The following is an analysis of the reasons for the above two aspects, and proposes methods and measures to improve the solution
1. Reasons for line-prone obstacles
1. Line-prone obstacles are mainly five items: broken wire, mixed wire, poor insulation, ground gas, crosstalk and so on. Broken wires, mixed wires (referred to as overt obstacles in this article). These two obstacles are clearer than the other three obstacles, the search is simple, and the solutions and methods are mature and regular. Most can be solved in a short period of time with mature maintenance experience. After the treatment, it can be restored as before, not easy to repeat, and the consolidation effect is good. However, the causes of poor insulation, ground gas, and cross-talk (referred to as hidden obstacles in this article) are complicated, difficult to find and judge, and there is no ready-made unified solution. According to the traditional solutions and methods in the past, it is difficult to cure the obstacles of ADSL. The main reason is that ADSL transmits high-frequency signals, which have high or even strict requirements on the transmission quality of the line. If the line quality is not high, it is easy to cause current leakage of high-frequency signals.
2. Due to the above three hidden obstacles (poor insulation, ground gas, crosstalk), it is closely related to the leakage current of the high-frequency signal transmitted by the line. For example: the insulation strength between the cable cores or the core to the ground is poor; the quality of the user's incoming wires and the quality of the joint process are inseparable; the cable transfer box and the maintenance and use of the distribution equipment are inextricably linked. Therefore, the main solution is to block the transmission of high-frequency signal leakage current of the line, improve the insulation of the line, and clear the line leakage high-frequency signal current source.
3. The countermeasures to solve the leakage current source of high-frequency signal transmission of blocking line
â‘ . Main cable: In order to keep the insulation of the cable lines always good, the main trunk must be inflated and maintained. Qualified units and regions can implement automatic inflation maintenance on all main cables. Unconditional units and areas should also use portable inflators and manual inflating methods to periodically (generally once a month) inflate and maintain the cables to keep the cable cores always dry to a high degree.
â‘¡. Distribution cable: Before the joint of the overhead distribution cable is sealed, the joint must be tied up and bulged upwards, and the cables on both sides run down. Prevent the cable from entering the cable and the joint tube because of the inadequate sealing. In case of line obstacles caused by water, the zipper of the cable joint must be installed below the joint pipe; in addition to the shape of the overhead cable, the joint of the pipeline cable is also required to place the cable joint as far as possible above the annual groundwater level. Especially not For distribution cables that are inflated for maintenance, you should grasp this point as much as possible to avoid immersing the cable connector all the year round in order to prevent the cable connector from cracking or leaking tightly into the moisture and water. The zipper of the cable connector must be installed above the connector tube ;
â‘¢. Cable shielded wire: The shielded wires (including the cross-connect box and branching equipment) of the trunk and distribution cables and open wire cables must be connected in the whole process, and the resistance value meets the requirements of the maintenance regulations. Note that the installation quality of the shielded cable is closely related to the quality of ADSL. In the past, the traditional installation method of the cable shielding wire on the distribution frame and the junction box was mostly to directly crimp the shielded wire connection wire to the ground screw. Due to the increase in service life, the exposed joint of the shielded wire tends to oxidize. Seriously, the contact resistance increases a lot. For this reason, special copper joints should be used at the connection line of the cable shielding wire and welded. After such treatment, the connection resistance of the cable shielding wire is generally reduced by 10-20%.
â‘£. Terminal line: The terminal line mainly grasps the construction quality of the pole stop leather line and the user's lead-in line. Do not twist and twist multiple leather lines with each other, but bind them in parallel and uniform spacing between the leather lines in strict accordance with the construction requirements. Disturbance of magnetic induction coupling between wires. The best solution is to replace more than one bar gear and more than three leather wires in the same direction with open wire cables; do not leave connectors between the force bar gear wires of ADSL telephone leather wires. If it is necessary to leave a joint, it should be on the bow and nose of the unloaded lever. To avoid the long-term influence of the tension of the leather thread joint, the quality of the joint or the aging and cracking of the joint covering layer will be affected. ; As long as the quality of the installation and maintenance of the terminal line is solved (especially the quality of the sheath connector), it can effectively reduce the barriers of poor insulation and disconnection, and improve the quality of ADSL opening.
Second, the reason for the long line transmission distance
1. The transmission distance of the line is very important for the opening and operation quality of ADSL. In general, the effective opening distance of ADSL is within 4 kilometers (including cables, covered wires, etc.). If, within the same cable and the same distribution equipment, the installation ratio of ADSL exceeds 50%, due to ADSL
High-frequency signals are likely to form high-frequency signal crosstalk at the far end of the line, and the superposition of stray reflected currents increases, and their turn-on distance and quality will be greatly affected. According to the author's actual tracking and verification since 2002, when the installation rate of ADSL exceeds 50% in the same cable and the same distribution equipment, the effective opening distance of ADSL can generally be reduced to 3 kilometers or 2 kilometers. To increase the effective transmission distance of the line and the quality of the ADSL operation, it is necessary to eliminate the increase in the crosstalk and stray reflection current formed at the far-end line (generally referring to the cable) when the high-frequency signal is turned on.
