How can i implement Chirp Signal using C? [closed]

Question

I would like to implement Chirp signal using C code

Do you have any idea how can I do it?

Edit

Goal is to send this signal to an DAC Component (µC intern or external peripheral). But I need fast sample rate like 10 Msamples or 20 Msamples. FPGA is not provided, any other µC is possible

Answer 1

Make your external peripheral a DDS (direct digital synthesis) chip. This sort of thing is well within the capabilities of even a relatively low-end chip such as the Analog Devices AD5930.

Answer 2

This reference has a simple Chirp function. Call it with the parameters and the time and it returns the signal value at that time. The w1, w2 are angular frequencies, so \$2\pi f_1\$, \$2\pi f_2\$, M is the chirp duration, A is the peak amplitude.

double Chirp(double w1, double w2, double A, double M, double time)
   {
   double res;
   res=A*cos(w1*time+(w2-w1)*time*time/(2*M));
   return res;
   }

Edit: With 10-20MSps you'll likely be looking at dedicated hardware such as a DDS that supports a chirp function and has internal trig tables. You may be able to find a processor with a DMA function that would allow a pre-calculated table to be output to a DAC, but that would be a peripheral function.

Answer 3

I think the way to go would be to generate a look up table of full-integer-scale of one cycle of a sine wave at your lowest frequency, and then modulo-index into it with increasing step sizes, possibly doing linear interpolations between two points if using the nearest point is too rough.

Lastly, depending on the relationship between your output rate and your highest wave frequency, you might consider sending this out via low-pass-filtered high res PWM as opposed to a DAC. It might be a lot faster.