NVGate Monitor Plug In
Monitor
The Monitor input can be connected and hot swapped independently of any plug-in analysis. It is used to monitor one or several signals.
Available results:
- Triggered block: This displays the time domain signal.
- Inst. spectrum: It displays the FFT processing results.
- Avg. spectrum: It displays the average spectrum.
- DC, Max, Min, RMS, Kurtosis on a specified band
Channel
Contains the source of the signal to be monitored.
- Source<ref>Using input 5 to input 8 as source with an OR35 analyzer will cause Non-real-time analysis. This way may lose some trigger event samples.</ref>: input source to be analyzed. It may come from the Front-end input or from the Player in post analysis mode (see the post analysis chapter). In post analysis mode, tracks with a signal bandwidth lower than the range of the Monitor cannot be plugged.
FFT analysis
Contains the settings related to the FFT analysis of the signals to be monitored.
- Range: the frequency range of the Monitor plug in.
Hidden/fixed: The monitor range is fixed by the input frequency range (in connected mode on-line) and by the max bandwidth of the player (in post analysis mode).
- Frequency Span: This is a fixed setting, for information only. It displays the frequency span between two points of a spectral result. The FFT frequency span is obtained by dividing the frequency range of the FFT by the resolution minus 1. For example if the FFT Range is 20kHz and the resolution is 401 lines, then the frequency span is: 20000 / (401 - 1) = 20000 / 400 = 50Hz.
- Resolution: the resolution of the FFT. The FFT frequency span is obtained by dividing the FFT frequency range by the resolution minus 1. For example, if the FFT Range is 20kHz and the resolution is 401 lines, then the frequency span is: 20000 / (401 - 1) = 20000 / 400 = 50Hz.
Hidden/fixed: fixed to 401 lines
- Domain: The averaging domain: spectral domain averaging computes the average after FFT processing.
Hidden/fixed: fixed to spectral
- Avg duration: Exponential coefficient for averaging.
Overall analysis
- Avg duration: Each scalar is computed for each block of signal (length of the block is 256/ (Front-end / Input Sampling), and then average during the value of the setting.
- Filter order: the order of the filter: 2, 4, 6, 8 or 10.
- Low cut-off frequency: the low cut-off frequency of the filter. Its minimum value is 0.055 * FR, where FR is the input frequency range. However, the following conditions must also be fulfilled:
0.0075 * FR <= B <= 0.5 FR,
Where B is the bandwidth between Low and high cut-off frequency
and FR is the input frequency range.
- High cut-off frequency: the high cut-off frequency of the filter. Its maximum value is the input frequency range. However, the following conditions must also be fulfilled: see Low cut-off frequency.
- Filter: On / Off. The filter is not applied if Filter is Off
Waterfall
The Waterfall module is used to stack data such as Spectra, 1/n Octave, RPM or DC values picked up from available Plug-ins into slices. Data into slices are synchronized and can be sorted by references (time, RPMs or DC levels).
The following scheme describes the waterfall slices collection behavior. When selected event (trigger) occurs, the latest computed data from each associated plug-in are collected into the current slice. Then data can be displayed into 2D (for scalar) and 3D graph in function of each reference.
Stackable results
| 3D | 2D (profiles) | |
| FFT | * Triggered block * Weighted block * Inst. Spectrum * Average Spectrum * Inst. Cross Spectrum * Average Cross Spectrum * FRF H1 * FRF H2 * Coherence * Inst. Zoom Spectrum * Average Zoom Spectrum * Zoom Cross Spectrum * Zoom Average Cross * Zoom FRF * Zoom Coherence |
* Overall Power * Order x |
| Sync. Order | * Triggered block * Weighted block * Order Inst. Spectrum * Order Average Spectrum |
* Order x * Overall Power |
| 1/n Octave | * 1/n Octave * Average results: - AvNoct - MinOct - MaxOct |
* Overall level: OvrLin * Overall Weighted level: OvrWgt |
| Overall acoustic | - Lxypeak - Lxy inst * Lxy eq 1/8s * Lxy eq 1s * Lxy eq t X = Applied weighting (A or C), in case of Z selection (no weighting) X is not displayed. Y = Applied time filter (None, Fast, Slow or Impulse), If none is selected (no time filtering) Y is not displayed. t = Short time integration duration. T | |
| Tachometer | * Tach Angular Speed (ref) * Virtual Angular Speed (ref) * Ext Tach Angular speed (ref) * DC Tach speed (ref) * Combined tach speed (ref) * Fractionnal tach (speed) | |
| Front end |
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| Monitor |
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| Time domain |
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| N.A. |
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Computation SPUs
Unlike other plug-in, the memory of the waterfall depend on the capacity of the PC and others applications running on it. The depth of the waterfall is function of the free memory of your PC, and is limited to around 3 millions samples per DSP.
