Glossary

NI Signal Generators Help (NI-FGEN 18.1)

Edition Date: April 2018

Part Number: 370524V-01

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Prefixes

Symbol Prefix Value
p pico 10 -12
n nano 10 -9
µ micro 10 -6
m milli 10 -3
k kilo 10 3
M mega 10 6
G giga 10 9
T tera 10 12

Numbers/Symbols

nV nanovolts 10-9 volts
µV microvolts 10-6 volts
µΩ microohms 10-6 ohms
mΩ milliohms 10-3 ohms
MΩ megaohms 106 ohms
pA picoamps 10-12 amperes
nA nanoamps 10-9 amperes
µA microamps 10-6 amperes
mA milliamps 10-3 amperes

A

AC alternating current
ADC Analog-to-Digital Converter—An electronic device, often an integrated circuit, that converts an analog voltage to a digital value. Also abbreviated as A/D Converter.
alias A false lower frequency component that appears in sampled data acquired at too low a sampling rate.
arbitrary video generator Instrument for generating arbitrary video waveform; this instrument is not restricted to standard waveforms such as sine or square.
array Ordered, indexed list of data elements of the same type.
attribute Parameter or configuration applied to the video signal.

B

bandwidth The range of frequencies present in a signal, or the range of frequencies to which a measuring device can respond. For signal generators, bandwidth is the frequency at which the amplitude of the frequency response is 3 dB lower than the amplitude of the frequency response at DC or a low frequency.
.bin File extension for a binary file. See binary file.
binary file 16-bit file format used to save the data of a complete composite video signal. See .bin.
bitmap image RGB image format. See .bmp.
block mode Optimized calculation mode where a block of video lines is computed simultaneously.
.bmp File extension on a bitmap image. See bitmap image.

C

C Chroma component in a composite video signal. See S-Video or Y/C.
.cfg File extension on a configuration file. See configuration file.
chroma The color part of the video signal in the M-NTSC and PAL video signal.
composite luma A monochrome composite video signal. See Y.
composite video signal A single signal that contains color video and timing information.
configuration file A file where you can save your specific video signal setup conditions such as the video parameters or attributes, video format, and some other information regarding the signal.
Csync Composite synchronization signal; a single signal including both horizontal and vertical synchronization pulses.

D

DAC Digital-to-Analog Converter—An electronic device, often an integrated circuit, that converts a digital number into a corresponding analog voltage or current.
data marker event An event that allows you to export any one of the waveform data bits to any valid destination on the device.
data mask Static value bits used to shield bits of waveform data.
DC direct current
DDS direct digital synthesis—A signal generation technique giving very high-frequency resolution.
digital synchronization Digital TTL signals delivering Csync, Vsync, Hsync, and field ID signals.
DMA direct memory access—A method by which data can be transferred to/from computer memory from/to a device or memory on the bus while the processor does something else. DMA is the fastest method of transferring data to/from computer memory.
DMM Digital Multimeter—A digital instrument capable of measuring several different fundamental electrical characteristics, most often voltage, resistance, and current.
done event An event that indicates that the generation of the previous waveform is complete.

E

ENOB Effective Number of Bits—A way of specifying the signal-to-noise-and-distortion ratio (see SINAD) that indicates how close a DAC is to an ideal DAC of the same size.
event A signal generated by the NI device at a device state. Typically, events are configured to indicate when a specific hardware condition has been met.

F

FCW Frequency Control Word—The phase accumulator is incremented by the value of the FCW to generate the desired frequency of the output signal.
field ID Signal that identifies the even or odd field in an interlaced video frame.
filter coefficients Constant values that characterize a digital filter.
filter data See filter coefficients.
filters Digital or analog circuits that change the frequency characteristics of a video signal.
frequency modulation sub-carrier Carrier signal in SECAM used to represent the chroma information.
frequency hop The continuous generation of a single waveform with user-defined frequency changes.
frequency sweep The continuous generation of a single waveform with a linearly-changing frequency.

G

gain Amplification of a signal. A gain of two corresponds to a doubling of the signal level.

H

high-level driver VI Hardware dependent VI that simplifies the needed programming. All high-level drivers are based on low-level Vis.
Hsync Horizontal sync—the portion of the video signal that tells the display where to put the picture in the left-to-right dimension. See horizontal sync pulse.
horizontal sync pulse Pulse that controls line–by–line scanning.

I

insertion test signals Test signals to be inserted on specific lines either in the vertical blanking interval or in the active image region.
IRE Unit used to describe the level of a video signal. Pure white is defined as 100 IRE. The blanking level is defined as 0 IRE.
ITS Insertion Test Signals

L

line-by-line mode Calculation mode where the video lines are computed one at a time.
least significant bits The four bits present in the 16-bit data word that are not used to represent the analog signal. These bits contain the digital synchronization signals.
lookup memory Fixed-size memory that stores one cycle of a periodic waveform.
looping Repeating the same buffer in the waveform memory. This method of waveform generation decreases memory requirements.
low-level driver VI The lowest level of programming. The low-level driver VIs offer the most functionality but require more programming.
lsbs See least significant bits.
luma The monochrome part of the composite video signal.

M

maps A bitmap image needs to be mapped by the software before it is used to compute a composite video signal.
marker event An event that the device generates in relation to a waveform that is generated. The event is configured to occur at the time that a specific location or sample n in the waveform generates on the CH 0 connector.
modulation cosine Cosine function representing the sub-carrier for the second chroma component in PAL or NTSC systems.
modulation sine Sine function representing the sub-carrier for the first chroma component in PAL or NTSC systems.
M-NTSC see NTSC.
M-PAL Video standard used in Brazil. Uses 525 lines per frame.

