ADSL Broadband Speeds – 101

Broadband users are often asked to check their internet connections speeds, but often we do not understand what exactly it is that we are checking. All most people know is that a fast internet connection gives a less frustrating internet experience. Downloading movies, games and software becomes so much easier with a faster broadband speed.
Traditional Fixed Connections
The actual speed of your broadband connection has no relevance to the internal wiring or length of your line where traditional ADSL with fixed speed is concerned. If your line connection synchronises at 512Kbps, 1Mbps or 2Mbps, then that is the maximum speed you will achieve on that service.
It a misconception that when your service has a long line, it slows down your speeds. This is untrue as your connection either synchronises to the exchange at the specified speed or it simply does not. An exception to this rule is that you may have a low SNR margin if you are on a long line. This means that your line appears slower because it has difficulty in sending data packets. When this happens it drops the data packets and this gives the impression of a slow connection. These errors may be recorded on your router and it is a good idea for you to check if it does. If there is a record of the errors, it will be displayed as a HEC or CRC error on the router.
Rate Adaptive DSL
If you have a rate adaptive DSL connection it operates differently to the traditional fixed connections. In this case the maximum speed that your service will be able to achieve is dependent upon a range of factors such as the condition of your exchange line and the distance of your residence from the exchange. The SNR (signal to noise ratio) is an important factor in determining the maximum speed of the connection to the exchange. With rate adaptive DSL, your router will synchronise at the top speed possible whilst optimising a safe level of SNR, which means the chances of obtaining higher speeds is increased if the SNR margin is better.
It is possible for your connection speed to alter at each logon.
Internet Speed Test
When you do an internet speed test on your connection, you should use a speed checker that is based within the UK. If you use one that is not based in the UK, it will indicate additional time and will not provide an accurate result.
There are many speed testing sites available online that you can use. There are times when these speed checking facilities are extremely busy and the results you get may vary. In this case it is best that you try at least two or three of them to ensure that you are indeed obtaining accurate results.
Speed Types
Line Speed
This is the provided speed of your connection which is commonly 2Mb, 1Mb or 512Kb.
Connection or Sync Speed
The connection speed is calculated to obtain the rate at which the modem you use is synchronised to the local exchange. This is not your actual speed of connection.
True Speed
The actual speed at which the data you are sending or receiving travels with the inclusion of any overheads.
Actual Speed
This is the rate at which any useful data is received or sent excluding any overheads. This is the figure that users should mention when they quote the speed of their line. Many speed testers will determine an actual speed as the speed in between the actual and true speed and this may vary depending on the speed tester you utilise.
An internet speed test can be really handy!
What are Overheads?
Each time we transmit data on a network, additional information such as where the data is coming from and where it is being sent to, along with other factors such as how the data should be read once received at its destination, is sent. This extra information is what is termed as overheads.
Different forms of overheads will increase the size of your original data. The simplest way to imagine this is to think of a package and the data you are sending is the item, whereas the wrapping of the item is the overhead. There are many different types of overheads that may be attached to your data, the most common being IP/TCP overheads.
What Speeds to Expect
The theoretical maximum speeds that you should be obtaining on an ADSL line should look something like this:
Line Speed: 2Mb
Sync Speed: 2272 Kbps
Max Actual Theoretical Speed: 1920 Kbps
Your download speed: 1910 Kbps (238.8 KB/sec)
Line Speed: 1Mb
Sync Speed: 1152 Kbps
Max Actual Theoretical Speed: 960 Kbps
Your download speed: 955 Kbps (119.4 KB/sec)
Line Speed: 512 Kb
Sync Speed: 576 Kbps
Max Actual Theoretical Speed: 480 Kbps
Your download speed: 478 Kbps (59.8 KB/sec)
Bear in mind that it is extremely rare that you will reach the maximum actual speed stated. The figures shown above are based on a stable, steady connection that was tested at various times. These figures are dependent upon stability of your line and the distance from the exchange. It is also dependent on whether your line is free of interference and whether or not maintenance is being undertaken at the exchange.
Causes of Slow Test Results
When you make use of a speed tester, you should bear in mind that there are various factors that may affect the results obtained, such as.
Congestion on your internet service providers network
Problems at your local telephone exchange
Problems with your computer, such as malware or a virus
Can You Improve The Speed?
It is possible to improve speed of your internet connection if your internet speed test is not very impressive. There are ways that you can tweak your connection and there is a lot of information on this is available online. Alternatively, if you are not tech savvy, you should consult someone who may be able to help you tweak your internet connection. If this is not an option and the slowness of your internet connection is causing you to pull your hair out, you could opt for a faster connection, such as fibre optics.

Sam Jones ran an internet speed test at work due to sluggish responses. He knew it was likely to be due to the amount of employees online at the same time but searched for another provider just in case. He found that there were several suitable deals on price comparison sites like uSwitch.com

 

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