Reference Materials

General | Dynamic Measurement | Environmental Testing | Structural Testing | DAQ (Strain/Temperature)

Recent Articles

Dynamic Signal Analysis Advanced (Product Note #002, 50 pages, 2.34 MB)
Describes the advanced dynamic signal analysis theory including swept sine test with tracking filter, real-time digital filters, octave analysis, sound level meters, order tracking analysis, automated test, shock response spectrum analysis. Read online here.

Digital Filters and Resampling in Post Analyzer (Product Note #088, 19 pages, 1.64 MB)
Digital filters are powerful tools utilized during the data conditioning phase to analyze signals. Read online here.

Intelligent Drive Clipping – Improved Sigma Clipping (Product Note #087, 8 pages, 1.18 MB)
Intelligent Clipping modifies the drive signal to minimize the loss in dynamic range of the profile. Read online here.

Accurate GPS Time Stamping (Product Note #086, 29 pages, 2.06 MB)
Accurate time stamping based on GPS brings great benefits to dynamic signal measurement applications.

Spectral Processing for GPS Time Stamped Signals (Product Note #085, 26 pages, 2.07 MB)
We developed the theory and algorithms to calculate the auto and cross spectrum between measurement channels on separate data acquisition units that can be distanced thousands of miles apart. Read online here.

Shutdown Protection System with Tracking Filters (Product Note #084, 13 pages, 1.42 MB)
Assessing the endurance of a device through shaker-induced vibration is a widely used technique that poses potential damage to the Device Under Test. The implementation a secondary shutdown protection system is crucial to mitigate the risk of substantial damage. Read online here.

General

Dynamic Signal Analysis Basics (Product Note #001, 35 pages, 2.85 MB)
Describes the basic dynamic signal analysis theory including Fourier Transform, data windowing, linear spectrum, power spectrum, cross spectrum, FRF and coherence, averaging, transient capture and hammer test, overlapping process, SDOF system. Read online here.

Define and Measure 160 dBFS Dynamic Range (Product Note #003, 4 pages, 631 KB)
Describes how Crystal Instruments defines the dynamic range of the measurement system and the advanced capabilities of CI products. Read online here.

Industrial Ethernet Switches for Spider Systems (Product Note #005, 2 pages, 291 KB)
Requirements for Industrial Ethernet switches for use with the Spider Vibration controller system. Read online here.

Applying ASAM-ODS in Crystal Instruments Products (Product Note #014, 5 pages, 288.23 KB)
ASAM-ODS is a new industrial standard of data format that are particularly designed for dynamic measurement systems. Read online here.

Anti-Aliasing Filter and Phase Match (Product Note #021, 5 pages, 636 KB)
Crystal Instruments is among the very first companies using sigma-delta converters in early 90s. This paper discussed the sigma-delta converter, anti-aliasing filter and phase match issues in a DSA instrument. Read online here.

What am I going to do with 128 Channels? (Product Note #026, 4 pages, 986 KB)
Applications of a high channel count system are discussed. Read online here.

You have 10 fingers, but that doesn't mean the input range has to be 10 volts! (Product Note #038, 4 pages, 468 KB)
The input channels of the CoCo-80X, Spider-80X and Spider-81 series are very similar in hardware design except the number of channels. Typically, the Spider-80X and the Spider-81 series have 2~16 analog input channels with an isolated BNC connector. The input range is ±20 V with single-ended, differential, IEPE, Charge Mode, and TEDS input type. Read online here.

Patented Technology & Improved Hardware Extends Spider System Dynamic Range to 160 dB (Product Note #053, 2 pages, 378 KB)
Crystal Instruments integrated the advances in electronics into the Spider systems to achieve an additional 10 dB in dynamic range, extending the dynamic range of Spider systems to 160 dBFS. An experimental analysis highlighting this new achievement is published in this article. Read online here.

Running Multiple Large Channel Systems on a Network in Real-time (Product Note #054, 3 pages, 513 KB)
With the implementation of IEEE 1588 Precision Time Protocol (PTP), the same Ethernet connection used for data transmission also provides time clock synchronization. This advanced technology is applied to CI Spider systems, ensuring the possibility of nearly any topology of device and computer connections. Read online here.

