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IWR1462: Zero-IF receiver architecture?

David Ding
Prodigy 50 points
Other Parts Discussed in Thread: AWR1642, IWR1642

Hello,

From block diagram of the receive subsystem, we can see that the IF filter is actually a band-pass filter (achieved by a high-pass filter cascaded by a low-pass filter).

When measuring range between radar and targets, there should be a minimum detection distance limited by the lower cutoff frequency of the low-pass filter (say, 350kHz).

Is there any misunderstanding?

  • 0
    TI__Guru 71516 points

    Hello David,

      You stated this is for the IWR1462, but we don't know what that is.  Did you mean the AWR1642 (PREVIEW)?

    Also same number in your other related post.

    Regards,

    ~Leonard 

  • 0 in reply to LeonardEllis
    TI__Mastermind 37500 points

    Hello,

    The IWR1642, industrial version of AWR1642, has a set of low pass filters, and a high pass filter after the block downconversion mixer.

    There are two low pass filter banks, these are used to attenuate the close in (radome reflection) radar signal.   The high pass filter provides filtering 

    for the 1st nyquist zone sampling of the ADC.

    Regards,

    Joe Quintal

  • 0 in reply to Radio-Joe
    Prodigy 50 points

    Hello Quintal,

    Thanks for your reply!

    Low pass filter provides filtering for the 1st nyquist zone sampling of the ADC, high pass filter is used to attenuate the close in (radome reflection) radar signal.

    If ramp slope=20MHz/us, cutoff frequency of the high pass filter is 100kHz, then the round-trip time=100kHz/(20MHz/us)=5e-9s, that is to say, the minimum detection range=0.5*3e8*5e-9=75cm

    So, if the cutoff frequency of the high pass filter is 100kHz, the radar cannot detect objects within 75cm?

    BTW, could you please provide the detailed cutoff frequencies of the high pass filter?

    Thanks a lot!

    Regards,

    David

  • 0 in reply to David Ding
    TI__Mastermind 37500 points

    Hello David,

    the High pass filter example is shown in the following attachment.   Note: there are 2 filters to get the desired attenuation.   The light green is the least intenal filter setting.   You can still detect close in objects, if you have enough range resolution, signal level, and SNR for object detection.

    Regards,

    Joe Quintal

  • 0 in reply to Radio-Joe
    Prodigy 50 points

    Hello Joe,

    Thank you very much for your detailed explanation!

    Regards,

    David.