Related Links
Java Security

My results come nowhere near what they should be. What can I do?

Firstly, determine what actual line speed you are connected at. Unless you modem has LEDs or an LCD display to tell what your current line speed is, you will only be able to determine the initial connection speed from a connection window, such as Windows 95/98's Dial Up Networking connection window. You could also use a terminal program to determine the connection speed, and, depending on your modem, the minimum and maximum line speed. If you are using Windows 95/98, and your modem is properly set-up, the modemlog file will record the initial connection speed.
Secondly, make sure that your connections are using Error Control. If error control is not used the Windows 95/98 Ppplog file will have recorded CRC errors.

I think my problem lies with my line, how can I test it?

Temporarily swap your computer and modem with another computer and modem that doesn't have connection problems. If the other computer uses the same ISP and dials into the same point-of-presence, this should help prove that the problem lies with the line (or internal wiring), or with the computer and modem.

Why does my modem always connect at 26.4Kbps?

Telephone companies are increasingly using multiplexing devices to provide telephone service to more than one customer on a single cable pair. Common configurations give a 2-to-1 or 4-to-1 line/pair ratio. These systems (often called pair gain units, analogue carriers or digital carriers), increase the number of customers that can be served by a cable at the expense of bandwidth. Ironically, they are often used for providing a second telephone line which is intended for Internet use, but, consequently limit the maximum possible line speed.
In many cases a connection of 26.4Kbps indicates a 2 line system, whereas a 4 line system may restrict the maximum speed to 16,800bps or less. Telephone companies will usually have an obligation to provide you with a voice grade telephone line, which they won't guarantee to carry data at any speed, but should, in most cases, be able to put your line on a dedicated cable pair. Also, they may be more inclined to help you if you use your line for FAX, which operates at a maximum speed of 14,400bps.

I have called your technical support people, but.....?

Some ISPs, such as Bell South, provide links to the "Modem Speed Test Page" on their websites. The page appears to be part of their site, but isn't. Many ISPs also shy away from providing a technical support contact email address, insisting that you talk to technical support directly. This means that the only visible contact is "Leslie Long". Queries regarding service provided by ISPs should be directed to the relevant ISP.

Why does my throughput vary so much?

The tests are affected by "Internet congestion", which could be occuring anywhere between your ISP's Point-of-presence and the computer that servers the test pages. Your throughput readings may be more stable if you try the tests at an off-peak time, such as late at night. You could also try the mirror site which is based in Ohio.

Where can I find an initialisation string for my modem?

Try the modem maufacturer's web-site, or some of the sites that list initialisation strings, such as www.56k.com , www.interport.net and www.accessone.com.

My modem connects OK, but my calls usually break down?

Many modems, by default, disconnect after a certain number of re-transmits of a data block. Try forcing your modem to connect at a lower speed (2400 or 4800 bps less). A stable connection at a lower speed can often give more data throughput than an unstable connection. Check your modem's handbook to find out how to set the maximum line rate.

What's the difference between data throughput and modem speed?

Modem speed (or more accurately line speed) is generally regarded as the rate at which a modem is connected to another modem.

Throughput is the amount of data transferred over a period of time.

For example, I usually have a stable connection to the internet at 44,000bps (bits per second). My ISP's modem 'talks' to my modem at 44,000bps for the duration of the call.
When I download my 56K test page from my ISP's server I transfer the data in around 6 seconds, which is about 41,600bps or 5,200 bytes per second (or characters per second). This is my throughput. The different is due to overheads incurred from protocols, error correction etc.
When I download a file from a server across the internet at a busy time of the day I may find that I download a 180K(bytes) zip file in 3 minutes. This is a throughput of 1,000 bytes per second, but, my modem is still 'talking' to my ISP's modem at 44,000bps.
It is worth pointing out that the throughput in this case is lower, because the data arrives in chunks with pauses. The average throughput is regarded as 1,000 bytes per second, even though the throughput during the download may have been 5,200 bytes per second at one or more times.

Although the Modem Speed Test Pages really measure average throughput, if data flow is steady, the results can indicate the actual line speed.

I have tried the Modem Speed Test but it does not work on my computer. What am I doing wrong?

Because my test pages use JavaScript and some browsers interpret JavaScript differently, the test pages don't work on some browsers, such as Opera and IE 4.05 for the Mac.
I have tested the pages on Internet Explorer Versions 2.1, 3.0 and 4.0, and also on Netscape 2.3 and 4.03. I am currently using Windows 98 and IE5.0.

What is the purpose of the test page?

The purpose of the test page is to provide a quick and easy way of measuring Internet connection performance. If you spend a lot of time waiting for your browser to load pages from the Internet then this is the page for you.

What does CPS stand for?

CPS stands for characters per second. Data throughput is normally measured in characters per second. CPS is roughly equal to bytes per second.

In practice, transfer of a text file containing 1,000 characters (or bytes) involves transmission of a small number of extra bytes used by the transmission protocols. Similarily, transfer of the document and protocol bytes involves extra information being sent over the telephone line between the two modems.

The rate of data transfer between the modems is measured in bits per second.

I have a 28.8K modem but it takes ages to download ZIP files from the net. How long should it take?

Assuming that your DTE rate is set higher than the line rate expect about 4 minutes per Megabyte. So downloading an 8 Mbyte file, for example, would take over 40 minutes.

Test Page | Test Information | Leslie Long's Homepage | Email
Copyright Leslie Long, 1997-2001