Signalling

Question 1

Digital Signal

Answer 1

Represents data as a series of discrete values, where at any point the data can only be one of a number of finite values

Question 2

Analogue Signal

Answer 2

Represents data as a continuous series of values where at any point there is an infinite number of possible values that the data can be

Question 3

Digital - pros and cons

Answer 3

+ Less impacted by noise
Easy to process quickly and in large quantities
Easier to manipulate and edit

• Can’t exactly recreate a signal
  Requires lots of memory and bits to process
  More vulnerable to things like hacking and airbrushing

Question 4

Analogue - pros and cons

Answer 4

+ Recreates exact values
Requires less memory to process

• Affected greatly by noise

Question 5

Quantisation level

Answer 5

Possible values within a range that digital signals can take

Question 6

Resolution of a sample

Answer 6

p.d. range of signal / # of quantisation levels

Question 7

Maximum number of useful quantisation levels

Answer 7

total variation / noise variation

Question 8

Maximum # of bits to use

Answer 8

b = log2 (total variation / noise variation)

Question 9

Minimum sampling rate and why

Answer 9

Min sampling rate > 2 x highest frequency component

This is to avoid aliasing

Question 10

Bit rate

Answer 10

bit rate = samples per second x bits per sample

Question 11

Duration of signal

Answer 11

number of bits in signal / bit rate