Multi-Resolution Spectrum Analysis (Product Note #057, 6 pages, 737 KB)
After over twenty years of research and development, Crystal Instruments successfully introduced and implemented the so-called multi-resolution spectrum analysis in many lines of its products, including CI Random vibration controller, dynamic signal analyzer and modal data acquisition. The multi-resolution spectrum analysis solves the problem mentioned above with enormous benefits. This paper shows how it was realized and example results. Read online here.

Vibration Visualization (Product Note #060, 5 pages, 732 KB)
The vibration visualization approach proposed by Crystal Instruments not only helps in overcoming the difficulty of producing 3D geometries of any complicated models with a simple procedure but also animates the structure’s deformation which makes it possible to visualize the vibration experienced by the testing article during a vibration test. Read online here.

Spiders with 256 kHz Sampling Rate (Product Note #067, 2 pages, 297 KB)
Crystal Instruments EDM 9.0 release introduces new additions to the Spider product line featuring support for sampling rates up to 256 kHz. The new Spider-80Hi and Spider-80Ci are scalable versions of the Spider system featuring the impressive new 256 kHz sampling rate. Recording can also be performed at sampling rates up to 256 kHz for all eight channels on these Spider modules. The compact, ultra-portable four channel version of the Spider has also been developed to support a 256 kHz sampling rate. Currently, three variations of the compact Spiders supporting the 256 kHz sampling rate are available: Spider-20H, Spider-20HE, Spider-20i. Read online here.

CI Data File Reader Manual (C#, PYTHON, MATLAB, LABVIEW) (Document ver. 3.6, 5 MB)
The CI Data File Reader Application Programming Interface (API) consists of 2 Windows Dynamic-Linked Libraries (DLL) providing third-party applications an interface to access the signal data stored in the ASAM Transport Format XML (ATFX) files. Learn more here.

Dynamic Measurment

Basic Theory of Frequency Response Function (FRF) (Product Note #063, 3 pages, 591 KB)
A common application of dynamic signal analyzers is the measurement of the Frequency Response Function (FRF) of mechanical systems. This is also known as Network Analysis, where both system inputs and outputs are measured simultaneously. Read online here.

FRF Limiting Function (Product Note #020, 5 pages, 1.14 MB)
When running a test to measure the FRF of a structure, it may need to check the measured data against a pre-defined limit profile to see whether the measured signal has any point or portion over the limit. This can be done through the so-called FRF Limiting Function. Read online here.

The Modern Maturation of Machinery Monitoring (Product Note #008, 4 pages, 335 KB)
This article discusses the history of machinery monitoring and modern advances today. Read online here.

Wyle Labs Acoustic Testing with the CoCo-80 Acoustic Analyzer (Product Note #011, 3 pages, 410 KB)
Wyle Labs, in California, uses the CoCo for acoustic testing. Read online here.

Vibration Criteria for Facilities with Sensitive Equipment (Product Note #012, 6 pages, 415 KB)
How vibration criteria are used to classify environmental vibration in facilities with sensitive equipment. Read online here.

Audio Functions (Product Note #013, 5 pages, 211.95 KB)
This paper presents the advanced audio functions, including microphone, earphone and voice annotation. Read online here.

Manage Dynamic Signal Analysis Signals using Database (Product Note #016, 11 pages, 1.45 MB)
Describes how thousands of data files are conveniently managed by the EDM database tool. Read online here.

Time Synchronous Average (Product Note #017, 5 pages, 422 KB)
Describes how the time synchronous averaging is applied to the rotating machine analysis. Read online here.

Configurable Signal Analysis (Product Note #018, Paper published in Sound & Vibration Magazine, 3MB)
This feature allows the user to dynamically configure the DSP functions so that data processing flow can be customized from application to application. Read online here.

Consolidation of Dynamic Signal Analyzer and Vibration Data Collector (Presentation, 5MB)
Thoughts behind creating the CoCo-80: integrating a dynamic signal analyzer, a data recorder and a vibration data collector into one package.

