The highlighted channel affected by front panel functions.
Active Marker
The marker on a trace that can be repositioned either by front panel controls or by programming commands
Active Trace
A trace that is being swept (updated) with incoming signal information.
Admittance (Y)
The inverse of an impedance (i.e. the ratio of current to voltage). Complex admittances take the form Y = G + jB(t).
Annotation
The labeling of specific information on the display (such as frequency or power).
Aperture
The frequency span of the network analyzer used for calculating group delay. The narrower the aperture, the finer the resolution of the group delay variations, but noise is reduced by increasing the aperture.
Array
A set of numbers or characters that represents any given function.
Attenuation
Denotes 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.
Attenuator
An RF or microwave device used to reduce the power level of a signal by precise, incremental amounts over its entire frequency range.
Automatic Level Control (ALC)
A circuit used in amplifiers and other active devices to keep its RF power level constant as other parameters change, such as frequency.
Autoscale
An analyzer feature that evaluates waveforms and adjusts controls to stable and enhance the display.
AUX
Auxiliary; refers to rear-panel input connector.
Averaging
A noise reduction technique that computes each data point based on consecutive sweeps and weighted by a user-specified averaging factor. Each new sweep is averaged into the trace until the total number of sweeps is equal to the averaging factor.
A range of frequencies that are passed through a device, such as a filter. Frequencies not within the band pass are limited or attenuated. See also Cutoff Frequency.
Bandwidth (BW)
The difference between the frequencies of a continuous frequency band within which performance of a device falls within specifications.
Bandwidth Limit
The condition prevailing when the system bandwidth is exceeded and signal distortion occurs beyond specifications.
Binary
A method of representing numbers in a scale of two (on or off, high-level or low-level, one or zero). A compact, fast format used to transfer information to and from the analyzer.
Broadband Device
A device that operates over a very wide frequency range and exhibits only small variations in response over that range.
BW
Bandwidth
In Agilent instrumentation, the process of periodically (usually annually) verifying an instrument is performing to specifications. A calibration certificate is awarded after verification. In network analyzers, the process of removing systematic errors from measurements. See Error Correction.
Calibration Kit
Hardware and software required to perform error correction on a network analyzer for a specific measurement and/or test set.
Calibration, Blackburn
Calibrations of transmission path with corrected source match involving 15 calibration terms. Synonym: 15-term error correction
Calibration, Frequency Response
The simplest error correction procedure to perform, but only corrects for a few of the twelve possible systematic error terms. Frequency response corrections can be made for reflection measurements, transmission measurements, and isolation measurements.
Calibration, Interpolation
A user selectable network analyzer feature that calculates (interpolates) new error correction terms from existing terms when there is a change in network analyzer parameters, such as IF bandwidth, power, or sweep time. The resulting error correction is not as accurate as completing a full 2-port calibration.
Calibration, Set Z
Sets the system impedance, usually 50 or 75 ohms.
Calibration, SOLT
A calibration using four known standards: Short-Open-Load-Through. Also known as a full two-port calibration and 12-term error correction. See also Error Correction.
Calibration, TRL and LRM
A calibration used in environments where the DUT cannot be connected directly to the network analyzer ports, (MMIC, microstrip, beam-lead diodes etc.). Thru-Reflect-Line (TRL) and M (Match) standards are fabricated and used because known high-quality standards are not readily available. The requirements for characterizing these standards are less stringent, but the calibration is not as accurate as the traditional full two-port calibration using S-O-L-T standards. The terms are used interchangeably (TRL, LRL, LRM etc.) but they all refer to the same basic calibration method.
Characteristic Impedance
The impedance looking into the end of an infinitely long lossless transmission line.
Command
A set of instructions that are translated into instrument actions. The actions are usually made up of individual steps that together can execute an operation.
Continuous Sweep Mode
The analyzer condition where traces are automatically updated each time trigger conditions are met.
