In 1962, Lincoln Laboratory used a selection of System Building Blocks to implement a small 12-bit machine, and attached it to a variety of analog-to-digital ( A to D ) input / output ( I / O ) devices that made it easy to interface with various analog lab equipment.

However, often, the required output signal is another analog output signal, which requires a digital-to-analog converter ( DAC ).

Class-D and class-E amplifiers are sometimes mistakenly described as " digital " because the output waveform superficially resembles a pulse-train of digital symbols, but a class-D amplifier merely converts an input waveform into a continuously pulse-width modulated ( square wave ) analog signal.

When placed on the external address bus, it replicates the original functions of B and C. Port A has input capture, output compare, pulse accumulator, and other timer functions ; port D has serial I / O, and port E has an analog to digital converter ( ADC ).

A less common feature on some microcontrollers is a digital-to-analog converter ( DAC ) that allows the processor to output analog signals or voltage levels.

Digital camcorders or DVD players ( with the exception of some early models ) do not accept or output a SECAM analog signal.

In analog circuit design, a multiplexer is a special type of analog switch that connects one signal selected from several inputs to a single output.

The output is a binary state often used to interface real world signals to digital circuitry ( see analog to digital converter ).

When the voltages are nearly equal, the output voltage will not fall into one of the logic levels, thus analog signals will enter the digital domain with unpredictable results.

In LTI system theory, control theory, and in digital or analog signal processing, the relationship between the input signal,, to output signal,, of an LTI system is governed by the convolution operation:

# An analog or digital source of unpredictable ( i. e., high entropy ), unbiased, and usually independent ( i. e., random ) output bits.

The sensors can output the analyzed level as a continuous analog signal or switch output signals.

( Modern devices may use digital signal processing to synthesize waveforms, followed by a digital to analog converter, or DAC, to produce an analog output ).

Regardless of the specific type, the output of a video generator will generally contain synchronization signals appropriate for television, including horizontal and vertical sync pulses ( in analog ) or sync words ( in digital ).

Secondly, due to inherent analog digital conversion problems, the effect of aliasing is unavoidable, so that the audio output is " reflected " at equal amplitude in the frequency domain, on the other side of the sampling frequency, causing an unacceptably high level of ultrasonics to accompany the desired output.

If the filter response changes linearly with frequency, the final analog output will be proportional to the input frequency, as desired.

Digital produced a version of the PDP-11 / 03 called the MINC-11, housed in a portable cart, and equipable with Digital-designed laboratory I / O modules supporting capabilities such as analog input and output.

Often, the current in the output coil is integrated, yielding an output analog voltage, proportional to the magnetic field.

Since the widespread adoption of digital setting circles, any classical engraved setting circle is now specifically identified as an " analog setting circle " ( ASC ).

An analog or analogue signal is any continuous signal for which the time varying feature ( variable ) of the signal is a representation of some other time varying quantity, i. e., analogous to another time varying signal.

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

The physical variable is converted to an analog signal by a transducer.

The voltage or the current is said to be an " analog " of the sound.

In practice an analog signal is subject to electronic noise and distortion introduced by communication channels and signal processing operations, which can progressively degrade the signal-to-noise ratio.

Therefore as analog signal processing systems become more complex, they may ultimately degrade signal resolution to such an extent that their performance is surpassed by digital systems.

However a comparable performing digital system is more complex and can require more bandwidth than its analog counterpart.

In analog systems, it is difficult to detect when such degradation occurs.

The main advantage is the fine definition of the analog signal which has the potential for an infinite amount of signal resolution.

Another advantage with analog signals is that their processing may be achieved more simply than with the digital equivalent.

The primary disadvantage of analog signaling is that any system has noise – i. e., random unwanted variation.

Even if the resolution of an analog signal is higher than a comparable digital signal, the difference can be overshadowed by the noise in the signal.

Another method of conveying an analog signal is to use modulation.

It is the two-dimensional analog of the length of a curve ( a one-dimensional concept ) or the volume of a solid ( a three-dimensional concept ).

" Analog " indicates something that is mathematically represented by a set of continuous values ; for example, the analog clock uses constantly-moving hands on a physical clock face, where moving the hands directly alters the information that clock is providing.

Thus, an analog signal is one represented by a continuous stream of data, in this case along an electrical circuit in the form of voltage, current or charge changes ( compare with digital signals below ).

Analog ( or analogue ) television is the analog transmission that involves the broadcasting of encoded analog audio and analog video signal: one in which the information to be transmitted, the brightness and colors of the points in the image and the sound waves of the audio signal are represented by continuous variations of some aspect of the signal ; its amplitude, frequency or phase.

In many countries, over-the-air broadcast television of analog audio and analog video signals is being discontinued, to allow the re-use of the television broadcast radio spectrum for other services such as datacasting and subchannels.

This service involves installing a special telephone interface at the customer's premises that converts the analog signals from the customer's in-home wiring into a digital signal, which is then sent on the local loop ( replacing the analog last mile, or Plain old telephone service ( POTS )) to the company's switching center, where it is connected to the Public switched telephone network ( PSTN ).

These are connected via T1 lines with the central office switch, replacing older analog two-way and direct inward dialing ( DID ) trunks.

For an analog meter movement, DC voltage is measured with a series resistor connected between the meter movement and the circuit under test.

For analog current ranges, low-resistance shunts are connected in parallel with the meter movement to divert most of the current around the coil.

Similar to the analog VESA display power management signaling ( DPMS ) standard, a connected device can turn a monitor off when the connected device is powered down, or programmatically if the display controller (" graphics card ") of the device supports it.

Telephones for traditional residential analog service are usually connected directly to telephone company phone lines which provide direct current to power most basic analog handsets independently of locally available power.

However, older fax machines, connected to an analog system, benefit from UDP near real-time characteristics due to the " no recovery rule " when a UDP packet is lost or an error occurs during transmission.

While 1960s-era analog synthesizers such as the Moog used a number of independent electronic modules connected by patch cables, later analog synthesizers such as the Minimoog integrated them into single units, eliminating patch cords in favour of integrated signal routing systems.

The analog modular synthesizer is a type of synthesizer consisting of separate specialized modules connected by wires ( patch cords ) to create a so-called patch.

Early attempts at motion control came about when John Whitney pioneered several motion techniques using old anti-aircraft analog computers ( Kerrison Predictor ) connected to servos to control the motion of lights and lit targets.

The DSLAM port where the subscriber local loop is connected converts analog electrical signals to data traffic ( upstream traffic for data upload ) and data traffic to analog electrical signals ( downstream for data download ).

The design allowed for four analog axes and four buttons on one port, allowing two joysticks or four paddles to be connected via a special " Y-splitter " cable.

Regardless of whether the joystick uses analog signals ( from potentiometers ) or digital signals ( using microswitches or contacts ), peripherals connected using the game port require calibration prior to use.

In the early to mid-1980s, most Internet access was from personal computers and workstations directly connected to local area networks or from dial-up connections using modems and analog telephone lines.

The PAD service could be connected to via a dedicated four-wire telephone circuit using a PSS analog modem and later on via a Kilostream digital access circuit.

When connected at a distance, each endpoint would be fitted with a modem to convert analog telecommunications signals into a digital data stream.

In analog connected picture displays such as CRT TV sets, the horizontal scanlines are not divided into pixels, but by the sampling theorem, the bandwidth of the luma and chroma signals implies a horizontal resolution.

A motor controller is connected to a power source such as a battery pack or power supply, and control circuitry in the form of analog or digital input signals.

The summing registers were connected to a digital to analog converter that increased power to the motors as the count in the registers increased, making the controls move faster.