Modem is a device that is used to transmit digital information through Analog systems. The term is derived from”modulator-demodulator”. Modems are categorized on the basis of two criteria:
• The first one is Data sent/unit time
• And the second one is Change in the state of the signal/unit time
The first modem was used in the ’60s decade, in order to connect over a network of telephone lines. It was 1977 whenModem was first used with a computer for transmitting data to another computer.The device is used for modulating an Analog carrier signal to carry digital information as well as for demodulating a similar signal so as for decoding the digital information from the Analog carrier signal. In this post, we will explore types and roles of modem.
Types of Modems
As the name signifies the internal modems are being connected with the motherboard of our computer. The internal modems are generally, dial-up or wireless (Wi-Fi). The telephone network is being used for sending and receiving signals in case of dial-ups.
Authentication is required for the connection. In comparison to other modems, dial-up are markedly slower. Coming to the Wi-Fi modems, there is no need to connect them with the telephone network and authentication is not required for such devices.
An external modem is an unconnected unit packed in a case. Basically, we connect an external modem with the telephone line and the computer through cables.
The name says it all! We have seen these sorts of modems at our homes or at cable operators place. The radio frequency that range that cable television uses is also being used by the cable modems. The using of the existing cable television infrastructure that allows the cable TV companies to provide Internet services.
Asymmetric Digital Subscriber Line or what we call ADSL modems to use telephone lines for sending and receiving data. ASDL modems are really faster than any conventional voice band modem. The ASDL,as well as Cable modems, are used for providing the broadband internet connection. These types of modems allow more data transfer and that make the using of internet faster.
There are two types of data transmission used by Modems and those are synchronous and asynchronous. To make it more clear for you timing signals are used for Synchronous transmission and error-correcting formulas are used for asynchronous transmission. These device scan be used for one method of transmission or the other or can be used for both the ways.
What is the role of a modem? – Let’s take a look:
For reducing the amount of time, it takes for sending data and for cutting down on the amount of error in the signal, modems need to employ data compression. The data compression technique decreases the size of the signal that is needed for sending the required data.
This is the process in which theModem checks the information they have received is undamaged. Sometimes damage of data is being noticed in the form of altered or lost data. To get rid of this issue, the modem uses error correction. Batches of the information are being made and those frames are tagged with a checksum.
What is checksum? So, the checksum is basically and unique identity of frames. The receiving modem compiles its own checksum from the frame that is sent to it and then checksum data is being compared with it. Matching checksums results in undamaged data transmission. If they don’t match, the receiving modem sends it back and waits for the frame that the transmitting modem will re-send.
The speed of sending information differs from modem to modem. There is a huge necessity of slowing down the speed of the fast modems so that the slow ones can work properly. The difference of wifi speed makes the slower modem receive more data that it is capable of processing. If this starts happening the slow modems will transmit a character to the faster one. This character would be a signal to the faster modem for Pausing the information transfer until the slow modem gets caught up.
Similarly, when the slower modem is ready to receive more data, it will send another character to the faster modems a symbol that it is now ready to receive more data. This is how the slower and the faster modems match wifi and internet speed. Now, with the use of recent models of modems we are capable of transmitting data to more hosts, and the Internet network. This shows how fast the development in the technology has taken place.
Modem plays an important role in the networking of your computer. With the changing time and improving technology the working of these devices has changed and now they are providing much better service than ever before.