Characteristic Impedance

• This corresponds to the input impedance of a uniform transmission line of infinite length that is terminated in its own characteristic impedance.  In general, the characteristic impedance is a complex number with a resistive and reactive component. It is a function of the frequency domain of the applied signal, and is unrelated to length, express in Ohm (or Ω). At the higher frequency level, the characteristic impedance asymptotes to a fixed value which is resistive. For example, coaxial cables have an impedance of 50 or 75 Ohms. Typically, twistedpair telephone and networking cables have an impedance of 100 Ohms above 1 MHz. At high frequencies (> 100 kHz).

Far-end crosstalk (FEXT)

• FEXT loss is the unwanted signal coupling between the signal source and receiver. However FEXT loss portions at the far-end into difference pairs or cords, (express in dB), even though FEXT loss shall be measured for all pair or cord combinations of more than two pairs or cords cables.

Insertion Loss/Attenuation

• It is a measure of the signal loss resulting from any cables, patch cords and assemblies or component between a transmitter and receiver. It is the ratio of signal power at the receiver end to the input power determined from measured voltages, expressed in dB.

Near-end crosstalk (NEXT)

• NEXT loss is a measure of the unwanted signal coupling from a transmitter at the near-end into neighboring pairs or cords measured at the nearend. NEXT loss is expressed in dB relative to the transmit signal level. Then, NEXT loss shall be measured for all pair or cord combinations of more than two pairs and cords cables.

Propagation delay

• Propagation delay is the time it takes for a signal to propagate from near end to far end of a conducting pair or cord in any cables, patch cords and assemblies, expressed in nanosecond (ns). It should be measured for all pairs or cords of cables.

Propagation delay skew

• Propagation delay skew is a measurement of the signaling delay difference from the fastest pair (or cord) to the lowest one, expressed in nanosecond (ns). It is calculated from the propagation delay measurement.

Return Loss

• It is a measure of the reflected energy caused by impedance mismatches in the cabling, connector, source, receiver and other system and is especially important and major for applications that use simultaneous bi-directional transmission. Return Loss is the ration of the reflected signal power to the input power determined from measured voltages, expressed in dB.

Rise-time (or Bandwidth)

• It is a differential signal and measurement across the output of a differential pair with a load present (includes test equipment). Rise time edges are measured. The 100% and 0% level is normalized 1 and 0 levels present when sending half clock characters.

  Once the normalized amplitude, the time base is changed to a finer scale to measure the rise-time. The half clock data pattern is transmitted for the rise time measurement. This specification is definite the time interval between the normalized 20% and 80% amplitude levels. It is recommended to utilize the averaging feature of the equipment to read more stable values.