Justin King Lecture

Question 1

What are the advantages of digital filters

Answer 1

1. Simple implementation through computer code
2. Performance stability -> analogue components vary with temp etc.
3. Adjustable in comparison to analogue filters which requires hardware change.

Question 2

What are the disadvantages of digital filters

Answer 2

1. Require discrete-time signal - need ADCs and DACs
2. Need analogue anti-alias and reconstruction filters
3. Speed limitation - fast ADCS/DACS expensive and impractical
4. Quantisation

Question 3

How do we reduce the size of antennas

Answer 3

Can shift the frequency up and move the signals up in the RF spectrum

Can now have multiple signals, centred at different frequencies

Question 4

What effect does the power amplifier have on the system?

Answer 4

PA is nonlinear, will cause ‘spectral growth’ -> adding unwanted harmonics into the system

Question 5

How should we design the transmitter of an antenna

Answer 5

1. Audio signal
2. Shift up signal so you can transmit more signals
3. Amplifier using a power amplifier
4. Band-pass filter

Question 6

How should we design the receiver of an antenna

Answer 6

1. Antenna picks up signals
2. Filter to get desired signal
3. Signals are very weak -> use low-noise amplifier
4. Shift down to BB and sample, DSP

Question 7

What is the problem with the design proposed of the antenna receiver?

Answer 7

Very difficult to design narrowband filter