An Ear for Gears - Understanding Gearbox Signatures (Product Note #022, 6 pages,1.31 MB)
Speed reducers and other gearboxes are common industrial components. Monitoring their case vibration with accelerometers is an effective means of detecting problems within. Read online here.

Coherence Function - A Brief Review (Product Note #023, 4 pages, 1.18 MB)
A brief review of the Coherence Function and its applications. Read online here.

Data Recording and EDM Post-Analyzer – the Thinking Man’s Alternative (Product Note #024, 3 pages, 4.04 MB)
CI offers EDM Post- Analyzer software, a powerful adjunct to your Spider-based analysis tool kit, allowing you to analyze recordings made using your Spider front-end modules. Read online here.

Vibration Data Collector: Signal Analysis (Product Note #019, 32 pages, 0.7 MB)
Describes algorithms used in vibration analyzers, including computing the RMS, Peak, Peak-Peak values, FFT spectrum, demodulation spectrum and digital integration for transforming acceleration into velocity or displacement. Read online here.

Remote Condition Monitoring (Product Note #035, 6 pages, 895 KB)
Remote Condition Monitoring (RCM) by Crystal Instruments is designed for the remote monitoring of equipment or structures that are inaccessible to configure within a local network. Read online here.

Synchronous Data Acquisition Across A Large Structure or Space (Product Note #037, 2 pages, 530 KB)
Dynamic data acquisition and machine monitoring in a large structure (e.g. airplane) or a large space (e.g. a factory or a plant) often requires data to be acquired synchronously at various locations. Read online here.

Power System Stabilizer Test and Measurement (Product Note #052, 4 pages, 378 KB)
Power system stabilizer testing consists mainly of frequency analysis of power generator systems. The CoCo-80X can be used to evaluate the performance and stability of power generator systems. By determining the phase-frequency characteristics of the excitation control system, the PSS can be tuned to improve small-signal stability. Read online here.

Pyroshock Data Acquisition Using Crystal Instruments Spider (Product Note #059, 6 pages, 1.78 MB)
Pyroshock or Pyrotechnic testing using simulation or explosive devices are typically used to test and qualify components for the aerospace industry. Components and methods used for acquiring Pyroshock data plays an important role to ensure that the acquired data is valid and not corrupted by several possibilities including the choice of sensors and the acquisition device. Read online here.

New Ultra-compact Spider-20HE & Spider-20i with 256 kHz Sampling Rate (Product Note #068, 2 pages, 310 KB)
Featuring the highest sampling rate provided in the industry at 256 kHz. Handheld battery powered system with wired & wireless network options and 20V input range. Sync between multiple devices. Choose the convenient portable model or industrial model for permanent mounting. Read online here.

Dynamic Stiffness Measurement or Conversion (Product Note #082, 3 pages, 449 KB)
Users can derive other types of FRF measurements from acceleration by converting acceleration to velocity or displacement, or vice versa. Crystal Instruments data acquisition system supports this conversion. Read online here.

Spectral Processing for GPS Time Stamped Signals (Product Note #085, 21 pages, 2.07 MB)
We developed the theory and algorithms to calculate the auto and cross spectrum between measurement channels on separate data acquisition units that can be distanced thousands of miles apart. Read online here.

Accurate GPS Time Stamping (Product Note #086, 29 pages, 2.06 MB)
Accurate time stamping based on GPS brings great benefits to dynamic signal measurement applications.

Environmental Testing

What's Required to Bring Vibration Testing In House? (5 MB)
Cover Story for March 2016 Sound and Vibration Magazine

A History of Vibration Test Controllers (Product Note #004, published in Sound & Vibration Magazine, 0.4MB)
This article discusses the four generations of digital vibration control systems developed by US companies in the past 4 decades. Read online here.

Understanding Random Vibration Testing Signals (Product Note #027, 6 pages, 2.43 MB)
Random vibration testing signals are explained and discussed for the testing professional. Read online here.

Using Fatigue Damage Spectrum with Vibration Control (Product Note #028, 3 pages, 2.10 MB)
Fatigue Damage Spectrum (FDS) allows users to compare the potential damage caused by different Random profiles, swept Sine profiles or a combination of both. Read online here.

