name of the measurement results are immediately set.
- The entire setting, selected in preparation for the test, performing a test or re-processing its results, can be saved as a separate file for reuse. When you turn on the program, it can start immediately with this file or at any time you can load another prepared installation file. The changes to the settings during the work can be recorded in the working file very quickly, with just one click, or saved under a different name.
- Functions performed by the software during test preparation only:
- Checking the sensitivity and quality of installation of AE sensors
- Automatic check of “hearing” of each other by AE channels
- Automatic measurement and loading of the matrix of sound propagation speeds, dependent from the direction
- Measuring the attenuation coefficient of the sound, depending from the distance
- Selection of AE channel for test mode, setting parameters for test pulses and repetition period.
- Parameters determining the operating conditions of the equipment, receiving AE pulses and recording waveform:
- Enabled AE channels involved in testing
- Gain mode for enabled AE channels
- Frequency range of bandpass LC filter, common for all AE channels
- The lower and upper cut-off frequency of the bandpass digital filter, common for all AE channels (the corresponding LC filter is selected automatically)
- Choice between fixed and floating threshold for receiving AE Hits for enabled AE channels
- Individual threshold levels for enabled AE channels. Automatic setting of optimal threshold levels for all enabled AE channels is possible
- Dead time when receiving AE Hits, common for all AE channels
- Period of registration of the average signal level on AE channels, low-frequency parametric signals and logic levels at general digital inputs / outputs
- Voltage or current measurement mode on external analogue inputs of low-frequency parametric signals
- Configure universal digital input / output lines: Choice the direction (input or output) of digital lines, Setting the logic level on the digital output lines.
- Conditions for registration of original waveforms (snapshots) on AE channels (only for the “leader” device: AE channels for registration, manual start or start from the next AE Hit, AE channels for registration start, automatic restart period, “Pretrigger” time).
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- Functions and their parameters determining the type and conditions of test results processing, the form and type of their presentation both in real time during test execution and at re-processing (these settings can be entered or changed both in the course of preparation for the test, and during the test or when re-processing):
- Configure analogue low-frequency parametric inputs. (Each AE device of the system continuously measures its supply voltage, internal temperature and relative humidity. These parameters, together with the levels at the external analogue parametric inputs, are recorded in the measurement file and can be selected for processing along with them)
- Determination of the linear transformation function of analogue inputs, correction of the name and dimension of parameters
- Setting filtering of measurement results.
- Configure analogue low-frequency parametric inputs. (Each AE device of the system continuously measures its supply voltage, internal temperature and relative humidity. These parameters, together with the levels at the external analogue parametric inputs, are recorded in the measurement file and can be selected for processing along with them)
- Functions and their parameters determining the type and conditions of test results processing, the form and type of their presentation both in real time during test execution and at re-processing (these settings can be entered or changed both in the course of preparation for the test, and during the test or when re-processing):
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- Processing received AE Hits
- Parametric filtering of received AE Hits (you can prepare several (up to 8) combined parametric filters at once and then select the actual one)
- Selection of primary (measured) and calculated AE Hit parameters for inclusion in a combined filter
- Selection of boundary values and conditions for permitting the Hit
- Selection of current combined filter.
- Parametric filtering of received AE Hits (you can prepare several (up to 8) combined parametric filters at once and then select the actual one)
- Processing received AE Hits
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- Tabular presentation of results (you can prepare several (up to 8) combined parameter groups at once and then select the actual one)
- Selection of primary (measured) and calculated AE Hit parameters for inclusion in a parameter group
- Select the current table to display.
- Tabular presentation of results (you can prepare several (up to 8) combined parameter groups at once and then select the actual one)
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- Graphic presentation of results. It is possible to prepare at once many graphs of the form X ̶ Y1, Y2 (their total number is up to 128)
- Selection for inclusion on the graph for the X, Y1 and Y2 axes of the primary (measured) or calculated AE Hit parameters, or low-frequency parameters. When choosing for the Y1 axis the distribution of some parameter AE, the Y2 axis remains free.
