Analogue and a Digital control systems -...

Analogue and a Digital control systems

Lecturer: Owen Funnell Unit 24 - Controlling Systems Using IT

P2 - Explain the characteristics of digital and analogue control systems

M1 - Compare analogue and digital signals

M2 - Explain the need for signal conversion


Signals are passed between devices in order to

send and receive information, which might be

video, audio, or some sort of encoded data.

Usually the signals are transmitted through

wires, but they could also pass through the air via radio frequency (RF) waves.

Signals in Control Systems



Digital signals are a series of pulses consisting of just two

states: ON (1) or OFF (0). There are no values in between.

DAB radio is Digital Audio Broadcast radio - it is transmitted as

digital signals. high, also known as 1 or 'on'

low, also known as 0 or ‘off’



Music and speech vary continuously in frequency and amplitude. In the same way, analogue signals can vary in frequency, amplitude, or both. You may have heard of FM and AM radio - Frequency Modulated radio and Amplitude Modulated radio.



All of electronics can be divided into two broad categories: analogue and digital.



The inputs that make upAnalogue Control Systems

Analogue inputs vary over a range, for example a temperature sensor can measure minus to plus temperatures. A volume control goes from low

(Silent) to high (Loud). An analogue stick on a gamepad starts a position zero ( 0X and 0Y) and can move in various direction (X and Y axis)



The outputs that makeAnalogue Control Systems

Analogue outputs like inputs work by displaying a range. For example a speaker can output a range of sound.



The processing used in theAnalogue Control Systems

Analogue signals must be processed by an analogue-to-digital converter (ADC) before they can be processed by a logic gate.



Analogue Control Systems

Sensing system - Light Sensor

Conditional Systems - Temperature Monitor



The Inputs that makeDigital Control Systems

Digital inputs are ether on or off like the digital signal. For example a Light switch is either on (1) or Off (0)

Momentary switch's are off (0) until you pressed down and make a connection On (1)



The outputs that makeDigital Control Systems

Again Digital outputs are either On (1) or Off (0) LEDs are On or Off. LCD screens are made of pixels which are on or off. Turning certain pixels on

allows you to make words or pictures



The processing used in theDigital Control Systems

Digital signals must be processed by a logic gates.Logic gates allow an electronic system to make a decision based on a number on its inputs.


P2 - Explain the characteristics of digital and analogue control systemsAnalogue Control Systems

Command Systems - Button Blink

Programmable Systems - Decision Maker



Best done in a tableDigital Analogue

Inputs

Outputs

Processing



Signal Structure

Digital signals are ether on (1) or off (0) . Each 1 or 0 is called a bit. Known as square waves.

Analogue signals vary over a range. Know as a sine waves.



Response to Noise

Less affected since noise response are analogue in nature

More likely to get affected reducing accuracy

Think of your Telly vison before digital switchover



Bandwidth and Data

Digital Signals store data Stored in the form of binary bit (1 or a 0) Large Bandwidth (lots of data)

Stored in the form of wave signal. Ranging from 0 (in the middle) to 5 (High) and -5 (low) Low amount of data

This is best done in a Table



1. What is Signal Conversion

2. Why we need Analogue to Digital (ADC) and Digital to Analogue (DAC) conversion

3. How do Analogue to Digital (ADC) and Digital to Analogue (DAC) work including discussing sampling


M2 - Explain the need for signal conversionWhat is Signal Conversion

Signal Conversion is the process of changing one signal type to another. digital to analogue (DAC) and analogue to digital (ADC)A microphone takes sounds (analogue waves) which are then converted to digital for storing Theses Digital signals then need converting from digital back to analogue to play out of speaker.

ADC DAC

Why we need Analogue to Digital (ADC) and Digital to Analogue (DAC) conversion



How do Analogue to Digital (ADC) and Digital to Analogue (DAC) work including discussing sampling

Analogue to Digital (ADC)

When an analogue signal is being converted it is first sampled Step 2.The sampled signal can then be converted into a digital format (Step3)Sample rate is the number of samples carried per second



How do Analogue to Digital (ADC) and Digital to Analogue (DAC) work including discussing sampling

Digital to Analogue (DAC)

A digital signal is again sampled and changed into a sine wave analogue signal



Not every pin on a microcontroller

has the ability to do analogue to

digital conversions. On the

Arduino board, these pins have

an ‘A’ in front of their label (A0

through A5) to indicate these pins

can read analogue voltages.

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