In the sine wave source is the formula that links samples per period and sample time correct? It says: Samples per period = 2*pi / (Frequency * Sample time), but I believe it should be Samples per period = Sample time / Frequency.

See attached file

[Srikar]

Hi do you think Samples per period = Sample time / Frequency will balance the units ? sample time is in sec and Frequency in hertz (hertz is 1/sec) in that case your equation will end up having samples as sec2. I think the Math equation is right.

Answer 1

[David Goodmanson]

Hello Ilaria,

I believe it is neither of those. Rather it is what is in the PNG with the 2pi crossed out:

samples/period = 1/(frequency*sample time)

since frequency = cycles/sec, period = sec/cycle =1/frequency

# samples = period/sample time = 1/(frequency*sample time)

[Daniele Ferretti]

I tried what you said, and it doesnt work because the formula on simulink is wrong too I suppose.

Then I tried what Ilaria said and it seems correct. We should report this correction to the staff for a patch :D

[Daniele Ferretti]

So the correct formula probably is : frequency*sample time

units measure : [frequency] = Hz , [sample time] = Seconds

[David Goodmanson]

It's

number_of_ samples = 1/(sample_time * frequency)         in which case
number_of_samples * sample_time = 1/frequency = period      which is correct