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IWR1443: Raw Data (IF signal) amplitude fluctuation

TAKAYUKI USHIKUBO
Prodigy 20 points
Part Number: IWR1443

It is used in 1TX-1RX. Amplitude fluctuation of Raw Data (IF signal) is confirmed near the low temperature state (-4deg), and it is detected as noise in the waveform after FFT. What is the cause of this phenomenon? Is there a control that changes the amplitude of the IF signal in the transmission / reception state? Is there a way to solve this with software?One of the reasons for this is that the TX-RX isolation of our hardware is not sufficient, but we are looking for a way to deal with it with software.

Best Regars,

Ushikubo

  • 0
    TI__Genius 10295 points

    Hi Ushikubo,

    Thank you for reaching out on our e2e forum. Please give us 3 business days to look into this and if we have not responded by 6/22 please reach out again.

    Thank you,

    Angie

  • 0
    TI__Mastermind 32805 points

    Hi, Ushikubo:

    Can you show us some plot showing signal power variation over time?  So we understand whether it is one time change or up and down behavior and what is the level of variation.   The signal gain will change over temperature change, but it is more graduate change then fluctuation.   There is also run-time calibration that may cause a sudden change when the temperature is reaching a special level.   But it is more of an one time change.  

    Best,

    Zigang 

  • 0 in reply to zigang Yang
    Prodigy 20 points

    Hi Zigang

    Thank you for your reply. The IF signal waveform is shown below. The upper waveform is the predicted waveform before passing through the filter, and the lower waveform is the measured waveform after passing through the filter. Amplitude fluctuations appear as noise components after FFT processing, which interferes with distance measurement.

    Best Regars,

    Ushukubo

  • 0 in reply to TAKAYUKI USHIKUBO
    TI__Mastermind 32805 points

    HI, Ushukubo:

    Could you plot the range FFT of the IF signal?  How did you predict the waveform before passing through the filter?  Are you testing in the super clean environment with single corner reflector?  Even that is the case, there is TX-RX leakage that goes into the RX chain.  

    In the original message, you mentioned that temperature.  Do you observe a different IF signal behavior with different temperature?   

    Best,

    Zigang

  • 0 in reply to zigang Yang
    Prodigy 20 points

    Hi Zigang

    The FFT waveform is shown below. At -4degC, the noise becomes large and affects the distance measurement.
    Not yet confirmed at temperatures other than -4degC.
    In addition, the leakage of TX-RX is large on the circuit. We construct the circuit using one antenna + rat race circuit, and the leakage of TX-RX is only about -20dB of the isolation of the rat race circuit.
    We believe that the cause of this phenomenon is a large leakage of TX-RX in terms of hardware, but we hope to take measures by controlling the software. I want to change software that does not control the amplitude of the IF signal during transmission and reception. If you know the part that controls to change the amplitude, please let me know. Thanking you in advance.

    Best,Regards

    Ushikubo

  • 0 in reply to TAKAYUKI USHIKUBO
    TI__Mastermind 32805 points

    Hi, Ushikubo:

    I have never seen a glitch like that.   Any other radar resource that can interfere? What system are you using for data capture, is it DCA1000?   

    Best,

    Zigang