N

N-PAL Video standard used in Argentina. Uses 625 lines per frame.
NTSC(M-NTSC) National Television Standards Committee; the video standard used in North America and Japan. Uses 525 lines per frame.

O

offset Constant value added to a signal.
OSP onboard signal processing

P

PAL Phase Alternation Line—color video standard used in Europe and in many other countries outside the US M-PAL uses 525 lines per frame. All other PAL formats use 625 lines per frame.
parameters Non–programmer's term for video signal conditions that you can modify using the NI-VDG.dll. See attribute.
passband The range of frequencies which a device can properly propagate or measure.
passband flatness A measure of the amplitude accuracy of the frequency response with respect to frequency. Passband flatness is typically specified in ±dB and referenced to the amplitude of the frequency response at a designated frequency.
PCI peripheral component interconnect—A high–performance expansion bus architecture originally developed by Intel to replace ISA and EISA. It has achieved widespread acceptance as a standard for PCs and workstations, and offers a theoretical maximum transfer rate of 132 Mbytes/s. Future versions of the bus will be 64-bits wide and offer double-clock speed.
PFI Programmable Function Interface—I/O channels to the digital waveform generator/analyzer. Functionality and specifications will vary by device and operation.
PLL phase-locked loop—An electronic circuit which forces an output frequency to be locked to the same phase as a reference frequency.
prepare mode Mode to be called before lines calculation in block mode.
PXI PCI eXtensions for Instrumentation—Rugged, open system for modular instrumentation based on CompactPCI, with special mechanical, electrical, and software features.
PXI Express (PXIe) PCI Express eXtensions for Instrumentation—The PXI implementation of PCI Express, a scalable full-simplex serial bus standard that operates at 2.5 Gbps and offers both asynchronous and isochronous data transfers.
PXI trigger bus PXI equivalent of the RTSI bus, with additional timing and synchronization capabilities.

R

ready for start event An event that indicates that the signal generator is configured and ready to receive a Start trigger.
release mode Mode to be called after lines calculation in block mode.
resolution The smallest signal increment that can be detected by a measurement system. Resolution can be expressed in bits, in proportions, or in percent of full scale. For example, a system has 12-bit resolution, one part in 4,096 resolution, and 0.0244 percent of full scale.
RGB red, green, blue
RGB ITS Three data arrays (R, G, and B) of unsigned 16-bit data (U16).
rms root–mean–square—The square root of the average value of the square of the instantaneous signal amplitude; a measure of signal amplitude. The rms voltage of a signal is computed by squaring the instantaneous voltage, integrating over the desired time, and taking the square root.
RTSI bus Real–Time System Integration Bus—The National Instruments timing bus that connects DAQ devices directly, by means of connectors on top of the devices, for precise synchronization of functions.

S

s seconds
S samples
sample rate The rate at which digital data is transferred from the memory to the DAC.
saturation factor The amount of color pigment present. The less saturated a color is, the more white that is present in the color.
scaling The act of changing the effective resolution of an image.
script A series of instructions that indicates how waveforms saved in the onboard memory should be sent to the device under test.
SECAM Sequential Couleur Avec Memoire or Sequential Color with Memory. Video standard used in France and parts of Africa and Middle East. Uses 625 lines per frame. In SECAM, the chroma is FM modulated and the R’-Y and B’-Y signals are transmitted line sequentially.
settings Video signal conditions, which are also knows as video parameters or attributes.
SFDR spurious-free dynamic range—The dynamic range from full-scale deflection to the highest spurious signal in the frequency domain.
SGL single precision
signed 16-bit values 16-bit integer values in the range [–32,768 to +32,767].
SINAD Signal-to-Noise-and-Distortion ratio—ratio of the rms signal amplitude to the rms sum of all other spectral components, including the harmonics, but excluding DC.
started event An event that indicates when the signal generator has received a Start trigger and is generating a waveform.
streaming A way to generate waveforms that are too large to fit in the onboard memory of the signal generator by repeatedly filling free onboard memory with blocks of new waveform data until the entire waveform generates.
S-Video see Y/C
sync Synchronization signals controlling the horizontal and vertical deflections in a TV.

T

THD total harmonic distortion—The ratio of the total rms signal due to harmonic distortion to the overall rms signal, in dB or percent.
transient A brief oscillation resulting from a sudden change of voltage, current, or load.
trigger Signal that causes the NI device to perform an action such as starting or stopping a generation operation.
TTL Transistor-Transistor Logic

U

unmap The bitmap image is unmapped after being used to compute a composite video signal.

V

VCXO voltage-controlled crystal oscillator
vertical sync pulses Pulses that control the vertical scanning. See Vsync.
video attribute A parameter of a video signal.
video data file File containing the binary data that represent a video signal.
video format Specifies the video norm used to compute the video signal such as M-NTSC or SECAM.
video lines The lines that compose a video signal.
NI 5431 Composite Video Generator The software package from your installation CD, which takes care of the needed calculations and driver functions especially developed to interface between your computer and your NI 5431.
video waveform What the signal looks like to the video output device.
Vsync Vertical sync; the portion of the video signal that tells the display where to place the image in the top-to-bottom dimension. See vertical sync pulses.

Y

Y Luma component in a composite video signal. See S-Video or Y/C.
Y/C Video signal where the luma signal Y and the chroma signal C are distributed independently.
YIQ Color space used in the M-NTSC color system. Y represents the luma component while I and Q are the two color difference components.
YUV Color space used by the PAL color system. Y is the luma component while U and V are the two color difference components.

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