- Selection of AE channels to apply to the curve
- Selection of the type of curves (line / step line / columns / points / large points)
- Selection of the type and splitting axes
- Selection of the current schedule for display and selection of its place on the field of graphs or with location maps
- Set the size of the graph and its place on the displayed field.
- Graphic presentation of results. It is possible to prepare at once many graphs of the form X ̶ Y1, Y2 (their total number is up to 128)
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- Formation and processing of AE Events
- Setting conditions for forming AE Events (these settings are also necessary and determine the conditions for location of AE sources)
- Entering sensor coordinates to the table
- Setting the average speed of sound propagation or loading the matrix with direction-dependent velocities
- Choice of location algorithm (linear / planar / universal) and its refinement (linear-circular, linear “Guard Mode”, on a cylinder with dimensions, with a shell and bottoms, a sphere with a radius)
- Formation of location antennas (assignment of AE channels to location arrays)
- Determination of the minimum number of Hits to form an AE Event
- Setting conditions for forming AE Events (these settings are also necessary and determine the conditions for location of AE sources)
- Formation and processing of AE Events
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- Parametric filtering of AE Events (you can prepare several (up to 8) combined parametric filters at once and then select the actual one). These filters do not affect the source location)
- Selection of primary (measured) and calculated AE Event parameters for inclusion in a combined filter
- Selection of boundary values and conditions for permitting the Event
- Selection of current combined filter.
- Parametric filtering of AE Events (you can prepare several (up to 8) combined parametric filters at once and then select the actual one). These filters do not affect the source location)
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- Tabular presentation of results (you can prepare several (up to 8) combined parameter groups at once and then select the actual one)
- Selection of primary (measured) and calculated AE Event parameters for inclusion in a parameter group
- Select the current table to display.
- Tabular presentation of results (you can prepare several (up to 8) combined parameter groups at once and then select the actual one)
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- Graphic presentation of results It is possible to prepare at once many graphs of the form X ̶ Y1, Y2 (their total number is up to 128)
- Selection for inclusion on the graph for the X, Y1 and Y2 axes of the primary (measured) or calculated AE Event parameters, or low-frequency parameters. When choosing for the Y1 axis the distribution of some parameter AE, the Y2 axis remains free.
- Selection of AE antenna (formed from a group of AE sensors) to apply to the curve
- Selection of the type of curves (line / step line / columns / points / large points)
- Selection of the type and splitting axes
- Selection of the current schedule for display and selection of its place on the field of graphs or with location maps
- Set the size of the graph and its place on the displayed field.
- Graphic presentation of results It is possible to prepare at once many graphs of the form X ̶ Y1, Y2 (their total number is up to 128)
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- AE source location
- Setting all conditions for the formation of AE events
- Preparation of location maps (their number is not more than 32): selection of active antennas, determination of size and position on the display field, selection of the AE parameter for colouring of points.
- Selection of active location maps
- Formation of a parametric filter for location: Selection of AE event parameters to be included in a combined filter with boundary values and conditions for permitting the Event.
- AE source location
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- Registration of the original waveform
- Selection of AE channels for recording the 8 ms long snapshot of the original waveform (only the channels of the “leader” device can be selected)
- Selection of AE channels for triggering waveform registration in the mode of triggering from the next AE Hit
- Selection of the trigger mode: manual or from the next AE Hit
- Selection of the Pretrigger time for the trigger mode from the next AE Hit
- Setting of the frequency range for FFT calculation.
- Registration of the original waveform
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- Alarm generation
- Formation of a parametric filter for an alarm: Selection of parameters: the value of external or internal analogue inputs, logical levels of universal digital inputs, AE Hit or AE event parameters for inclusion in a combined filter with limit values and conditions for issuing an alarm
- Defining the action for the alarm activation event
- Assigning a universal input / output line for a logical alarm
- File definition for audible alarm
- Entering e-mail address and message text for email.
- Alarm generation
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- Continuous monitoring mode
- Entering the access path and base name for the measurement results files
- Selection of the mode of periodic measurements
- Determination of the duration of the measuring and waiting phases
- Configuration of the test mode “Ahoy”, conditions of issue and type of the warning signal.
- Continuous monitoring mode
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