A-level Physics (Advancing Physics)/Digitisation/Worked Solutions

1. Take samples for the signal below every 0.1ms, and then produce a reconstructed signal. How does it differ from the original? Image:Digitisation_q1_solution.svg The high frequency elements of the signal have been lost. 2. A signal is sampled for 5 seconds at a sampling rate of 20 kHz. How many samples were taken? 3. Most sounds created by human speech except for 'ss' and 'ff' have a maximum frequency of 4 kHz. What is a suitable sampling rate for a low-quality telephone? 4. Using a sampling rate of 20 kHz and 3 bits, sample the following signal, and then produce a reconstructed signal. What is the maximum frequency that can be perfectly reconstructed using this sampling rate? First, calculate the length of each sample, by letting the number of samples equal 1: Then, we can sample the waveform and create a reconstructed signal: Image:Digitisation_q2_solution.svg To calculate the maximum frequency that can be perfectly reconstructed using this sampling rate (20 kHz):