Presence sensing using MATLAB demo algorithm with BGT60TR13C

[bright_sun]

Hi everyone, I want to use BGT60TR13C radar to realize presence detection of moving targets. I have a question about the official matlab demo of presence detection. The document says that  a moving object in the range of 20 to 80 centimeters over the radar surface can be detected and the code has the following comments:

（SDK\apps\matlab\examples\presence_detection.m)

I don't understand why 'chirp_samples/8' corresponds to 20cm and 'chirp_samples/2' corresponds to 80cm. Besides,  if I want to detect whether there is a moving target within the range of 5m, how should I configure it?

Best Regards,

Lee

[Deepa_V]

Hi @bright_sun ,

We are looking into this. Will get back to you soon. 

Best regards,

Deepa

[Deepa_V · Accepted solution]

Hi @bright_sun ,

Sorry for the delay ! 

The maximum range is given as : R_max = num_samples / 2 * c0 / (2 * BW)
R_max = 64 / 2 * 3e8 / (2 * (62366068720-59133931281)) = 1.4851m

The maximum range has been divided into 64 range bins. So, each range bin = 1.4851/64 = 0.0232m = 2.32cm

In this case,
detect_start_sample = round(chirp_samples/8); % detection start sample corresponding to 20cm [2.32cm*(64/8)= 18.56 ~ 20cm]
detect_end_sample = round(chirp_samples/2); % detection end sample corresponding to 80cm [2.32cm*(64/2)= 74.24 ~ 80cm]

Please note that the detect_start_sample and detect_end_sample can be more appropriately termed as detect_start_bin and detect_end_bin.

For 5m, Increasing the number of samples is one option, the other option is to reduce the BW.
But not sure how the motion detection part performs with larger range bins as this hasn't been tested.

Best regards,

Deepa