Glossary
This section will explain specific vocabulary of the Waterfall.
- Slice: this represents one acquisition of the Waterfall. A slice is a set of scalar and spectrum data acquired at the same time. The Waterfall is a stack slices.
- Depth: this is the maximum number of slices you can acquire on the Waterfall.
- Section: section at the current position of the cursor. The extraction section is created only if a tach has been selected in the Waterfall (see chapter 2 Display, Waterfall window menu).
- Reference: A scalar collected by the waterfall acquisition that can put in order the slices. The reference corresponds to the X-axis of the profiles and the Z-axis of the 3D graphs.
- Profiles or 2D Results: profiles of a scalar evolution in function of time or any reference associated with the waterfall
- Results 3D: spectra collected by the waterfall acquisition putted in order by a reference. These types of results are displayed in 3D graphs (3D, isometric or color-spectrogram).
Channel
The different channels are available by putting selected inputs in the plug-in.
It contains the results to be picked up by the Waterfall.
The following window let you select for each analysis plug-in, the channel related to the result.
- Source: In the ASB the channels are different from other ASB channels, the source of channel 1 and following are the results. The source of channel 64 and previous ones are the references. By default the time reference is always associated with a result source.
Trigger
Contains the settings related to triggering events and how to start and stop signal computation.
- Start: selects the event to start the waterfall acquisitions. This setting selects the event, which enable acquisition that is to say data collection does not operate while start event is no occurred. Any event can be chosen among the list of defined events. By default only the Free run and Manual events are available. Additional events can be defined in the "Event Definition" shared resource. The start time corresponds to the zero of the waterfall time scale. By default start is set to "free run" this allows waterfall acquisition to start immediately after run.
- Stop: selects the event to stop the waterfall acquisitions. This setting selects the event, which ends acquisition that is to say data collection, does not operate after stop event occurred. Any event can be chosen among the list of defined events. By default only the Free run and Manual events are available. Additional events can be defined in the "Event Definition" shared resource.
- Trigger: selects the event that trigs waterfall acquisitions. This setting selects the event which trig acquisitions that is to say a new data collection occur each time trigger event occurred. If trigger is set to periodic (period 20ms) the Waterfall acquisition will operate as fast as possible, this can hang user interface during acquisitions. The first time a source is selected for the Waterfall, if trigger = Periodic, then the event corresponding to the availability of the source results is assigned to the trigger. Ex: Setting FFT1 spectra into the waterfall plug-in will set Trigger to ’FFT1 result available’. By default the trigger is set to ’Periodic’ with a period of 20.
