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[FAQ] AWR1642: mmWave Chirp Configuration Delay FAQ

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Part Number: AWR1642

How can we configure chirp delays on mmWave devices?

  • The foundational document to understand chirp configuration on mmWave devices is the following Application Note:

    www.ti.com/.../swra553.pdf


    QUESTION #1:

    How do I add a delay to a chirp in a standard frame configuration environment? What is the maximum delay I can add?

    ANSWER #1

    The answer will depend based on the value of the delay. It is possible to add a smaller delay in the chirp configuration and a larger delay in the profile configuration

    ADDING A DELAY IN THE CHIRP CONFIGURATION

    A delay can be added to a chirp by using the "idleTimeVar" in the rlChirpCfg_t structure. In the mmWave SDK folder structure, see " C:\ti\mmwave_sdk_##_##_##_##\packages\ti\control\mmwavelink\include\rl_sensor.h" and related doxygen information.

    Notice that this delay variation value will be added to the "idleTimeConst" defined in the rlProfileCfg_t structure.

    Notice that this property is part of the Chirp Configuration. On the xWR#### devices there are 512 chirp configurations possible.

    The maximum delay variance supported is defined in the doxygen documentation:

    1 LSB = 10 ns

    Valid range: 0 to 4096

    This means that the maximum delay is 4096*10ns = 40.96us

    In the profile format used by the SDK, this field is part of "chirpCfg" and is called "idle time variation". Notice that in the SDK only value "0" was tested.



    ADDING A DELAY IN THE PROFILE CONFIGURATION

    A delay can be added to a chirp by using the "idleTimeConst" in the rlProfileCfg_t structure. In the mmWave SDK folder structure, see " C:\ti\mmwave_sdk_##_##_##_##\packages\ti\control\mmwavelink\include\rl_sensor.h" and related doxygen information.

    Notice that this property is part of the Profile Configuration. On the xWR#### devices there are 4 profiles possible. If other chirps in the frame have different idle time, then, at least 2 profiles have to be used.

    The maximum delay supported is defined in the doxygen documentation:

    1 LSB = 10 ns

    Valid range: 0 to 524287

    This means that the maximum delay is 524287*10ns = 5.24287ms

    In the profile format used by the SDK, this field is part of "profileCfg" and is called "idle Time"
  • Thanks Cesar