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AWR1642BOOST: Time scaling for time domain plot from raw data captured using AWR1642BOOST and TSW1400EVM

Bao Wei Loh
Prodigy 70 points
Part Number: AWR1642BOOST
Other Parts Discussed in Thread: AWR1642

Hi!

I am trying to output the time domain plot from the data collected using AWR1642 and TSW1400. I managed to get the raw ADC data using the code on page 19/20 on https://www.ti.com/lit/an/swra581b/swra581b.pdf. However, I am lost at the time scale which should be used when plotting the raw data.

Given the following settings in Radar Studio,


Which of the following (if any is correct) should be the time between each data:
1. period / (number of chirp loops * ADC samples)
2. ramp end time / ADC data
3. 1 / sampling rate 

If it is not any of these, may I know what equation I should use then? 
Also, what is the difference between ADC Samples and Sample Rate?

Thank you!

Regards,
Bao Wei

  • 0
    TI__Guru*** 147854 points

    Hi,

    For difference between ADC samples and Sampling Rate please read a book about Analog to Digital Converters.

    For the time scale, you do not need to worry about it. Usually an FFT is performed on the ADC samples. If you would like to plot the raw data you can just plot each point.

    Thank you

    Cesar

  • 0 in reply to Cesar
    TI__Mastermind 24955 points

    The ADC samples variable refers to the number of ADC samples that are captured for each chirp. The sampling rate refers to the operating frequency of the ADC. The distinction is slight but important.

    The time between each frame is determined by the frame periodicity. Each frame starts at a fixed internal in a simple use case where a single frame is defined. The active time of each frame is determined by the total chirp time defined as the sum of the idle time and ramp end time. This number is then multiplied by the number of chirp loops set in the frame definition.

    Please refer to Cesar's note above. Most, if not all, of the analysis is done in the frequency domain and not in the time domain which is why the radar algorithms are built on FFTs.

    Regards,

    Kyle