Glossary of Oscilloscope Probe Terms

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Any difference  from the norm; in probing this is related to the flat tops and bases of  waveforms or pulses. 

Aberrations in observed signals can be caused by  the circuit conditions of the signal source, and/or injected upon a  signal by a measurement system. 

Aberrations are specified as a  percentage deviation from a flat response.

A probe incorporating transistors or other active devices as part of the  probe’s signal conditioning network to further minimize circuit  loading.

Signal amplitude reduction. 

Example: x10  attenuation reduces an observed signal to one tenth of its actual level;  therefore using a x10 probe setting would attenuate a 100 volt  peak-to-peak signal to 10 volts peak-to-peak for viewing on an  oscilloscope’s 2 or 5 volt/cm scale by producing effectively a 20 or 50  volt/cm scale.

The impedance across a signal source; an open circuit would have no load.

Drawing current from a signal source by  applying an impedance. The lower the impedance the more current is drawn  away from the source.

ezTip:  On a 10x setting, when added to the 1 megaohm (1M) input resistance of  an oscilloscope, the probe tip will have a total 10 megohm (10M)  resistance to ground, minimizing possible circuit loading. Maximize  impedance to minimize the loading of the circuit under test.

A probe with no active components, consisting  of a network equivalent of only static resistive, inductive, or  capacitive elements.

An expression of the time-related positions of waveforms or waveform components relative to a reference point or waveform.

Power supplied to the probe from a probe  amplifier or even the circuit under test. 

Typically active probes  require external power to prevent circuit under test loading.

A non-resistive component of an impedance  element that reacts to an AC signal by restricting its current flow  based on the signals frequency. Either capacitive (XC) or inductive  (XL), if these reactive components are equal they cancel, leaving only a  resistive component.

Digital information displayed on an  oscilloscope screen providing waveform scaling information, or even  frequency measurement results in some modern digital oscilloscope  systems.

A specialty BNC probe connector with a  built-in spring loaded shorting pin that facilitates the proper  translation of digital information displayed on an oscilloscopes with  actuator features.

ezTip:  To activate your oscilloscopes x10 readout factor insert 12k between the  outer activation ring of the scope’s BNC input connector and ground.  For x100 readout factor use 6k. Without an outer ring BNC connection, or  greater than 15k, your readout defaults to x1.

The resulting oscillations of circuit  resonation. Example: The damped sinusoidal variations seen on pulses are  referred to as ringing.

ezTip: With  probing, longer ground leads create a higher ringing susceptibility and  subsequent poorer quality signal display as the test signal frequency  rises. The convenience of longer grounding leads are OK for lower  frequency applications; however, we recommend, and supply, 6 inch ground  leads and BNC tip adapters with all our probe sets designed for  bandwidths higher than 100MHz.

On the rising transition of a pulse, rise time  is the time it takes the pulse to rise from the 10% amplitude level to  the 90% amplitude level.

A grounded conductive sheet of metal between a  circuit and external noise sources. This shielding material intercepts  noise signals and conducts them away from the circuit.

The ratio of signal amplitude to noise amplitude, expressed in dB as: SNR = 20 log (Vsignal / Vnoise)

Signal voltage or current supply.

The impedance (Z) seen when looking back into a source.