Which of the following kinds of modems is a modem that sends and receives digital data over and information to and from a digital line?

A modem in data communication stands for modulator/demodulator. It is a commonly used communication device. It is a device that converts digital signals into analog signals and analog signals into digital signals. The modem sends and receives data from one computer to another through telephone lines. The sending and receiving computers must have modems.

The process of converting digital signals to analog signals is called modulation and the conversion of analog signals into digital signals is called demodulation. The modem on receiving computer receives data in analog form. The incoming analog data is converted back into digital format to be used by the computer.

The US Department of Defense, news services, and other large enterprises used the first commercial modems, which had a speed of 110 bits per second. In the late 1970s and early 1980s, as public message boards and news services like CompuServe were developed on early internet infrastructure, people grew more familiar with modems. Then, when the World Wide Web exploded in popularity in the mid and late 1990s, dial-up modems became the primary way of internet access in many homes throughout the world.

• Working of Modem
• Features of Modem
• Why We Use Modem?
• 7 Types of Modems in Data Communication
  • Internal Modem in Data Communication
  • External Modem in Data Communication
  • Wireless Modem in Data Communication
  • ISDN Modem
  • DSL Modem
  • Cable Modem
  • Satellite Modem
• Final Thoughts

Working of Modem

Computer stores information in the form of digital signals. However, the information transmitted over the telephone lines is in the form of analog signals. The modem receives digital data from the computer and converts it into analog form. This process is called modulation. It sends analog signals to other computers using telephone lines.

The modem on receiving computer receives data in analog form. It converts the analog data back into digital form. This process is called demodulation. The modem is one of the best computer network devices. At the transmitting end, a modulator translates data from digital to analog, while at the receiving end, a demodulator turns data from analog to digital. Digitizing refers to the act of turning analog signals from one computer network into digital signals from another computer network so that they may be processed by a receiving computer.

Modern dial-up network modems transmit data at a maximum rate of 56,000 bits per second. The first commercial modems supported modern dial-up network modems. However, due to the inherent constraints of public telephone networks, modem data speeds are frequently limited to 33.6 Kbps or less.

When you use a dial-up modem to connect to a network, the modem transmits the characteristic handshaking sounds between your device and the distant modem through a speaker. Hearing the sound pattern lets you evaluate whether the connection procedure is working because the connection process and data patterns are similar each time.

Features of Modem

Some important features of modem are as follows:

Speed: Speed is the rate at which the modem can send data in bps. Typically modem speeds are 300 bps to 56kbps.

Self-Testing: Modem can test the digital connection with the computer. It can also test analog connections with the remote modem.

Voice over Data: Modem provides the facility of voice conversation while data is being transmitted. Both the source and destination modems should have this feature.

Error Control: Modems use different methods to control errors for transmitted data.

Bit per Second(bps): The speed at which the modem can send and receive data. Modems are measured in baud rates when used at lower speeds. 300 baud is the slowest rate (about 25 eps). Modems are measured in bits per second at higher speeds (bps). The fastest modems operate at 57,600 bits per second (bps), however, they can compress data to obtain even greater data transmission speeds.

The higher the transmission rate, the quicker we can send and receive data. Please keep in mind that we cannot receive data any quicker than it is supplied. If the device providing data to our computer sends it at 2,400 bits per second, we must also receive it at 2,400 bits per second. As a result, having a fast modem does not always pay off.

Why We Use Modem?

The modem’s main job is to connect you to the internet. You might connect the modem directly to your computer without using a router if you just have one internet-connected device with an Ethernet connection (such as a desktop computer). However, because most homes do not utilize the internet in this manner, you will want a router for your smartphone, streaming services, and laptop computer.

A modem is required to even have an internet connection in your house. You should have received one from your internet service provider (ISP), but you may not be aware of it. The modem, which looks like a little box that sits inside your home with a cable heading to the service outside for cable, fixed wireless, satellite, or fiber internet, is a small box that sits inside your home with a cable running to the service outside. If you have DSL service, you may also notice a phone line coming in.

3 types of modems in terms of physical size, shape, and working are as follows:

Internal Modem in Data Communication

An internal modem is a circuit board that is inserted into an expansion slot on the motherboard. The internal modem cannot be moved from one computer to another easily. It is more difficult to set up than other types of modem. It is less expensive than an external modem. These  Dial-ups send and receive signals through the telephone network. To connect, they require authentication.

Dial-up is significantly slower than other types of modem connections; the fastest stated speed for a dial-up modem as of the date of writing is 56.6 Kbps. Or we can just say that a modem that is embedded into a PCI slot on a contemporary desktop computer or an ISA port on an older one. A PCI modem is similar to the internal modem illustrated above.

External Modem in Data Communication

The external modem is attached to the system unit as an external device through telephone lines. It is connected to the telephone wall jack by another cable. An external modem is connected to a computer using a serial cable to COM1 and COM2 ports. It requires an external power supply. It is easy to set up. An external modem is expensive.

External modems connect to an external internet interface, such as a cable line, on one end and a home broadband router or other home gateway device on the other. The signal is directed to all of the devices in the business or house as needed by the router or gateway. As a single physical unit, some broadband routers have an integrated modem.

A serial cable is used to connect the external modem to the computer system. The setup is simple, and it also offers a high data transmission rate. It is pricey, but it is still utilized in offices because of its high-speed data transfer, which helps to avoid network outages.

Wireless Modem in Data Communication

A wireless modem transmits the data signals through the air instead of a cable. It is also known as a radio-frequency modem. It is designed to work with cellular technology and wireless local area networks. Most handheld computers, smartphones, and other mobile devices use the wireless modem to connect to the internet wirelessly. It can also be used with notebooks and desktop computers.

ISDN Modem

ISDN modem allows digital transmission of data over telephone lines. It is also known as an ISDN adapter. It uses the same twisted pair wiring as dial-up modems but it can transmit data faster. It supports data transfer rates up to 1.54 Mbps.

DSL Modem

DSL modem allows faster transmission over the standard telephone lines. It is faster than ISDN. There are two types of DSL:

ADSL: It stands for Asymmetric Digital Subscriber Line. It uses faster transmission downstream than upstream. It is frequently used for faster internet services. It provides an upload speed of up to Kbps and a download speed of up to 8.1 Mbps.

SDSL: It stands for Symmetric Digital Subscriber Line. It uses the same transmission rate for both directions. It transfers data at 3 Mbps approximately in both directions.

DSL can only be used within three miles f a telephone switching station. Its speed degrades as the distance increases.

Cable Modem

A cable modem is also known as a broadband modem. A cable modem is a stand-alone device connected with a cable to the USB port. It sends and receives data over the cable television network. It provides faster internet speed than dial-up modems, DSL modems, and ISDN.

Satellite Modem

A satellite modem is used to send and receive data using satellite technology. It is commonly used for high-speed internet service. Many satellite internet services use satellite technology for downstream data only. The satellite modem is a little slower than DSL and cable transmission.

Final Thoughts

A modem in data communication is basically a networking device that is used to connect with the internet. Modem stands for modulation/demodulation. It is a device that converts digital signals into analog signals and analog signals into digital signals. The modem sends and receives data from one computer to another through telephone lines. The sending and receiving computers must have modems. There are 7 types of modems, Internal modem, External modem, Wireless modem, ISDN modem, cable modem, DSL modem, and Satellite modem. You can not connect to the internet without using a modem.

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