Two Radar module (RPI + X4SIP02)

Discussion in 'X2 & X4 SoC' started by Jaeho, Jul 24, 2018.

  1. Jaeho

    Jaeho New Member

    Hi, Novelda.

    I saw your answer regarding using two tranmitters at same space in other Q&A thread.
    I would like to clarify further with following two questions.

    We are going to use the X4 for indoor positioning of objects.

    As shown at the following figure, two transceivers are separated by at least 3 meters.


    (1) Can we use two transceivers (with same center frequency: 8.74GHz) simultaneous at the same space without interference?
    We are concerning that transmitted signal from left-side transmitter could be received (results in interference) by the right-side receiver
    and vice versa.

    (2) If we can, how the two transmitted signals are filtered at the X4?
    Is the transmitted signal frequency modulated? What is the filtering technique?

    Thank you very much.
  2. Magnus Bache

    Magnus Bache New Member Staff Member

    Hi, Jaeho

    1) You shouldn't have any problems with interference for your application with > 3 meters between the radars. Due to the way the sampling is done in the receiver, the interference seen from another radar will simply work as additive noise, meaning you might get a slightly less sensitive system, but no direct interference. At 3 meters however, this effect should be negligible. We usually recommend users to have at least 0.5 meters between radars.

    2) The transmitted pulses are created using a pulse synthesizer which generates bi-phase pulses. The result is a Gauss shaped pulse with 1.5 GHz bandwidth and 8.748 GHz center frequency.

    For futher information about the X4 radar chip, I recommend reading the X4 datasheet found here:

    Jaeho likes this.
  3. Jaeho

    Jaeho New Member

    Thank you for your answer.

    [What is minimum signal transmission period?]
    According my experience, it looks the minimum signal transmission period is one second.
    Even the FPS is set to 1, I could receive next frame after one second elapsed.
    Can we reduce the period from one second to few ms, for example 100ms?

  4. Magnus Bache

    Magnus Bache New Member Staff Member

    The period will depend on the chip settings and FPS you have configured. FPS = 1 means one frame per second will be output.

    You can adjust the FPS and chip settings as you wish, but keep in mind that 1/FPS must be less than the sweep time for a frame. I strongly suggest to read chapter 7 of the datasheet so you understand how the transceiver works and how to configure it.

    Last edited: Jul 27, 2018