Week 8

Question 1

What is the curse of Inverse-Square Law?

Answer 1

Power is proportional to 1 / (distance^2)

Question 2

What is a big problem in communication?

Answer 2

inverse-square law
If received power is low, noise becomes a severe problem

Question 3

What is compression?

Answer 3

Removing redundancy

Question 4

What is error correction?

Answer 4

Adding redundancy to improve reliability

Question 5

What are the two main methods of error correction?

Answer 5

Reverse error correction
Forward error correction

Question 6

How does reverse error correction work?

Answer 6

Receiver checks message, if error is detected transmitter resends the message

Question 7

What are some issues with reverse error correction?

Answer 7

Unsuited for real-time applications
Unsuited for simplex communication like broadcasting

Question 8

How to detect bit errors?

Answer 8

Parity Check
Cyclic redundancy check

Question 9

What are some issues with parity check?

Answer 9

If there are even number of errors, we can’t detect them

Question 10

What are some issues with Hamming Code?

Answer 10

Can only correct 1 bit error
Can detect 2 bit errors, but not correct them