Visualizing Mode Shapes with a Stroboscope and Cola Output (Product Note #029, 3 pages, 1.44 MB)
Product application note discussing the use of a stroboscope to visualize mode shapes with Crystal Instruments' Spider systems. Read online here.

Random Control Feature: Non-linear Control (Product Note #030, 3 pages, 756 KB)
Crystal Instruments’ Random Control implements an advanced algorithm which compensates for the effect of non-linearity in the control loop, regardless of whether it is caused by the type of shaker system or the resonance of the device under test. Read online here.

Sine - Resonance Search Track & Dwell Tracking (RSTD) (Product Note #31, 5 pages, 878 KB)
This product note demonstrates the use of Crystal Instruments’ Spider 80X along with EDM (Engineering Data Management) software to determine the resonant frequency of a test object with a very high Q and dwell on the resonant frequency along with tracking the changes in the resonant frequency using the phase value. Read online here.

Random Control Feature: Multi-Resolution Control (Product Note #32, 6 pages, 945 KB)
The Multi-Resolution function perfectly fulfills the requirements of many Random profiles having details in the low frequency range and up to 2kHz. Adequate loop time, spectrum refresh rate, and storage are maintained without using high resolution (large block size) that is not needed in the high frequency. Read online here.

Multiple Shaker Control in EDM Software (Product Note #34, 7 pages, 1043 KB)
Multi-shaker control (MSC) is a unique feature offered by Crystal Instruments EDM Software versions 7.0 and above. The EDM MSC function enables users to view and monitor multiple shaker tests from one PC station. Users can observe testing status, view individual signals from different shaker systems, and send commands to each controller from one centralized application. Read online here.

Center of Operation and Monitoring of 12 or More Shaker Systems with API (Product Note #039, 2 pages, 600 KB)
With these advanced features and robust qualities, Crystal Instruments has been successful in deploying 12 Spider controllers to control 12 shaker systems independently, which are being monitored through one PC from the API. Read online here.

High Resolution Random Control at Low Frequencies (Multi-resolution) (Product Note #041, 3 pages, 588 KB)
The trade-off between control performance at low frequencies and the whole system response is always difficult, but Crystal Instruments has the solution: Multi-Resolution Random Control. Read online here.

Automotive Multi-Sine (Product Note #042, 2 pages, 739 KB)
Multi-Sine is a new type of Sine test which facilitates multiple sine tones sweeping simultaneously at once. In automotive testing, engine mounted components such as fuel lines, turbos, headers, sensors, heatshield… are all subjected to high vibration levels during their operational life cycle. Read online here.

Importance of Spectrum History Sine Signals in a Sine Test (Product Note #044, 3 pages, 366 KB)
Crystal Instruments uses Spectrum history signals, a special type of signals plot to conveniently plot a user defined signal property vs. time or cycles on the X-axis. To ensure the best readability and analysis, the plot is enhanced to accommodate the entire test duration even when the test durations run into several days, weeks or months. With the PC memory as the limitation, test durations of several months or even years can be plotted and viewed simultaneously, thus eliminating any necessity to section the data plot. Read online here.

MIMO Vibration Control vs. Single Shaker Vibration Control (Product Note #046, 3 pages, 561 KB)
With the development of multiple shaker table systems, the availability of Multiple-Input Multiple-Output (MIMO) controllers and Multiple-Input Multiple-Output (MIMO) vibration control started emerging a couple of decades ago. Read online here.

Multiple Shaker Table Systems (Product Note #047, 3 pages, 461 KB)
The Multiple Shaker Table System ranges from Multiple Exciter Single Axis (MESA) to Multiple Exciter Multiple Axis (MEMA) with 2 to 6 shakers involved (e.g., three axis translational shaker table, four-poster, 6 DOF Multi Axis Shaker Table (MAST), etc.) Read online here.

Streamlined & Efficient Process of Viewing Signals Acquired in Vibration Tests (Product Note #048, 3 pages, 1.62 MB)
The repetitive manual addition and removal of signals to the display becomes a tedious task. (The purpose of this task is for viewing purposes or for comparisons of the same signals saved in different files.) The Review and Compare mode in EDM streamlines the process, rescuing us from the sheer boredom and inefficiency. Read online here.

