I’m working independently from Ken Steiglitz’s Intro to Signal Processing textbook.

Problem 9 in Chapter 3 asks about the period of a sampled square waveform. I understand that he’s getting to the fact that the “fractional” sampling frequency per wave period has to be accounted for (in the example in the text: 40k sampling frequency and a 700Hz wave frequency equates to 57 1/7 samples per wave period- making the sampled waveform’s period 7*700Hz).

However, I’m not entirely sure how this periodicity is reflected in the spectrum of the square wave. I can’t seem to explain the connection between how this alteration of sampled frequency vs original frequency attributes to the aliasing, resulting in some of the ‘extraneous’ frequencies present in the spectrum. Any hints?

I’m working independently from Ken Steiglitz’s Intro to Signal Processing textbook.

Problem 9 in Chapter 3 asks about the period of a sampled square waveform. I understand that he’s getting to the fact that the “fractional” sampling frequency per wave period has to be accounted for (in the example in the text: 40k sampling frequency and a 700 Hz wave frequency equates to 57 1/7 samples per wave period- making the sampled waveform’s period 7*700Hz).

However, I’m not entirely sure how this periodicity is reflected in the spectrum of the square wave. I can’t seem to explain the connection between how this alteration of sampled frequency vs original frequency attributes to the aliasing, resulting in some of the ‘extraneous’ frequencies present in the spectrum. Any hints?

I’m working independently from Ken Steiglitz’s intro. to signal processing textbook. Problem 9 in chapter 3 asks about the period of a sampled square waveform. I understand that he’s getting to the fact that the “fractional” sampling frequency per wave period has to be accounted for (in the example in the text: 40k sampling frequency and a 700Hz wave frequency equates to 57 1/7 samples per wave period- making the sampled waveform’s period 7*700Hz).

However, I’m not entirely sure how this periodicity is reflected in the spectrum of of square wave. I can’t seem to explain the connection between how this alteration of sampled frequency vs original frequency attributes to the aliasing resulting in some of the ‘extraneous’ frequencies present in the spectrum. Any hints?

I’m working independently from Ken Steiglitz’s Intro to Signal Processing textbook. 

Problem 9 in Chapter 3 asks about the period of a sampled square waveform. I understand that he’s getting to the fact that the “fractional” sampling frequency per wave period has to be accounted for (in the example in the text: 40k sampling frequency and a 700Hz wave frequency equates to 57 1/7 samples per wave period- making the sampled waveform’s period 7*700Hz).

However, I’m not entirely sure how this periodicity is reflected in the spectrum of the square wave. I can’t seem to explain the connection between how this alteration of sampled frequency vs original frequency attributes to the aliasing, resulting in some of the ‘extraneous’ frequencies present in the spectrum. Any hints?