Analogue electronics

Analogue Electronics refers to electronics systems with analogue signals with any continuously variable signal. It differs from digital electronics in that small fluctuations in the signal are meaningful in that they are continuously variable rather than digitally quantised. Analogue is usually thought of in an electrical context, however mechanical, pneumatic, hydraulic, and other systems may also use analogue signals. Analogue Electronics is frequently confused with other sub-divisions of the general field of Electronics which include Power electronics and Digital electronics.

The word "analogue" implies an analogy between cause and effect, voltage in and voltage out, current in and current out, sound in and sound out. Or in the field of Power Electronics can be the Energy Storing variables such as the current in an Inductor or the Voltage across the terminals of a Capacitor.

An analogue signal uses some property of the medium to convey the signal's information. For example, an aneroid barometer uses rotary position as the signal to convey pressure information. Electrically, the property most commonly used is voltage followed closely by frequency, current, and charge.

Any information may be conveyed by an analogue signal, often such a signal is a measured response to changes in physical phenomena, such as sound, light, temperature, position, or pressure, and is achieved using a transducer.

For example, in an analogue sound recording, the variation in pressure of a sound striking a microphone creates a corresponding variation in the current passing through it or votage across it. An increase in the volume or amplitude of the sound causes the fluctuation of the current or voltage to increase proportionally while keeping the same waveform or shape and electrical analogue.

The primary disadvantage of analogue signalling is that any system has noise, that is random disturbances or variations in it. As the signal is copied and re-copied, or transmitted over long distances, these random variations become dominant and lead to signal degradation. Electrically these losses are lessened by shielding, good connections, and several cable types such as coax and twisted pair and using low noise amplifiers.

The effects of random noise can make signal loss and distortion impossible to recover, since amplifying the signal to recover attenuated parts of the signal often generates more noise and amplifies the noise as well.

Another method of conveying an analogue signal is to use modulation. In this, some base signal (e.g., a sinusoidal carrier wave) has one of its properties altered: amplitude modulation involves altering the amplitude of a sinusoidal voltage waveform by the source information, frequency modulation changes the frequency. Other techniques, such as changing the phase of the base signal do also work.

Analogue circuits do not involve quantisation of information into digital format. The source signal information being measured over the circuit, whether sound, light, pressure, temperature, or an exceeded limit, remains continuous from end to end.

Clocks with hands are often called analogue displays; those that display digits are usually called digital displays. However, many analogue clocks are actually digital since the hands do not move in a smooth continuous motion, but in small steps every second or sub division of a second.

A Clock Would Like to Ride On My Lollacoaster of Love

See digital for a discussion of digital vs. analogue.

Sources: Some of an earlier version of this article was originally taken from Federal Standard 1037C in support of MIL-STD-188.