| List of events | Description |
| Manual | This event occurs when the user requests a manual trigger. |
| Events from Event module | see Event module |
| FFTx result available | This event is in the list if a signal is connected to an FFTx channel source. This event occurs when an FFT measurement starts. This event is generated at each calculation of a new spectrum in exponential averaging and at the end of averaging in linear. |
| Oct result available | This event is in the list if a signal is connected to an Octave channel source. This event occurs when an Octave measurement starts. This event is generated at each new spectrum calculated (every 256 samplings) for CBT, Fast, Slow, Impulse and exponential averaging. For the others averaging this event is generated at the end of averaging on t. |
| Order x result available | This event is in the list if a signal is connected to an Order x channel source. This event occurs when an Order x measurement starts. This event is generated at each calculation of a new spectrum in exponential averaging and at the end of averaging in linear. |
| Overall acoustic result available | This event is in the list if a signal is connected to an Overall acoustic channel source. This event occurs when an Overall acoustic measurement starts. This event is generated at each new spectrum calculated (every 256 samplings) for CBT, Fast, Slow, Impulse and exponential averaging. For the others averaging this event is generated at the end of averaging on t. |
| Periodic |
This event simplifies the instrument setup by shortcutting periodic event activation. Selecting periodic for the trigger will make appears the period setting. |
There is two ways to trigger the waterfall:
- The analyzer is running, it keeps in memory last measurements. Then with the waterfall you can select some specific results (for example for rpm or time).
- The plug-in triggering, at the end of each average the plug-in send an event. The plug-in put the rhythm into the waterfall. This mode is the default mode.
Mode
Contains the settings related to the Waterfall display mode.
- Mode:
Off: the Waterfall is inactive. This mode is useful to check your signal and your settings before the analysis.
One shot: the Waterfall is active between ’start’ and ’stop’, there’s only one acquisition (for example: coast downs or run ups). The Waterfall ends on stop or when the number of slices is full.
Continuous: this mode memorizes the n last slices (selected number of slices) before the stop event. This mode is similar to the ’time to stop’ mode of the recorder. This mode is different from the monitoring; the continuous mode is storage of measurement (for example: detection of ultimate strain).
- Number: the number of Waterfall slices (from 2 to 100 000). If the Waterfall trigger is a Delta RPM event, the "Event number" of this Delta RPM event is assigned to the number of Waterfall slices.
The waterfall depth is managed automatically, allowing the user to get the larger slices/points number depending on the current available physical memory on the PC running NVGate. This functionality protects waterfall or profiles acquisition from memory overloads. That means the depth of the Waterfall is a function of slices weight (which depend on the type of analysis).
The area is fixed. If the slices weight are important, then the depth would be small.
The area is function of the free memory space available when you select to use the Waterfall. The memory space has to be exactly the same during all the measurement that means the measurement could hang if you start another application on your computer during the measure.
The acquisition/display and save memory usages are managed separately and are sequenced. It result a larger of data managed by the waterfall and secured acquisition.
NVGate takes advantage of 64bits PC memory (> 2 GB) for larger memory allocation for the Waterfall. As NVGate remains a 32-bit application, PC memory is not used above 4 GB.
The following table summarizes the evolutions of the waterfall depth (for a given configuration: 32 ch 3,201 lines and PC):
For example a waterfall of 32 ch 3,201 lines handles up to:
| PC configuration | Slices |
| XP 32 bit 2GB RAM | 260 |
| Win7 64 bit 4GB RAM | 640 |
NB: In the stand-alone mode, the depth is limited (about 3 million samples per DSP) due to the analyzer memory size.
Notes:
- OVA: if the waterfall trigger selected were « OvA Leq result available », the slices number would depend on durations (average duration « T » and short duration « t ») from the sub module Average in Overall acoustic.
| Average type | Slices number |
| short Leq (t) | T/t |
| short Leq 1/8s | T/t |
| short Leq 1s | T/t |
| Linear, with repeat = End Of Averaging | T |
| Linear, with repeat != End Of Averaging | Independent |
- 1/N Octave: if the waterfall trigger selected were « Oct result available », the slices number would depend on durations (average duration « T » and short duration « t ») from the sub module Average in 1/N Octave.
| Average type | Slices number |
| Linear, with repeat = End Of Averaging | T |
| Linear, with repeat != End Of Averaging | Independent |
| Repeat | T/t |
| Exponential | Indepedent |
| Constant BT | Independent |
| short Leq 1/8s | T/t |
| short Leq 1s | T/t |
| Fast | Independent |
| Slow | Independent |
| Impulse | Independent |
The on line display uses more power and could slow displays but acquisitions and analyses remain real-time.
Waterfall status
All statuses are available to add to the control panel
