• State TI Thinks Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 3 answers
  • Subscribers 31 subscribers
  • Views 503 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AWR2243: Configuration using TI supplied Cascade_Configuration_MIMO.lua script

Malcolm Barbour
Prodigy 30 points
Part Number: AWR2243

Hi,

We have an AWR2243 which we are using with the TI supplied example Cascade_Configuration_MIMO.lua script. 

The script uses 12 transmitters across the 4 devices to give us 192 virtual receivers. 

ramp_end_time is set to 40us and chirp_loops is set to 64.

Q1 - It looks like this script is setting up to use TDM (and not BPM), can anyone confirm this? 

Q2 - If this is the case would it be correct to assume that total frame capture time would be 40 x 64 x 12 = 30.72ms?

Q3 - Can this frame time be reduced by using BPM at all?

Many thanks!

  • 0
    TI__Mastermind 20605 points

    Hi Malcom,

    1. Yes. It strictly uses TDM without any BPM.

    2. I'm not sure what the values are here but a general formula to determine the frame time would be Total chirp time * Number of chirps where Total chirp time will be Active + Idle chirp time and number of chirps will be number of distinct TDM chirps times the chirp loops. Now there would also be an idle frame time component where there isn't any active transmit going on which you would have to add to account for the Total frame time.

    3. Can you explain what you mean by this? BPM phase sifts apply a 180 deg phase shift per chirp within the same chirp timing window. I'm not able see the direct correlation between this and frame time.

    Regards,

    Kaushik

  • 0 in reply to Kaushik Gowda
    Prodigy 30 points

    Kaushik, 

    Thanks so much for your reply.

    1. Great, that makes sense.

    2. I understand. My main question was centred around whether the chirps from the 12 individual transmitters across the 4 devices would be sequential, as opposed to simultaneous. Because this is using TDM the answer to this seems to be yes. So I believe what you are saying is that with 64 chirps being sent by each transmitter the total number of chirps would be multiplied by 12 (64 for each transmitter so 768 chirps in total) and therefore the total frame time would be total chirp time * 768 plus any inter-frame idle time. "number of distinct TDM chirps" in this case is 12 - representing the 12 transmitters. "chirp loops" is 64. Is that correct? 

    3. I was just wondering if the radar could be configured so that chirps from two transmitters at a time could be sent in the same timing window thus reducing the time to send all 768 chirps by a factor of two? 

    Thanks again!

  • 0 in reply to Malcolm Barbour
    TI__Guru 69960 points

    Hi Malcolm,

    I would suggest to refer ICD or mmWaveLink document to refer APIs which can configure the chirp configuration in the given frame and enable require set of TX  or even disable TX for individual AWR device (of cascade).

    With those APIs you can configure to select any no. of Tx (0,1,2,3 TX).

    .

    Now in cascade, all devices works together in terms of RF-front end and even for given frame.

    For e.g. 768 no. of chips in a frame. if you want to transmit from each AWR device in sequence that means 1st 192 chirp from 1st AWR, 2nd 192 from 2nd AWR chip and so on.

    so while 1st 192 chirps are transmitted from 1st AWR chip, all other devices for this 192 chirps TX should be selected to 0 (no TX and no transmit).

    rlSetChirpConfig () -> 
    rlChirpCfg_t -> txEnable
    Similar changes are wrt LUA with **chirp** API name, in the LUA Shell you can give 'help API_NAME' to get parameter details which will be similar as I mentioned above.
    .
    I hope further you can understand technically to implement at your end.
    .
    Regards,
    Jitendra
  • 0 in reply to Jitendra Gupta
    Prodigy 30 points

    Hi Jitendra,

    Thanks for your reply. 

    All I want to do is understand how the provided example Cascade_Configuration_MIMO.lua script sets up the chirp transmissions and how this then determines the total frame time.

    In the script there's a comment on line 91:

    --[[
    Function to configure the chirps specific to a device
    12 chirps are configured below, individually for each AWR device

    |-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|
    | | Dev 1 | Dev 1 | Dev 1 | Dev 2 | Dev 2 | Dev 2 | Dev 3 | Dev 3 | Dev 3 | Dev 4 | Dev 4 | Dev 4 |
    | Chirp | TX0 | TX1 | TX2 | TX 0 | TX1 | TX2 | TX0 | TX1 | TX2 | TX0 | TX1 | TX2 |
    |-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|
    | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
    | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 |
    | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
    | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 |
    | 4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 |
    | 5 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
    | 6 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
    | 7 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
    | 8 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
    | 9 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
    | 10 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
    | 11 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
    |-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|-------|
    --]]

    Is this determining the TDM transmission sequence? So that would be:

    (Dev4,TX2) then (Dev4,TX1) then (Dev4,TX0), then (Dev3,TX2) .... (Dev1,TX1) then finally (Dev1,TX0)

    And that would be repeated for each of the 64 chirps?

    So the total frame transmission time would be 64 * 12 * (total time for a single chirp) + inter frame delay. Is that correct?

    Thanks,

    Malcolm.

  • 0 in reply to Malcolm Barbour
    TI__Guru 69960 points

    Hi Malcolm,

    Your understanding is correct for the chirping scheme towards TDM where RF signal is transmitted by each device (per TX) sequentially for total no. of 12 chirps. Then this 12 chirp patterns are repeated by 64 times in the given frame.

    You can correct even with one frame total time calculation.

    .

    Regards,

    Jitendra

  • 0 in reply to Jitendra Gupta
    Prodigy 30 points

    Ah excellent, thanks Jitendra!

    I didn't understand what you meant by "You can correct even with one frame total time calculation", can you clarify please? 

    Going back to the chirp scheme - is it possible to modify this so that the radar uses BPM to send 6 pairs of concurrently broadcast chirps (still 12 in total but one chirp in each pair is phase shifted) and thus halve the total frame time? If so, how would I do this?

    Thanks again!

  • 0 in reply to Malcolm Barbour
    TI__Mastermind 20605 points

    Hi Malcom,

    I believe what Jiten meant was that the total chirping time and sequence can be determined by looking at a single frame alone. 

    Malcolm Barbour said:
    Going back to the chirp scheme - is it possible to modify this so that the radar uses BPM to send 6 pairs of concurrently broadcast chirps (still 12 in total but one chirp in each pair is phase shifted) and thus halve the total frame time? If so, how would I do this?

    Please refer to the BPM config in the mmWave ICD document for the AWR2243. You can look up for the same option in the Studio. 

    Alternate option is to configure the chirps with BPM using the phase shifter mechanism for which there is an example in the Cascade_Configuration_TXBF.lua file.

    Regards,

    Kaushik