Controller
A device capable of specifying the talker and listeners for an information transfer. An external computer connected to an instrument to control its operation.
Corrected
Measurements made after performing error correction.
Crosstalk
The occurrence of a signal at one port of a device being affected by a signal in any other path. Isolation is the measurement of crosstalk.
Cutoff Frequency
In filters, the frequency at which attenuation is 3dB below the band pass signal level, known as the 3dB points.
CW
Continuous wave: A single frequency (rather than a swept frequency).
Decibel: a relative unit of measure. The ratio in dB is given by: 10 log10 (P1/P2) where P1 and P2 are the measured powers. The dB is preferred instead of arithmetic ratios or percentages because when components are connected in series, their effect on power, expressed in dB, may be arithmetically added and subtracted. For example, if a 3dB attenuator is connected to a 10dB amplifier, the net gain of the two components is (-3dB + 10dB = +7dB).
dBm
Absolute unit of measure in decibels: 0dBm = 1 mW. The conventions of the dB (adding and subtracting) continue to apply.
Default
A known set of conditions used in the absence of user-defined conditions.
Dimension
To specify the size of an array. The number of array rows or columns.
Directional Coupler
A 3-port device typically used for separately sampling the backward (reflected) wave in a transmission line.
Directivity
In a 3-port directional coupler, the ratio of the power present at the auxiliary port when the signal is traveling in the forward direction to the power present at the auxiliary port when the same signal is traveling in the reverse direction.
Display Formats
Graphical formats for displaying measurement data. These include single channel, overlay (multiple traces on one graticule), split (each trace on separate graticules).
Display Modes
The ways in which measurement data can be presented graphically. On a network analyzer, the choices are Cartesian/rectilinear (XY plot with log or linear magnitude, phase, group delay, SWR, real and imaginary, and dBV, dBmV and dBuV), polar (magnitude and angle), magnitude and phase, and Smith chart. Not all display modes are available on all network analyzers. In addition, displays can present this information in various combinations of traces. Common modes are dual, (the ability to display more than one trace, usually over the same frequency range), and alternate, (the ability to display more than one trace, each with different frequency range and type).
Distortion
Deterioration of a signal's quality due to the nonlinear characteristics of a device or system transfer function. Distortion is measured as a combination of the changes in amplitude, frequency and phase of signal at the output of a device or system as compared to the signal at the input.
Drift
The slow change in signal frequency.
DUT
Device Under Test
Dynamic Range
In a receiver, the range of signal levels, from minimum to maximum, that can be reliably measured simultaneously. Dynamic range allows small signals to be measured in the presence of large signals. Source power and receiver compression usually limits the maximum boundary to dynamic range. Receiver residual responses and noise floor usually limit the minimum power boundary.
A simulated variable length of lossless transmission line, added to or subtracted from a receiver input, to compensate for interconnecting cables. The firmware equivalent of mechanical or analog \"line stretchers\" in other network analyzers.
Electronic Calibration (ECal)
A calibration system for electronic calibration of RF and microwave vector network analyzers. The electronic calibration system creates a twelve-term, two-port error model and then provides a confidence check of the calibration. The Ecal system consists of a repeatable, variable-impedance, solid-state calibration standard and a mainframe control unit which interfaces with the 8510, 8720 series, and the 8753 network analyzers or a USB module which interfaces with the PNA series network analyzers.
EMI
Electro-Magnetic Interference: Unintentional interfering signals generated within or external to electronic equipment. Typical sources could be power-line transients, noise from switching-type power supplies and/or spurious radiation from oscillators. EMI is suppressed with power-line filtering, shielding, etc.
Engage
To activate a function.
Enter
The process of inputting information.
EPROM
Electronically Programmable, Read-Only Memory
Error Correction
In network analyzers, a process that removes or reduces systematic (repeatable) measurement errors by measuring known standards from a calibration kit. Synonym: measurement calibration
Error Correction, 1-Port
Corrects a test set for port 1 or port 2 directivity, frequency response, and source match errors. The process requires three known standard terminations, for example, open, short, and load.
