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AWR1443: Can two sensors be used simultaneously?

Andrew Redman
Intellectual 435 points
Part Number: AWR1443

Is it possible to use two sensors side-by-side simultaneously without interference?  I have two mmWave AWR1443 sensors that I am interested in using simultaneously. How will separation distance between sensors affect their operation? Will these sensors interfere with each other in the following situations?

  • Sensors are pointed in the same direction
  • Sensors are pointed towards each other
  • Sensors have the same chirp configuration
  • Sensors have different chirp configurations
  • Sensors are operated indoors vs outdoors

I am interested in recording a scene with two sensors simultaneously so that I may compare the same scene recorded with different chirp parameters.

  • 0
    TI__Mastermind 37500 points

    llo,

    There are specific methods to combine the sensors, or provide precise timing, and use software to decorelate the radar sensors.

    If we use an external TCXO 40Mhz clock, AC coupled 1.8v, to CLKP, 50 ohm resistor to GND CLKM, and connect the SYNC OUT of one of two radar sensors to the SYNC IN of both radar sensors, we can start them at the same time.  

    The sensors facing towards each other, or facing the target, can have some specific interaction.  There are controls within the radar chirp parameters and radar profile parameters to decouple the two radar sensors:

       1) if the radar sensors start their frame at the same time, you can decorrelate the FMCW chirp by:

             a) the FMCW starting frequency - you can separate the scanning by radar sensor into 2 bands example 77-78.9Ghz, 79 - 80.9Ghz, in this manner the beat

             frequency is outside the expected range.

             b) the chirp has several components; ADC start time (adjustable by chirp) , ADC sampling time (adjustable by profile), ADC excess sample time (adjustable

             by profile) and idle time (adjusted by chirp time, you could have a chirp time that samples in the first half of the period; 

    Radar Sensors that have the same chirp configurataion, can be separated with Binary Phase Modulation, requires special Hardware Acceelerator or DSP programming.

    Radar Sensors that have different chirp configurations could have different start times (two separate SYNC In times), if the Chirp period has a large idle time, then one radar sensor can be chirping, while the other radar sensor is not chirping.

    Indoor and Outdoor operation, is not typically different than the above.  However another concept is that the radar sensors are spatially separated so they can't share a common 40Mhz and Sync in time.  In this case you can develop a disciplined 40Mhz clock from a GPS receiver, and use the 1 pulse per second frame synchronization to start another timer for the Sync Input.

    If you use the mmWave SDK Visualizer and Out of Box demo, you can save the Visualizer configuration files to a specific name.   You can experiment with the chirp,profile, and frame configurations, to illustrate that the sensor still functions.   The dfp package for Radar Studio can also be used to provide a GUI like programming interface.  The Sensing Estimator can be used for the Chirp, profile, frame parameters values.

    Sensing Estimator - ' dev.ti.com/.../'

    mmWave SDK - ' www.ti.com/.../MMWAVE-SDK  '

    radar Studio ' http://www.ti.com/tool/mmwave-dfp  '

    mmWave SDK Out of Box Demo Visualizer PC software - 'dev.ti.com/.../  ' 

    Note: if you have two radar sensors that are started randomly it is possible that the chirp Tx frequencies cross.  This can cause an interference between the two sensors, this is why there is a suggestion above to use the sensors with a common CLKP and common SYNCIN signal.  evaluating the time series of the complex data in Complex 2x mode, for the negative frequency portion can illustrate if the interference is detected.

    Regards,

    Joe Quintal