Glossary

- Symbols -
.SnP	.SnP data format creates component data files that describe frequency dependent linear network parameters for n port components. This format is used to import/export S-parameter data. Also see Touchstone
g (Gamma)	Gamma is the complex propagation constant. g = a + jb where a is the attenuation per length and b is related to the wave velocity.
G (Gamma)	In network analysis, G (Gamma) is the ratio of the reflected voltage signal level to the incident signal voltage level (G = Vreflected/Vincident). It is the complex reflection coefficient that consists of magnitude (r) and phase (F) components.
d (delta)	Skin depth. A measure of the depth of current penetration towards the center of a conductor from the perimeter at a particular frequency.
Tan d	Loss tangent of a material. This is mostly a measure of the ease at which electric fields penetrate (or propagate through) a material. Typical values in electronic materials are in the 0.001 - 0.025 range.
er	er is the relative permittivity of a material (also referred to as dielectric constant), which is mostly a measure of a material's density. Most insulators used in electronics are in the range of 3 to 10. eo is the permittivity of air, which is 8.85e-12.
m (mu)	m (mu) is the relative permeability of a material. A measure of how easily a material is magnetized. Most all non-magnetic materials have a value of 1. mo is the permeability of a vacuum, which is 4pe-7.
mW	1. Microwave. See Microwave 2. Microwatts (one-millionth of a watt)
r (rho)	1. (Material properties) Bulk resistivity of a material (e.g. Cu = 1.7e-8 ohm-meters). A measure of a materials resistance to current flow. 2. (Network analysis) Magnitude portion of the complex reflection coefficient (G). The magnitude of the ratio between the reflected and the incident voltages.
s (sigma)	1. (Material properties) Bulk conductivity of a material (the inverse of resistivity). 2. (Statistics) Standard deviation, which is the measure of the dispersion or spread of the statistical average of all results for a particular measurement. See Standard Deviation
t (tau)	In network analysis, t (tau) is the magnitude portion of the complex transmission coefficient (T). The magnitude of the ratio between the transmitted and the incident voltages.
T (Tau)	T (Tau) is the ratio of the transmitted voltage signal level to the incident signal voltage level (T = Vtransmitted/Vincident). It is the complex transmission coefficient that consists of magnitude (t) and phase (ø) components.
ø (phi)	In network analysis, ø (phi) is the phase angle portion of the complex transmission coefficient (the ratio between the transmitted and the incident voltages).
F (Phi)	In network analysis, F (Phi) is the phase angle portion of the complex reflection coefficient (the ratio between the reflected and the incident voltages).
- Numeric -
2-Level (PAM2)	A 2-level data signal generates 1 bit per symbol.
4-Level (PAM4)	A 4-level data signal generates 2 bits per symbol consuming half the bandwidth of a 2-level signal.
Active Device	An active device is a device that requires a source of energy to add gain to a signal or control a circuit. Examples of active device are LEDs, transistors, and integrated circuits.
American Wire Gauge (AWG)	AWG is the standard for determining wire size. The gauge number varies inversely with the diameter of the wire.
Analog	Analog is a method of transmitting information. Analog is characterized by adding data of continuously varying frequency or amplitude to carrier waves. Digital transmissions depend on the varying between two discrete levels. An analog signal responds to changes in light, sound, heat and pressure.
Arbitrary Bitstream (ABS)	Arbitrary Bitstream is a random-like bit stream used to generate eye diagrams. The "number of bits" and the "number of patterns" user inputs is used to create the ABS. The "number of bits" entry identifies the number of unique bit patterns that are available. The "number of patterns" identifies the number of these unique bit patterns that are used to create the eye diagram. Using both of these values, a random number generator selects unique bit patterns until the appropriate number of bit patterns is identified. Each of these unique bit patterns are then used to create the eye diagram, one bit pattern at a time.
Attenuation	Attenuation is a reduction in signal amplitude. The difference between transmitted and received power due to loss through equipment, lines, or other transmission devices; usually expressed in decibels.
Averaging	Averaging is a waveform acquisition mode in which the instrument acquires waveforms from multiple data acquisitions and then averages the waveforms together, point by point. Averaging significantly reduces noise and improves resolution of the displayed waveform. The noise sources can average to zero over time while the underlying waveform is preserved. The effective resolution of the displayed waveform increases as more acquisitions are averaged together. This improves the stability of both the display and waveform measurements.
Backplane	A backplane is a circuit board that has sockets and circuitry and serves as an interconnection between other cards (circuit boards) that are plugged into the sockets. Typically refers to a special, heavy-duty printed or discrete wired circuit board. In terms of PCs, this circuit board is synonymous with the motherboard. Typically the backplane is designed for a longer life than the daughter cards and has improved signal integrity. It is often manufactured out of more expensive PCB materials. Backplanes are either active (also called intelligent) or passive. Active backplanes also contain a microprocessor or circuitry that performs computing functions. Passive backplanes have no computing circuitry.
Balanced Device	A balanced device is composed of two nominally identical halves. Practically speaking, the signals on each side of the device can have any relative amplitude and phase relationship, but they can be decomposed into a differential-mode (anti-phase) component, and a common-mode (in-phase) component.
Balanced Measurement System (BMS)	The BMS is the predecessor to the Physical Layer Test System. The BMS acquires 2-, 3-, or 4-port frequency domain test data using a network analyzer and multiport test set and displays the data in either frequency or time domain. ATN Microwave originally developed this product before being acquired by Keysight Technologies.
Balun	A balun (balanced-unbalanced) is an impedance matching device used to connect a balanced line or device with an unbalanced coaxial line or device.
