sinusoidal signal with varying frequency

I want to generate a variable frequency sinusoidal signal. I am changing the frequency from 0Hz to 30Hz, but the frequency sine output increases above 30Hz during first 1 second simulation and finally after 1 second the frequency settles down to 30Hz. Please suggest me why the frequency of the sine wave not following the frequency.

Answer 1

[Sourabh]

Hey @Neerparaj Rai

To generate a variable-frequency sine wave, you should integrate the frequency over time to get the phase:

Then compute:

Kindly follow the steps given below to fix the issue:

• Replace the Clock block with an Integrator block.
• Multiply 2π with the time-varying frequency input (f(t)).
• Feed that result into the Integrator (which now accumulates phase).
• Pass the Integrator output to the Sin block.
• Connect the Sin block to the Scope

The final model looks like this:

The scope output is:

I hope this helps!