Glossary

AJAX progress indicator
  • a

  • A/D
    The digital representation of analog voltages in an analog-to-digital (A/D) conversion. The accuracy of the conversion is dependent on the resolution of the system electronics. Higher resolution produces a more accurate conversion.
  • Acceleration
    In physics,acceleration is the change in the rate of speed (velocity) of an object over time.
  • Acceleration Compensation
    A design incorporating components within the sensor to cancel the effect of motion (vibration) on the sensor output signal.
  • Acceleration Sensitivity
    In a pressure transducer or impulse hammer, this refers to the unwanted out- put signal from the sensor in response to vibration in the sensitive axis of the sensor. This parameter is specified in terms of psi/g for pressure sensors and Lbs/g for impulse hammers. Certain Dytran sensors such as(...)
  • Accelerometer
    A sensor used to detect and measure magnitute and direction of an acceleration force (g-force) in reference to its sensing frame. For example, at rest perpendicular to the Earth's surface an accelerometer will measure 9.8 meters/second squared as a result of gravity. If the device is tilted(...)
  • ADC
    Analogue-to-Digital Converter
  • AHRS
    Attitude and Heading Reference SensorA navigation device consisting of sensors on the three primary axes used to measure vehicle direction and orientation in space. The sensor measurements are typically processed by an onboard algorthim, such as an Estimation Filter, to produce a standardized(...)
  • AKF
    Adaptive Kalman FilterA type of Extended Kalman Filter (EKF) that contains an optimization algorithm that adapts to dynamic conditions with a high dependency on adaptive technology. Adaptive technology refers to the ability of a filter to selectively trust a given measurement more or less(...)
  • Algorithm
    In math and science, an algorithm is a step-by-step process used for calculations.
  • Altitude
    the distance an object is above the sea level
  • Angular rate
    The rate of speed of which an object is rotating. Also know as angular frequency, angular speed, or radial frequency. It is typically measured in radians/second.
  • API
    Applications Programming InterfaceA library and/or template for a computer program that specifies how components will work together to form a user application: for example, how hardware will be accessed and what data structures and variables will be used.
  • ASTM
    Association of Standards and Testing
  • ATEX
    The ATEX directive describes what equipment is allowed in an environment with an explosive atmosphere. ATEX derives its name from Appareils destinés à être utilisés en ATmosphères EXplosibles.
  • Attitude
    the orientaion of an object in space with reference to a defined frame, such as the North-East-Down (NED) frame
  • Azimuth
    A horizontal arc measured between a fixed point (such as true north) and the vertical circle passing through the center of an object
  • b

  • Bias
    A non-zero output signal of a sensor when no load is applied to it, typically due to sensor imperfections. It is also called offset.
  • c

  • Calibration
    to standardise a measurement by determining the deviation standard and applying a correction, or cal- ibration, factor
  • CF
    Complementary FilterA term commonly used for an algorithm that combines the readings from multiple sensors to produce a solution. These filters typically contain simple filtering elements to smooth out the effects of sensor over-ranging or anomalies in the magnetic field.
  • Charge Mode
    Sensors which contain piezoelectric crystals but no built-in electronics. These sensors may use quartz or piezoceramics to generate electrostatic charge sig- nals in response to input measurands.
  • Convergance
    when mathematical computations approach a limit or a solution that is stable and optimal.
  • Current Source Power Unit
    A power supply expressly designed for use with integrated electronic piezoelectric accelerometer (IEPE) sensors consisting of an energy source (batteries or DC power supplies) and a constant current element. These units are characterized by stable constant current output and high dynamic(...)
  • d

  • Data Acquisition
    the process of collecting data from sensors and other devices
  • Data Logging
    the process of saving acquired data to the system memory, either locally on the device, or remotely on the host computer
  • Delta-Theta
    the time integral of angular rate expressed with reference to the device local coordinate system, in units of radians
  • Delta-velocity
    the time integral of velocity expressed with refernce to the device local coordinate system, in units of g*second where g is the standard gravitational constant
  • DHCP
    Dynamic Host Configuration Protocol is the standardized networking protocol used on Internet Protocol (IP) networks, which automatically configures devices that are attached to it by assigning and configuring the device IP address.
  • Discharge Time Constant (TC)
    The time required for the output voltage from a sensor or system to discharge to 37% of its original value in response to a zero rise time step function input. This parameter determines low frequency response.
  • Dytran
    Dytran Instruments, Inc. has been serving the test and measurement community with innovative products and outstanding customer service for over thirty years. Their expansive product line includes piezoelectric and DC MEMS accelerometers, piezoelectric force and pressure sensors, impulse(...)
  • e