Bandwidth	In analog terms, bandwidth is the difference between the maximum and minimum frequency. It is measured in hertz (Hz). In digital terms, bandwidth is the data transmission capacity of an electronic circuit or system. It is measured in bits (or bytes) per second.
Baud	Baud refers to the number of level transitions through a device in a one second period. One baud is one state-transition or level-transition per second. In the past, baud was the accepted units for data transmission rate. However, bits per second (bps) is replacing baud as a more accepted unit of measure.
Bit	Bit is an abbreviation of the term "Binary Digit". A bit is the smallest unit of computer data. It is a single digit number, either a one or a zero. A collection of bits makes up a group called a "byte" or a "word" which is equivalent to one alphanumeric character.
Bit Pattern	A bit pattern is a series of bits that are convolved with a time domain impulse response of a system to create an eye diagram.
Bits Per Second (bps)	Bits per second (bps) is the unit of measure for the rate or speed of data transfer. Refer to Data Transfer Rate
Bit Rate	Bit rate is the number of bits that are sent through a circuit per second, calculated as inverse of the bit period (1/bit period). The bit period is a measure of the horizontal opening of an eye diagram at the crossing points of the eye.
Broadband	Broadband is high-speed transmission. Although not a standard, it commonly refers to computer data and telecommunication rates in excess of 1.544 Mbps, the rate of T1 lines. Broadband often refers to Internet access using cable modems and DSL. A broadband network can carry voice, video and data all at the same time.
Bus	A collection of wires in a cable (or copper traces on a circuit board) that serve as a common data path between multiple devices. The bus is used to transmit signals (data, status, and control) between the devices that share the bus. Bus typically refers to a parallel data transmission structure (1 clock, multiple data channels). As designs transition from parallel to serial with data rates in excess of 1 Gbps barrier, the terms "Channel" or "Lane" may become more commonly used than "Bus".
Byte	A byte is a unit of data that is eight bits in length. A byte represents a single character, such as a letter, number, or symbol. "Byte" may be preceded with Kilo (Kilobyte) for 1 thousand bytes, Mega (Megabyte) for 1 million bytes, or Giga (Gigabyte) for 1 billion bytes.
C (capacitance)	Capacitance (farads) is a measure of stored electric charge.
Calibration	In network analyzer systems, calibration is the process of removing systematic errors from measurements (also known as accuracy enhancement or error correction). See SOLT Calibration and Thru Reflect Line (TRL) Calibration
Calibration Kit	A calibration kit contains hardware and software required to perform error correction on a network analyzer for a specific measurement and/or test set.
Characteristic Impedance (Zo)	Characteristic impedance is the impedance looking into the end of an infinitely long lossless transmission line.
Coaxial Cable (Coax)	Coaxial cable is a cable with the inner solid or stranded wire acting as the primary conductor wire that is surrounded by a solid or braided metallic shield serving as the ground with an insulating medium between the two.
Common Instrumentation Transfer and Interchange File (CITIfile)	CITIfile is an ASCII data format that is useful when exchanging data between different computers and instruments. CITIfile is a data storage convention designed to be independent of the operating system, and therefore may be implemented by any file system that has the ability to transfer ASCII files. A typical CITIfile package is divided into two sections, the header and the data. The header section contains information about the data that will follow. It may also include information about the setup of the instrument that measured the data. The Data is a numeric array of data that is arranged with one data element per line. The data section may contain more than one array of data. Arrays of data start after the BEGIN keyword, and the END keyword follows the last data element in an array.
Common Mode	Common mode is the in-phase mode of a balanced measurement.
Continuous Sweep Mode	Continuous sweep mode is the vector network analyzer condition where traces are automatically updated each time trigger conditions are met.
Crossing Percentage (Eye)	Crossing percentage (eye) is a measure of the amplitude of an eye diagram crossing points relative to the one level and zero level. Crossing percentage = 100 (Vcross - Vzero level) / (Vone level - Vzero level))
Crossing Point (Eye)	Crossing point (eye) is the point in time, in an eye diagram, where the rising edge of a waveform intersects with the falling edge.
Crossstalk	Crosstalk is the occurrence of a signal at one port of a device being affected by a signal in any other path. Isolation is a description of each signal path (or channel's or lane's) immunity from noise from other channels or outside sources.
Data Sharing	Data Sharing is a Physical Layer Test System utility that is used to overlay the plot of one measurement parameter over the plot of the same measured parameter from a different data set so that differences and similarities can be readily seen.
Data Transfer Rate	The number of bits that are sent during a one second period. This is generally associated with high-speed serial data transfer systems. The base unit of measure is bits per second (bps). "bps" may be preceded with K (Kbps) for 1000 bits per second, M (Mbps) for 1,000,000 bits per second, or G (Gbps) for 1,000,000,000 bits per second.
De-embedding	De-embedding eliminates the effects (loss, phase shift, mismatch) of the test fixture, connectors, cables and other equipment. De-embedding combines these effects with the errors determined during a coaxial calibration to account for errors of all of the equipment required to measure the DUT. This characterized data is mathematically removed from the measured data, thus ensuring that only the effects of the DUT are displayed. This technique is very useful for measuring DUTs that require fixtures, such as wafers and packages.
Deterministic Jitter	Deterministic jitter is the deviation of a transition from its ideal time caused by reflections relative to other transitions or events happening on neighboring lines. It is pattern dependent, occurring in a predictable, systematic manner due to the varying data patterns. It adds linearly and is measured in peak-to-peak means.
Differential Mode	Differential mode is the anti-phase mode of a balanced measurement.
Direct Current (DC)	Direct Current is electron flow at zero hertz.
DUT	DUT is an acronym commonly used for the device under test.
