The computer modem

A modem simply stands for  (modulator-demodulator)and it is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information it lets you connect your computer to a standard telephone line so you can transmit and receive electronically transmitted data. Modems are generally classified by the amount of data they can send in a given unit of time, usually expressed in bits per second (bit/s, or bps), or bytes per second (B/s). Modems can alternatively be classified by their symbol rate, measured in baud

Basically there are 3 major types of modem which are

External modem, Internal modem. PC Card modem.

Now let us address them one after the other

1        external modem    This is the simplest type of modem to install because you don't have to open the computer. External modems have their own power supply and connect with a cable to a computer's serial port. The telephone line plugs into a socket on the rear panel of the modem.

Because external modems have their own power supply, you can turn off the modem to break an online connection quickly without powering down the computer. Another advantage over an internal modem is that an external modem's separate power supply does not drain any power from the computer. You also can monitor your modem's connection activity by watching the status lights.

2          internal modem             Most internal modems come installed in the computer you buy. Internal modems are more directly integrated into the computer system and, therefore, do not need any special attention. Internal modems are activated when you run a communications program and are turned off when you exit the program. This convenience is especially useful for novice users.

Internal modems usually cost less than external modems, but the price difference is usually small. The major disadvantage with internal modems is their location: inside the computer. When you want to replace an internal modem you have to go inside the computer case to make the switch.

3              PC Card modem.

These modems, designed for portable computers, are the size of a credit card and fit into the PC Card slot on notebook and handheld computers. These modems are removed when the modem is not needed. Except for their size, PC Card modems are like a combination of external and internal modems. These devices are plugged directly into an external slot in the portable computer, so no cable is required other than the telephone line connection. The cards are powered by the computer, which is fine unless the computer is battery-operated. Running a PC Card modem while the portable computer is operating on battery power drastically decreases the life of your batteries.

Having known these how do modem works

When a modem first makes a connection, you will hear screeching sounds coming from the modem. These are digital signals coming from the computer to which you are connecting being modulated into audible sounds. The modem sends a higher-pitched tone to represent the digit I and a lower-pitched tone to represent the digit 0.
At the other end of your modem connection, the computer attached to its modem reverses this process. The receiving modem demodulates the various tones into digital signals and sends them to the receiving computer. Actually, the process is a bit more complicated than sending and receiving signals in one direction and then another. Modems simultaneously send and receive signals in small chunks. The modems can tell incoming from outgoing data signals by the type of standard tones they use.

Modems convert analog data transmitted over phone lines into digital data computers can read; they also convert digital data into analog data so it can be transmitted. This process involves modulating and demodulating the computer’s digital signals into analog signals that travel over the telephone lines. In other words, the modem translates computer data into the language used by telephones and then reverses the process to translate the responding data back into computer language.

I hope you found these informations helpful

How can i check my computer internet speed

The speed in which a computer connects to the Internet can vary because of many factors, so the speed that the ISP posts gives an average or a range that a user can expect when connecting. Many sites offer free speed testing. One of the easiest to use is Speakeasy because there is no software to download or install.

steps involved

1     Click on the Internet Explorer icon or any other browser you have on the computer's desktop or the taskbar.

2     Enter the URL "www.speakeasy.net/speedtest" in the Internet browser address box.

3     Choose a server from the list that is provided to start the testing process.

4     Read the results that will be provided when the test is complete at the bottom of the graph near the bottom of the page.

5     Consider running the test a couple of times to get a better reading of the average speed of the computer's Internet connection.

Tips & Warnings

·         The test can be run at various times of the day to see when the speed might be faster or slower. This can aid in deciding when to download or upload a large file or files.

·         Beware of sites that offer to download and install software on the computer before the test is run. Most likely, these are spyware or virus sites, because this test can be completed without installing any software on the client computer.
earlier on i told you that some factors are responsible for your computer network speed.
some of these factors are 
1  Bandwidth and
2 Latency
check out these article to find out about what is bandwidth

WHAT IS BANDWIDTH

  Bandwidth in computer networking refers to the data rate supported by a network connection or interface. Network bandwidth is not the only factor that contributes to the perceived speed of a network But we are only concerned with letting you know the basic expaination of what a bandwidth means.

