how do i randomly sample a sinewave?

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Kel
Kel 2014-3-15
回答： Sulaymon Eshkabilov 2021-8-14
hey can someone help me?i am trying to randomly sample sinewave but i am having no luck. i have tried Google, i tried using the help function on the 'rand' command and still i am no closer to sampling the signal.
  2 个评论
Kel
Kel 2014-3-15
i have signal shown by the code below and would like to take random samples of the signal,
fo=4 fs=100 ts=1/fs t=0:ts:1-ts n=length(t) y=2*sin(2*pi*fo*t) plot(t,y)

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采纳的回答

dpb
dpb 2014-3-15
yrand=y(randperm(length(y),K));
returns K random samples from y

更多回答（2 个）

Image Analyst
Image Analyst 2014-3-15
Try this:
fo=4
fs=100
ts=1/fs
t=0:ts:1-ts
n=length(t)
y=2*sin(2*pi*fo*t)
plot(t,y)
numberOfSamplesToTake = 20;
sampleIndexes = randperm(numel(y), numberOfSamplesToTake)
% Plot the samples;
ts = t(sampleIndexes)
ys = y(sampleIndexes)
hold on;
plot(ts, ys, 'r*');
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Image Analyst
Image Analyst 2014-3-16
You must have a really old version of MATLAB before they added the second input argument of randperm. Try this:
numberOfSamplesToTake = 20;
sampleIndexes = randperm(numel(y))
sampleIndexes = sampleIndexes(1:numberOfSamplesToTake)
dpb
dpb 2014-3-16
Ah...good catch, IA. Never crossed my mind but my R12 doesn't include it--how quick we forget! :)
Presuming you're correct (and that's a good bet) perhaps a good use for a utility function for the OP to take the second argument.

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Sulaymon Eshkabilov
An alternative solution is:
N_samples = 20;
y_rand = datasample(y, N_samples);
% OR
y_rand = randsample(y,N_samples);

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