Dynamic Range	Dynamic range specifies the amplitude (size) of a signal that can be input into the instrument at a particular vertical scale without overdriving the front end, resulting in an inaccurate acquisition of data.
Electromagnetic Interference (EMI)	Any electromagnetic energy created by an outside source that interrupts, degrades, or limits the performance of electronics equipment or systems. It can result from unintentional sources, such as spurious emissions and responses, or it can be induced intentionally, as a form of electronic warfare.
Electronic Calibration (ECal)	Electronic calibration performs a SOLT (Short-Open-Load-Thru) calibration on the Physical Layer Test System using an ECal module controlled by the N1930A software. The ECal module is a state-of-the-art, solid-state device with programmable and highly repeatable impedance states that provide consistent calibrations and eliminate operator errors while bringing convenience and simplicity to your calibration routine. The PLTS uses the N4430A and N4430B ECal modules to calibrate to maximum frequencies of 6 GHz and 9 GHz, respectively.
Ethernet	Ethernet is a network that adheres to the IEEE 802.3 Local Area Network standard.
Extinction Ratio	Extinction ratio is the ratio of the one level and the zero level of an eye diagram. This measurement is made in a section of the eye referred to as the eye window.
Eye Amplitude	Eye amplitude is the difference between the logic 1 level and the logic 0 level histogram mean values of an eye diagram.
Eye Diagram or Pattern	An eye diagram is a waveform display that has a specific number of bits sliced and folded on top of one another to produce an overlaid display. In PLTS, the eye diagram is produced by convolving the time domain impulse response of SDD21 with a repetitive bit pattern, which is wrapped.
Eye Height	Eye height is a measure of the vertical opening of an eye diagram.
Eye Opening Factor	Eye Opening Factor is a measure of the vertical opening of an eye diagram.
Eye Width	Eye width is a measure of the horizontal opening of an eye diagram.
Eye Window	The eye window provides the time boundaries within which signal parameters for eye diagrams are measured.
Fall Time	Fall time is the transition time for the falling edge of a pulse to decrease from 90% of its peak value to 10% of its peak value.
Fast Fourier Transform (FFT)	The Fast Fourier Transform is an algorithm for transforming data from the time domain to the frequency domain.
Fixturing	Fixturing is the process of using a test fixture as an interface between your test equipment and your device under test (DUT). See Test fixture
Forward Orientation	Forward orientation is the direction an adapter is inserted into the Physical Layer Test System equipment setup. An adapter is "forward oriented" when the end labeled "1" at the PLTS test cable and the end labeled "2" will be connected to the DUT. See Orientation
FR-4	FR-4 is a common epoxy resin glass laminate that is used as substrate for PC boards.
Frequency	Frequency is the number of periodic oscillations, vibrations, or waves per unit of time, usually expressed in cycles per second, or Hertz (Hz).
Frequency Accuracy	Frequency accuracy is the uncertainty with which the frequency of a signal or spectral component is indicated, either in an absolute sense or relative to another signal or spectral component. Absolute and relative frequency accuracies are specified independently.
Frequency Band	Frequency band is a term that identifies a range of frequencies in the electromagnetic spectrum.
Frequency Range	Frequency range is the range of frequencies over which a device or instrument performance is specified.
Frequency Response	In frequency mode, frequency response is the peak-to-peak variation in the displayed amplitude response over a specified center frequency range. Frequency response is typically specified in terms of dB, relative to the value midway between the extremes.
Frequency Span	Frequency span is represented by the horizontal axis of the display. Generally, frequency span is given as the total span across the full display. Sometimes frequency span (scan width) is represented as a per-division value.
Functions (Math)	Functions (Math) are mathematical operations (such as Add, Subtract, Multiply, Integrate, Versus for XY plots) that can be performed on input waveforms, stored waveform memories, or even other functions.
G (conductance)	Conductance is the resistive component in shunt impedance from a signal to ground or across transmission lines.
Gating	Gating enables a network analyzer to remove displayed data between specific intervals. This function is used in the time domain mode to separate device connector and coupling effects.
General Purpose Interface Bus (GPIB)	The GPIB bus provides an easy and reliable interface between GPIB instruments and a computer GPIB interface card using GPIB cables. These cables are available in various lengths. Multiple cables can be daisy-chained together to simplify the system interconnection.
Gigabits per Second (Gbps)	Gigabits per second or one billion bits per second. Refer to Data Transfer Rate
Gigabyte	Gigabyte is generally defined as either 1,000 or 1,024 megabytes. See Byte
Gigahertz (GHz)	One billion cycles per second. Refer to Frequency
Golden Device	A device under test that is measured and its test results are saved for comparison against future measurements as a metric of calibration quality and repeatability.
Graticule	Graticules are the horizontal and vertical grid lines making up the plot area. Graticules allow for easier, more accurate viewing of the waveform data and markers.
Group Delay	A measure of the transit time of a signal through a DUT versus frequency. Group delay can be calculated by differentiating the DUT's insertion-phase response versus frequency. -D Phase / (Df) (360) where, D Phase is the phase difference between two adjacent frequencies, Df.
Hertz (Hz)	One cycle per second. Refer to Frequency
Horizontal Scale	Horizontal scale is an instrument control that controls the x-axis (time or frequency per division) of displayed waveforms. Horizontal scale is often referred to as sweep speed in some instruments.
HSPICE	HSPICE is a circuit simulation tool based on SPICE (Simulation Program for Integrated Circuits Emphasis). Physical Layer Test System data can be exported in an HSPICE format. HSPICE is a product of Synopsys, Inc.
Hub	A hub is a central connection point for devices in a network. It receives a signal from one device and retransmits the signal to one or more devices. Passive hubs are data conduits that just connect devices, adding nothing to the data passing through them. Active hubs regenerate the data bits in order to maintain a strong signal. Intelligent hubs have additional features that monitor traffic. Switching hubs read the destination address of each packet of information and then forward the information to the proper destination.