Now what does a Network Bandwidth means?

Bandwidth is the primary measure of computer network speed. Virtually everyone knows the bandwidth rating of their modem or their Internet service that is prominently advertised on network products sold today.

In networking, bandwidth represents the overall capacity of the connection. The greater the capacity, the more likely that better performance will result. Bandwidth is the amount of data that passes through a network connection over time as measured in bits per second (bps).

Bandwidth can refer to both actual and theoretical throughput, and it is important to distinguish between the two. For example, a standard dial-upmodem supports 56 Kbps of peak bandwidth, but due to physical limitations of telephone lines and other factors, a dial-up connection cannot support more than 53 Kbps of bandwidth (about 10% less than maximum) in practice. Likewise traditionalEthernet networks that theoretically support 100 Mbps or 1000 Mbps of maximum bandwidth, but this maximum amount cannot reasonably be achieved due to overhead in the computer hardware and operating systems.

Broadband and Other High Bandwidth Connections

The term high bandwidth is sometimes used to distinguish faster broadband Internet connections from traditional dial-up or cellular network speeds. Definitions vary, but high bandwidth connections generally support data rates of minimum 64 Kbps (and usually 300 Kbps or higher). Broadband is just one type of high bandwidth network communication method.

Measuring Network Bandwidth

Numerous tools exist for administrators to measure the bandwidth of network connections. On LANs (local area networks),someof these tools include netperf and ttcp. On the Internet, numerous bandwidth and speed test programs exist, most available for free online use.

Even with these tools at your disposal, bandwidth utilization is difficult to measure precisely as it varies over time depending on the configuration of hardware and characteristics of software applications including how they are being used



There is another factor that is responsible for the computer internet speed that factor is called Latency.Although it is less important but you can on the name to know more about it.

WHAT IS BANDWIDTH

  Bandwidth in computer networking refers to the data rate supported by a network connection or interface. Network bandwidth is not the only factor that contributes to the perceived speed of a network But we are only concerned with letting you know the basic expaination of what a bandwidth means.

Now what does a Network Bandwidth means?

Bandwidth is the primary measure of computer network speed. Virtually everyone knows the bandwidth rating of their modem or their Internet service that is prominently advertised on network products sold today.

In networking, bandwidth represents the overall capacity of the connection. The greater the capacity, the more likely that better performance will result. Bandwidth is the amount of data that passes through a network connection over time as measured in bits per second (bps).

Bandwidth can refer to both actual and theoretical throughput, and it is important to distinguish between the two. For example, a standard dial-upmodem supports 56 Kbps of peak bandwidth, but due to physical limitations of telephone lines and other factors, a dial-up connection cannot support more than 53 Kbps of bandwidth (about 10% less than maximum) in practice. Likewise traditionalEthernet networks that theoretically support 100 Mbps or 1000 Mbps of maximum bandwidth, but this maximum amount cannot reasonably be achieved due to overhead in the computer hardware and operating systems.

Broadband and Other High Bandwidth Connections

The term high bandwidth is sometimes used to distinguish faster broadband Internet connections from traditional dial-up or cellular network speeds. Definitions vary, but high bandwidth connections generally support data rates of minimum 64 Kbps (and usually 300 Kbps or higher). Broadband is just one type of high bandwidth network communication method.

Measuring Network Bandwidth

Numerous tools exist for administrators to measure the bandwidth of network connections. On LANs (local area networks),someof these tools include netperf and ttcp. On the Internet, numerous bandwidth and speed test programs exist, most available for free online use.

Even with these tools at your disposal, bandwidth utilization is difficult to measure precisely as it varies over time depending on the configuration of hardware and characteristics of software applications including how they are being used



There is another factor that is responsible for the computer internet speed that factor is called Latency.Although it is less important but you can on the name to know more about it.