Topic 2 - analogue and digital signals

Question 1

What is analogue signal

Answer 1

Is one where the amplitude and frequency of the signal continually varies with time. The amplitude can take any value. The signal can be easily effected by noise meaning the finer detail in the signal is often lost

Eg) when a person speaks in to a microphone

Question 2

What is a digital signal

Answer 2

Are a series of pulses of voltage consisting of just two states on (1) or off (0)

Eg) digital files stored in mp3

Question 3

How do we convert analogue to digital

Answer 3

Sampling
At regular time intervals we take a sample of the original analogue wave and make a list of what the numbers should be

This number is then converted into a binary number

Chain of 0 and 1 sent as pulses of voltage and we have created a digital signal

Question 4

Frequency of sampling

Answer 4

The more frequent we sample the analogue signal the more of the original message is retained

Intensity can be lost if you don’t sample enough - this is called innervating

Question 5

Converting analogue to digital

Answer 5

Select transducer

Connect transducer to ad converter

Set up ad converter

Select sampling rate

Select binary sensitivity

Connect converter output to transmitter

Question 6

Benefits of using digital signal

Answer 6

Huge amount of digital data sent in a short amount of time - a gigabyte a second

Reliable- it is a series of pulses not much can go wrong

Interference free - digital signals maintain their quality over long distances better than analogue. You will notice far less noise and crackle

Question 7

advantages of digital signals

Answer 7

can be regenerated
can travel a greater distance without degrading

can carry many channels
less bandwidth cable can be thinner

noise can be removed
better quality signal

don’t need to be converted by computer
so process time is lower