What is the ADSL? »

As its “A” indicates, ADSL is distinguished from other DSL technologies by its asymmetrical character. It simply means that there is a important difference between

All about the ADSL

From 28 or 56 kilobits per second, the downward flow has instantly passed to 1 or 2 megabits per second. And this, in many households, or even more. This thus allows access to richer content such as videos, Internet television, very bandwidth consumers.

But how rightly works the ADSL, and how to explain the Differences in flow sometimes blatant between different districts ? Because it always depends on the good old copper network of the phone. However, this technology remains subject to limits that should be known.

Definition of ADSL

The ADSL acronym covers the English expression “Asymetric Digital Subscriber Line”, or digital connection on asymmetrical flow subscriber line. Digital data, sent or received from your computer position, pass on The same wired network that your landline phone. On the other hand, they use different and higher frequencies.

The classic telephone line, in fact, uses the frequency band located between 300 and 3400 Hz, but the cable is able to have data transit on much higher frequencies, Going up to 80 kHz: it is this segment that is used by ADSL, and which allows you to telephone without cutting your internet connection, or vice versa. The installation of ADSL filters on each of your telephone sockets allows your various equipment to receive only the signals that concern them. This avoids pollution.

The installation of the ADSL only requires minimal formalities : Just provide you with a compatible terminal (such as an internet box for example), which will send its signals to the local switch (or distributor) in your neighborhood. It is the latter, at the end of the race of the copper network, which communicates with the rest of the network.

Different cables housed in a plastic envelope make up the copper network. They each include two pairs of twisted drivers. The largest network cables can contain up to 2400 twisted pairs.

An asymmetry between reception and data emission

As its “A” indicates, ADSL is distinguished from other DSL technologies by its asymmetrical character. It simply means that there is a important difference between

• The downhill flow (the user receives data)
• and the ascending flow (the user sends data).

It’s a Purely technical choice, that many countries have favored for various reasons. First of all, an average user tends to consume more data than to send it. It therefore appears logical to reserve a greater number of frequencies for this task. Also, the signal tends to lose more in quality when sent to the distributor rather than when it is. This is explained by the growing concentration of cables during the signal path. This leads to electromagnetic disturbances and a phenomenon of “diaphony”.

Depending on the case (distance, cable diameter. ), ADSL can reach a Maximum theoretical downhill flow of 8.192 Mb/s , and one Maximum theoretical ascending flow of 800 kb/s .

The transmission distance: a variable to take into account

THE phenomenon of loss or weakening is the biggest disadvantage of the copper network. If your home is located beyond a certain distance from one of the 15,000 local distributors scattered in the territory, the available flow is likely to drop drastically. In general, the greater the length of the cable and its diameter is reduced, the greater the loss.

For exemple. To obtain a performance close to a theoretical flow of 2.048 Mb/s, the cable must be less than 3.6 kilometers if its diameter is 0.4 millimeter. If the diameter is 0.5 millimeter, then the distance goes to 4.9 kilometers. In any case, and even for the largest cables, the optimal distance does not never exceeds 5 kilometers. It therefore tends to strongly disadvantage the homes located in the most remote rural areas, far from the distributors.

Other DSL technologies

In addition to the ADSL and the ADSL 2+, other technologies make it possible to ensure high speed access to the Internet via a symmetrical architecture, that is to say an equal flow and downhill speed. This is particularly the case Hdsl (High Bit Rate DSL), historically the very first to have emerged in 1994. She then gave way to SDSL (Single Pair DSL), which allows a flow of up to 2.048 Mb/s over a distance of three kilometers. The new standard HDSL2/HDSL4 then replaced it.

ADSL, moreover, is not the only asymmetrical technology. It is particularly important to quote the VDSL2 (Very High Bit Rate DSL). The latter develops quickly in France as an alternative to the very expensive fiber optic connection. Thanks to an automatic adjustment of the transmission speed, the maximum drop -down flow in VDSL2 can reach 100 Mb/s. This immediately places it among the very high speed offers of operators who offer it.

ADSL nonexistent or low quality: what to do ?

The quality of the ADSL signal arriving to you depends on several intangible data, including in particular the cable length. Even in the event of a very weak signal or slow connection, it is very rare that the Orange network manager (ex-France Telecom) is considering upgrading work, which would necessarily imply the implementation of a new distributor.

If you find that your telephone connection is connected to a remote distributor while another is at a more reasonable distance, it is possible for the inhabitants of the district to formulate a common request to the operator, But this approach is rarely followed by effects.

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“What is the ADSL ?»

ADSL is an acronym which means “Asymetric Digital Subscriber Line”. It is data transmission technology that uses existing telephone lines to provide high -speed Internet access.

ADSL allows digital data to be transmitted at high speeds on a telephone line using frequencies that are not used for voice calls. ADSL is called “asymmetrical” because it allows you to download data (for example, web pages, files, etc.) at a higher speed than the data speed of data.

ADSL was one of the first technologies to provide high speed at home and played an important role in the development of the mainstream internet. Although the ADSL has been largely replaced by fiber optics in many regions, it is still used in certain areas where fiber optics is not available or too expensive to deploy.

It is important to note that the ADSL connection speed can vary depending on the distance between the telephone line and the telephone central, as well as the quality of the telephone line itself.

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