Error Correction, 12-Term
Correction for a two port device using six parameters: Directivity Source match Load match Reflection frequency response Transmission frequency response Isolation To completely characterize a two-port device, these six parameters must be characterized in the forward and reverse directions, making a total of 12 terms. The user usually has the option of omitting isolation from the correction process. Synonym: Full two-port error correction
Error Correction, 3-Term
Used to remove systematic measurement errors on a device with one port, such as a load.
Error Message
A message on a display that indicates an error condition. Missing or failed hardware, improper user operation, or other conditions that require additional attention can cause an error condition. Generally, the requested action or operation cannot be completed until the condition is resolved.
ESD
Electro Static Discharge
Ethernet
A network that adheres to the IEEE 802.3 Local Area Network standard.
Ethernet address
A hexadecimal number which is used to identify a machine on a network. Each analyzer is assigned a unique Ethernet address at the factory and it is stored in the analyzer's ROM.
External trigger signal
A TTL signal that is input to an analyzer and initiates a measurement sweep or similar event, making the measurements synchronous with the external triggering source.
A passive device that allows some frequencies to pass and attenuates others, depending on the type and specifications. A high-pass filter passes frequencies above the cutoff frequency, a low-pass filter passes frequencies below the cutoff frequency, and a band-pass filter passes frequencies between two specific frequencies.
Flatness
The amplitude and phase response of a device under test (DUT), a signal source, a receiver, or a combination of these. See also Frequency Response.
FM
Frequency Modulation
Frequency
The number of periodic oscillations, vibrations, or waves per unit of time, usually expressed in cycles per second, or Hertz (Hz).
Frequency Accuracy
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 Range
The range of frequencies over which a device or instrument performance is specified.
Frequency Resolution
The ability of a network analyzer to measure device characteristics at closely spaced frequencies and display them separately. Resolution of equal amplitude responses is determined by IF bandwidth. Resolution of unequal amplitude responses is determined by IF bandwidth and bandwidth selectivity.
Frequency Response
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
The magnitude of the displayed frequency component. Span is represented by the horizontal axis of the display. Generally, frequency span is given as the total span across the full display. Some analyzers represent frequency span (scan width) as a per-division value.
Frequency Stability
The ability of a frequency component to remain unchanged in frequency or amplitude over short and long-term periods of time. Stability refers to an oscillator's ability to remain fixed at a particular frequency over time.
Front Panel Key
Keys that are located on the front panel of an instrument. The key labels identify the function the key activities. Numeric keys and step keys are two examples of front panel keys.
Function
The action or purpose that a specific item is intended to perform or serve. The network analyzer contains functions that can be executed via front panel key selections, or through programming commands.
Fundamental Frequency
In any waveform, the lowest frequency component; all other components are harmonics. A pure sinusoid has only one component, the fundamental.
Gigabit
GHz
Gigahertz
Giga
Prefix for one billion.
GPIB
General Purpose Interface Bus - IEEE 488 bus is interconnect bus and protocol, allows linking of instruments and computer.
Graticule (or Grid)
Enclosed area where waveform is displayed on instrument. Tick marks, on frame or axis, are a scaling aid for making visual measurements.
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 with respect to frequency.
Paper copy of data.
Hardkey
A front-panel key, which engages a single analyzer function or presents a single menu of softkeys.
Horizontal Resolution
The analyzer's ability to take closely spaced horizontal data points over the full sweep.
Host Name
A unique name that is used to identify each host machine on a network. The host name is directly linked to, and can usually be used in place of, the IP address. The user or the system administrator usually creates the host name.
HTTP
HyperText Transfer Protocol: Used to carry World Wide Web (WWW) traffic.
Input/Output
IF
Intermediate Frequency: the frequency at which a signal is processed after mixing.
Impedance
The ratio of voltage to current at a port of a circuit, expressed in ohms.
