EC01 · Sem 4 · Signals & systems
Sampling theorem and aliasing
Aim: Show what happens when a signal is sampled below twice its frequency.
🧪 Live simulation🧊 Real-time 3D bench⚠ Simulated values, not physical measurements
🔬 Virtual lab
Starting the lab…
📘 Theory
A band-limited signal can be rebuilt from samples taken faster than twice its highest frequency (Nyquist). Sample slower and frequencies above fs/2 fold back and appear as false, lower frequencies: aliasing.
f_alias = |f − k·fs| (nearest multiple) · fs > 2·f_max
🧰 Apparatus (virtual)
- Signal generator
- ADC with adjustable sampling rate
- spectrum analyser
📝 Procedure
🎤 Viva questions
At what rate is CD audio sampled, and why
44.1 kHz, a little over twice the 20 kHz limit of hearing.
What does an anti-aliasing filter do
It removes frequencies above fs/2 before sampling.
🛡️ Safety
Virtual lab. With real RF equipment, respect exposure limits, never transmit without a licence, and keep antennas away from people.