A Level    Signals    Questions 0 to 24   -->  View All  

Voltages, Currents, Light Pulses, Smoke Signals which Represent Information

Input transducers produce electrical currents or voltages which are proportional to a measurement from the outside world.

Examples of signals representing ...

• Music
• Voice
• Temperature
• Light Level
• Pressure
• Water Level
• Time of Day
• Still or video Images
• Control signals for industrial machines, vehicles, drones and even toys.

Analogue Signals

• Analogue signals have an infinite range of values between a minimum and a maximum.
• Analogue signals are processed using Comparators and Amplifiers.
• Analogue signals are usually smoothly varying - there are exceptions like lightning strikes

Digital Signals

• Digital signals have exactly two values - ON or OFF
• Digital signals are mostly processed using LOGIC CIRCUITS
• Digital signals have the typical square wave shape.

D to A and A to D Converters

A to D: It's possible to convert analogue signals into digital. The simplest converter is a Comparator. To record voice or music onto a phone, iPod or similar computing device, the analogue signal must be converted into digital.

D to A: It's possible to convert digital signals into analogue. To play music from a phone, iPod or similar device, digital data is first converted into analogue.

Signal Conditioning

There are many types of signal conditioning.

A simple example is to remove sudden changes from a light sensing circuit. For example, street lights come on at night by sensing the lack of daylight. It would be quite inconvenient if passing cars with bright headlights caused the streetllights to turn off. The light sensor signal must be processed to prevent this effect.