Keysight Signal Analyzer Glossary

A sensor mode that captures the magnitude of the frequency spectrum over an interval of time using a linear array transducer. Acoustic measurements are made with acoustic sensors, such as hydrophones, MEMS microphones, and vibration sensors.

Aliasing is an effect that causes a signal to be incorrectly identified as another signal or signals.

The amplitude range of a signal is the span between the highest positive value and the lowest negative value. The amplitude range of a system, for example, may depend on gain settings or other external conditions.

A time varying electrical signal, such as a voltage or current. In an analog signal, information is encoded by the magnitude and rate of change in the signal over time.

An arbitrary waveform memory (AWM) is a type of digital storage medium used to store time-domain signals, such as test and measurement instrument signals. Like other forms of data storage, it can save a copy of a signal for later analysis.

A bandwidth setting that allows a user to specify the frequency range of interest in an acquired waveform. The waveform is resampled to match the specified bandwidth. This method increases acquisition speeds by reducing the size of the data set while giving users freedom in choosing their signal bandwidth.

A setting that allows a spectrum analyzer to capture noise and distortion signals over a wide frequency range. In some cases, the lower limit of the broad range is defined by the current sweep span while the upper limit is either user-definable or factory programmed.

A Cell Advisor Signal is a continuous, wideband pseudo random signal with a known spectral envelope and an adjustable level range. A cell advisor can be used as a reference stimulus for testing the dynamic range of audio products such as cell phones, MP3 players, or PC speakers.

Channels are regions of time on the display of a spectrum analyzer in which measurements are made. The number of channels displayed depends on the bandwidth of the signal, with narrower signals occupying more channels than wider ones.

A measure of signal quality, coherence is the degree to which two signals are correlated. For example, sine waves with perfect correlation will have a coherence value of 1. A coherence between two waveforms indicates that they share a common frequency and phase, which may indicate a cause-and-effect relationship.

Committed response times are the minimum time intervals that a control system can respond to the changes in set point, controller output, or load disturbance. Response times in control loops must be designed to meet this specification in order for the process to operate at maximum efficiency and with desired performance.

Consistent measurements allow users to compare measurements captured under different conditions. For example, if you capture a noise spectrum at one power level and then redo the measurement at another power level, consistent measurement ensures that both results will be mathematically correct.

A measurement of the similarity between two signals. Mathematically, cross-correlation can be expressed as a normalized dot product of two signal vectors. In most cases, it is used as a measure of time synchronization between two signals. Cross-correlation is also known as "autocorrelation" when measured within a sign.

To extract information from a carrier wave by extracting the modulation signal that is encoded within it. This process is also referred to as "detection."

A disk file is a file stored on an external hard drive, flash drive, or other storage medium. Disk files are the most common method used for storing data acquired by spectrum analyzers.

The DANL is the average noise level displayed on a spectrum analyzer's display. This value is determined by adding all of the power within the display bandwidth and dividing tthat number by the span width.

The presence of unwanted frequencies that were not present in the original signal. Using a spectrum analyzer, this can be measured by examining the level of harmonic and intermodulation components within a frequency range.

A dynamic range is the ratio between the largest and smallest values a sensor can measure. Dynamic range is most often measured with regard to audio and video equipment, with different standards for dynamic range referring to frequency response or distortion levels.

A Dynamic Signal Analyzer is a type of spectrum analyzer that captures and displays the power of signals over time. This type of analyzer is often used to analyze the energy within a signal.

Electrochemical signal analyzers are instruments that measure conductivity or resistance of liquids, gases, or solids. These analyzers are used for corrosion detection and other chemical processes.

Refers to the process of isolating a single signal from a large group of overlapping signals. A spectrum analyzer does this by performing an FFT on the captured data and setting detection levels for each individual channel.

The process of converting a time-based signal into frequency components. This allows users to view the signal in terms of power versus frequency, or how much power exists between certain frequencies. An FFT is also known as a spectral analysis.

FFTs have four properties that affect the accuracy of measurements. These properties are: resolution, maximum hold, number of points, and sweep speed.

A representation of a signal in terms of power over frequency. In the frequency domain, an analytical instrument can display both amplitude and phase data from a signal.

A representation of a signal in terms of power over frequency. In the frequency domain, an analytical instrument can display both amplitude and phase data from a signal.

A Guzik signal analyzer is a type of electrochemical signal analyzer.

A measurement of the relative phase difference between two signals. A high level of I/Q mismatch can cause signal distortion and interference.