IEEE 802	IEEE 802 is a series of documents that define the standards for Local and Metropolitan Area Networks. The Institute of Electrical and Electronics Engineers, Inc. (IEEE) publish these standards. The following is a list of subjects that the standards define: IEEE Std 802: Overview and Architecture IEEE Std 802.1: Bridging and Management IEEE Std 802.2: Logical Link Control IEEE Std 802.3: CSMA/CD Access Method IEEE Std 802.5: Token Ring Access Method IEEE Std 802.6: DQDB Access Method IEEE Std 802.7: Broadband LAN IEEE Std 802.10: Security IEEE Std 802.11: Wireless LANs IEEE Std 802.12: Demand Priority Access Method IEEE Std 802.15: Wireless Personal Area Networks IEEE Std 802.16: Broadband Wireless Metropolitan Area Networks
Imaginary	Imaginary is a format that displays the reactive portion of the measured data on a Cartesian format. This is the corollary to the Real format where the resistive portion is displayed.
Impedance	Impedance is the ratio of voltage to current at a port of a circuit, expressed in ohms.
Insertion Loss	Insertion loss is the difference between the power measured before and after the insertion of a device or the attenuation between the input and output of a device.
Inverse Fast Fourier Transform	The Inverse Fast Fourier Transform is an algorithm for transforming data from the frequency domain to the time domain.
Isolation	Isolation is the specification or measure of the immunity that one signal has to being affected by another adjacent signal. Low isolation in digital systems manifests itself as crosstalk or noise on the victim channel.
Jitter	Jitter is the measure of the time variances of the rising and falling edges of an eye diagram as these edges affect the crossing points of the eye.
K28.5	K28.5 is an industry standard, finite length, specific bit sequence than includes a comma character and 8B/10B encoding.
Kilobits per Second (Kbps)	Kilobits per second or one thousand bits per second. Refer to Data Transfer Rate
Kilobyte	Kilobyte is generally defined as either 1,000 or 1,024 bytes. See Byte
Kilohertz (kHz)	One thousand cycles per second. Refer to Frequency
L (inductance)	Inductance (henries) is stored magnetic charge.
Line Reflect Match (LRM) Calibration	LRM calibration is a calibration type that utilizes three simpler, more convenient standards to define the error terms to be removed from the measurement. The measured parameters of the Line, Reflect, and Match standards in a LRM calibration kit provides the same information as a SOLT calibration via a different algorithm. A calibration at the coaxial ports of the test system removes the effects of the system and any cables or adapters before the fixture; however, the effects of the fixture itself are not accounted for. An in-fixture calibration is preferable, but SOLT standards may not be readily available to allow a conventional full 4-port calibration at the desired measurement port of the device.
Line Reflect Match (LRM) Calibration (continued)	LRM calibration is convenient because calibration standards can be fabricated for the specific measurement environment. The characteristic impedance of these fabricated transmission lines can be determined from the physical dimensions and substrate's dielectric constant. The LRM calibration relies on the characteristic impedance of simple transmission lines.
Linear Device	A linear device is a device that only modifies phase or magnitude of frequency components present on the input signal.
Linear Mag	Linear Mag is the display mode in which the vertical deflection is presented in linear function (vertical divisions are uniformly space). This format is used for unit-less measurements, such as reflection coefficient magnitude and for linear measurement units. It is used to display conversion parameters and time domain transform data.
Load	1) A load is a one-port microwave device used to terminate a path in its characteristic impedance. 2) A load is a calibration standard that is an actual line that terminates a path with the path's characteristic impedance. See SOLT Calibration
Load Match	Load match is a measure of how close the device's terminating load impedance is to the ideal transmission line impedance. Match is usually measured as return loss or standing wave ratio (SWR) of the load.
Log Display	Log display (logarithmic display) is the display mode in which vertical deflection is a logarithmic function of the input signal amplitude. The display calibration is set by selecting the value of the reference level position and scale factor in dB per division.
Log Mag	Log Mag is the display mode in which vertical deflection is a logarithmic function of the input signal amplitude. Log Mag is also called logarithmic display.
Low Voltage Differential Signals (LVDS)	LVDS is a high-speed (gigabits per second), low-noise, low-power, low voltage method of transmitting digital information. The differential signals are transmitted over two traces or over balanced cable using a very low voltage swing between high (binary 1) and low (binary 0). The low swing voltage means that data can switched very quickly which provides the higher data transfer rate. LVDS uses the two traces (cables) for two signals, which are 180 degrees out of phase from each other. Thus, the noise travels at the same level making filtering very effective. This mode of transmission is often used with SCSI hardware.
Magnitude	Magnitude is the amplitude of a signal measured in its characteristic impedance without regard to phase.
Markers	Marker lines are used to determine the position or amplitude of the selected point on the display graticule. Marker lines can be positioned on either: · A selected waveform source (input channel, waveform memory, or waveform function) · Independently, anywhere on the display graticule
Mask	A mask is a template consisting of numbered, shaded regions on the instrument display screen. The input waveform must remain within these regions in order to comply with industry standards. The waveforms that intrude these regions are mask violations.
Masking	Time domain responses are most accurate closest to the location of the source. A discontinuity in the DUT will reflect some power back to the source, meaning less power is transmitted to the rest of the DUT. This loss of power going away from the source is referred to as masking, and allows the true impedance of the next discontinuity to be misrepresented.
Mask Test	A mask test is a test process used to verify that waveforms generated by a test device conform to industry standards.
