Glossary

Analog to Digital.
See also ADC.

Alternate Current

Analog to Digital Converter

Amplitude Modulation

AFM mode where the amplitude change between drive and measured signal encodes the topography or the measured AFM variable.
See also Atomic Force Microscope.

Application Programming Interface

American Standard Code for Information Interchange

Microscope that scans surfaces by means an oscillating mechanical structure (e.g. cantilever, tuning fork) whose oscillating tip gets so close to the surface to enter in interaction because of electrostatic, chemical, magnetic or other forces. With an AFM it is possible to produce images with atomic resolution.
See also Amplitude Modulated AFM, Frequency Modulated AFM, Phase Modulated AFM.

Allen Variance

The signal bandwidth represents the highest frequency components of interest in a signal. For filters the signal bandwidth is the cut-off point, where the transfer function of a system shows 3 dB attenuation versus DC. In this context the bandwidth is a synonym of cut-off frequency f_cut-off or 3dB frequency f_-3dB. The concept of bandwidth is used when the dynamic behavior of a signal is important or separation of different signals is required.
In the context of a open-loop or closed-loop system, the bandwidth can be used to indicate the fastest speed of the system, or the highest signal update change rate that is possible with the system.
Sometimes the term bandwidth is erroneously used as synonym of frequency range.
See also Noise Equivalent Power Bandwidth.

Bayonet Neill-Concelman Connector

Clock Fail (internal processor clock missing)

Specification of a differential amplifier (or other device) indicating the ability of an amplifier to obtain the difference between two inputs while rejecting the components that do not differ from the signal (common mode). A high CMRR is important in applications where the signal of interest is represented by a small voltage fluctuation superimposed on a (possibly large) voltage offset, or when relevant information is contained in the voltage difference between two signals. The simplest mathematical definition of common-mode rejection ratio is: CMRR = 20 * log(differential gain / common mode gain).

Comma Separated Values

Digital to Analog

Digital to Analog Converter

Direct Current

Direct Digital Synthesis

Dynamic Host Configuration Protocol

Digital Input/Output

Domain Name Server

Digital Signal Processor

Device Under Test

The measure of a lock-in amplifier’s capability to withstand the disturbing signals and noise at non-reference frequencies, while maintaining the specified measurement accuracy within the signal bandwidth.

Extensible Markup Language.
See also XML.

Fast Fourier Transform

First In First Out

Frequency Modulation

Measure of an instrument’s ability to faithfully indicate the correct frequency versus a traceable standard.

AFM mode where the frequency change between drive and measured signal encodes the topography or the measured AFM variable.
See also Atomic Force Microscope.

Instrument capable to stimulate a device under test and plot the frequency response over a selectable frequency range with a fine granularity.

See also Frequency Response Analyzer.

See also Vector Network Analyzer.

General Purpose Interface Bus

Graphical User Interface

Input / Output

Instrument suited to stimulate a device under test and to measure the impedance (by means of a current measurement) at a selectable frequency and its amplitude and phase change over time. The output is both amplitude and phase information referred to the stimulus signal.

Measure of instrument’s capability to faithfully indicate the signal amplitude at the input channel versus a traceable standard.

Internet Protocol

Total noise generated by the instrument and referred to the signal input, thus expressed as additional source of noise for the measured signal.

Local Area Network

Light Emitting Diode

Instrument suited for the acquisition of small signals in noisy environments, or quickly changing signal with good signal to noise ratio - lock-in amplifiers recover the signal of interest knowing the frequency of the signal by demodulation with the suited reference frequency - the result of the demodulation are amplitude and phase of the signal compared to the reference: these are value pairs in the complex plane (X, Y), (R, Θ).

Refers to the unique identifier assigned to network adapters for physical network communication.

Refers to the simultaneous measurement of signals modulated at arbitrary frequencies. The objective of multi-frequency is to increase the information that can be derived from a measurement which is particularly important for one-time, non-repeating events, and to increase the speed of a measurement since different frequencies do not have to be applied one after the other.
See also Multi-harmonic.

Refers to the simultaneous measurement of modulated signals at various harmonic frequencies. The objective of multi-frequency is to increase the information that can be derived from a measurement which is particularly important for one-time, non-repeating events, and to increase the speed of a measurement since different frequencies do not have to be applied one after the other.
See also Multi-frequency.

Effective bandwidth considering the area below the transfer function of a low-pass filter in the frequency spectrum. NEPBW is used when the amount of power within a certain bandwidth is important, such as noise measurements. This unit corresponds to a perfect filter with infinite steepness at the equivalent frequency.
See also Bandwidth.

For sampled analog signals, the Nyquist frequency corresponds to two times the highest frequency component that is being correctly represented after the signal conversion.

Measure of an instrument’s ability to faithfully output a set voltage at a given frequency versus a traceable standard.

Over Volt (signal input saturation and clipping of signal)

Personal Computer

Phase Detector

Electronic circuit that serves to track and control a defined frequency. For this purpose a copy of the external signal is generated such that it is in phase with the original signal, but with usually better spectral characteristics. It can act as frequency stabilization, frequency multiplication, or as frequency recovery. In both analog and digital implementations it consists of a phase detector, a loop filter, a controller, and an oscillator.

AFM mode where the phase between drive and measured signal encodes the topography or the measured AFM variable.
See also Atomic Force Microscope.

Proportional-Integral-Derivative

Packet Loss (loss of packets of data between the instruments and the host computer)

Reduced Instruction Set Computer

Statistical measure of the magnitude of a varying quantity. It is especially useful when variates are positive and negative, e.g., sinusoids, sawtooth, square waves. For a sine wave the following relation holds between the amplitude and the RMS value: U_RMS = U_PK / √2 = U_PK / 1.41. The RMS is also called quadratic mean.

Real-time

Instrument that measures the voltage of an analog input signal providing just the amplitude (gain) information.
See also Spectrum Analyzer, Vector Network Analyzer.

Sample Loss (loss of samples between the instrument and the host computer)

Instrument that measures the voltage of an analog input signal providing just the amplitude (gain) information over a defined spectrum.
See also Scalar Network Analyzer.

Secure Shell

Time Constant

Transmission Control Protocol / Internet Protocol

An independent sequence of instructions to be executed by a processor.

Measure of the non-linearity of signal channels (input and output)

Transistor to Transistor Logic level

Ultra-High Frequency

Ultra-High Stability

Universal Serial Bus

Voltage Controlled Oscillator

Instrument that measures the network parameters of electrical networks, commonly expressed as s-parameters. For this purpose it measures the voltage of an input signal providing both amplitude (gain) and phase information. For this characteristic an older name was gain phase meter.
See also Gain Phase Meter, Scalar Network Analyzer.

Extensible Markup Language: Markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable.

Zurich Instruments Control bus

This technique performs FFT processing on demodulated samples, for instance after a lock-in amplifier. Since the resolution of an FFT depends on the number of point acquired and the spanned time (not the sample rate), it is possible to obtain very highly resolution spectral analysis.

Zurich Instruments Synchronization bus