MIS 383 Final

Electrical Performance Terms

Attenuation (Insertion Loss)

Amount of loss in signal strength as the signal moves down the wire.

10 x LOG10(Pin / Pout)

Power Sum (Power Sum)

Unwanted interface caused by signal from nearby cables or circuits.

−10×log10(i=1∑n 10−Value i / 10)

NEXT (Near-End Crosstalk)

Amount of unwanted signal coupling (interference) from one twisted pair to another. (Measured at the transmitting end of the cable)

10Log10(P Tx / P NEXT)

FEXT (Far-End Crosstalk)

Measure of interference (unwanted signal coupling) that occurs when signal transmitted on one wire pair in cable induces a voltage on another wire pair (measures at opposite (far end ) of the cable from where the original signal was transmitted.

10Log10(P Tx / P FEXT)

PSNEXT ( Power-Sum Near-End Crosstalk)

measures total crosstalk of all cable pairs (high value = better cable perf)

-10 x LOG10(i=1∑n 10−NEXTi / 10)

PSFEXT (Power Sum Far-End Crosstalk)

measures total (interference) crosstalk occurring at Far-End cable, caused by signals transmitted simultaneously on all other wire pairs within the same cable.

-10 x LOG10(i=1∑n 10−FEXTi / 10)

ELFEXT( Equal level far - end crosstalk)

Subtracts attenuation value from Far-End Crosstalk Loss (Value is the difference between test signal level and the crosstalk measured at far-end of the table)

FEXT (dB) - Attenuation (dB)

PSELFEXT( Power Sum Equal-Level Far-End Crosstalk)

Uses all four wire pairs to obtain combined ELFEXT performance measure. (value is difference between test signal level and cross talk measured at far-end of cable)

-10 x LOG10(i=1∑n​ 10−FEXTi / 10)

ACR (Attenuation to Crosstalk Ratio)

Measure compares signal level from transmitter at far-end crosstalk measured at near-end (larger value = greater data capacity, and cables ability to handle greater bandwidth.

NEXT (dB) - Attenuation (dB)

AXT ( Alien Crosstalk)

Measure of unwanted signal coupling from one permanent link to another(EX: from one four- paired cable to another)

-10 x LOG10(i=1∑n 10−Palien noise/ Psignal)

PSACR (Power-sum Attenuation to Crosstalk Ratio)

Uses all four wires to obtain attenuation/crosstalk, ratio, measuring difference between PSNEXT and attenuation (insertion loss) (Higher dB value = better cable performance)

PSNEXT (dB) - Attenuation (dB)

ANEXT ( Alien Near - End Crosstalk)

Measurement for Crosstalk at the near-end of the victim cable, caused by signals from adjacent disturbing cables at their near ends.

-10 x LOG10(Palien/Psignal)

AFEXT (Alien-Far-End Crosstalk)

Measure at the far -end victim cable, caused by signals from adjacent cables, transmitting simultaneously.

-10 x LOG10(Palien,far/Psignal)

PSANEXT (Power-Sum Alien Near-End Crosstalk)

Parameter for 10 Gigabit internet (bc ATX is main electrical engineering limiting parameter for 10 Gigabit Ethernet. Electronics have troubling cancelling AXT noise created, which disturbs neighboring cables.

-10 x LOG10(i=1∑n 10−ANEXT i / 10)

PSAFEXT (Power Sum Alien Far- End Crosstalk)

measures the total unwanted signal coupling from multiple surrounding "disturber" cables into a single "victim" cable at the opposite end of the transmission

-10 x LOG10(i=1∑n 10−AFEXT i / 10)

PSAACRF (Power-Sum Alien Attenuation to Crosstalk Ratio)

Both Gigabit and 10 Gigabit Ethernet require use of all four wire pairs. Tests cable compatibility with data transmission and reception (used on all four wire pairs)

PSAFEXT (dB) - Attenuation

TCL ( Transverse Conversion Loss)

Measure balance or symmetry or signal over the wire pairs to minimize leekage of signal (measure obtained by applying common-mode signal to input and calculating differential signal level on the output (sometimes called LCL(Longitudinal Conversion Loss)

20 x LOG10(Vdiff/Vcm)

ELTCTL (Equal Level Transverse Conversion Transfer Loss0

Measure of difference between TCTL and differential mode insertion loss of the wire pair being evaluated (differential signal flows in one direction in one wire but opposite direction in a wire pair

20 x LOG10(Vdiff, far/Vcm, near)

TCTL (Transverse Conversion Transfer Loss)

Loss from balanced signal at Near-End to unbalanced signal at far end.

20 x LOG10(Vdiff, near/Vcm, far)

Optical Performance Terms

OSNR (Optical Signal -to-Noise Ratio)

Measures signal strength relative to noise

10 Log10(P signal / P noise)

CD (Chromatic Dispersion)

Light Spreading due to the different wavelengths traveling at different speeds.

CD(ps/nm * km) = d(Δ t) / d λ

WD (Waveguide dispersion)

Arises due to the fibers geometry and refractive index profile, affecting how different wavelengths are confined in the core.

λd2β / c dλ2

MD (Material Dispersion)

A measure of wavelength dependence of the refractive index of the core material (typically sillica)

λd2n / c dλ2

DIPB (Dispersion- induced Pulse Broadening)

The temporal spreading (widening) of an optical pulse as it travels through an optical fiber, caused by different spectral components (wavelengths) of the pulse traveling at different velocities.

D Δλ L

PMD (Polarization Mode Dispersion)

Light polarization of causing transmission delays. this is distinct from chromatic dispersion, and occurs from birefringence in the fiber.

DPMD * L

APD (Avalanche Photodiode)

Type of photo detector used in fiber optics to convert incoming optical signals into electrical current. Similar to a regular photodiode, but with internal gain achieved through an avalanche multiplication process.

Itotal / Iprimary

FWM ( Four - Wave Mixing)

Non linear distortion caused by wavelength interference. This phenomenom occurs when three light waves interact within a medium(like and optical fiber) to generate a fourth wave through the mediums third order linearity.

f1 + f2 − f3

RS (Return Signal)

Reflection loss in fiber optics,

10 log10 (P reflected / P incident)

IL (Insertion Loss)

power loss due to connections or splices in fiber cables

10 log10 (P input / P output)

RL (Return loss in Fiber)

Similar to copper, signal reflection back to the source.

10 log10 (P incidence / P reflected)

SNR (Signal to Noise Ratio)

measure of the quality of the received optical signal relative to background noise .

P signal / P noise

R ( responsivity)

Measurement of the effectiveness level of photodetector at converting optical power ( light) into electrical current)

I photo / P optical [A/W]

BW ( Bandwidth)

Fundamental parameter that includes how much data (or signal frequencies ) that can pass through the optical systems without distortion loss.

1 / (2 π Δ t)