Measurement Uncertainty	Measurement uncertainty is the quantified amount of error in a measurement situation. Calibrations are intended to reduce the amount of uncertainty. The following are sources of measurement errors that lead to uncertainty: · Systematic errors (imperfections in calibration standards, connectors, cables, and instrumentation) · Random errors (noise, connector repeatability) · Drift (source and instrumentation)
Megabits per Second (Mbps)	Megabits per second or one million bits per second. Refer to Data Transfer Rate
Megabyte	Megabyte is generally defined as either 1,000 or 1,024 kilobytes. See Byte
Megahertz (MHz)	One million cycles per second. Refer to Frequency
Microprocessor Unit (MPU)	A microprocessor is a computer (central processing unit, CPU) on a single digital semiconductor chip. It performs math and logic operations and executes instructions from memory. A microprocessor requires a power supply, clock and memory to function as a computer.
Microstrip	Microstrip is a planar transmission line that consists of a thin conductive trace (or traces) printed or etched on the top side of an insulating substrate with a parallel ground plane on the other side of the substrate. Microstrips are also used for antennas and antenna arrays.
Microwave	Microwave is the frequency band where radio waves are very short. This band ranges from approximately 1 GHz to 40 GHz, within the UHF, SHF, and EHF frequency bands.
Mixed Mode S-parameters	Mixed-mode S-parameters describe the performance of a device when measuring a balanced device. Each balanced port will support both a common-mode and a differential-mode signal.
Mode Conversion	Mode conversion is a measure of isolation when making balanced S-parameter measurements where there is a: · Differential-mode stimulus with a common-mode response (SCDXX). Mode conversion in this configuration can result in device asymmetry and generation of electromagnetic interference (EMI). · Common-mode stimulus with a differential-mode response (SDCXX). Mode conversion in this configuration can result in device asymmetry and susceptibility to EMI.
Near End Crosstalk (NEXT)	Signal distortion as a result of signal coupling from one wire pair to another wire pair at various frequencies. When measuring the NEXT, it is usually the resultant voltage excursion expressed as a percentage of the incident voltage swing of the culprit line.
Network Analysis	Network analysis is the characterization of a device, circuit, or system derived by comparing a signal input going into the device to a signal or signals coming out from the device.
Noise	Noise is an unwanted disturbance (voltage or current) superimposed on a useful waveform.
Non-insertable Calibration	A non-insertable calibration is one in which the test port connectors are of the same gender (male-to-male or female-to-female).
Non-linear Device	A non-linear device is a device in which frequency components are added or deleted (not just modified) from the original signal.
Non-Return to Zero (NRZ) Signaling	NRZ signaling is used in differential signaling to describe that swing about some offset voltage do no return to 0 volts.
Normalize	To normalize is to subtract one trace from another to eliminate calibration data errors or to obtain relative information.
Offset	Offset is used to move or set off a determined amount. Used in instruments for offsetting frequencies, limits, delay, loss, impedance, etc.
One Level	One level is a measure of the mean value of the logical 1 of an eye diagram.
Open	An Open is a calibration standard that is an actual line that terminates a path with an electrical open. See SOLT Calibration
Orientation	Orientation is the direction that an adapter is inserted between the Physical Layer Test System port's coaxial test cable and the DUT. Each end of the adapter should be labeled: either "1" or "2". Identifying the adapter orientation is important when calibrating the test system. An adapter is "forward oriented" when the end labeled "1" at the test cable and the end labeled "2" will be connected to the DUT. An adapter is "reverse oriented" when the end labeled "2" at the test cable and the end labeled "1" will be connected to the DUT.
Passive Device	A passive device is a device that requires only a signal to perform its function. It does not require a source of power for its operation and it provides no gain to a circuit. Examples of passive devices are resistors, inductors, capacitors, cables, and filters.
Pattern Length	Pattern length is the number of bits that are used to create a bit pattern used to create an eye diagram in the Physical Layer Test System. Bit patterns may be between 8 and 32 bits long.
Phase	The fractional part of a cycle through which an oscillation has advanced, measured from an arbitrary starting point; usually measured in radians or degrees. In network analysis, the phase response of the device under test is the change in phase as a function of frequency between the input stimulus and the measured response. In network analysis, the phase response of the device under test is the change in phase as a function of frequency between the input stimulus and the measured response.
Phase Rotation	See Phase Skew
Phase Shift	Phase shift is the change in phase of a signal between two points of time. Phase shift is expressed in degrees of lead or lag.
Phase Skew	Phase skew is a technique to remove the time delay caused by a fixture. Since the SOLT calibration only calibrates to the end of the test cables, the effects added by the test fixture can be removed mathematically. Phase skew moves the reference plane from the end of the test cables to the connection between the fixture and the DUT by accounting for the electrical length of each fixture path. Other terms for phase skew are phase rotation, port extension, port rotation, and reference plane rotation.
Physical Layer	The physical layer is layer 1, the lowest layer, of the seven-layer Open System Interconnection model. In broad terms, the physical layer is responsible for activating and using physical connections for transfer of electronic bits (zeros and ones) between a device and its transmission medium. The physical layer defines the electrical, mechanical, and handshaking protocols that govern transmission media and signals over the interface connecting a device to the transmission medium. In doing so, the physical layer insulates the data link layer (layer 2) from the physical characteristics of the transmission medium, such as baseband, broadband, or fiber-optic transmission. The physical layer is subdivided into the physical medium-dependent sublayer and the transmission convergence sublayer. Physical layer has three basic mediums: electrical (where SIO is focused), wireless/over air, and optical. All three are used in today's communications systems.