Vibration Tests for Seismic Qualification (Product Note #050, 3 pages, 838 KB)
Earthquakes are one of the most destructive forces of nature with the potential to cause devastating life and property losses. In addition to buildings and structures, equipment damaged by earthquakes may directly or indirectly generate hazards for people or the environment. For the safety of employees and the public, equipment designed to perform safety measures (e.g. shut down a reactor) or to function under certain levels of earthquakes for specified periods of time should pass a seismic qualification or a verification of earthquake resistance. Read online here.

Multiple Channel Control Strategies for MIMO Vibration Control (Product Note #062, 3 pages, 535 KB)
Multiple-Input Multiple Output (MIMO) Testing has gained a huge momentum in the past decade with the development of multiple shaker table systems, the availability of MIMO vibration control systems, and the readiness of standards (e.g., MIL-STD 810G Method 527, IEST DTE 022 Working Group Recommendation). Read online here.

Multi-Resolution Application in MIMO Sine Control (Product Note #064, 2 pages, 325 KB)
The tests discussed here were carried out on the Sentek Dynamics three-axis shaker system. Multiple MIMO sine tests were carried out to illustrate the effect of the multi-resolution method on the MIMO sine pretest. Read online here.

Earthquake Testing on a Three-Axis Shaker System (Product Note #070, 3 pages, 623 KB)
Earthquake testing is a crucial process that is used to determine the seismic performance of a structure. The utilization of a physical testing method helps users better understand the complexity involved in earthquake forces. A shaker table is typically used to execute a physical method of testing. Read online here.

Multi-Resolution Spectrum Analysis and Sine-on-Random Testing (Product Note #072, 3 pages, 833 KB)
In this article, we will discuss the benefits of using Multi-Resolution, a feature available in Vibration Control Systems, to offer a better frequency resolution in the lower frequencies of the Sine-on-Random vibration spectrum. The same benefits are also applied to the general Random test, and Random-on-Random mixed mode test. Read online here.

Dual Excitation Shaker Push-push Testing (Product Note #073, 2 pages, 398 KB)
Here we examine the details of dual excitation shaker system testing. In this case, two shakers are placed horizontally, side by side. Driving bars are connected between the shaker armature and slip table for each shaker. Read online here.

MIMO Control Null Test on Three-Axis Shaker Systems (Product Note #074, 3 pages, 530 KB)
The Control Null feature provided in Crystal Instruments’ Multiple-Input Multiple-Output Random vibration control software allows users to perform single axis or dual axis vibration control tests on a three-axis shaker setup with a simple setup in the software. Read online here.

Swept Sine Test Measurement Strategy (Product Note #075, 2 pages, 392 KB)
A Swept Sine test is a type of vibration test where the controller excites one specific frequency via sinusoidal voltage drive. As opposed to a Random test, where a broadband of frequencies is excited together like white noise, the Swept Sine test produces a response with energy in the primary frequency and its harmonics (i.e., frequencies that are multiples of the primary frequency). Read online here.

Output Ground Isolator (Product Note #076, 1 pages, 309 KB)
The output ground isolator is the most user-friendly solution for controlling multiple shakers while simultaneously improving accuracy of control and ensuring safe operation. Read online here.

Sine Sweep in High Frequency Range (Product Note #077, 12 pages, 1.65 MB)
This article analyzes the obstacles to running a sine test over a high frequency range, including the dynamic characteristics of the Unit Under Test (UUT) and fixtures, the control dynamic range of the vibration controllers, and the sensor mounting locations. Several strategies and recommendations are then discussed with results. Read online here.

Acoustic Control (Product Note #079, 3 pages, 530 KB)
Running a high intensity acoustic test requires an acoustic controller and an RATF. Crystal Instruments current EDM 10.0 software release provides Acoustic Control. Read online here.

