1 The same batch of optical fiber has the same mode field diameter. After the fiber is disconnected at a certain point, the mode field between the two ends can be regarded as the same. Therefore, the welding at the breaking point can make the mode field diameter to the fiber fusion loss. The impact is minimized. Therefore, the optical cable manufacturer is required to use the same batch of bare fiber to continuously produce according to the required length of the optical cable, sequentially numbered on each disk, and respectively indicate A (red) and B (green) ends, and must not jump.

When locating the optical cable, it should be laid out according to the determined routing sequence according to the number, and ensure that the B end of the front cable is connected with the A end of the latter optical cable, so as to ensure that the mode fields of the two optical end faces are basically the same when connecting, so that the welding loss value is Achieve the minimum.

2 aerial cable can be used as a hanging wire for suspending the cable with 72.2mm galvanized steel strand. The hanging wire and the optical cable should be well grounded, and should have lightning protection and anti-electric measures, and have mechanical properties such as shockproof and windproof. The horizontal and vertical distance between the overhead suspension line and the power line should be more than 2m, the minimum height from the ground is 5m, and the minimum distance from the roof is 1.5m. There are three types of overhead cable hanging: hanging wire hanging type, hanging wire winding type and self-supporting type. Self-supporting type does not use steel hanging wire, the cable is drooping, and the wind load is poor, so it is commonly used.

3 aerial cables are laid. Since the length of the reel of the cable is much longer than the cable and may be several kilometers in length, it is limited by the allowable rated tensile force and bending radius. During construction, special attention must be paid to the fact that it cannot be yanked and kinked. Generally, the allowable tensile force of the optical cable is 150-200kg, and the bending radius of the optical cable should be greater than or equal to 10-15 times of the outer diameter of the optical cable. The bending radius of the optical distribution cable should be greater than or equal to 20 times of the outer diameter.

In order to avoid placing the optical cable in the middle of the road section, it should be erected in two opposite directions from the pole 20m. Firstly, the first half of the coil is erected, and then the rear half-reel cable is put off the disc and placed on the ground in the shape of “8”. Then lay it out.

4 When laying the optical cable, it is strictly forbidden to make small loops, folds and twists, and a certain number of walkie-talkies. The cable-feeding method of “front and rear heel, cable shoulder” can effectively prevent the back buckle from happening. Pay attention to uniform force, the traction force does not exceed 80% of the allowable cable, and the instantaneous maximum traction does not exceed 100%. In addition, when erecting, there should be someone responsible for the turning of the cable or the complex terrain, and it is strictly forbidden to crush the vehicle.

The overhead cable is used for the overhead cable. The pulleys are pre-mounted on the poles and suspension lines (generally one pulley is placed every 10~20m), and the sag is reduced on the upper and lower pulleys of the cable to reduce the tension. Then, the traction rope is put between the pulleys, and the traction rope is tied to the traction head of the optical cable, and the optical cable is climbed on the pole with a certain traction force and hung on the hanging wire. The spacing of the cable hooks is 40cm, the direction of the hooks on the hanging wires should be the same, and each pole should have a convex drip groove. Each cable should have a balance of 3m in the joint at the joint for the connection and Ground welding operation.