Polar Chart	The Polar chart is a format where each point corresponds to a particular value of both magnitude and phase. Quantities are read vectorally: the magnitude at any point is determined by its displacement from the center (which has zero value), and the phase by the angle counterclockwise from the positive x-axis. Magnitude is scaled in a linear fashion, with the value of the outer circle set to a ratio value of 1. Since there is no frequency axis, frequency information is read from the markers. The default marker readout for the polar format is in linear magnitude and phase.
Port	Port is a network-analysis term for the path that sends/received data to/from the DUT. In logic analysis and oscilloscope terminology a port is more like a channel. A channel in a logic analyzer or an oscilloscope is usually unidirectional (acquisition only) where as a port in a network analyzer is bi-directional. A port is also equivalent to the "pin" of an IC or board tester, which is usually bi-directional as well. So a port is similar to a pin on a package or connector.
Port Extension	See Phase Skew
Port Rotation	See Phase Skew
Power Level	Power level (dBm) is the stimulus level at the test port required for the measurement of the device under test.
Probe	A probe is the test device is connected to the Physical Layer Test System (or some other electronic device) that is used to make contact with a DUT to deliver or detect a signal for the purpose of on-circuit measurements. It is often a stylus-like device having multiple conductors for signal and ground paths. The tip is also often spring loaded to apply a constant pressure to the DUT.
Probing	In the frequency domain, probing is the process of using a probe to perform on-circuit measurements. In the time domain, probing typically refers to the technique of either browsing (single probe) or attaching (multiple probes, as in a logic analyzer) to the DUT and attempting to be non-intrusive with respect to the signal. Oscilloscope or logic analyzer-based measurements probing is designed to be as non-intrusive to the active electrical signal as possible while retaining the high bandwidth required to make accurate measurements.
Pseudo-Random Binary Sequence (PRBS)	Pseudo-Random Binary Sequence is a fixed length, somewhat random, digital signal pattern.
Pulse Width	Pulse width is the difference in time between the rising and falling edges of a signal that is transitioning, away from and then back to, its steady state.
R (resistance)	Resistance (ohms) is the opposition to the flow of current in a conductor.
Rack Units	A rack unit (U) is the vertical distance (height) between screw holes in an equipment rack. One rack unit (1U) equals 1.75 inches (44.45 mm) of rack space for equipment. 2U provides 3.5 inches of rack space for equipment, and so forth.
Radio Frequency (RF)	RF is the frequency band where radio waves are below the microwave band. The RF band ranges from approximately 50 kHz to 3 GHz, within the LF, MF, HF, VHF, and UHF frequency bands.
Range Resolution	Range resolution is defined as the ability to locate a single response in the time domain. If only one response is present, range resolution is a measure of how closely you can pinpoint the peak of that response. The range resolution is equal to the digital resolution of the display, which is the time domain span divided by the number of points on the display. The range resolution is always much finer than the response resolution.
Real	Real is a format that displays the resistive portion of the measured data on a Cartesian format. This is the corollary to the Imaginary format where the reactive portion is displayed.
Record Length	In frequency domain, record length refers to number of frequency points measured by the network analyzer. A longer record length (number of points) in a VNA implies either more resolution (closer points in the frequency domain) or a wider bandwidth measurement. In time domain, record length refers to the number of time points or instances acquired by the scope or logic analyzer. A longer record length (also occasionally called "points") means greater resolution for any given time duration.
Reference Level	Reference level is an instrument function that allows the user to set the amplitude value at the reference position. On network analyzers, the reference position is also selectable.
Reference Plane	A reference plane is the electrical location at which a network analyzer assumes the system connectors and fixturing ends and the device under test (DUT) begins. The reference plane is set by using calibration standards with known electrical lengths. The closer the reference plane is to the DUT, the better the characterization of the device because of the elimination of test system uncertainties.
Reference Plane Rotation	See Phase Skew
Reflection	Reflection is the phenomenon in which a traveling wave strikes a discontinuity and returns to the original medium.
Reflection Coefficient	The reflection coefficient is the ratio of the reflected voltage to the incident voltage into a transmission line or circuit. If a transmission line is terminated in its characteristic impedance, the reflection coefficient is zero. If the line is shorted or open, the coefficient is 1.
Reflection Measurements	Reflection measurements characterize the input and output behavior of the device under test. Measured as the ratio of the reflected signal to the incident signal as a function of frequency. Parameters are called return loss, reflection coefficient, impedance match, and standing wave ratio (SWR), all as a function of frequency.
Response	The Physical Layer Test System applies reference signals that are transmitted through the DUT or are reflected from the DUT's input. The transmitted or reflected signal is then detected and compared against the reference signal. A detected signal is called the "response". A reference signal is called the stimulus.
Response Resolution	Response resolution is defined as the ability to resolve two closely spaced responses, or a measure of how close two responses can be to each other and still be distinguished from each other in the time domain.
Reverse Orientation	Reverse orientation is the direction an adapter is inserted into the Physical Layer Test System equipment setup. An adapter is "reverse oriented" when the end labeled "2" at the PLTS test cable and the end labeled "1" will be connected to the DUT. See Orientation
Rise Time	Rise time is the transition time for the leading edge of a pulse to rise from 10% of its peak value to 90% of its peak value.
RMS	RMS is the root-mean-square (rms) of the voltage values of a waveform. Typically, the rms is taken over the first period of the displayed waveform.
Router (Networking)	A router is an electronic device that links local and wide area networks (LANs and WANs), allowing them to talk to one another even though the networks may be based on different standards. Using routing tables and protocols, routers read the network address in each transmitted frame and decide how to send it based on the most expedient route. Gateway is a generic term for a router. Most routers are specialized computers that are optimized for communications; however, router functions can also be implemented by adding routing software to a file server.
