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IWR1642: Interference prevention function

user5305835
Prodigy 100 points
Part Number: IWR1642

Dear support forums,

I'm currently considering to use IWR1642 in Japan.

According to the Japanese Radio Law or ARIB STD T-111, an interference prevention function is required.

However, as far as I understand, IWR1642 doesn't have such functions.

Could you let me know how I can realize/implement this function in order to pass the Japanese radio regulations ?

As for ARIB STD T-111, please refer to the page 6 of this link.

Thank you in advance,

Yoshiharu Koshikawa

  • 0
    TI__Mastermind 39955 points

    HI, Yoshiharu:

    My understanding to your document is that the interference prevention function require the designer to add some randomized sequence that is known to the receiver.   And after demodulation at the receive side, the interference signal will look more like noise instead of ghost signals.   This randomization can be a per chirp phase rotation or per chirp starting time variation and etc.

    You can see some details on section 5 for the following application note on interference management. 

    https://www.ti.com/lit/pdf/swra662

    TI mmwave radar devices all have this capability to add randomization.  But it is up to the user to properly apply them and may need to add some change to receive side to demodulate them.   

    Best,

    Zigang

  • 0 in reply to zigang Yang
    Prodigy 100 points

    Hi Zigang,

    Thank you for the reply.

    1. I did a test with two sensors placing face to face, but didn't observe any interference, as long as I looked at the radar plot of visualizator. Is this because the local oscillators of the two sensors were not synchronizing?
    2. In general, local oscillators of each sensor are not synchronizing with each other. This fact can be regarded as a kind of randomization. As long as we don't want a perfect solution for interference prevention, this fact works to some extent. Is my understanding correct ?

    Best Regards,

    Yoshiharu Koshikawa

  • 0 in reply to user5305835
    TI__Mastermind 39955 points

    HI, Yoshiharu:

    Did you program the two sensor the same profile/chirp configuration? 

    IF the chirp slope is very different between the two sensors, then the interference signal becomes noise and only increases noise floor.  You may be able to observe the increase of noise profile in the visualizer.  

    IF the chirp slope are the same between the two sensors, it is very hard to observe it because the probability of interference is usually small.  And even it happens once after a while, your eyes may not catch it.  It is very hard to observe the interference without sync the two sensors.    If you add some kind of interference indicator in the target code, and stop the visualizer when the indicator is on, you may catch that moment. 

    I agree that if each local oscillators have a unique frequency variation sequence, then it works as interference prevention function.

    Best,

    Zigang

    Best,

    Zigang

  • 0 in reply to zigang Yang
    Prodigy 100 points

    Hi Zigang,

    The chirp slope were the same between the two sensors when I tested.

    Thanks to your answer, I understood why I couldn't observe interference. 

    Thank you very much for your support.

    Best Regards,

    Yoshiharu Koshikawa