Chapter 3- Signalling

Question 1

What does an e-m wave look like

Answer 1

Magnetic must go to the right, Electric must got up .

Question 2

How can unpolarised and polarised light be drawn simply.

Answer 2

Question 3

What happenes to analogue and digital signals with added noise?

Answer 3

Analog- gets gradually worse with added noise

Digital- Noise can be completly removed until a certain amout at which it stops working.

Question 4

Sampling rate has to be…

Answer 4

at least twice the max frequency (20kHz) acutal rate is 44.1kHz

Question 5

Making irregular wave forms?

Answer 5

any regularilly occuring waveform can be made from the weigthed sum of the harmonics (in different proportions)

Question 6

Bandwidth(B) needed =

Answer 6

bits per second/2

as one cycle can represent 2 bits

(With B=Wb you can tranmit 2Wb bits per second)

Question 7

samples needed (2W) =

Answer 7

2x highest frequency(W)

Question 8

(b)Number of bits needed for 1 sample =

Answer 8

log₂(V_total/V_noise)

Question 9

(rate of transmission) bits per second=

Answer 9

samples per second x bits per sample