Lab 2

 
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Question 1: Basics
In order to understand the rest of the lab, some basic terminology and understanding is required.

a. Frequency is typically expressed in what terms (give name).

b. Nyquist  rate is, at least, how many samples more than the original frequency?

c. If a signal range is from +5volts to -5volts, and you wish a resolution of .5 volts, how many bits is needed to represent this range?

d. Using the answer in 1C above, if you sampled a wave form 6 times a second, what is the bit rate for the signal?

e. Why is most high quality audio sampling rate at 44Khz or 48Khz?

Question 2: Using Nyquist frequency
You have just been hired by the government. Your new boss, eager to make his mark, puts you in charge. He is starting a digital phone service, using the internet. He wants to make a basic service, using as little bandwidth as possible. Of course, he puts you in charge of figuring out how to keep costs to a minimum. Use https://cosmos-cluster-6.courses.soe.ucsc.edu/system/files/attachments/sampling.xlsx For the next few questions (2a-d)

(a). You first decide to try a 1200 Hz signal, and to sample it 1200 times per second.

- Mark the waveform with sampling rate shown on the web site

 

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- Is this sampling rate sufficient to reproduce the original signal? Why/why not?

(b). Now you decide to try the Nyquist sampling rate. Set "Original Frequency" to 1200 Hz and the "Sampling rate" to the Nyquist sampling rate.

- Mark the waveform with sampling rate shown on the web site

 

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- Is this sampling rate sufficient to reproduce the original signal?   Why/why not?

(c). Your boss, decides to save money by reducing the Nyquist sampling rate. He figures ‘close enough for government work’, so use the same settings as in (b), but set the ‘Sampling rate’ to 2300.

- Mark the waveform with sampling rate shown on the web site

 

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- Is ‘close enough’ good enough to reproduce the original waveform? How do you think this would affect signal quality for someone listening

Question 3: Quantization
Digital systems tend to create square waves (instead of drawing between points, like in Q2, you continue at the same level, until you reach a new sampling point, and have, a new level). Using a sampling interval of 5 ms, and 4 bit resolution, draw a digitized (square) version of the signal in the graph below. Label each axis with correct time or voltage value, starting at time = 0.

Quantization_voltage

Files must be less than 10 MB.
Allowed file types: gif jpg png bmp pdf.