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AWRL6432: How to understand the value of compRangeBiasAndRxChanPhase

Shawn Li(Radar)
Intellectual 775 points
Part Number: AWRL6432

Tool/software:

Hi team,

I have one question on AWRL6432 about this command

Fullscreen
1
compRangeBiasAndRxChanPhase 0.0 1.00000 0.00000 -1.00000 0.00000 1.00000 0.00000 -1.00000 0.00000 1.00000 0.00000 -1.00000 0.00000
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
In the userguide, this command is descripted like below:
The virtual antenna pattern of TI EVM and antennaGeo is like below:
If we choose BPM waveform, then the phase should be:
virtual antenna 1-3 are same as virtual antenna 4-6 or
virtual antenna 1-3 are opposite as virtual antenna 4-6.
 
But it seems the phase compensation of virtual antenna of 1, 3, 5 is set to 1, and virtual antenna 2, 4, 6 is set to -1.
Can you help me understand this?
Regards,
Shawn
  • 0
    TI__Mastermind 38235 points

    Hi, Shawn:

    Where did you get the conclusion that 

    If we choose BPM waveform, then the phase should be:
    virtual antenna 1-3 are same as virtual antenna 4-6 or
    virtual antenna 1-3 are opposite as virtual antenna 4-6.
     
    Let us give an example between virtual antenna #1 (TX1-RX1) and visual antenna #4 (TX2-RX1).  With BPM mode, between these two virtual antennas, you always have 
    chirp0: (TX1-RX1) + (TX2-RX1)
    chirp1: (TX1-RX1) - (TX2-RX1)
    you will need to have BPM demodulation to demodulate virtual ant #1 and #4
    TX1-RX1 = (chirp0 + chirp1)/2;
    TX2-RX1 = (chirp0 - chirp1)/2;
    Since we know there is 180 degrees of phase offset between virtual ant #1 and #4, after BPM demodulation, we can now apply the phase compensation.  Let me know if you see any problem with this procedure.
    since 

    Best,

    Zigang

  • 0 in reply to zigang Yang
    TI__Intellectual 775 points

    Hi Zigang,

    I understand your procedure.

    The initial phase of 

    Chirp 0: TX1 0 deg, TX2 0 deg

    Chirp 1: TX1 0 deg, TX2 180 deg

    So,

    TX1-RX1(virtual 1), TX1-RX2(virtual 2), TX1-RX3(virtual 3) are all equal to (Chirp1+Chirp0)->2*TX1 (phase: 0deg).

    TX2-RX1(virtual 4), TX2-RX2(virtual 5), TX2-RX3(virtual 6) are all equal to (Chirp1-Chirp0)->2*TX2 (phase: 180deg).

    Consider the command's format, it should be 

    compRangeBiasAndRxChanPhase 0 1 0 1 0 1 0 -1 0 -1 0 -1 0

    Please help review the error in my understanding.

    Regards,

    Shawn

  • 0 in reply to Shawn Li(Radar)
    TI__Mastermind 38235 points

    HI, Shawn:

    There is 180 degree phase difference between TX1 and TX2.  

    There is also 180 degree phase difference between RX1 and RX2, and 180 degree phase difference between RX2 and RX3. So the phase between the three RX are [1 -1 1].

    So when you combine these two factors, the phase shifting among all the visual antenna becomes

     [[1 -1 1],  -1*[1 -1 1]] => [1 -1 1 -1 1 -1]

    Best,

    Zigang

  • 0 in reply to zigang Yang
    TI__Intellectual 775 points

    Hi Zigang,

    Understand. Thanks! And can you tell me the source of 180 degree phase difference in RX?

    Regards,

    Shawn

  • 0 in reply to zigang Yang
    TI__Intellectual 775 points

    Hi Zigang,

    Thanks for your reply.

    Regards,

    Shawn