Signal original form to a waveform expressed as a current ("I") or a voltage ("V"), or an electromagnetic waveform, for example, an optical signal or radio transmission. Once expressed as an electronic signal, the signal is available for further processing by electrical devices such as electronic amplifiers and electronic filters, and can be transmitted to a remote location by electronic transmitters and received using electronic receivers. In Electrical engineering programs, a class and field of study known as "signals and systems" (S and S) is often seen as the "cut class" for EE careers, and is dreaded by some students as
Analog device a real physical system in a computer is called simulation. In electronics, a digital-to-analog converter (DAC or D-to-A) is a circuit for converting a digital signal (usually binary) to an analog signal (current, voltage or electric charge). Digital-to-analog converters are interfaces between the digital world and analog world. An analog-to-digital converter (abbreviated ADC, A/D or A to D) is an electronic circuit that converts continuous signals to discrete digital numbers. There is quite a bit of controversy in the photographic world as to whether or not a film camera should be considered an "analog device" since the photographic film isn't