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A B C D H L M N O P R S T U V W X Y Z
Acceleration The motion of objects can be described by words - words such as distance, displacement, speed, velocity, and acceleration. These mathematical quantities, which are used to describe the motion of objects, can be divided into two categories. The quantity is either a vector or a scalar. These two categories can be distinguished from one another by their distinct definitions:
Acceleration is a vector quantity, which is defined as "the rate at which an object changes its velocity”. An object is accelerating if it is changing its velocity. If an object is not changing its velocity, then the object is not accelerating. Sometimes an accelerating object will change its velocity by the same amount each second. This is referred to as a constant acceleration since the velocity is changing by a constant amount each second. An object with a constant acceleration should not be confused with an object with a constant velocity. If an object is changing its velocity - whether by a constant amount or a varying amount - then it is an accelerating object. An object with a constant velocity is not accelerating.
Acceleration is measured in meters per second per second, a.k.a. meters per second squared (e.g. 100 M/s/s or 100 M/s2).
See also Velocity, Displacement, Compression Deceleration, Compression Acceleration
Acoustics The science dealing with the transmission of sound waves.
Acquisition The process of sampling an analog input waveform, then digitizing the sampled data, and finally storing the samples in memory, or, the process of obtaining a stream of individual data points already in digital format and storing the samples in memory (e.g. ShockClock). The stored values represent the waveform record that can be displayed as a waveform on the display graph.
See also Data Acquisition
Attenuation The process of reducing the amplitude of a waveform without introducing significant distortion.
Auto Zero A feature of ShockClock Software that allows automatic determination of the suspension zero point (i.e. the point of the furthest extension of the suspension) by searching the entire record for the lowest data point and then adjusting the Travel Axis such that zero corresponds to this data point. This feature can be turned off (Manual). In motocross, where front and rear wheels frequently leave the ground, auto zero will cause the Travel Axis zero point to equal the point of full suspension extension.
For all other ShockClock recordings where the suspension does not reach full extension during the test, the Manual Zero procedure should be followed.
Array The collection of data points captured by the ShockClock is stored in a one-dimensional array of data. This array corresponds to a single column of data in a spreadsheet program. In fact, if a recorded ShockClock file is exported from the program, the user will get a single column of data, whereby the number of rows of data corresponds to the number of recorded samples. Since the sampling rate is 240 samples per second (hertz or hz) each data point is 1/240 th of a second apart.
Average See Mean
Average Ride Height ShockClock Software finds the statistical mean (Mu or average) suspension travel of the entire waveform array. This function also returns the standard deviation.
The values are computed using the following formulas: Mean = Sum (X[i])/n, where n is the number of elements in X. Variance = ((X[i] - mean)^2)/w where w is n for population and (n-1) for sample. Standard deviation = sqrt (variance). Baud Rate Baud rate is a measure of the number of times per second a signal in a communications channel varies, or makes a transition between states. One baud is one such change. Thus, a 300-baud modem's signal changes state 300 times each second. In the case of the ShockClock, baud rate is the same as Bits per second (though this not always the case with a modem).
In the ShockClock recorded data file, individual position data point samples (numbers), also referred to as bytes or characters, are composed of 2 bytes per character (number), and 10 bits per byte. If a user records 4.5 minutes of data, there are 64,800 samples (4.5 times 240 samples per second times 60 seconds per minute). Since each sample is two bytes of data containing 20 bits, there are 1,281,600 bits for each 4.5 minute recording (64,800 times 2 bytes times 10 bits). The baud rate used by the ShockClock is 115,200 baud or bps, thus the time to download a 4.5 minute recording is 11.2 seconds (1,281,000/115200).
Bottom Out Cone A hydraulic piston and cup arrangement or super energy absorbent material used in (forks and shocks) to prevent harsh bottoming.
