Digital and analog Flashcards
Analog
Analog transmission and storage of information involve making an exact copy of the original information in a new medium.
Examples of analog
- Painting medium 1: persons face medium 2: canvas
- AM and FM radio
- Printing press
Digital
Digital transmission and storage of information involve converting information first into numbers, then sending or storing it.
Samples
- Analog technology copies the whole wave and all of the original information
- Digital technology converts certain points of the original information, called samples, so some information is always lost.
Samples-analog-advantage
Copies the whole wave, information isn’t lost
Samples-analog-disadvantage
Size cannot be made smaller by sampling.
Samples-digital-advantage
Size can be made smaller by sampling
Samples-digital-disadvantage
Copies only parts of waves
Noise
Anytime information is copied from one form to another, errors appear. This is called noise.
Analog and noise
- Analog tries to copy all information exactly.
- Since all copies have some noise, this mean’s making a copy of an analog copy will also copy the noise.
- Therefore, every time you make an analog copy, you also copy the noise.
Digital and noise
- Digital signals also have noise, but they are converted to numbers, which don’t have noise.
- When there is only a small amount of noise, digital signals do not lose any information (it’s perfect)
- When there is a large amount of noise, digital signals can be completely lost.
Noise-digital-advantage
If small amount of noise, copy is perfect.
Noise-digital-disadvantage
If large amount of noise, copy loses all information.
Noise-analog-advantage
If small amount of noise, copy is poor but understandable
Noise-analog-disadvantage
Noise builds on noise when copies are made of copies
Compression
- Digital signals can be compressed or shrunk so that they take up less space
- Compressed information is easier to store and is quicker to transmit
Compression and analog
Analog signals cannot be easily compressed.
Lossy compression
In lossy compression, information is lost, but the size of the file can be shrunk by a lot.
Lossless compression
In lossless compression there is no change in the numbers, so no quality is lost, but there is only a small change in the size of the file.
Digital-compression- advantages
Digital signals can be compressed saving space.
Digital-compression- disadvantages
if compression is lossy, quality suffers
Analog-compression- advantages
N/A
Analog-compression- disadvantages
Analog signals are difficult to compress.
Copying analog vs digital
- Digital signals are easy to copy since they are made of numbers.
- analog signals are harder to copy since they are stored on physical media.
Copying-analog-advantages
must be physically present to steal, easy to keep private.
Copying-analog-disadvantages
Hard to “back up” information or share it with others.
Copying-digital-advantages
Easily moved and easily stored
Copying-digital-disadvantages
Easily stolen and can be hacked
Encryption
Digital data can be put into code so that they can be kept private. Analog data is very difficult to encrypt and can be harder to keep private.
Loss of quality with use analog and digital
Machines have to touch the physical media when accessing analog information, this damages the media and makes it lower quality after many uses. Accessing digital information is just reading numbers, so digital information does not lose quality after use.
Storage-digital-advantages
All types can be stored and sent on computers
Storage-digital-disadvantages
Requires expensive and complex computers
Storage-analog-advantages
Storage machines are simpler and cheaper
Storage-analog-disadvantages
Each type of analog needs a special piece of equipment.
Number of signals
Many digital signals can be sent at once. It is hard to send many analog signals at the same time.
Reversible reaction
- In a reversible reaction, a chemical equation can go in both directions.
- Left-side substances can react to form the right-side substances
- Right-side substances can react to form the left-side substances.
Equilibrium
- A reversible reaction is at equilibrium if the reaction rate to the right is the same as the reaction rate to the left.
- When a reaction has reached equilibrium, the concentrations of all substances don’t change, even though the reaction doesn’t stop.
Conditions and equilibrium
- reversible reactions only stay at equilibrium when the conditions stay the same.
- If you change the conditions, the reaction will no longer be at equilibrium
- The reaction will now have a higher reaction rate either to the right or to the left until a new equilibrium is reached and the reaction rates in both directions are equal again.
Three conditions that affect equilibrium
- Concentration
- Pressure
- Temperature
Le Chatelier’s principle
If a chemical system at equilibrium experiences a change in concentration, temperature, or pressure, then the equilibrium shifts to counteract (or undo) the change, and a new equilibrium is reached.
Endo and exothermic reversible reactions
A reversible reaction that is endothermic when going to the left must be exothermic when going to the right.
Pressure and Equilibrium
Pressure effects the equilibrium of a reversible reaction only if all the substances involved are gases.
Pressure
Gas pressure is cause by the force of gas particles hitting the wall of a container. If more particles hit the wall of the container, the pressure is higher.
Pressure and Le Chatelier’s principle
Shifting toward the side of the equation that has more particles increases the pressure.
