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AWR1642BOOST: The difference between Sample rate and ADC Samples in mmWave studio

Running Zhao
Prodigy 10 points
Part Number: AWR1642BOOST

In mmWave studio, If I set the 'Sample rate (ksps)' is 5000, it means 5M points are sampled per second. At the same time, if I set the 'ADC samples' is 256, it means 256 points are sampled per chirp. Also, I set 'No of Frames' as 160, 'No of Chirp Loops' as 255 and 'Periodicity (ms)' as 50.

In theory, if I use the formula 'Number of collected samples = No of Frames * No of Chirp Loops * ADC samples' to calculate, I should get 10,485,760 samples. But if I use the formula 'Number of collected samples = Sample rate * No of Frames * Periodicity' to calculate, I should get 40,000,000 samples.

But in practical experiment, I only collected 10,444,800 samples  (which means these samples contain 159.375 frames) by using above setting parameters.

So my questions are:

(1) How should I calculate the number of collected samples? By using 'Number of collected samples = No of Frames * No of Chirp Loops * ADC samples', or by using 'Number of collected samples = Sample rate * No of Frames * Periodicity'. And why do these two methods get different results of number of collected samples?

(2) Why is there a difference between the number of collected samples and the calculated number of samples?

Thanks in advance!

  • 0
    TI__Genius 13805 points

    Hi,

           For the simplification purpose and better understanding, please follow the doc at this link. https://www.ti.com/lit/an/swra581b/swra581b.pdf

    Number of samples will depend on other parameters too. Do let me know in case you have any doubts.

    Regards

  • 0 in reply to Abhed Misra
    Prodigy 10 points

    Thanks for your explanation.

    I could understand the data format illustrated in the link and the matlab script output that each receiver contain a number of samples equal to the number of ADC samples per chirp multiplied by the total number of chirps. 

    (1) But I don not konw why the formular 'Number of collected samples = Sample rate * No of Frames * Periodicity' to calculate the number of samples is wrong?  The sample rate is set to 5 Msps, and it means 5M points will be sampled per second. So if I set chirp duration is 130 us, there should be 650 samples (sample rate * chirp duration). But there is only 256 samples in one chirp due to the ADC samples is set to 256. How to explain this?

    (2) In addition to the above parameters, what other parameters will affect the actual number of samples? It seems a few samples are lost during collection. According to the above description of my experiments, 10,444,800 samples per receiver (which is obtained by your matlab script) corresponds to 40,800 chirps. But according to my settings ('No of Frames' as 160, 'No of Chirp Loops' as 256 and 'Periodicity (ms)' as 50), there should be 160*256=40960 chirps. So I speculate that some samples are lost. 

  • 0 in reply to Running Zhao
    TI__Genius 13805 points

    Hi Running,

                       I would advice to go through the documentation and training on the ti.com. There are various parameters of the RADAR Chirp and Frame which are very configurable and flexible in nature and hence based on the specific Chirp configuration allow different use cases to be addressed. For in cabin sensing demand short range but high angular resolution and hence would require accordingly BW, Slope and periodicity configured. 

    Regards