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IWR6843ISK-ODS: How 3 transmitters on IWR6843ISK-ODS work and how their data can be separated and saved by DCA1000EVM

Saeid Haghighatshoar
Prodigy 140 points
Part Number: IWR6843ISK-ODS
Other Parts Discussed in Thread: DCA1000EVM,

Dear TI support Team,

I am working with IWR6843ISK-ODS mmWave antenna module together with IC Boost and DCA1000EVM to obtain raw I/Q data, which I would like to process offline.

Since the antenna module has 3 TX and 4 RX antennas, in theory one may have 3*4=12 data streams corresponding to 12 TX-RX pairs. I would like to know how this is possible with this board and how data can be separated.

More specifically:

-- I would like to know how the signal is transmitted from 3 TX antennas. Are all TX antennas transmit the same FMCW signal, which I do not think so, since then the signal from different TX antennas cannot be separated at RX antennas. Or doTX antennas work in time division mode, where at each instant signal is transmitted through one of the TX antennas while the other two do not transmit any signal. Or is there any other transmission protocal between TX antennas which allows their signals to be separated.

-- How can these 12 data streams be extracted from the file generated by DCA1000EVM on my computer? Is there any specific code that I can run.

I would be grateful if you can forward me the related documents.

thanks a lot.

Best Wishes,

Saeid

  • 0
    TI__Mastermind 25825 points

    Saeid,

         In IWR6843ODS EVM TDM (Time division multiplexed) MIMO antenna configuration is used, Hence it is possible to separate all the 12 virtual antenna configuration.

    You could refer to below App-note for DCA1000 capture.

    Section 9.2 has specfic example of Matlab code for interpreting the ADC data. 

    https://www.ti.com/lit/an/swra581b/swra581b.pdf

    Thanks and regards,

    CHETHAN KUMAR Y.B.

  • 0 in reply to CHETHAN KUMAR Y.B.
    Prodigy 140 points

    Dear Chethan,

    thank you very much for your reply.

    This solved in fact half of my problem. The things is that by working in TDM mode, I am losing in terms of transmit power and it is better to use BPM (binary phase modulation), which is more efficient.

    -- For the moment, assuming that I am just using TDM mode, the received data at 4 RXs can be read using the Matlab file you mentioned. Now in the transmit side, I should make sure that the 3 TXs are transmitting periodically one at each time. So, that I can extract the data recordered at the RX side.

    (a) How can I do this from mmWave Studio?

    (b) How are TXs numbered, e.g., TX1 refers to which TX radar on IWR6843ISK-ODS board? Since the TXs are arranged in L-shape, how are they numbered?

    I am asking since this makes a difference in terms of the angular pattern and orientation of the targets.

    -- If I want to use the more efficient BPM mode, what should I do in mmWave Studio? Is there a simple Matlab file to extract data in this case?

    I would be grateful if you can forward me to a document that explains these things in detail. I read the document you mentioned but it simply gives naive explanations of MIMO radar, without mentioning the step-by-step procedure on how the data can be extracted. 

    Thank you very much and looking forward to your reply.

    Best Wishes,

    Saeid

  • 0 in reply to Saeid Haghighatshoar
    TI__Mastermind 36435 points

    HI, Saeid:

    Please find the answers inline.

    Regarding TDM mode, the received data at 4 RXs can be read using the Matlab file you mentioned. Now in the transmit side, I should make sure that the 3 TXs are transmitting periodically one at each time. So, that I can extract the data recordered at the RX side.

    (a) How can I do this from mmWave Studio?

    [ZY] In chirp configuration, you can select which TX to enable in the chirp configuration.   You can enable TX1 only in chirp0, enable TX2 only in chirp1, and TX3 in chirp2.  After you program this three chirps, in frame configuration, you can program startChirp to 0, and endChirp to 2 and then repeat this pattern for num_loop times.  The command sequence is like below:

    ar1.ChirpConfig(0, 0, 0, 0, 0, 0, 0, 1, 0, 0)
    ar1.ChirpConfig(1, 1, 0, 0, 0, 0, 0, 0, 1, 0)
    ar1.ChirpConfig(2, 2, 0, 0, 0, 0, 0, 0, 0, 1)
    ar1.frameConfig(0, 2, 8, 32, 40, 0, 0, 1)

    You can find the Doxygen documentation regarding each parameter at: file:///C:/ti/mmwave_sdk_03_04_00_03/packages/ti/control/mmwavelink/docs/doxygen/html/group___sensor.html

    (b) How are TXs numbered, e.g., TX1 refers to which TX radar on IWR6843ISK-ODS board? Since the TXs are arranged in L-shape, how are they numbered?

    [ZY] You can find the visual antenna pattern for ODS antenna module at industrial toolbox at http://dev.ti.com/tirex/explore/node?node=AEHINipfikce5tr4bK3rtg__VLyFKFf__LATEST, please pay attention to the small numbering in the figure like " TX1-RX3".

    -- If I want to use the more efficient BPM mode, what should I do in mmWave Studio? Is there a simple Matlab file to extract data in this case?

    [ZY] for BPM mode, please refer to the e2e thread 

    https://e2e.ti.com/support/sensors/f/1023/t/894562?tisearch=e2e-sitesearch&keymatch=BPM

    The data format for BPM mode is the same.  Only after you get ADC raw data, you will need to demodulate the signal further.  So far, there is no MATLAB FILE for demodulation.  But ADC data parsing should be similar. 

    Best,

    Zigang