Parameters of the relative influence

The crosstalk attenuation is an attenuation of a sinusoidal signal at the transition from influencing circuit to the exposed to an influence circuit.

The near-end crosstalk attenuation is an attenuation of a sinusoidal signal at the transition from near-end influencing circuit to the near-end exposed to influence circuit on conditions that circuits are matched at the ends.

The matched load is a load, whose parameters correspond to the reception on it greatest power, load lines, where the line is no reflected wave.

The far-end crosstalk attenuation is an attenuation of a sinusoidal signal at the transition from near-end influence circuit to the far-end exposed to influence circuit on conditions that circuits are matched at the ends.

Immunity between the circuits at the far-end (immunity) - attenuation (crosstalk) sinusoidal signal at the transition from the far-end of the influencing circuit to the far-end of the exposed to influence circuit, on conditions that circuits are matched at the ends.

Immunity between the circuits is defined as the difference between the signal level at the end of the influencing circuit and the noise level at exposed to influence circuit.

The attenuation of the asymmetry is an attenuation of a sinusoidal signal at the transition from an artificial circuit formed by wires of cable and the "ground" in working pair cable.

Mutual influence in the cable caused by electromagnetic coupling between the pairs. The level of interference occurring within the cable is determined by the crosstalk between pairs. Distinguish between near-end crosstalk ratio А ₀, at the far-end of А_l and immunity at the far-end А_i.

Fig. 2.1 shows a model of transitional influences between pairs of the cable. Vertical dashed lines indicate the two ends of the cable.

The pair connected to the generator is influencing, while the pair connected to the ends of the load is one exposed to influence. End of the pair which is connected to pair of generator is near-end. End of the cable pairs which are connected to the load R_l is the far-end. Load R_l must be matched with the impedance Z_R of pairs.

Figure 2.1 – Determination of near-end crosstalk attenuation А ₀, at the far-end of А_l and immunity at the far-end of A_i

The value of crosstalk attenuation at the near-end of the А ₀ in dB is 10 logarithm of the module power ratio signal Р ₁₀ at the near-end of an influencing pair to a noise power Р ₂₀ at the near end pair, that exposed to influence:

А ₀ = 10lg│ Р ₁₀ /Р ₂₀│.

The value of crosstalk attenuation at the far end А _l (in dB) is 10 logarithm of the module power ratio signal Р ₁₀ at the near-end of an influencing pair to a noise power Р _2l at the far-end pair that exposed to influence:

А_l = 10lg│ Р ₁₀ /Р _{2 l} │.

The value of the immunity at the far-end А _i (in dB) is 10 logarithm of the module power ratio signal Р _{1 l} at the far-end of an influencing pair to a noise power Р _{2 l} at the far-end pair that exposed to influence:

А _з = 10lg│ Р _{1 l} /Р _{2 l} │.

The crosstalk attenuation at the far-end and the immunity at the far-end are related by own attenuation of a pair equal to the product of the attenuation coefficient α on the cable length l:

А_l = А _з + αl.

Дата добавления: 2015-10-26