Initialize
The process that assigns information locations to a disk to prepare the magnetic media to accept files.
Input
A path intended for putting a signal into an instrument. Most network analyzers have either 3 (labeled A, B, and R) or 4 inputs (labeled A, B, R1, and R2). Inputs are not the same as channels.
Input Attenuator
An attenuator between the input connector and the first mixer of a spectrum analyzer (also called an RF attenuator). The input attenuator is used to adjust the signal level incident to the first mixer, and to prevent gain compression due to high-level or broadband signals. It is also used to set the dynamic range by controlling the degree of internally-generated distortion. For some analyzers, changing the input attenuator settings changes the vertical position of the signal on the display, which then changes the reference level accordingly. In Agilent microprocessor-controlled analyzers, the IF gain is changed to compensate for changes in input attenuator settings. Because of this, the signals remain stationary on the display, and the reference level is not changed.
Insertion Loss
The difference between the power measured before and after the insertion of a device. The attenuation between the input and output of a device.
Intensity
Brightness; emitting or reflecting light; luminosity.
Interface
A connection that allows a common communication link between two or more instruments.
Interpolate
To determine a value of a signal between to adjacent points by a procedure or algorithm.
IP
Internet Protocol
IP Address
Internet protocol address: a unique number that is assigned to each device which is to be connected to a TCP/IP network. Before using an analyzer on a network, your network administrator will need to assign an IP address. An IP address consists of a 32-bit value presented in decimal dot notation: 4 octets (bytes) separated by a dot.
Isolation
A specification or measure of the immunity that one signal has to being affected by another adjacent signal. The occurrence is known as crosstalk.
Isolator
An RF device used for providing isolation between paths and components. Made from a 3-port circulator, the third port being terminated in a 50ohm load.
Kilobytes per second
Lines input by the user that overlay the analyzer's measurement data to allow automatic detection of data that is out of the acceptable range. Pass/Fail annotation, audio alarms, or electronic output can be triggered to notify the operator or on-line computer program of the over-limit condition.
Limit-Line Table
The line segments of a limit line are stored in the limit-line table. The table can be recalled to edit the line segments, then restored in the limit-line file.
Linear Device
A device in which the output is continuously proportional to the input.
LO
Local Oscillator. In a superheterodyne system, the LO is mixed with the received signal to produce a sum or difference equal to the intermediate frequency (IF) of the receiver.
Load
A one port microwave device used to terminate a path in its characteristic impedance.
Load Match
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
Logarithm
Log Display
The display mode in which vertical deflection is a logarithmic function of the input signal amplitude. Log display is also called logarithmic display. The display calibration is set by selecting the value of the reference level position and scale factor in dB per division.
LRM
Line-Reflect-Match.
A graphical symbol along a display trace that is annotated with measurement characteristics of that specific data point.
Marker Functions
Mathematical or statistical computation on the data of one or more markers to provide the operator more information. For example, the marker delta function calculates and displays the difference between two markers.
Maximum Input Level
The maximum signal power that may be safely applied to the input of an analyzer. The maximum input level is typically 1 W (+30 dBm) for Agilent spectrum analyzers.
Measurement Uncertainty
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)
Modulation
The process, or the result of the process, of varying a characteristic of a carrier signal with an information-bearing signal, causing the carrier to contain the information.
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
Random variations of unwanted or disturbing energy in a communications system from man-made and natural sources that affects or distorts the information carried by the signal. See also Signal-to-Noise Ratio.
Noise Floor
The analyzer's internal displayed noise. The noise level often limits how small a signal magnitude can be measured. In network analysis, noise floor is measured with the test ports terminated in loads, full two-port error correction, 10 Hz IF bandwidth, maximum test port power, and no averaging during the test.
Non-Insertable Devices
In measurement calibration, a device that cannot be substituted for a Zero-Length Through Path. It has the same type and sex connectors on each port, or a different type of connector on each port.
Normalize
To subtract one trace from another to eliminate calibration data errors or to obtain relative information.