  • EASA
    European Aviation Safety Agency
  • ECEF
    Earth Centered Earth Fixeda reference frame that is fixed to the earth at the center of the earth and turning about earth's axis in the same way as the earth
  • EKF
    Extended Kalman filterUsed generically to describe any estimation filter based on the Kalman Filter model that can handle non-linear elements. Almost all inertial estimation filters are fundamentally EKFs.
  • EMI
    Electromagnetic InterferenceElectromagnetic Interference is an inductive or radiated disturbance that can create signal degradation on electrical signals, including loss of data.
  • ESD
    Electrostatic Discharge is the sudden flow of electricity that can occur between two charged objects of different potential that come in contact or in close proximity of each other. Static electricity is a common source of ESD.
  • Estimation Filter
    A mathematical algorithm that produces a statistically optimum solution using measurements and references from multiple sources. Best known estimation filters are the Kalman Filter, Adaptive Kalman Filter, and Extended Kalman Filter.
  • Euler angles
    Euler angles are three angles use to describe the orientation of an object in space such as the x, y and z or pitch; roll; and yaw. Euler angles can also represent a sequence of three elemental rotations around the axes of a coordinate system.
  • Event-Based Sampling
    a mode of operation in which the node sampling is started when a sensor measurement value (threshold) is achieved
  • f

  • Fault Monitor Meter
    A DC Voltmeter incorporated into IEPE power units to read the DC voltage at the output of the current source. If a sensor is connected, the meter reads the sensor bias voltage and can be used to indicate open and shorted cables and sensors or to verify normal system operation.
  • FFT
    fast Fourier transform A fast Fourier transform (FFT) algorithm computes the discrete Fourier transform (DFT) of a sequence, or its inverse. Fourier analysis converts a signal from its original domain (often time or space) to a representation in the frequency domain and vice versa
  • Frequency Response
    The highest and lowest frequencies at which measured deviations from a reference sensitivity (usually 100 Hz) lie within a specified error. The deviations are usually specified as -5%, but in some cased -3dB is specified.
  • g

  • GNSS
    Global Navigation Satellite System
  • GPS
    Global Positioning System
  • GSM
    Global System for Mobile Communications
  • Gyroscope
    a device used to sense angular movements such as rotation
  • h

  • Heading
    an object's direction of travel with reference to a co-ordinate frame, such as latitude and longitude
  • HUMS
    Health & Usage Monitoring System
  • i

  • IEPE
    Integrated electronic piezoelectric (IEPE) accelerometers are a class of piezoelectric accelerometers that incorporate an electronic amplifier and use a single two-pole coaxial connector for both power input and signal output
  • IMU
    Inertial Measurement Unit
  • INS
    Inertial Navigation System
  • k

  • Kalman Filter
    a linear quadratic estimation algorithm that processes sensor data or other input data over time, factor- ing in underlying noise profiles by linearizing the current mean and covariance to produces an estimate of a system’s current state that is statistically more precise than what a single(...)
  • l

  • LAN
    Local Area Network
  • Linearity
    Actually the non-linearity or deviation from a straight line in a plot of output amplitude vs. input amplitude of a sensor or system. At Dytran, we use the popular zero based best straight line method of determining linearity. Full scale is determined, a zero based best straight line plot of(...)
  • LIVM
    Also known as IEPE Low Impedance Voltage Mode, Dytran’s Trademark describing its line of piezo- electric sensors with built-in impedance converting electronics.
  • LORD MicroStrain
    LORD MicroStrain offer a range of high quality sensors and systems in three categories Inertial - The LORD MicroStrain® series of advanced inertial sensors provide a range of measurement options including orientation (pitch, roll, yaw or azimuth), single axis or dual axis inclination,(...)
  • LOS
    Line of SightDescribes the ideal condition between transmitting and receiving devices in a wireless network. As stated, it means they are in view of each other with no obstructions.
  • LXRS
    Lossless Extended Range Synchronized is the proprietary LORD Sensing data communications protocol used in the wireless sensor network. The wireless protocol is a 2.4GHz IEEE 802.15.4-compliant communication architecture featuring LXRS® (Lossless eXtended Range Synchronized) data. LXRS(...)
  • m

