Glossary
CT100B can emulate this protocol.
Stability
The change in the accuracy of a measurement or piece of test equipment over a period
of time such as the calibration interval. Stability may also refer to changes in accuracy
related to a specific environmental influence such as vibration, temperature, or humidity.
TDR
Acronym for Time-Domain Reflectometer or Reflectometry. TDR instruments use a form
of closed-circuit radar to detect cable faults. A series of pulses are sent into a cable and
reflected voltage is measured as a function of time. If the velocity of propagation (Vp) is
known, the length of a cable and the distance to cable faults can be determined. TDR
traces produced by step-rise TDRs like the CT100B describe the impedance of a cable
along its length and can accurately detect a wide range of cable faults that can impair
high-frequency analog/RF and digital communications systems.
Trace
A displayed or stored signal. When displayed, a trace appears as a line across the screen.
A trace may be a direct TDR measurement, as with the live trace, or derived trace, such
as a difference trace or an S
11
trace. A trace is sometimes referred to as a “waveform”. A
scanned or saved trace may be called a “scan”. A trace is a visual representation of the
waveform generated by a TDR. Traces on the CT100B may be in either time or frequency
domain depending upon their purpose.
Trace Averaging
See Noise.
USB
Universal Serial Bus. A common system for connecting a peripheral, such as a printer,
phone, or CT100B to a computer.
Velocity of Propagation (Vp)
Velocity of propagation of an electrical signal within a cable as a
fraction of c, the speed of light in a vacuum. Coaxial cable usually has a Vp of between 0.6
and 0.9.
Vertical Reference (Vert Ref )
A feature of the CT100B that improves vertical measurements
by referencing them to scans from short and open calibration terminations.
CT100B TDR Cable Analyzers Operator’s Manual
115
