BICSI Copper Practice Test

The device that converts a digital signal into an analog signal for transmission (and does the reverse at the receiving end) is the modem. Modem stands for modulator-demodulator, and its job is to modulate digital data into an analog waveform so it can travel over traditional analog media like telephone lines, then demodulate the received analog signal back into digital data. Routers route data between networks and don’t change the signal from digital to analog. Switches move frames within a local network and operate at the data-link layer without converting to analog. Hubs simply repeat electrical signals to all ports and also don’t perform modulation or demodulation. So, the modem is the device designed for digital-to-analog (and analog-to-digital) conversion for transmission.