  • Magnetometer
    A type of sensor that measures the strength and direction of the local magnetic field with refernce to the sensor frame. The magnetic field measured will be a combination of the earth's magnetic field and any magnetic field created by nearby objects.
  • Mass Loading
    The change in actual sensitivity of a back-to-back accelerometer when loaded with masses significantly different from the transfer standard with which it was originally calibrated. Correction curves of actual sensitivity vs. frequency are referred to as “mass loading correction curves”.
  • MEMS
    Micro-Electro-Mechanical System
  • MIP Monitor
    MIP Monitor is PC software specifically for LORD Microstrain inertial products. Configure inertial nodes, start sampling, and view their data in real time. MIP packets can also be viewed in their raw form to aid in development of custom software.
  • MRI
    Magnetic Resonance Imaging
  • MSCL
    The MicroStrain Communication Library (MSCL) makes it simple to write code that interacts with our Wireless sensors. It is hosted on GitHub and is completely open source under the MIT License. Full documentation, example code, and a quick start guide are provided to help you get started. If(...)
  • n

  • NED
    North-East-Down
  • Node
    The node is the wireless transceiver to which the sensor(s) is connected, providing communication with the gateway. The G-Link® -LXRS®, V-Link® -LXRS®, and SG-Link® -LXRS® are examples of nodes manufactured by LORD MicroStrain®.
  • Node Commander
    Node Commander is the legacy PC software for Wireless products. Note: Node Commander will no longer be updated with new features or product support. It is recommended that SensorConnect be used for improved data collection, analytics, and configuration.
  • o

  • OEM
    Original Equipment Manufacturer
  • Offset
    A non-zero output signal of a sensor when no load is applied to it, typically due to sensor imperfections. Also called bias.
  • p

  • PCL
    Pitch Control Link
  • Periodic Burst Sampling
    a mode of operation in which the node is sampled for a fixed window of time (burst) and then repeats that window at set intervals. The burst duration and time between bursts is configurable. Also referred to as burst sampling.
  • Phase Shift
    The difference in phase angle between input measured and output electrical signal, measured in degrees. The response may lag or lead the input.
  • Picocoulomb
    A measure of electrostatic charge output from piezoelectric sensors. 1 Picocoulomb= 1 x 10-12 Coulomb.
  • Pitch
    In navigation pitch is what occurs when vertical force is applied at a distance forward or aft from the cen- ter of gravity of the platform, causing it to move up or down with respect to the sensor or platform frame origin.
  • PVA
    Position, Velocity and Attitude
  • q

  • Quaternion
    Mathematical notation for representing orientation and rotation of objects in three dimensions with respect to the fixed earth coordinate quaternion. Quaternions convert the axis–angle representation of the object into four numbers and to apply the corresponding rotation to a position vector(...)
  • r

  • Resolution
    In digital systems, the resolution is the number of bits or values available to represent analog voltages or information. For example, a 12-bit system has 4096 bits of resolution and a 16-bit system has 65536 bits.
  • Resonant Frequency
    Also called “natural frequency”. The lowest frequency of a second order system (spring-mass system) which satisfies the solution to the differential equation of motion
  • RF
    Radio Frequency
  • Rise Time
    The time required for a sensor or system to respond to an instantaneous input step function, measured from the 10% to 90% points on the response wave- forms.
  • RMS
    Root Mean Square. In AC theory, this is the “heating value” of an AC wave- form and it is equal in amplitude to .707 times the peak value of the waveform. Most AC meters are calibrated to read in RMS. To obtain the peak value of the waveform, multiply the RMS value by 1.414.
  • Roll
    In navigation roll is what occurs when a horizontal force is applied at a distance right or left from the cen- ter of gravity of the platform, causing it to move side to side with respect to the sensor or platform frame origin.
  • RPY
    Roll, Pitch & Yaw
  • RS232
    a serial data communications protocol
  • RSSI
    Received Signal Strength Indication is a measurement of the transmission power in a radio signal. It is measured in decibels with reference to 1 milliWatt (dBm).
  • RTC
    Real Time Clocka computer clock that keeps track of the current time
  • RTD
    Resistance Thermometer Detector
  • s

