matlab sampling problems, how does Matlab sample signals?

t=:2*pi;%% sampling frequency1 and the number of sampling points is length(t).

f0=;y=cos(2*pi*f0*t);

stem(y)

The above result y is originally the result after sampling, and you have to sample the result after sampling, which is obviously problematic.

t=:1t =0

There are infinite consecutive values between 0 and 1, and the value of t you can see is the result of sampling, and the number of points sampled is length(t)=11 points.

xs(i)=y(i*ts); In ts=, even if i starts from 1, many of your array subscripts are decimals, and the array subscripts must be integers, 1,2,3,4,5,6,..

1. If the signal with a sampling frequency of 20Hz and a number of 200 points is sampled at 20Hz in a cycle, only 126 points can be obtained, and 200 points can not be obtained. If you want to get 200 points, the sampling frequency needs to be changed.

t=0:2*pi (200-1):2*pi, so the number of sampling points is 200 and the sampling frequency is (200-1) 2*pi.

2 If the sampling frequency is required to be 20Hz and the number of points is 200 points, then extend the period, and after the harvesting, go to the first 200 points.

t=0:1 20:4*pi, the t has 252 points, you can take the first 200 points.

t=t(1:200)。

The previous line of this line: "for i=0:n".

Instead: "for i=0:n".

Array subscripts are counted from 1.

1. Open Solv MATLAB and create a new script.

2. Enter ** in the device.

3. TP is the observation time, and we set the cautious leakage ear to 64 subtle, that is, 64 1000;The next input ** is to generate the m long sampling sequence x(n).

4. Set the given value in the experimental content; Then input the given analog signal formula.

5. subplot(3,2,1) means: three rows and two columns, plotting in the first position.

6. After the input is completed, click Run.

7. Obtain the wide distribution to the result and sample the signal.

Hello dear <>

Very happy to have a question for you. In MATLAB, sampling frequency refers to the number of times a digital signal is sampled per second. The sampling frequency is also known as the sampling rate or sampling period.

In MATLAB, we can use sampling rate or sampling period to represent the sampling frequency. The unit of sampling frequency is Hz (Hertz), which indicates the number of times samples are taken per second. For example, if the data is sampled at 1000Hz, it means that the signal is sampled 1000 times per second.

Therefore, when determining the sampling frequency, it is necessary to consider the characteristics of the signal and the accuracy requirements of the sampled data.

1.t is the abscissa copy, i.e. sending positive.

The start and end times of the string signal bai. According to the program you gave, the starting time is 0, every interval.

The interval t1 (about seconds) takes a DAO point, and the termination time is t2 (20*pi-t1 is about equal to seconds), so you see a waveform from 0 to about 62 seconds.

2.The frequency of the sine wave is 50Hz, the duration of a cycle is, according to the time interval of t1 (about seconds) sampling, the number of sampling points in a cycle is one, depending on how the system chooses the decimal part, in short, there is the so-called "sampling rate of a week wave is 82 points" phenomenon.

3.Give you a program and its results, and hopefully you will understand the relationship between periods, frequencies, and sampling points.

clcclear all

close all

dt = 1e-3;% sampling interval in seconds.

t=;% Signal duration, unit: seconds.

va = ;Signal waveform.

figure

plot(t, va, 'o--');Waveform plot, where the circle is the sampling location.

grid on

xlabel('t');

ylabel('va');