Telephone cable transmission distance

In our general construction process, we do not consider the transmission distance of large logarithmic local telephone cables and ordinary telephone lines. The theoretical transmission distance is as follows:

It doesn't matter what the logarithm is, it matters what the diameter of the conductor is

For telephone cables with a wire diameter of 0.4mm, the loss per kilometer is 1.64db (800Hz), and the national standard for loop resistance of 1000m is 296 ohm or less, which is calculated as a pair of wires.

For telephone cables with a wire diameter of 0.5mm, the loss per kilometer is 1.33db (800Hz), and the national standard for loop resistance of 1000m is less than or equal to 190 ohms, which shall be calculated as one pair of wires.

For telephone cables with a wire diameter of 0.6mm, the loss per kilometer is 1.06db (800Hz), and the national standard for loop resistance of 1000m is 131.6 ohm or less, which is calculated as 1 pair of wires.

For telephone cables with a wire diameter of 0.8mm, the loss per kilometer is 0.67db (800Hz), and the national standard for loop resistance of 1000m is 73.2 ohm or less, which is calculated as a pair of wires.

It is generally assumed that if the maximum attenuation of the user line is allowed to be 7.0db:

Theoretical transmission distance of telephone cable with wire diameter of 0.4mm, 4.26km,

Theoretical transmission distance of telephone cable with line diameter of 0.5mm, 5.26km.

The theoretical transmission distance of telephone cable with a wire diameter of 0.6mm is 6.6km.

Theoretical transmission distance of telephone cable with a wire diameter of 0.8mm is 10.44km.

At the same time, consider that the loop resistance required by SPC switches is less than or equal to 1000 ohms (generally not more than 1500 ohms depending on the manufacturer's brand).

Reference data reference standards

YDN 088-1998 technical system of automatic switched telephone (digital) network

YD 2001-1992 technical specification for construction and acceptance of municipal communication all-plastic cable line project