RasberryPi + X4M03 frame data

Discussion in 'X4M03' started by Jaeho, Jul 4, 2018.

  1. Jaeho

    Jaeho New Member

    Hi! Novelda.

    I use X4M03.

    1. Matlab example : XEP_X4_plot_frame

    [Matlab] XEP_X4_plot_frame.JPG

    2. Pyrhon example : simple_xep_plot2

    [Python] simple_xep_plot2.JPG

    3. RasberryPi example : x4driver_raspbian (I used a data_frame_normolized value to draw a graph.)

    I am working on a setup consisting of the X4M03 and RasberryPi3 B (instead of XTMCU02).
    Unlike Matlab and Python, x4driver_raspbian frame buffer size is 346.
    What is different result and graph?

    [RasberryPi] x4driver_raspbian.JPG

    Sorry, I'm not good at English.
    Thank you.
  2. Charlie Shao

    Charlie Shao Moderator Staff Member

    Hi Jaeho,
    Do you mean you connect X4M05 and RaspberryPi3 through SPI?
  3. Jaeho

    Jaeho New Member

    I bought the x4m03 development kit.
    I tested the matlab and python example using x4m03 development kit.

    I connect RaspberryPi3 instead of Ateml board.

    x4sip02+antenna.jpg + RaspberryPi3 through SPI

    x4driver_raspbian example.
    Last edited: Jul 5, 2018
  4. Charlie Shao

    Charlie Shao Moderator Staff Member

    Hi Jaeho,
    Just to make it more clear:
    The label on your picture is marked for the whole X4M03, but it is actually an X4M05 module.
    X4M03 = X4M05 + XTMCU02.
    X4 radar chip support two types of radar raw data output: RF data and baseband data. Frame size is decided by the frame area you set during initialization.
    The first two plots show RF data, the third plot shows baseband data. There is one application note introducing about frame format: https://www.xethru.com/community/resources/xethru-file-formats.55/
    Jaeho likes this.
  5. Jaeho

    Jaeho New Member

    Thank you very much. It is very helpful to me.
    I have more questions.

    (1) What equation have used for generating baseband signal from RF data?
    Is that envelope or LPF?

    (2) I am having trouble in finding "Tx signal setup/option" in RaspberryPi control code (like sampling time, Tx power...).
    I find x4driver_set_tx_power in x4driver.c but I don't know How to setting.
    Last edited: Jul 6, 2018
  6. Charlie Shao

    Charlie Shao Moderator Staff Member

    Hi Jaeho,
    1) Please refer to the definition of baseband data: https://en.wikipedia.org/wiki/Baseband and sampling process to get baseband IQ data: https://en.wikipedia.org/wiki/Pulse-Doppler_signal_processing
    The X4 chip has a built-in down-conversion chain and then you can select RF data or complex baseband data output. Since the signal is digitized at RF, the down-conversion from RF to BB is implemented digitally. This is done by multiplying every frame with a complex down-conversion vector and subsequent anti-aliasing LP filtering and decimation by a factor of 8. This is equivalent to an analogue down-conversion chain (I/Q mixers and LP filters). However the digital process guarantees perfect amplitude/phase balance.
    2) The introduction on setting can be found at X4 datasheet: https://www.xethru.com/community/resources/x4-datasheet.106/
    Jaeho likes this.