Introducing SRS Predictive Notching (Product Note #081, 3 pages, 443 KB)
In Sine or Random control, notching and limiting is a common technique used to limit the response level within a certain frequency range. Previously, users were not able to limit the SRS spectrum level within a certain frequency range for any response channel. Predictive Notching provides a limiting function for any input channel. Read online here.

Linear and Angular Displacement Protection for Multiple-Exciter Single-Axis testing (Product Note #083, 6 pages, 825 KB)
The proposed Displacement Protection feature adds extra protections to testing equipment (including the shaker, armature, head-expander, slip-table and UUT). Read online here.

Shutdown Protection System with Tracking Filters (Product Note #084, 11 pages, 1.87 MB)
Assessing the endurance of a device through shaker-induced vibration is a widely used technique that poses potential damage to the Device Under Test. The implementation a secondary shutdown protection system is crucial to mitigate the risk of substantial damage. Read online here.

Structural Testing

Basics of Structural Vibration Testing and Analysis (Product Note #006, 14 pages, 2.69 MB)
This application note provides an introduction to the basic concepts of structural vibration. It presents the fundamentals and definitions in terms of the basic concepts. It also discusses practical applications and provides real world examples. Read online here.

Basics of Modal Testing and Analysis (Product Note #007, 12 pages, 4.15 MB)
This paper discusses the concept of modal analysis, its applications where modal analysis is useful, data acquisition and visualization techniques. Read online here.

Modal Testing On Hockey Sticks (Product Note #009, 3 pages, 1.1 MB)
Discusses how one popular hockey stick manufacture used the CoCo signal analyzer to characterize the modal behavior of their hockey sticks. Read online here.

Modal Analysis on Strut Parts (Product Note #010, 6 pages, 490 KB)
Modal analysis is used to analyze the dynamic characteristics of structures and mechanical parts. Read online here.

Modal Data Acquisition Using the CoCo-80X/90 (Product Note #015, 8 pages, 953.85 KB)
Explains how the CoCo-80X interfaces to the modal analysis software in EDM Modal (Engineering Data Management software) and how the modal data is captured. Read online here.

Modal Testing Preparation Considerations (Product Note #033, 3 pages, 881 KB)
In this technical note, the emphasis is to discuss the necessary technical details regarding the preparation of a successful modal test to acquire a set of FRF signals. Read online here.

Experimental Modal Analysis Overview (Product Note #043, 4 pages, 470 KB)
Experimental Modal Analysis (EMA) has developed into a major technology for the study of structural dynamics in the past several decades. Read online here.

Modal Shaker Testing Using Periodic Random Excitation (Product Note #040, 4 pages, 744 KB)
Modal shaker testing is widely used for experimental modal analysis and to acquire frequency response functions. Either single or multiple modal shakers can be used. The type of excitation used may influence the quality of the testing result and frequency response functions. Read online here.

Applications of Experimental Modal Analysis (Product Note #045, 4 pages, 543 KB)
With modal analysis results, quite a large number of applications are performed for a variety of industries. This note will discuss popular applications that are performed by engineering in industries such as aerospace, automotive, (etc.) Read online here.

Modal Testing Excitation Consideration (Product Note #049, 4 pages, 582 KB)
There are several modal testing methods that consider different types of excitations used. Commonly known methods include Hammer Impact testing and Modal Shaker testing. Please note that Operational Modal Analysis utilizing Ambient Excitation will not be discussed here. Read online here.

Operational Modal Analysis (Product Note #051, 3 pages, 738 KB)
The availability of an operational model opens the way for in-situ model-based diagnosis and damage detection. Hence, a considerable interest exists in extracting valid models directly from the operating data. This develops into the Operational Modal Analysis (OMA). Read online here.

MIMO Stepped Sine Testing Technique (Product Note #055, 3 pages, 622 KB)
The EDM Modal MIMO Stepped Sine Testing option provides multiple Stepped Sine excitations to measure Frequency Response Functions (FRFs). Read online here.

Understanding the Stability Diagram (Product Note #056, 3 pages, 548 KB)
The Stability Diagram is an effective way to display and identify the modes of a structure under test. Nowadays, the Stability Diagram is the standard method for the modal parameter identification stage. Read online here.