2. In order to effectively eliminate the factors of increasing the crosstalk and stray reflected current formed by the ADSL high-frequency signal at the far end of the line, in addition to improving the quality of the line maintenance (reducing and reducing the obvious and hidden obstacles of the line) and try not to Beyond the prescribed distance for opening ADSL, we must grasp the following situations
â‘ . Strict line selection comparison process is implemented: when opening and installing ADSL, the cable core must be selected. Generally, the core with a loop resistance of about 1000-2000 ohms is opened. If the loop resistance is too large, you can use the two-wire combination method (that is, use two pairs of cable cores on top. Note that when using two-wire combination, one pair of wires is not allowed to be used as one, and the two pairs of wires should be used separately. The AA and BB wires are used in parallel, and the twisting pitch of the cable core must not be changed or destroyed.) Reduce the loop resistance. If there are many cores idle, you can also use three or more pairs of cores in parallel to reduce the loop resistance.
â‘¡. Modification of the terminal line: For the user introduction line to open ADSL, if the distance is too long or the total resistance is large. The method of replacing the iron wire with copper, copper-clad steel or copper twisted pair can also be used, or the method of connecting two wires into one (the two pairs of AA, BB lines are used in parallel). In addition, it is better to change the overhead pole gear line to an open wire cable.
â‘¢. Jumper: Replace all the jumpers with a diameter less than 0.5 mm in the measuring frame, the junction box and the cross-connect box with qualified jumpers. It is not allowed to use 0.4 mm wire cores instead of jumpers. It is not allowed to use parallel telephone lines without twisting and pitch instead of standard jumpers.
The ADSL connection box is not allowed to directly wrap the jumper wire on the crimping terminal. It is also not allowed to have exposed connectors on the jumper, so as to avoid the serious oxidation of the exposed crimp terminals and connectors, increase the contact resistance and make the contact unstable, resulting in missing codes and error codes for transmitting high-speed signals, which directly affects the opening of ADSL And running quality. When setting or replacing a jumper, it should be twisted 2-3 turns along the natural twist of the jumper, which can effectively eliminate the magnetic coupling effect between the jumpers, thereby improving the quality and effect of transmitting high-frequency signals.
â‘£. Distributing equipment: When installing and opening ADSL, the use of distributing equipment is often negligent due to the negligence of the staff, or the remaining wires are not sorted out afterwards, resulting in increased contact resistance and unsteady contact, or the elimination of line pairs. The coupling effect of magnetic induction becomes worse, etc .; the correct treatment method should be to wipe the oxide layer where the crimping screw contacts the thread end with a screwdriver when crimping the wire of the branching device, and then turn the thread end clockwise to crimp On the connection terminal, the remaining wire ends are wound by hand, and it should not be cut with pliers, so as not to cause sharp wire ends and other wire pairs. After the work is completed, the remaining wires must be sorted and tied tightly with other wires of uniform length and bending (this process requirement is also a necessary condition for effectively eliminating the effect of magnetic induction coupling between adjacent wires). In addition, all shielded wires of the distribution equipment must be well grounded. If it is a wall-embedded distribution equipment on the floor, you can change the equipment with terminals to the equipment without terminals. If the opening distance is too long, you can also try the ADSL extender (generally, the control distance is less than 5 kilometers).
All in all, in order to ensure and improve the quality and operation quality of ADSL, it is necessary to strictly implement the regulations and technical standards, but also strengthen the work responsibility, study carefully, and grasp the key. Carefully analyze the reasons that affect the quality of ADSL opening and operation, and take effective countermeasures and operating processes to achieve fruitful results.
2inch Bluetooth Dot Matrix Printer is a Portable Dot Matrix Printer. Our Dot Matrix Printer equipped with Epson printer head, support long lifetime printing. Qunsuo are Dot Matrix Printer Bluetooth manufacturer in China. Due to its handy style, it is a handheld dot matrix printer, support printing 2 page copy paper.
Qunsuo will provide customer SDK for free, support any technical issues.
2inch Bluetooth Dot Matrix Printer
Printer Dot Matrix Bluetooth,Printer Bluetooth Dot Matrix,Dot Matrix Printer Bluetooth,Dot Matrix Printer Handheld
Shenzhen Qunsuo Technology Co., Ltd , https://www.qsprinter.com