Types of Modems

What is Modem?

A modem is an acronym for "Modulator-Demodulator." It is a hardware device that facilitates connections between devices and the internet. Data is transformed into a signal by a modem to transmit and receive signal through cables and phone lines. Its primary functions are modulation and demodulation. Analog signals must be transformed into digital signals through modulation before they can be transmitted across a communication channel. Analog signals are continuous waveforms with amplitude, frequency, and phase variations, whereas digital signals can be encoded by binary digits, sometimes known as bits (0s and 1s). Some modulation techniques modems use includes phase modulation, amplitude modulation, and frequency modulation. The analog signal received from the Internet Service Provider (ISP) is transformed into digital signals that a machine can interpret by the process of demodulation, which is the opposite of modulation. The modem detects and interprets amplitude, frequency, or phase variations to separate the digital data from the carrier signal. A modem can link a restricted amount of devices to the internet. Additionally, modems and routers can be used together to increase capabilities. A modem links your network to the internet, but a router allows a device to use that connection or interact with other devices on the same network.

Types of modems

There are several kinds of modems, including:

1. Dial-up modems
2. Cable modems
3. DSL modems
4. Fiber modems

Dial-up modems:

Dial-up modems were used in the initial stages of the internet to connect to the data services over the public switched telephone network. They provided rather slow but accessible internet connectivity and functioned over conventional telephone lines. It develops a data connection by dialling the Internet Service Provider (ISP)'s phone number using standard telephone equipment. Upon the establishment of the call, the modem transforms the digital signals transmitted by your computer into analog signals that can ultimately be sent over the phone line. Once the ISP's modem has demodulated the signals, you may connect to the internet to allow data to be sent between your system and the ISP's network.

Compared to current broadband technology, dial-up modems had comparatively modest internet connections. A dial-up modem's top speed is normally 56 kilobits per second (Kbps), while some models may go as fast as 112 Kbps. Dial-up connections were more affordable than other types of internet access since they didn't need any special hardware or infrastructure.

Dial-up modems improved over time, and various variants were produced to increase efficiency, reliability, and connectivity. Many V-series standards are compatible with dial-up internet, including:

• V.21: Introduced in the 1960s, this was the first dial-up modem standard. It supported up to 300 bits per second (bps) of data transmission.
• V.22: V.22, introduced in the late 1970s, increased the data transmission speed to 1,200 bps.
• V.32: When released in 1984, V.32 modems represented a substantial advance in dial-up technology. They featured quadrature amplitude modulation (QAM)-based data transmission speeds of up to 9,600 bps.
• V.32bis: Introduced in 1989, V.32bis modems were an improved version of V.32 that used QAM modulation to give data transmission speeds up to 14,400 bps.
• V.34: Introduced in 1994, V.34 modems enhanced data transfer rates by supporting up to 28,800 bps.
• V.90: launched in the late 1990s, it enables data speeds of 56 kbps for downstream data and 33.6 kbps for upstream data.
• V.92: provides an upstream data rate of up to 48 kbps and a downstream data rate of up to 56 kbps. With improvements like Quick Connect, connection times were shortened in V.92.

Cable modems:

Cable modems are used to access the internet by cable television networks. It transforms an analog signal into a digital signal to allow access to broadband Internet. High-speed internet connection is provided through coaxial cables, also used for cable TV transmission. Coaxial cables offer higher bandwidth than regular telephone lines, allowing for quicker data transmission rates. Both analog and digital signals can be carried through them. The maximum transmission speed using cabled internet is 30Mbps. Your system sends digital signals to the cable modem, which modifies those signals into a form that can be transmitted over the cable network. The data is encoded using various modulation methods, including Quadrature Amplitude Modulation (QAM), onto the frequency spectrum of the cable network. The cable service provider's hardware decodes the signals from the cable modem and converts them back to digital form. Data that has been demodulated is then sent to the internet.

A cable modem acts as a bridge between a customer's LAN and the ISP's coaxial cable network. In other words, it serves both as a modem and a bridge. In terms of the OSI network design model, it functions at the physical and data link layers. As a network node, the cable modem has its IP address and functions at the network layer, while it additionally implements protocols in the transport and application layers. In comparison to DSL or dial-up connections, cable internet delivers faster speeds. Depending on the particular cable network architecture and the service package offered by the ISP, the maximum speed of a cable modem connection might change. Customers in a certain neighborhood or location share the bandwidth in cable networks. The number of people using the network at once may impact the exact speeds customers experience. One or more Ethernet ports are frequently included on cable modems, enabling wired connections to gadgets like computers, game consoles, or routers. Asymmetrical speeds are offered through cable modem connections. Users looking for high-speed internet connection at their homes or places of business increasingly use cable modems.

DSL modems:

The abbreviation DSL stands for "digital subscriber line." This kind of data connection sends and receives information through phone lines. DSL uses conventional copper telephone lines to deliver high-speed internet access. The critical process of transforming digital signals from your computer into a format appropriate for transmission over the DSL network, and vice versa, is carried out by DSL modems. The telephone operates effectively even while the telephone connection is in use without being interrupted. Due to the difference in frequency between a telephone and a DSL connection, a telephone call remains possible while using the internet. It separates the telephone line's available bandwidth into channels for transmitting speech and data. Depending on the DSL technology and the condition of the copper telephone lines, the speed of DSL connections can range from a few megabits per second (Mbps) to tens or hundreds of Mbps.

Several DSL standards are suitable with DSL modems:

• ADSL: Its acronym is Asymmetric DSL. Because the data speed differs upstream and downstream, it is referred to as asymmetric. The top upload and download rates are 1.5 MHz and 512 kbps, respectively. You require an ongoing ADSL subscription from an internet service provider (ISP) to connect to the internet using an ADSL modem. The ISP gives the modem the required configuration information and login credentials to connect to their network.
• HDSL: It is an abbreviation for a High-bit-rate Digital Subscriber Line. Digital data is transformed into electrical signals for transmission over telephone lines by HDSL modems using digital transmission technology. High-speed connections are frequently provided using HDSL modems, with frequency ranges of 1.544 Mbps to 2.048 Mbps. The upload and download rates are equal since these speeds are symmetrical.
• SDSL: A form of DSL technology known as a symmetric digital subscriber line offers symmetric high-speed web browsing through telephone lines. Symmetric data transmission, or equal upload and download rates, is a feature of SDSL technology. Upstream and downstream data may be sent at the same speed using SDSL. DSL technology uses a single twisted pair connection to provide a data throughput of up to 768 kbps in full-duplex mode.
• VDSL: It is an abbreviation for Very High-Data-Rate DSL. Compared to conventional DSL technology, VDSL modems are intended to give much higher download and upload rates. VDSL can function in both asymmetric and symmetric modes depending on the intended configuration and service offered. It offers data speeds of up to 16 Mbps upstream and 52 Mbps downstream, respectively. It supports exceptionally high-speed data applications like streaming high-definition TV and is quicker than ADSL.

Fiber modems:

Fiber modems are devices that link end-user devices to a fiber-optic network. They are sometimes called fiber optic modems or optical network terminals (ONTs). They transform the optical impulses sent across fiber-optic cables into electrical signals that telephones, routers, and computers may access. Fiber optics has many benefits compared to conventional copper-based connections, including more bandwidth, quicker speeds, longer transmission lengths, and resistance to electromagnetic interference. Depending on the characteristics of the fiber-optic network, fiber modems offer high-speed internet access with data rates varying from tens of Mbps to several Gbps.