Five major measures to increase ADSL speed

First: Know Yourself And know yourself

To solve the problem, you must first know yourself and yourself. Let's take a look at the working principles of ADSL!

The biggest advantage of ADSL is that it does not need to set up a dedicated network. It can use the most widely distributed telephone copper wire in the world as the transmission medium, and can be used in a pair of Copper Twisted Pair wires (telephone lines) the following three information channels are obtained: one is a standard telephone service channel, and the other is 640kbps ~ 1 Mbps Medium Speed Uplink Channel, 1 Mbps to 1 Mbps ~ 8 Mbps high-speed downstream channel, and these three channels can work at the same time.

In the DMT modulation and demodulation technology, a pair of copper telephone lines 0 ~ The 4 kHz band is used to transmit telephone audio, with a bandwidth of 26 kHz ~ Transmit data in the 249 MHz band and divide it into 25 uplink and downlink sub-channels in the 4 kHz width. The input data is converted into bit blocks by bit allocation and caching, and then sent to the sub-channel after being modulated by TCM-encoded qamm. In theory, 15 bits data can be transmitted per Hz, therefore, the theoretical uplink speed of ADSL is 25 × 4 × 15 = 1.5 Mbps, while the theoretical downlink speed is 249 × 415 = 14.9 Mbps (of course, this is only the theoretical peak value, in reality, it is difficult to achieve such high speed due to the line quality and transmission distance ).

The speed and stability of ADSL are mainly related to two points. First, the distance between your ADSL and the local equipment (ADSL module data center) of the Telecommunications Bureau is far away, the slower and unstable the speed. Second, the quality of telephone lines and the size of electromagnetic interference. 3. Of course it is the reason for our own device.

Follow these steps to solve the problem.

Second TRICK: rebuild the line

Currently, the widely used telephone lines were originally designed for voice communication. The bandwidth was between Hz and Hz, and the data communication needs were not considered at all. When surfing the Internet, there is a certain degree of attenuation of the high-frequency part of the communication signal, especially when the line is aging, the bandwidth is narrower and the attenuation is more severe-this is the most fatal for ADSL. Because ADSL technology has high requirements on the quality of telephone lines, and currently uses a radsl (rate-adaptive ADSL ), if the telephone line from the module board to the user is disturbed by external factors for a certain period of time, radsl dynamically adjusts the access speed of the user.

ADSL is a Transmission Technology Based on twisted pair wires. Twisted Pair wires wrap two insulated copper wires together with each other according to certain rules, which can effectively resist external electromagnetic interference. If the number of parallel lines in the household exceeds 20 meters, You need to replace the parallel lines with twisted pair wires, preferably the brand's Category 5 lines. When changing the cable, pay attention to the fact that the strength of the twisted pair wires is not enough and you must fix the wires. Otherwise, you will have hidden dangers. After the change, do you feel that the Internet access speed is much faster?
Here is a secret: The Branch box cable of the Telecommunications Bureau is originally a twisted pair cable, but to reduce costs, the Telecommunications Bureau usually changes the telephone line to a single line connection. This was of course a small impact on the original use of the phone, but after receiving the extremely sensitive ADSL line, it became a bottleneck! After discovering this problem, you must change the line to a pair of wires. After this bottleneck is eliminated, the Internet access speed will be greatly improved.

After changing the external line and entering the room, pay attention to the following issues:

1. Because ADSL overlays high-frequency digital signals on the low-frequency voice of ordinary telephone lines, the addition of any device in the connection from the Telecommunications Bureau to the ADSL filter will endanger normal data transmission, therefore, do not use phone or phone anti-theft devices before filters. In theory, the connection phone number on the ADSL line does not affect the speed of the Internet, but when an unqualified device is connected, the speed will slow down or even fail to access the Internet. The author suggests that if conditions are met, it is best to install an ADSL leased line to avoid some inexplicable problems. Money? Don't worry, isn't the initial installation fee canceled? :)

2. Indoor wiring problems. Be sure not to wire the power cord in parallel. Many unit buildings place telephone lines and power cables in parallel for cabling when they are inside the building. The power cord has a very strong interference on telephone lines. Parallel cabling will greatly increase interference. When we rebuild the line, we must pull the line separately! It may take a lot of time to pull the cables separately, and it may easily damage the overall layout of the room, but it does have a great impact on the speed of surfing the Internet. As for how to do this, you should carefully consider it! I re-took the line.

3. connection between the line and the "Big Cat. Line and "Big Cat" RJ-11 connector connection point is more, because the market has some crystal head quality is not good, coupled with some "Big Cat" RJ-11 connector quality is not good, therefore, poor contact often occurs.

Step 3: select the NIC

After completing the above steps, we can connect the "Big Cat" with the computer. By interface, "Big Cat" mainly has two interfaces: Nic interface and USB interface, among which Nic interface is the most common. "Big Cat" is a new type of high-speed device. Many ISA interfaces (including some PCI interface NICS) cannot work well. Therefore, when selecting a network card, you must be sure to select a better network card. If you have the conditions, it is best to try several more network cards. It is best not to be superstitious that the network card with a high price is the most suitable.

At the very beginning, I was also very superstitious about high-priced NICs. I went to the best price principle and bought a 3com 3c905b-txnm NIC with a price of more than 400 yuan. The quality of 3Com indeed reassured me, in addition, it works very well in LAN. However, my Internet traffic has also started !! When I connected it to the "big cat", I found that the Internet speed was only a few poor K !! The debugging staff were stunned on the spot. This is ADSL Broadband, not dial-up! Why is the Nic? Test in local area. Everything works! Is it too far from the module board of the Telecommunications Bureau? This is only one kilometer away. Why is it "Big Cat? Testing elsewhere is also normal. Why is the operating system? There should be no problem with the newly installed system and the Internet access. After measuring the line and switching module, the problem still persists!
Calm down and consider that, since the ADSL signal is good and the computer can access the Internet, it indicates that the line and computer should be normal. Experience suggests that this may be a fault caused by poor compatibility. What else? I found a 8139-chip Nic, and the fault was eliminated! Plug in the 3Com Nic and the fault occurs again. When selecting and using NICs, I have the following suggestions:

1. You must select a 10/100 M Adaptive Network Card. Do not select a 10 m network card because it is cheap. The speed and compatibility of a 10 m network card are generally poor.

2. The "big cats" used by friends in most regions are presented by the Telecommunications Board, but some "Big Cats" have poor compatibility and stability. Therefore, we recommend that you replace several NICs with different PCI slots. I have not verified the specific reasons.