The common-mode rejection ratio (CMRR) specification defines how well a differential amplifier rejects common-mode signals. A common-mode signal is the same (common) to both conductors in a typical two conductor connection (signal conductor and ground conductor).
Read MoreIf we perform a roving impact hammer test and impact many points, is there any possibility of missing a mode? Well… you need to be careful where you place the accelerometer.
Read MoreStructural measurements on infrastructure are growing in demand given the aging buildings, bridges, and dams that populate countries around the world. Structural measurements are not the only measurements needed for aging infrastructure, but they do play a role. In the structural measurement category, Crystal Instruments offers products to measure and analyze data for large structure measurements like the measurements done on the Vieux Emosson Gravity Dam.
Read MoreIn any multi-channel DAQ or vibration control system, where each channel is capable of measuring unique sensors, it is necessary to quantify how the channels are different from each other. The channels are designed identically, but component tolerances will cause differences between channels.
Read MoreOn January 17, 2021, Virgin Orbit successfully reached orbit with LauncherOne and deployed 10 CubeSats into Low Earth Orbit for NASA. Prior to the launch, the engineers at Virgin Orbit performed extensive vibration testing using Crystal Instruments vibration controllers with hundreds of channels. A Virgin Orbit dynamics engineer confirmed that “the Spider controllers played an important role in our successful launch,”
Read MoreFounded in 1996, Crystal Instruments designs and manufactures instrumentation products for machine vibration monitoring, dynamic measurement, and environmental testing. The products are developed in Silicon Valley and our modern lab in North Carolina. Crystal Instruments products are thoroughly tested on a variety of vibration shakers and environmental chambers in our lab during the design phase to meet the extreme requirements of military and aerospace applications.
Read MoreWhich shaker excitation is best? Is there any difference? Well ... that's a good question. Let's talk about the different techniques.
Let's discuss the most commonly used excitation techniques for modal analysis today. These are random, burst random, sine chirp and digital stepped sine. But before we discuss the excitation techniques themselves, there are a few basics that we need to discuss first. Let's try to categorize the different techniques and explain when to use which technique. First of all, let's break up the excitations into deterministic and non-deterministic (or random) excitations.
Read MoreWatch Aakash Umesh Mange’s new video featuring the powerful Spider-80SG data acquisition system combined with the versatile EDM DSA software. This simple and efficient package for strain gage measurements can include the Spider-80Xi chassis, which scales up to 512 channels. Contact our team to schedule a demo or to learn more.
Read MoreThere are two steps for converting an analog signal into a digital signal – quantization in time (sampling) and quantization of amplitude. Any signal that goes through the sampling process is subject to the effect of aliasing. The common use of the word ‘alias’ is used to describe a false name or identity, which is similar to how the term is used in signal processing.
Read MoreWatch Darren Fraser’s Multi-resolution Overview presentation from this year’s ESTECH 2021 conference. Viewers will receive a brief review followed by several practical application examples. The Multi-Resolution function is patented by Crystal Instruments.
Read MoreWell, this is an area where I find people often get confused. Many times I hear people say that they have to tweak and tune the excitation frequency so that they get the excitation right at the natural frequency otherwise the frequency will not be identified properly. I also hear people say that the excitation method must have broadband energy at all frequencies otherwise the system will not be excited properly.
Read MoreWith the addition of the output ground isolator to the Spider-80M or Spider-81, there are no additional steps required for the customer to ensure safe and accurate operation when a Spider system is being used to control independent amplifiers and shakers. Previously, users were required to link the amplifier grounds together with a specific type of cable and then connect them to the Earth’s ground, but users did not always follow these instructions.
Read MoreEDM Modal software provides the Playback Analysis feature which allows users to import recorded time signals and process measurement data to obtain the related spectrum signals. This feature allows users to carry out all the field measurements in one attempt before post-processing and analyzing the measured data in detail on a lab PC.
Read MoreThe new Vibration Visualization video produced by Aakash Umesh Mange (Crystal Instruments Applications Engineer) features the creation of 3D models for modal analysis.
Read More
