sine wave with frequency up to 1MHz

I am trying to generate a sine wave with a frequency up to 1MHz, my code below can work for a frequency up to 300kHz, for frequency above no wave is generated, can someone help please? here is my code and screeshot.

sig_amp = 2.8; %amplitude

fs = 1e+6; %signal frequency Hz

sampleRate = 1e+6;

numSamplesPerCycle = floor(sampleRate/(fs));

T = 1/(fs); %sampling period

timestep = T/numSamplesPerCycle;

t = (0 : timestep : 5-timestep)';

x = sig_amp*sin(2*pi*fs*t)';

plot(t,x,'.-');

s.queueOutputData(x');

xlabel('temps (s)');

ylabel('Tension de sortie (V)');

title('Signal versus Time');

grid on

zoom xon;

s.ScansQueued

Answer 1

[Subhajyoti]

Hi @Alhassane Sylla,

It is my understanding that you are trying to plot a sine wave with a frequency up to 1MHz.

According to the Nyquist–Shannon sampling theorem, the sample rate must be at least twice the bandwidth of the signal to avoid aliasing, a type of distortion that occurs when the sample rate is too low.

Here, in the following implementation, I have increased the sampling rate for better resolution.

sig_amp = 2.8; %amplitude
fs = 1*1000*1000; %signal frequency Hz
sampleRate = 4*1000*1000;

numSamplesPerCycle = floor(sampleRate/(fs));
T = 1/(fs); %sampling period
timestep = T/numSamplesPerCycle;
t = (0 : timestep : 5-timestep)';
x = sig_amp*sin(2*pi*fs*t)';

plot(t,x,'.-');

xlabel('temps (s)');
ylabel('Tension de sortie (V)');
title('Signal versus Time');
grid on

[Alhassane]

Hello Subhajyoti,

thank you for your answer. I am not really trying to plot the signal, i want to generate sine wave for an analogue output device and it is limited to 1MHz per channel, i can't increase the sample rate anymore. According to the Nyquist–Shannon sampling theorem, the problem gonna be my device, right ?

PS: i do have a correct sine wave up to 400kHz, which is twice the device sampling rate.

[Subhajyoti]

Yes, you are correct.

[Alhassane]

Thanks.