Principal frequencies of a Waveform

[HDG]

Using 16 = 96.89%
Using 15.878 = 97.26%

Both obviously equate to 97% but Just wondering if there was something I'd missed about needing to round up a fundamental or something

 

[HDG]

Grappled with this for a few days and I'm happy I've got the answer. It's done using 15.878.

For part iv) I changed the 3 magnitudes to rms values ((square root of magnitude)x0.707). I then used the formula:

Amplitude(rms)*sin(2pi x f x t)

in 3 separate columns in excel (for each frequency and it's associated rms magnitude) and just dragged the formulas down to complete the 1024 entries. I then summed all of the 3 entries, created another column for time(s) and then inserted a scatter graph to synthesis the original waveform. Only did it over a short time period though as the graph wouldn't accept all 1024 entries.

(To get the formula to drag down I had to lock some of the fields when writing the formula with the $ sign) e.g. $b$2*sin(2pi*$a$3*a8)).

 

[Jason-Li]

Grappled with this for a few days and I'm happy I've got the answer. It's done using 15.878.

For part iv) I changed the 3 magnitudes to rms values ((square root of magnitude)x0.707). I then used the formula:

Amplitude(rms)*sin(2pi x f x t)

in 3 separate columns in excel (for each frequency and it's associated rms magnitude) and just dragged the formulas down to complete the 1024 entries. I then summed all of the 3 entries, created another column for time(s) and then inserted a scatter graph to synthesis the original waveform. Only did it over a short time period though as the graph wouldn't accept all 1024 entries.

(To get the formula to drag down I had to lock some of the fields when writing the formula with the $ sign) e.g. $b$2*sin(2pi*$a$3*a8)).

Hi HDG,

Did you get the question correct? I got a final answer also of 97.271%

How did you select the fields to create the scattergraph?

Thanks for any help!