Glossary

Prefixes

Symbol Prefix Value
p pico 10-12
n nano 10-9
µ micro 10-6
m milli 10-3
k kilo 103
M mega 106
G giga 109
T tera 1012

Numbers/Symbols

GHz gigahertz 109 hertz
kS kilosamples 103 samples
MHz megahertz 106 hertz
µs microseconds 10-6 seconds
µW microwatts 10-6 watts
ms milliseconds 10-3 seconds
mW milliwatts 10-3 watts
nW nanowatts 10-9 watts
A
acquisition mode One of the three ways in which the RF power sensor takes power measurements: continuous, time slot, or scope. Not all RF power sensors support all acquisition modes.
ADC analog-to-digital converter—An electronic device, often an integrated circuit, that converts an analog voltage to a digital value.
ADE application development environment—A software environment incorporating the development, debug, and analysis tools for software development.
aperture time The total time the sensor observes the input signal in order to make one power measurement.
API application programming interface—A standardized set of subroutines or functions along with the parameters that a program can call.
auto-averaging Operation mode in which the sensor firmware determines the optimal number of samples to average.
auto-ranging Operation mode in which the sensor firmware determines the appropriate range for sensor operation.
average count The specified number of measurements over which a measurement when using the moving or repeat averaging method.
C
calibration factor The ratio of RF input power to measured DC power at either the detector output or the input to the ADC
continuous acquisition mode Acquisition mode in which the RF power sensor starts measuring power immediately after the operation is initiated and continues until you stop the operation.
CW continuous wave—A continuous sine wave that is the carrier wave in a radio transmission.
D
dB, decibel The unit for expressing a logarithmic measure of the ratio of two signal levels: dB = 10*log10(V1/V2), for signals in volts.
dBm decibel milliwatt—Absolute power level referenced to 1 mW.
DUT device under test—Synonymous with unit under test (UUT).
duty cycle The percentage of the waveform period that the waveform is at logic high level at the active state.
F
fence Controls which portion of the time domain data is recorded in scope acquisition mode. All points that fall within the specified fence are rejected. A fence must be set up within the boundaries of a gate, unless the fence is disabled by setting the fence start and end to zero, or to the same value.
G
gate Controls which portion of the time domain data is recorded in scope acquisition mode. All points that fall within the specified gate are measured.
H
hertz, Hz (n., adj.)
  1. The SI unit for measurement of frequency. One hertz (Hz) equals one cycle per second.
  2. The number of scans read or updates written per second.
high aperture time (HAT) mode In HAT mode, the power sensor provides more accurate measurements of TDMA signals. In this mode, the ADC acquisition time is increased, and the display window update rate is decreased. This mode can be useful when measuring low power, modulated signals and when changing between ranges. With HAT selected, signals with pulse repetition periods as long as 50 ms can usually be measured.
hysteresis The hysteresis level describes the arming range of the trigger.
L
low aperture time (LAT) mode In LAT mode, the ADC acquisition time is decreased and the display update rate is increased. With LAT selected, the maximum recommended pulse repetition time is about 10 ms.
M
Mbps megabits per second
measurement uncertainty A parameter, associated with the result of a measurement, that characterizes the dispersion of values that could reasonably be attributed to the measurement.
moving averaging Averaging that is continuously performed over a specified number of measurements. When a specified number of measurements is completed, the average is calculated. As the next measurement is taken, the average is recalculated from the new start and end positions.
multitone Signal consisting of two or more sine waves. Using multitone signals, you can test a system at many frequencies at the same time, assuming that you use an FFT spectrum analyzer.
N
NI-568x The driver software needed to use National Instruments RF power sensor devices.
NI-568x device Refers to any device supported by the NI-568x instrument driver.
O
OFDM orthogonal frequency-division multiplexing—A frequency-division multiplexing scheme in which closely-spaced orthogonal sub-carriers carry data.
overshoot The amount that a square wave or transient signal exceeds the desired level when transitioning from one voltage to another.
P
power meter See RF power sensor.
R
repeat averaging Averaging that is performed over a specified number of measurements. The displayed power is updated after the next batch of measurements is complete.
RF power sensor Refers to the USB-5680, USB-5681, USB-5683, or USB-5684 device.
ringing The oscillating characteristic of a square wave that may occur immediately after the transition from one level to another. Ringing occurs due to resonances in the circuit that the signal passes through.
S
S sample—the value measured at a particular moment in time.
scope acquisition mode Measures the power of any specific time interval using gate and fence settings to define the interval. An internal or external trigger initiates the power sensor measurement with respect to time.
second s, seconds
  1. Measure of angle = 1/60 of one minute. Often denoted by ", for example 37 seconds is written 37".
  2. s—The fundamental unit for the measurement of time. The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.
slope The slope of a signal when viewed in the time domain. A positive slope occurs when the signal has an upward slope with increasing time. A falling slope occurs when the signal has a downward slope with increasing time.
SRAM static random access memory—A form of RAM that retains its data without refreshing.
SWR standing wave ratio—the ratio of the maximum amplitude of a standing wave to the minimum amplitude of the wave.
T
TDMA time division multiple access—A channel access method for shared networks. TDMA allows multiple users to share the same frequency channel by dividing a signal into different time slots.
time slot acquisition mode Divides the power measurement into "time slots" that you define for the measurement, and calculates the average power reading for each individual time slot.
trigger An external stimulus that initiates one or more instrument functions. Trigger stimuli include a front panel button, an external input voltage pulse, or a bus trigger command. The trigger may also be derived from attributes of the actual signal to be acquired, such as the level and slope of the signal.
U
USB universal serial bus—A serial bus for connecting computers to keyboards, printers, and other peripheral devices. USB 1.1 and USB 2.0 Full-Speed supports 12 Mbps, and USB 2.0 High-Speed supports up to 480 Mbps bandwidth. USB 2.0 retains compatibility with the original USB 1.1 specification.
V
VSWR voltage standing wave ratio—The loss due to the mismatch introduced into the signal by the load or source signal path characteristics. The ratio of the highest voltage to the lowest voltage found in the signal.
W
W watt—The practical unit of electric and other power. One watt is dissipated by a resistance of 1 Ω through which a current of 1 ampere flows.
Z
zeroing Procedure for eliminating sensor offsets.