Bottom – Hard A user definable parameter on the ShockClock Software Main Screen. A Hard Bottom is defined as a bottoming occurrence that is harsh enough to cause substantial compression of the bottom out cone material. Set by the user as a percentage of the Travel of the Bottom-out Cone or Bumper. ShockClock Software counts the number of times the suspension travel exceeds this Travel.
Bottom – Soft A user definable parameter on the ShockClock Main Screen. A Soft Bottom is defined as a bottoming occurrence that just barely comes in contact with the Bottom Out Cone. ShockClock Software counts the number of times the suspension travel exceeds this Soft Bottom Travel.
Bottom – Total The total number of bottoming occurrences. # of Soft Bottoms + # of Hard Bottoms = # of Total Bottoms Clickers External adjusters built in to modern forks and shocks that allow the user to make trackside fine tune adjustments to compression and/or rebound damping.
COM Port (a.k.a Serial Port) A communications channel built in to modern personal computers that allows for serial communications between the host PC and other PC’s and serial devices. ShockClock Software supports use of COM ports 1 thru 9.
See also Baud Rate
Compression Velocity (a.k.a. Compression Speed) Wheel Velocity computed during the compression stroke. It is defined in ShockClock Software as a positive number. Therefore, average compression velocity is always a positive number. Compression Speed can be used interchangeably with Compression Velocity though it is not considered cool with suspension gurus. In contrast, a calculation of velocity that results in a negative number indicates that the suspension stroke has entered the rebound phase.
Derivative x(t) Details: The differentiation f(t) of a function F(t) is defined as F(t) = d/dt F(t)
See also Velocity, Rebound Velocity
Compression Acceleration Acceleration measurements taken during the compression stroke of the suspension. You will see maximum compression acceleration as the bump is initially contacted. Positive numbers indicate acceleration, while negative numbers indicate deceleration.
See also Acceleration.
Compression Deceleration Acceleration measurements taken during the compression stroke of the suspension. You will see maximum compression deceleration as the bump is slowing down near it’s peak just before it starts rebounding. Positive numbers indicate acceleration, while negative numbers indicate deceleration.
See also Acceleration.
Cursors Cursors are used to select particular regions of a waveform for measurement. If the In Cursor (green) is located at 0.3 seconds and the Out Cursor (red) is located at 0.6 seconds, only the data between these cursors will be selected for analysis.
See also Cursor Tool
Cursor Tool The cursor tool allows the user to move the cursors.
See also Cursors Data Acquisition DAQ. Process of acquiring data, from analog to digital conversion (A/D) or direct digital input.
The ShockClock is an all-digital device; it acquires position data at each sample point using the Time-of-Flight method. It does this in real-time (240 samples per second), consequently each position data point is calculated in real-time and recorded to memory before the next data point is sampled.
Default The pre-set value. ShockClock Software has program defaults which are the original settings in the software and has user defined defaults. For example ShockClock Software has separate Fork and Shock Travel maximum available travel settings that can be set by the user.
Delta Greek letter that looks like a triangle used to represent a finite change in a variable.
Displacement (a.k.a. Travel, Suspension Travel, Position vs. Time) Distance and displacement are two quantities, which may seem to mean the same thing, yet have distinctly different definitions and meanings.
To understand the distinction between distance and displacement, you must know that a vector quantity such as displacement is direction-aware and a scalar quantity such as distance is ignorant of direction. When an object changes its direction of motion, displacement takes this direction change into account; heading the opposite direction effectively begins to cancel whatever displacement there once was.
The ShockClock transducer wave-guide tube makes linear displacement (Travel) measurements. Velocity and acceleration can be calculated with the first and second derivatives of displacement.
Download The process of transferring data from the ShockClock to the computer.
Dynamic Ride Height (DRH) One of the goals of suspension analysis is to understand the ride height when the bike is being ridden. In ShockClock Software the Travel screen provides a way to evaluate Dynamic Ride Height.