A magnitude is the positive or negative value of a signal. In an FFT, it is displayed as energy within a frequency range and over time.

A measurement marker is a visual reference on the display of a spectrum analyzer that marks specific frequencies or amplitude levels. These markers can be set manually by the user, or auto-placed by the instrument to show relevant signal properties.

Refers to the operating system used by a spectrum analyzer to process and display data. Most modern spectrum analyzers use embedded Windows computers, while older models may have different firmware.

The modal domain represents a signal as a set of sinusoidal waves, using phasors. In this domain, both amplitude and phase information is displayed for each frequency.

Network stimulus is a term used to refer to any signal or test equipment that is connected to a network.

Offset Range Vertical Sensitivity measures the difference between a signal's base frequency and the fundamental output level. When designing a spectrum analyzer, this parameter is usually adjusted to optimize the display of signals at a certain offset.

Overlap processing is the process of combining data from two or more spectrum analyzers. This process can be done for several reasons, such as to increase the amount of data collected by sampling the signal more often, or to compare two signals.

A term used in signal processing that refers to the frequency response of an amplifier or other device for filtering signals. Passbands can be either narrow or wide and may also include filters for both amplitude and phase responses.

This is the industry standard for motherboard slots. The PCI Express card was developed in order to address the limitations of older PCI cards. For example, PCI Express cards offer higher bandwidth and improved power management.

An instrument for processing signals. This blade can be programmed to adjust filters and other signal processing tools.

A PXI Vector Signal Transceiver is an analog-to-digital converter that can be used to transmit or receive signals. It uses Pulse Width Modulation (PWM), allowing these transceivers to communicate with very small voltage swings.

A RADAR test set is a type of instrument used to generate and measure electromagnetic waves. These sets are able to transmit and receive waves in the form of radio or microwaves.

Range refers to the span of frequencies that can be measured by a particular signal analyzer. For example, an analyzer with a full scale range of 1GHz will be able to measure any frequency within that range.

Rate of change refers to the speed at which a signal changes. It can also refer to the slope of that curve, or how fast voltage or current is changing with respect to time.

The resolution channel scale is the smallest increment on a signal analyzer’s display or unit of measure for frequency. It plays an important role in the measurement resolution of any spectrum analyzer, and can be adjusted using span controls to get better measurements.

RFIC characterization is a term that refers to the testing and analysis of RF integrated circuits, otherwise known as Radio Frequency Integrated Circuits.

Sample rate refers to the speed at which data is collected by a spectrum analyzer. It can also refer to the number of samples per second that are displayed on the screen or recorded in memory.

Signal Display refers to the method that is used to display data. Depending on the type of spectrum analyzer, this could be in vector form (i.e. phasors), modal domain, or time-based domain.

A signal is an electrical representation of information or data. There are many different types of signals. These can be analog (continuous) or digital (discrete).

The spectrum, also known as a frequency range, is the range of frequencies within a signal. This is often measured in hertz, although there are other units that can be used as well.

Spectrum analysis is the process of measuring and examining signals through their spectrum. The term can also be used to refer to the equipment that makes this process possible, such as a Spectrum Analyzer.

The third-order intercept point is a measurement of the gain of an RF component or system. It measures the amount of power that a device can handle without being overdriven and creating distortion. This is important because it requires less signal for optimal performance.

The time domain is a way of representing a signal as a function of time. In other words, it shows the changes to voltage or current over time. The opposite is frequency domain, or how much change occurs per unit of frequency.

Time signal acquisition bandwidth refers to how quickly a spectrum analyzer can capture data within a given amount of time. The lower the measurement, the faster the excitation and response will be, allowing for more precise measurements with less setup time.

Tracking measurements are used to follow the performance of an RF component over time. This allows for trends in the behavior of a system, which can be useful data when designing an entire wireless network.

Transient response refers to the behavior of a signal after it has been turned off. This is an important measurement for power efficiency and reliability.

Vector signal analysis is a method of displaying signals through vector diagrams. These are also known as phasor diagrams, so the terms are often interchangeable.

Wide range refers to an analyzer’s ability to measure a broad range of frequencies on the spectrum using a single span setting. This is measured in decibels and shows how wide of a range can be measured with one sweep.

Windowing data refers to the process of filtering out noise from a signal. In this context, “noise” refers to any frequencies that are not within the wanted range. This is done by adding a window function that makes those outside frequencies essentially zero.