Modems

• Modem is communication device that enables a computer to transfer data over the telephone or cable lines.
• The process of converting the binary information into analog signal is called modulation.
• The process of converting the analog signal back to the binary information is called demodulation.
• Data transmission speed, data compression, data or voice communication , Fax capability are the most common features of a modem.
• An internal modem is a modem char that you can plug into an expansion slot on the motherboard.
• An external modem is connected to the PC through a cable, which is plugged into a serial port on the back of the system unit.
• X2 technology transmits data at the speed of 56 Kbps because of the high-speed digital lines connected to most phone switching stations.
• V.90 technology was built with an assumption that one end of a modem session has a pure digital connection to the telephone line.
• Integrated Services Digital Network (ISDN) is a set of international communication standard for transmitting digital data over a telephone line.
• DSL needs a device called DSL modem to convert digital signals to analog signals and analog signals back to the digital signals.
• A cable modem is a device that enables to connect a PC to the cable TV line.
• Modems use a modulation method to communicate with each other.
• Modem protocol are used to transfer data over a telephone line.
• Internal modems are plug-in cards that can be inserted into an ISA or a PCI slot.
• Configuring a modem helps to modify the properties of the modem such as the communication port to which the modem is attached or the maximum port speed.
• Diagnostics sends the standard AT commands to the modem and displays a report indicating how modem responds to each of these commands.
• AT commands are used to communicate directly with the modem.
• Troubleshooting modem enables to solve the problem that might arise due to improper functioning of the modem