See also Static Ride Height Histogram A bar graph of a frequency distribution in which the widths of the bars are proportional to the classes into which the variable has been divided and the heights of the bars are proportional to the class frequencies. (Source – American Heritage Dictionary)
ShockClock Software does not display a bar graph but simply puts a dot on the graph to represent the height of the bar (the number of samples as a percent of the total samples). This is done for ease of viewing multiple records.
Horizontal Scale Horizontal scale, or x-axis, depicts the time per division of waveforms displayed on the graph.
Hard Bottom See Bottom - Hard
High Speed Compression An external clicker setting found on some dampers that allow the user to make fine-tune adjustments to an internal high-speed damping circuit. Linear Interpolation A ShockClock Software software option (Line or Dots) that draws a line between consecutive data points on the display graph allowing you to view what the waveform actually looks like. Connect waveform dots is a display feature and has no affect on the actual waveform data stored in the saved (.svf) ShockClock Software data file.
Low Pass Filter Filters alter or remove unwanted frequencies. A low pass filter passes low frequencies, but attenuates high frequencies.
Low Speed Compression An external clicker setting found on some dampers that allow the user to make fine-tune adjustments to the internal low speed damping circuit. Mean Mean is the average. It is defined as the sum of the values divided by the number of values. Example: The Mean or Average of the three numbers; (34, 23, 42) is (34+23+42)/3 or 99/3 = 33. Also known as Average.
Median Median applies to the value that represents the point at which there are as many instances above as there are below <average of a group of persons earning 3, 4, 5, 8, and 10 dollars a day is 6 dollars, whereas the median is 5 dollars>.
Mode Mode is the value that occurs most often in a sequence of values. For example, if the input sequence is X = {0, 1, 3, 3, 4, 4, 4, 5, 5, 7} then the mode of X is 4 because that is the value that most often occurs in X.
See also Histogram Noise Noise is an unwanted disturbance (voltage or current) superimposed on a useful waveform. Offset See ShockClock Software Travel Offset. When Manual Zero is selected, the user can enter a value that changes the vertical position of the waveform on the display screen without modifying the waveform itself. The offset value represents an absolute value on the display. The position of a waveform on the display screen is always relative to the offset value. This feature provides a means for calibrating the waveform to the correct zero point, the point of maximum suspension extension.
See also Auto Zero Packing The inability of the suspension to extend prior to encountering the next obstacle due to too much rebound damping.
Pan Tool A tool which allows the user to pan or scroll the waveform on the display. Rebound Velocity (a.k.a. Rebound Speed) Velocity computed during the rebound stroke is defined in ShockClock Software as a negative number. Therefore, average rebound velocity is a negative number. Rebound Speed can be used interchangeably with Rebound Velocity but, as we all know, savvy suspension tuners consider this term uncool. In contrast, a calculation of velocity that results in a positive number indicates that the suspension stroke has entered the compression phase. Derivative x(t) Details: The differentiation f(t) of a function F(t) is defined as F(t) = d/dt F(t)
See also Velocity, Compression Velocity Sample Rate The ShockClock sample rate is 240 samples/sec.
Standard Deviation Standard deviation is the measure of the dispersion or spread of the statistical average of all results for a particular measurement. Standard deviation is represented by the Greek letter sigma (x). In a Gaussian distribution, two Standard Deviations of the mean, is where 68.3 percent of the data points reside. Six Standard Deviations of the mean, is where 99.7 percent of the data points reside.
See also Average Ride Height, Dynamic Ride Height
Soft Bottom See Bottom - Soft
Spring Preload The distance the fork or shock spring is compressed with the suspension fully extended. This is used to set the desired static sag and affects the dynamic ride height.
Static Sag A measurement made to the suspension while the vehicle is not moving. Sag is the distance the suspension compresses from fully extended with the rider on board. Also known as Race Sag.