Poly-X, the Poly-reference LSCF Implementation and Experiment (Product Note #058, 4 pages, 671 KB)
A poly-reference least-square method for modal parameter identification of a system in frequency-domain is discussed and implemented. It can also be considered as a multi-reference frequency-domain implementation of the recognized time-domain based Least-Squares Complex Exponential (LSCE) estimator. Read online here.

Multi-Resolution Spectrum Analysis in Modal Testing (Product Note #061, 3 pages, 482 KB)
Crystal Instrument’s EDM Modal software features multi-Resolution spectrum technology implemented into the MIMO FRF testing suite. Multiple passes of FFT yield a much finer resolution in the lower frequency region. This provides the advantage of a better estimation of the quality factor (or damping) and the amplitude of the frequency response functions at the resonant frequencies. Read online here.

Comparison of Multi-Resolution Spectrum Technology and Regular FFT in Modal Analysis (Product Note #065, 4 pages, 626 KB)
Modal testing and analysis are crucial processes in the product development cycle. Sometimes the testing results are wrong by several magnitudes, especially in the low frequency bands where the frequency resolution is not sufficient. Crystal Instruments’ patented Multi-Resolution (MR) Spectrum technology helps overcome this issue with a unique solution. A modal test is carried out to examine data obtained through regular FFT technology and MR technology to quantify the modal results, such as damping, FRF amplitude, Auto-MAC chart, and mode shapes. Read online here.

Introducing Testing Plan in EDM Modal (Product Note #066, 3 pages, 370 KB)
With Modal Analysis software, all DOFs on the mesh of a structure under test needs be measured. The common practice is using the Input channel setting, with one incremental value to move on to the next batch of measurement points till all DOFs are measured. With the newly released EDM 9.1 Modal software, the new Testing Plan will solve this issue by providing users the complete picture of the testing DOF layout. Also discussed in this note are the details of the Testing Plan feature. Read online here.

Shaped Random & Burst Random Output Excitation in MIMO FRF Modal Analysis (Product Note #069, 3 pages, 422 KB)
Modal testing and analysis are important processes that improve the design of a product. Therefore, it is crucial to ensure testing is carried out with optimal settings. The Shaped Random and Burst Shaped Random output excitation introduced by Crystal Instruments provides unique advantages such as a better estimation of the quality factor, damping and FRF amplitude. This indicates that the obtained modal parameters are more accurate. Read online here.

Modal Data Acquisition Using CoCo Testing Plan on CoCo-80X/90X (Product Note #078, 10 pages, 1.88 MB)
The Modal Data Acquisition (MDA) function for the CoCo-80X/90 allows users to conveniently acquire modal data in the field. The CoCo Testing Plan provides an overview of the measurement process and also provides the ability to customize the measurement entries. Read online here.

Ground Vibration Testing (GVT) of Aircraft Assembly (Product Note #080, 8 pages, 990 KB)
A Ground Vibration Test (GVT) involves carrying out modal analysis of an aircraft and its sub-assembly components to analyze and detect any changes in their structural properties. Read online here.

DAQ (Strain/Temperature)

A New Approach to an Old Sensor – A Spider Tames the Strain Gage (Product Note #025, 4 pages, 2.28 MB)
The Spider-80SG is the first really modern piece of strain gage instrumentation to be commercially developed in decades. Read online here.

Spider-80SG System - Breakout Box Terminal Guide (Product Note #036, 4 pages, 663 KB)
The Spider-80SG is designed to be used with strain gages, with the added advantage of utilizing the same intuitive interface from our EDM software platform. The connection to Spider-80SG breakout box is the final piece of the puzzle and it is a lot simpler than it looks. Read online here.

PID Control Theory (Product Note #071, 10 pages, 2.12 MB)
PID control is a very simple and powerful method for controlling a variety of processes, including temperature. Suppose you have a Process (e.g. a temperature chamber with heater and compressor) which produces a measurable Process Variable y (e.g. the temperature measurement in the chamber). The Process is controlled via a drive signal u that comes from the controller, and your goal is to match the PV to a target value, also known as the Setpoint, or y_sp. Read online here.