Velocity estimation

[YourVoicee]

Hello! Thank you for a wonderful project. I tried to run your code and got completely different speed values. The parameter values I used are exactly the same as in your work. If it would not be difficult for you, could you suggest what this could be related to.

[kopytjuk]

I just re-run my notebook with a more recent Python version (3.10) and had to change the following:

t = np.linspace(0, 3*T_r, 1e6)  # old
t = np.linspace(0, 3*T_r, int(1e6))  # new

Refer to pyproject.toml in the project to see the library versions used.

I could reproduce my own results. Are you sure that you have nothing changed?

[YourVoicee]

Thank you for your reply!

We calculate the velocity value from the function angle_freq_to_velocity(w, f_0):
w = 2*np.pi*np.concatenate((np.arange(0, n_r//2), np.arange(-n_r//2, 0)[::-1]))
velocities = omega_second*c/(4*np.pi*f_0)
If we take the maximum value from w = 930 and calculate:
930 * 299792458/(4 * np.pi*77700000000.0) = 0.2855438222709367

[kopytjuk]

I see your problem @YourVoicee, you will cry and scream :D I spent now 30min thinking and while I was outside walking I opened the notebook on my phone ... I had a spark of idea to check:

On a screen with low screen width:

On a widescreen:

So this is an issue of GitHub notebook renderer rendering the cell:

omega_second = 2*np.pi*np.concatenate((np.arange(0, n_r//2), np.arange(-n_r//2, 0)[::-1]))*f_chirp/n_r

[YourVoicee]

Hello! It didn't even occur to me to check it out.... I fixed the code and now the values converge. I’m very thankful for your time and effort in responding. Can I ask you some more questions, please?
I am very interested in using FMCW specifically. In the FMCW chapter we did not address various problems like:

• multi target estimation
• angle estimation
  Would you recommend literature for studying this issue? There is a link to one book in the notebook (it is in German :(( ), but I did not find the formulas you refer to in it.

Thanks again for your attention and time!