To move or set off a determined amount. Used in instruments for offsetting frequencies, limits, delay, loss, impedance, etc.
Reads program messages from the input queue of a device in the order they were received from the controller. The parser determines what actions the analyzer should take. One of the most important functions of the command parser is to determine the position of a program message in the analyzer SCPI command tree. When the command parser is reset, the next element it receives is expected to arise from the base of the analyzer command tree.
Peak Search
A function on an analyzer that searches for the largest response and places a marker on it.
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.
Port
The physical input or output connection of an instrument or device.
Port Extension
Redefining the reference plane to other than that established at calibration. A new reference plane is defined in seconds of delay from the test set port.
Positive Peak
The maximum, instantaneous value of an incoming signal.
Power, Max Input
The upper limit to input power for which the specifications apply. Some specifications may have different levels of maximum inputs. For example, compression power maximum is usually higher than the harmonic distortion maximum.
Power, Safe Input
The input power, usually in dBm, allowed without damaging the instrument.
Preset
A pre-defined instrument state (that also runs an analyzer self-test). The action of pushing the Preset key.
Protocol
A set of conventions that specify how information will be formatted and transmitted on a network, and how machines on a network will communicate.
Any analyzer programming command having the distinct function of returning a response. These commands may end with a question mark (?). Queried commands return information to the computer.
Expression for complex impedance, where r represents the resistive portion and x represents the reactive portion.
R Channel
Reference Channel
Receiver
A circuit or system designed for the reception and/or measurement of signals in a specified frequency spectrum.
Reference Level
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. On some spectrum analyzers, the reference position is fixed at the top of the display.
Reference Plane
The electrical location at which a network analyzer assumes the system connectors and fixturing ends and the DUT begins. The reference plane is set by using calibration standards with known electrical length. The closer the reference plane is to the device under test (DUT), the better the characterization of the device because of the elimination of test system uncertainties.
Reflection
The phenomenon in which a traveling wave strikes a discontinuity and returns to the original medium.
Reflection Coefficient
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. See also Return Loss and SWR.
Reflection Measurements
Measurements that characterize the input and /or output behavior of the device under test (DUT). 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, and standing wave ratio (SWR), all as a function of frequency. See also S-Parameters.
Remote
A mode of operation where another device (or computer) controls an instrument via the HP-IB. In this mode, the instrument front panel keys are disabled. Front panel operation is called local operation.
Resolution
The ability of a receiver to resolve two signals.
Resolution Bandwidth
The ability of a spectrum analyzer to display adjacent responses discretely (Hertz, Hertz decibel down). This term is used to identify the width of the resolution bandwidth filter of a spectrum analyzer at some level below the minimum insertion loss point (maximum deflection' point on the display). Typically, it is the 3 dB resolution bandwidth that is specified, but in some cases the 6 dB resolution bandwidth is specified.
Return Loss
The amount of dB that the reflected signal is below the incident signal. If zero signal is reflected, the impedance of the device is equal to the characteristic impedance of the transmission system, and return loss is infinite. If the entire incident signal is reflected, the return loss is zero. See also S-Parameters, Reflection Coefficient, and SWR.
RF
Radio Frequency (from approximately 50 kHz to approximately 3 GHz). Usually referred to whenever a signal is radiated through the air.
S-Parameters (Scattering Parameters)
A convention used to characterize the way a device modifies signal flow using a network analyzer. A two port device has four S-parameters: forward transmission (S21), reverse transmission (S12), forward reflection (S11), and reverse reflection (S22).
S/N
Signal-to-Noise Ratio
Sensitivity
The minimum input signal required to produce a specified output signal having a specified signal-to-noise ratio, or other specified criteria. On a spectrum analyzer, the level of the smallest sinusoid that can be observed, usually under optimized conditions of minimum resolution bandwidth, 0 dB input attenuation, and minimum video bandwidth. The normalized change in YIG component's center frequency resulting from a change in tuning coil current, specified in MHz/mA.