S-parameters (Scattering Parameters)	A convention used to characterize the way a device modifies signal flow. A four-port device has sixteen S-parameters: four forward transmission parameters, four reverse transmission parameters, four forward reflection parameters, and four reverse reflection parameters.
Scale (horizontal)	Horizontal scale is an instrument control that controls the x-axis or time per division of displayed waveforms. Horizontal scale is often referred to as sweep speed in some instruments.
Scale (vertical)	Vertical scale is an instrument control that controls the y-axis or volts per division for the selected channel. This control allows you to adjust the sensitivity of the instrument.
Serializer-Deserializer (SERDES)	SERDES is a term applied to the serialization (conversion from parallel to serial) and deserialization (conversion from serial to parallel) of data. The serialization portion usually merges clock and data and performs encoding while the deserialization typically performs decoding and clock/data recovery. SERDES are commonly used in high-speed serial links.
Short	A Short is a calibration standard that is an actual line that terminates a path with a precision electrical short. See SOLT Calibration
Signal-to-Noise Ratio	Signal-to-noise is the ratio of the amplitude of a signal relative to the amplitude of the noise on the signal.
Signal Integrity Engineering	Signal Integrity Engineering is using digital design and analog circuit theory along with accurate models and simulation to design circuits correctly the first time to save time and cost. When problems do occur signal integrity engineering quickly finds the root cause of signal distortions and fixes them.
Single-ended	A singled-ended or unbalanced device, having all of its signals referenced to a common ground potential.
Single-ended Device	A single-ended device has all of its signals referenced to a common ground potential.
Single-Ended Mode (SEM)	Single-ended mode is a method of sending SCSI signals along a cable. Single-ended mode uses one wire for the signal, which is compared to a common ground. The signal is the voltage difference between the two wires. Cable lengths for single-ended mode are restricted to between 6 and 1.5 meters (20 to 5 ft.) with the length decreasing as the data speed increases.
Skew	Skew changes the horizontal position of a waveform on the display independent of any other waveforms on the display. Skew is typically used for overlaying waveforms, or eliminating timing difference caused by different cable and probe lengths. The time base position control moves all of the waveforms on the display at the same time, whereas skew moves individual waveforms.
Skin Effect	Skin effect is the tendency of high-frequency currents to flow close to the surface of the conductor restricting the flow to a small part of the conductor's cross-sectional area. As frequency increases, so does the resistance and thus the loss also increases due to skin effect.
Small Computer System Interface (SCSI)	SCSI (pronounced "skuzzy") is a standardized hardware interface for a computer that acts as an I/O bus that can be used to connect the computer to several peripheral devices, such as printers, disk drives, CD-ROM, CD-R, Zip drives, and scanners.
SOLT Calibration	SOLT is a calibration using four known standards: Short-Open-Load-Thru.
Smith Chart	The Smith chart is the most common way to display complex impedance. The Smith chart is a circular chart with a bisecting horizontal line. The amount of reflection that occurs when characterizing a device depends on the impedance the incident signal sees. Since any impedance can be represented as a real and imaginary part (R+jX or G+jB), these quantities can be plotted on a rectilinear grid (known as the complex impedance plane). All values of reactance and all positive values of resistance from 0 to infinity fall within the outer circle of the Smith chart. Impedances on the chart are always normalized to the characteristic impedance of the test system. A perfect termination (Zo) appears in the center of the chart. A pure open appears at the left end of the bisecting horizontal line (infinity on the x-axis), while a pure short appears at the right end of the same line (zero on the x-axis). Loci of constant resistance now appear as circles, and loci of constant reactance appear as arcs. Inductance (positive reactance) is displayed in the upper half of the Smith chart, while capacitance (negative reactance) is displayed in the lower half.
Source	The source (input channel, function, waveform memory, or constant) used when performing tasks, such as measurements, math, or mask tests.
Standard Deviation	Standard deviation, represented by the Greek letter sigma (s), is the measure of the dispersion or spread of the statistical average of all results for a particular measurement. In a Gaussian distribution, two sigma, or within 1s of the mean is where 68.3 percent of the data points reside. Six sigma, or within 3s of the mean is where 99.7 percent of the data points reside.
Start Frequency	Start frequency is the start point of the frequency domain measurement range, or the lowest frequency measured. Together with the stop frequency, they determine the span of the measurement range.
Stimulus	The Physical Layer Test System applies reference signals that are transmitted through the DUT or are reflected from the DUT's input. The transmitted or reflected signal is then detected and compared against the reference signal. A reference signal is called the "stimulus". A detected signal is called the response.
Stop Frequency	Stop frequency is the stop point of the frequency domain measurement range, or the highest frequency measured. Together with the start frequency, they determine the span of the measurement range.
Stripline	A stripline is a planar transmission line structure that consists of a thin conductive trace (or traces) printed or etched within an insulating substrate with parallel ground planes on both sides of the substrate.
Sweep	A sweep is the ability of the source to provide a specified signal level over a specified frequency range in a specified time period.
Sweep Cycle Time	Sweep cycle time is the time required for making a complete sweep and preparing for the next sweep. It can be measured as the time from the start of one sweep to the start of the next sweep.
Sweep Mode	Sweep mode is the way in which a sweep is initiated or selected.
Sweep Type	Sweep type is the method of sweeping the source, e.g., linear, log, or frequency step.
T-carrier	T-carrier is a full-duplex digital transmission type that uses four wire cables. One pair is used to transmit; the other pair is used to receive. The cable types were originally twisted pairs, but now include coaxial cable, digital microwave, optical fiber, and other media. Other T-carrier characteristics are: · Symmetry: the same amount of bandwidth is provided in each direction. · Time Division Multiplexing: multiple transmissions can be supported over multiple channels by interleaving the signals over a given carrier frequency. · Unbiasing: all applications and data types are treated the same. Every bit of each transmission is treated the same, regardless of whether it's a voice bit, a data bit, or a video bit.
