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Original question:

AWR1843BOOST: Radar interference measurement setup

AWR1843BOOST: Interference between two FMCW radar sensors

Sachidananda Swamy
Intellectual 310 points
Part Number: AWR1843BOOST

Hi,

     I am trying to observe the interference between two AWR1843BOOST radar sensors, using the interference lab provided by TI in Platform Toolbox. I am able to observe the interference using the interference lab in demo Visualizer.

Here the interferrer code is designed to transmit signal with constant frequency, which generates the interference between FMCW and a constant frequency signal. 

I wanted to observe interference between two FMCW signals, for which I modified the interferrer code to transmit chirps continuously with the following changes:

  • Added profile configuration, chirp configuration and frame configuration.
  • removed the continuous mode configuration.
  • modified the Channel configuration(enabled only 1 Tx antenna and disabled all Rx antennae - to reduce the frame periodicity).

With the above modifications I tried checking the interference in the Victim sensor, but I was unable to detect interference.

When I run the interferrer in CCS, I was getting the "RF start successfully" log from which I inferred that the interferrer sensor is successfully transmitting chirps. 

Could you please:

  1. verify the aforementioned interferrer code changes?
  2. provide the information about detecting the interference between FMCW - FMCW ?
  • 0
    TI__Guru*** 148944 points

    Hi,

    We are in the process of releasing an interference demo. This demo should be shortly available in the Automotive Toolbox on the TI Resource Explorer.

    Thank you

    Cesar

  • 0 in reply to Cesar
    Expert 1765 points

    Hi Cesar,

    Thank you for the prompt response on this item. Can you give us a timeline for this demo in the automotive toolbox? like within this month, quarter or year?

    Secondly, considering our customer timeline,  if you can also throw some light on where we are going wrong, this would be greatly helpful.

  • 0
    TI__Guru*** 148944 points
    I think it will be released as soon as next week. Let me confirm the schedule.
     
    Thank you
    cesar
     
  • 0 in reply to Cesar
    TI__Guru*** 148944 points

    Hi,

    The demo has already been released. Please see in TI Resource Explorer

    https://dev.ti.com/

    Resource Explorer -> Platform Toolbox->Labs-> Interference Mitigation and Detection Lab

    Thank you
    Cesar

  • 0 in reply to Cesar
    Expert 1765 points

    Hi Cesar,

    We are aware of this Lab and as mentioned in the question, we started with that and it is working fine. The query is about changing this Lab from FCMW<> CW to FMCW<>FMCW.

  • 0 in reply to Santhana Raj
    TI__Guru*** 148944 points

    Hi,

    Sorry for the confusion.

    It will be very difficult to create FMCW<>FMCW interferences because both sensors must be synchronized and use identical chirp configurations.

    I will assign this thread to the engineer who released the interference lab

    thank you

    Cesar

  • 0
    TI__Genius 15046 points

    Hi,

    Sorry for the delay in my response. Cesar is right, if you want repeatable interference between two radars with FMCW chirps, you would need to synchronize them. We have observed the same while experimenting on our end: two FMCW mode EVMs aren't guaranteed to produce an interference event at every chirp. Without synchronization, you might not see a significant difference in the noise floor from the GUI.

    This is the reason the lab uses CW mode for the interferer. An interference event happens when the frequency vs time lines of the victim and interferer EVMs intersect/cross (more formally when the transmission of the interferer falls in the IF band of the victim). For CW (slope 0), this intersection is guaranteed to happen once per chirp of the victim provided the interferer frequency is in sweep of the victim. For FMCW interferer with intermittent chirps, this might not happen. Note that even if the two EVMs are transmitting at the exact same time, an interference event isn't guaranteed (could happen if ramp slopes are the same). You can have a look at sections 2.3 and 3.2 of this app note: (https://www.ti.com/lit/an/swra662/swra662.pdf) to get some context for these statements.

    Note that this crossing/intersection is similar in both CW mode and FMCW mode interferer (both would intersect once, ignoring the rarer parallel interference case). If you must use an FMCW interferer, please have a look at the following e2e thread on how to synchronize two EVMs to start chirping at the same time:

    https://e2e.ti.com/support/sensors/f/sensors-forum/941081/iwr6843aopevm-giving-signal-for-time-synchronization

    This synchronization guarantees an interference event in every chirp, similar to having the interferer in CW mode.

    Alternatively, you could also try using different slopes for both devices and a high duty cycle (low interchirp and interframe times) and see if that helps, although I haven't tried this and am not sure how well this would work. 

    Regards,

    Aayush