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AWR1642BOOST: Active Beam forming for 4 Tx of AWR1642 using Time Delay Block (Because phase shifter is not available on the current EVM board)

thuan doan
Prodigy 140 points
Part Number: AWR1642BOOST

Because there’re no phase shifter in the current EVM board, so I’m thinking about using the time delay to achieve beam forming. But what I wonder is that when I want to make the phase of signal impinging on 4 RX the same by adding some time delay, then these amount of time are so tiny as I calculated in the figure below (roughly 2.6485.10-11 which is equivalent to 10^-5 an ADC sampling time) so I just concern this value is too small to use fractional delay . Therefore I want to ask is it possible to achieve beam forming by this way, and could you me offer me some advice and source code if available. Thank you so much!

  • 0
    TI__Expert 4720 points

    Hi Thuan, 

    I am not sure if I  understand you correctly.

    The signal impinging on each of the 4 Rx is digitized and provided to the ADC buffer. You can change (introduce a phase shift, or a frequency shift) and modify this signal on a per Rx level. Is that what you want to do? 

    The 'phase shifters' are intended for Tx antennas when multiple Tx antennas are enabled simulataneously. They introduce a phase delay between the transmitted signal on each of the Tx antennas, and thereby steer the transmitted beam. 

    Regards.

    Anil

  • 0 in reply to Anil Mani
    Prodigy 140 points
    Yes, that's what i want to do with Rx.

    In addition, I also want to use the time delay block to function as phase shifter in Tx part. However as I mentioned before, in that high frequency (79 GHz), the fractional delay is too small which makes me doubt the feasibility of this method. So I want to consult you about this.

    Thanks
  • 0 in reply to thuan doan
    TI__Expert 4720 points

    Hi Thuan,

    Since you have the ADC data for each of the 4 Rx, you can change the phase (or introduce delay) in the DSP. There is no need to have a physical delay on the antenna.

    Regards
    Anil

  • 0 in reply to Anil Mani
    Prodigy 140 points

    Hello Anil,

    Yes, I agree with u that we can introduce some time delay to make the phase change. However, my point here is that time delay is too small compared with ADC sampling, is it still possible to do that way. Do u have any suggestion about that?

    Thanks

  • 0 in reply to Anil Mani
    Guru 16800 points

    Hello Anil-san,

    Is there any update for thuan-san's question?

    I'm interested in the topic, too.

    Best Regards,

    Nomo

  • 0 in reply to Nomo
    TI__Expert 4720 points

    Hi Nomo-san,  Thuan Doan,

    Apologies for the delay in response.

    In an FMCW radar system, fine delays can be simulated by introducing a frequency shift in ADC data. This is because an additional delay between the transmitter and the receiver will appear like a frequency shift of the original tone.

    Regards

  • 0 in reply to Anil Mani
    Guru 16800 points
    Hello Anil-san,

    Thank you for your reply.

    Best Regards,
    Nomo