T1	T1 lines are a standard for broadband digital transmission over telephone lines. T3 lines consist of 24 channels at 1.544 Mbps. These lines are generally used by Internet Service Providers. See T-carrier
T3	T3 lines consist of 672 channels at 44.736 Mbps. These lines are generally used by Internet Service Providers and are also referred to as DS3 lines. See T-carrier
Termination	A termination is a load connected to a transmission line or other device.
Test Fixture	A test fixture is a fixture used to hold the DUT, route signals to and from the DUT, and to apply bias voltages and ground paths to the DUT.
Test Set	A test set is the arrangement of hardware (switches, couplers, connectors and cables) that connect a test device input and output to the network analyzer's source and receiver to make S-parameter measurements.
Thru	A Thru (through) is a calibration standard that is an actual through line. See SOLT Calibration
Thru Reflect Line (TRL) Calibration	TRL calibration is a calibration type that utilizes three simpler, more convenient standards to define the error terms to be removed from the measurement. The measured parameters of the Thru, Reflect, and Line standards in a TRL calibration kit provides the same information as a SOLT calibration via a different algorithm. A calibration at the coaxial ports of the test system removes the effects of the system and any cables or adapters before the fixture; however, the effects of the fixture itself are not accounted for. An in-fixture calibration is preferable, but SOLT standards may not be readily available to allow a conventional full 4-port calibration at the desired measurement port of the device. TRL calibration is convenient because calibration standards can be fabricated for the specific measurement environment. The characteristic impedance of these fabricated transmission lines can be determined from the physical dimensions and substrate's dielectric constant. The TRL calibration relies on the characteristic impedance of simple transmission lines.
Time Domain Network Analysis (TDNA)	TDNA includes both time domain reflectometry (TDR) and time domain transmission (TDT) measurements to characterize a network.
Time Domain Reflectometry (TDR)	TDR gives an intuitive measurement of any discontinuities in a circuit. It measures the location, electrical length, nature of the circuit (resistive, capacitive, inductive), and amount of reflection from discontinuities.
Time Domain Transmission (TDT)	TDT is a measurement technique that measures both attenuation and propagation delay of your device under test.
Topology	Topology is the way that circuits are connected to link the network nodes together. Several network topologies are listed: · Bus topology: A topology in which all nodes, i.e., stations, are connected together by a single bus. · Fully connected topology: A topology in which every node has a direct path to every other node. · Hybrid topology: A combination of any two or more other topologies. · Mesh topology: A topology in which there is a minimum of two nodes with each having a minimum of two (often more) paths. · Ring topology: A topology in which every node has exactly two branches connected to it forming a ring when all connections are made. · Star topology: A topology in which peripheral nodes are connected to a central node. The central node rebroadcasts all transmissions received from any peripheral node to all peripheral nodes on the network. · Tree topology: A topology in which multiple star topologies are connected together when their central nodes are connected to a higher level central node. In turn, this central node may be connected to other higher-level central nodes.
Touchstone	Touchstone data files, also known as .Snp files, are ASCII text files used to import and export S-parameter data. This file format displays the data line-by-line, one line per data point, in increasing order of frequency. Each line of data consists of a frequency value and one or more pairs of values for the magnitude and phase of each S-parameter at that frequency. Values are separated by one or more spaces. Comments are preceded by an exclamation mark (!). Comments can appear on separate lines, or after the data on any line or lines.
Trace	A series of data points containing frequency/time and amplitude information on a plot. In the Physical Layer Test System, a plot may have only one trace or it may be defined to have multiple traces.
Transition Time	Transition time is the time duration that a pulse takes to rise from the 10% level to the 90% level when turning on (the rise time) or the time duration that a pulse takes to fall from the 90% level to the 10% level when turning off (the fall time).
Transmission Measurements	The characterization of the transfer function of a device, that is, the ratio of the output signal to the incident signal. Most common measurements include gain, insertion loss, transmission coefficient, insertion phase, and group delay, all measured over frequency.
Twisted Pair	A twisted pair is a cable that is made up of one or more separately insulated twisted-wire pairs which reduces susceptibility to RF noise.
Uncorrected Measurements	Uncorrected measurements are measurements made without performing calibration (error correction).
uW	See Microwave
Velocity Factor	Velocity factor is a numerical value related to the speed of energy through transmission lines with different dielectrics (.66 for polyethylene). In making time domain measurements, a velocity factor of 1 = speed of light = 299.7925 x 106 m/s.
Vertical Resolution	Vertical resolution is the degree to which an instrument can differentiate amplitude between two signals.
Via	A via is a hole filled or lined with a conducting material which is used to link two or more conducting layers of a PC board. There are blind vias (a via that connects two or more layers including the top or bottom layer), buried vias (a via that connects two or more layers that does not include the top or bottom layer), and through-hole vias (a via that connects all layers).
Waveform	A waveform is a representation of a signal plotting amplitude versus time.
Wavelength	Wavelength is the physical distance that an electromagnetic wave travels during the time it completes one cycle. The distance between points of corresponding phase of two consecutive cycles of a wave. The wavelength (l) is related to the propagation velocity (v) and the frequency (f) by l = v / f.
Windowing	Windowing is a time domain feature that smooths (filters) overshoot and ringing displayed in time domain plots. Overshoot and ringing are caused by the abrupt transitions of start and stop frequencies used in frequency domain measurements.
Zero Level	Zero level is a measure of the mean value of the logical 0 of an eye diagram.
Zo	Zo is the characteristic impedance of a transmission line.