Signal-to-Noise Ratio
SNR: The ratio of the amplitude of the desired signal to the amplitude of noise signals, usually expressed in dB and in terms of peak values for impulse noise and root-mean-square values for random noise.
Smith Chart
A graphical mapping of the complex reflection coefficient into normalized complex impedance. Circles on the chart represent constant resistance and radiating lines orthogonal to the circles represent constant reactance. The center of the chart represents the characteristic impedance of the transmission system. Any point on the chart defines a single complex impedance. A line on the chart represents changing impedance over frequency.
SOLT
Short-Open-Load-Through calibration. See also Calibration, SOLT.
Source
A device that supplies signal power; a sweep oscillator or synthesized sweeper.
Source Amplitude Accuracy
The amplitude uncertainty, in dB, of the source power readout.
Source Amplitude Flatness
The amplitude flatness, in dB, of the source power over the frequency range specified.
Source Frequency Resolution
The smallest unit of frequency which can be set and/or measured, in Hz.
Source Harmonics
The level of harmonics generated by the analyzer's signal source, in dBc from the fundamental.
Source Match
A measure of how close the signal source impedance is to the ideal transmission line impedance of the test system. Match is usually measured as return loss or standing wave ratio (SWR) of the source.
Span
The stop frequency minus the start frequency. The span setting determines the horizontal-axis scale of the analyzer display.
Stop/Start Frequency
Terms used in association with the stop and start points of the frequency measurement range. Together they determine the span of the measurement range.
Sweep
The ability of the source to provide a specified signal level over a specified frequency range in a specified time period. Also see Sweep Mode and Sweep Type. In data processing mode, a series of consecutive data point measurements, taken over a sequence of stimulus values.
Sweep Mode
The way in which a sweep is initiated or selected, e.g., single, continuous, alternate, or chopped.
Sweep Type
The method of sweeping the source, e.g., linear, log, or frequency step.
SWR
Standing Wave Ratio, calculated as (1 + p) / (1 -p) where p is the reflection coefficient.
Syntax
The grammar rules that specify how commands must be structured for an operating system, programming language, or applications.
A load connected to a transmission line or other device.
Test Limit
The acceptable result levels for any given measurement.
Test Set
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
Through line: A calibration standard. See Calibration, SOLT.
Toggle
To switch states, usually to change a function from on to off, or off to on.
Trace
A series of data points containing frequency and response information. The series of data points is often called an array. The number of traces is specific to the instrument.
Tracking
The ability of the analyzer's receiver to tune to the source frequency over the measurement frequency range. Poor tracking results in amplitude and phase errors due to the receiver IF circuits attenuating and delaying the device under test output.
Transmission Intermodulation Spurious
A measure of the capability of the transmitter to inhibit the generation of intermodulation distortion products. Intermodulation spurious is sometimes called intermodulation attenuation.
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. See also S-Parameters.
Transmission/Reflection (T/R)
Refers to the suite of measurements made by a scalar or vector network analyzer to characterize a device's behavior over frequency. See also S-Parameters.
Trigger
A signal that causes the instrument to make a measurement. The user can select several options for triggering, such as manual, continuous, or external (for synchronizing measurements to an external source).
TRL
Through-Reflect-Line. See Calibration, TRL and LRM.
TTL
Transistor-Transistor Logic
Measurements made without performing error correction.
Units
Dimensions on the measured quantities. Units usually refer to amplitude quantities because they can be changed. In analyzers with microprocessors, available units are dBm (dB relative to 1 mW dissipated in the nominal input impedance), dBmV (dB relative to 1 mV), dBW (dB relative to 1 1W), V (volts), W (watts).
A symbol, the value of which changes either from one iteration of a program to the next, or within each iteration of a program.
Velocity Factor
A numerical value related the speed of energy through transmission lines with different dielectrics (.66 for polyethylene). Used in making time domain measurements.