  • Sampling Mode
    the type of sampling that is being utilized, such as event-triggered, continuous, or periodic. The nodes have several sampling modes that employ these types of sampling.
  • Sampling Rate
    the frequency of sampling
  • SCBG
    Semiconductor Bandgap (also known as the Gallium Arsenide / GaAs)
  • SDK
    Software Development Kit
  • Sensitivity
    The scale factor of a sensor or system, measured in terms of change in output signal per change in input measured. Accelerometer sensitivity is expressed in terms of mV/g or pC/g, pressure sensor sensitivity is expressed in terms of mV/psi or pC/psi and force sensor sensitivity is expressed in(...)
  • Sensor Bias
    When IEPE sensors are supplied with constant current, a DC voltage bias exists at the center conductor of the sensor connector. The output signal is superimposed on this DC bias. The power unit extracts the signal from this bias by various means, effectively “blocking” it. The normal range for(...)
  • SensorCloud
    SensorCloud allows you to upload unlimited amounts of Wireless data to view and analyze from anywhere in the world. Analyze your data with MathEngine, which allows you to run algorithms on your data. Take it a step further and write your own Python scripts, all in the cloud. Plug and(...)
  • SensorConnect
    SensorConnect is the main PC software for Wireless sensor configuration and data collection from LORD MicroStrain Configure nodes, start networks, and collect and analyze data in real-time from our Wireless products. Using the intelligent data collection and graphing algorithms, you are(...)
  • Slope
    When describing a mathematically linear relationship, the slope is the steepness of the line that represents that relationship on a graph. The equation of a straight line is: y = mx+b, where x is the x- axis coordinate, y is the y-axis coordinate, m is the slope, and b is the offset.
  • STA
    Synchronous Time Average
  • Streaming
    Streaming is a sampling mode in which all active channels (and the sensors attached to them) are measured, and the acquired data is transmitted to the gateway and software. The data is not written to non-volatile memory during streaming. Streaming can either be finite (have a user defined(...)
  • Synchronised Sampling
    a sampling mode that automatically coordinates all incoming node data to a particular gateway. This mode is designed to ensure data arrival and sequence.
  • t

  • Thermal Coefficient of Sensitivity
    The measured change in the sensitivity (of scale factor) of a sensor, from its room temperature (reference) value to the value at a higher or lower stabilized ambient temperature. This parameter is measured in percent of change in sensitivity per degree of temperature deviation.
  • Transient Thermal Response
    The time history of the change in output (voltage or charge) from a sensor resulting from a sudden change in ambient temperature.
  • Transverse Sensitivity
    The output of an accelerometer in response to motion in directions orthogonal to its sensitive axis, expressed as a ratio of measured output to cross axis input, in percent.
  • Triboelectric Noise
    The unwanted generation of electrical charges by the chafing together of insulation layers inside electrical cables during flexing caused by vibration and shock induced motion.
  • u

  • UAV
    Unmanned Aerial Vehicle
  • UTC
    Coordinated Universal Timethe primary time standard for world clocks and time. It is similar to Greenwich Mean Time (GMT).
  • UUV
    Unmanned Underwater Vehicle
  • v

  • Vector
    a measurement with direction and magnitude with refernce from one point in space to another
  • Velocity
    The rate of change of position with respect to time. Also called speed.
  • VRU
    Vertical Reference Unit
  • w

  • WAAS
    Wide Area Augmentation SystemAn air navigation aid developed to allow aircraft to rely on GPS for all phases of flight, including pre- cision approaches to any airport.
  • WGS
    World Geodetic Systema protocol for geo-referencing such as WGS-84
  • WLPI
    White Light Polarization Interferometry
  • WSDA
    Wireless Sensor Data Aggregator
  • WSN
    Wireless Sensor NetworkWireless Sensor Network describes a distribution of sensors and data acquisition equipment that autonomously monitors environmental characteristics, such as temperature, pressure, and strain.
  • y

  • yaw
    In navigation yaw is what occurs when rotational force is applied at a distance forward or aft from the center of gravity of the platform, causing it to move around the center axis of a sensor or platform frame origin.
  • z

  • Zero Shift
    The change in baseline level of the output voltage of an accelerometer immediately after a mechanical shock.