See also Static Ride Height, Dynamic Ride Height
Static Ride Height (SRH) One of the goals of suspension analysis is to understand the ride height. SRH is similar to a static sag measurement, except the static ride height measurement is taken while the vehicle is moving along on a flat, smooth surface (e.g. asphalt or pavement).
See also Static Sag, Dynamic Ride Height
Suspension Zero Point The point where suspension is at its fullest extension. The zero point reference for the Travel axis. In ShockClock Software, the zero point can be automatically or manually calculated.
See also Offset, Travel Offset,Auto Zero
SS Factor SS factor is the “Speed of Sound” factor used for temperature calibration. To measure distance the ShockClock measures the time it takes for a sound wave to bounce off a target inside a tube (wave guide). Since the Speed of Sound is affected by Temperature the SS Factor is essential to accurate measurement. SS Factor and time-of-flight are used to determine distance.
See also Temperature Calibration Temperature Calibration A ShockClock calibration procedure. Speed of sound is influenced by air temperature and humidity. By performing a temperature calibration, the user can improve the measurement accuracy of the ShockClock if temperature and humidity have changed since the last temperature calibration.
See also Time of Flight, SS Factor
Time-of-Flight Technique for calculating the distance to the target inside the wave-guide tubes by using the timing of the return echo from the target and the speed of sound in air between the target and the ultrasonic transducer.
See also Ultrasonic Transducer
Transducer A device which converts something you want to measure (e.g. distance, pressure, temperature, etc.) into an electrical signal.
See also Ultrasonic Transducer
Travel See Displacement
Travel Offset A method of calibrating the Transducer Travel measurement to the actual Wheel Travel.
See also Offset Ultrasonic Transducer In acoustics this term is used to describe an antenna, which converts electrical energy into sound wave and vice versa.
See also Transducer Velocity The motion of objects can be described by words - words such as distance, displacement, speed, velocity, and acceleration. These mathematical quantities, which are used to describe the motion of objects, can be divided into two categories. The quantity is either a vector or a scalar. These two categories can be distinguished from one another by their distinct definitions:
Velocity is derived from the change in displacement. Just as distance and displacement have distinctly different meanings (despite their similarities), so do speed and velocity. Speed is a scalar quantity, which refers to "how fast an object is moving.” A fast-moving object has a high speed while a slow-moving object has a low speed. An object with no movement at all has a zero speed.
Velocity is a vector quantity, which refers to "the rate at which an object changes its position." As such, velocity is "direction-aware." When evaluating the velocity of an object, one must keep track of direction. It would not be enough to say that an object has a velocity of 55 mi/hr. One must include direction information in order to fully describe the velocity of the object. For instance, you must describe an object's velocity as being 55 mi/hr, east. This is one of the essential differences between speed and velocity. Speed is a scalar and does not keep track of direction; velocity is a vector and is direction-aware. So an airplane moving towards the west with a speed of 300 mi/hr has a velocity of 300 mi/hr, west. Note that speed has no direction (it is a scalar) and velocity is simply the speed with a direction. Meanwhile, the average velocity is often computed using the equation: Average Velocity = change in d / change in t
In conclusion, speed and velocity are kinematics quantities, which have distinctly different definitions. Speed, being a scalar quantity, is the distance (a scalar quantity) per time ratio. Speed is ignorant of direction. On the other hand, velocity is direction-aware. Velocity, the vector quantity, is the rate at which the position changes. It is the displacement or position change (a vector quantity) per time ratio.
Velocity is measured in meters per second (e.g. 4 M/s).
See also Displacement, Acceleration, Compression Deceleration, Compression Acceleration, Rebound Velocity Wave-Guide Tube The telescoping set of tubes which act as means for guiding sound waves emitted from the ultrasonic transducer. X-Axis Horizontal scale, or x-axis, depicts the time per division of waveforms displayed on the graph. Y-Axis The vertical Scale on charts and graphs. Zero Point See Suspension Zero Point
Zoom Tool A tool which allows the user to zoom in, or out, on the waveform display. |
