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AWR1443: mmWave radar range resolution for high speed application

volkan karaca
Prodigy 60 points
Part Number: AWR1443
Other Parts Discussed in Thread: IWR1443, AWR1642

Hi,

  What is the maximum range resolution for high speed applications? For instance if the speed of vehicle is between 300m/s to 600m/s. Is it possible to detect the stationary object when we  exactly 15m away from the object?

Regards

  

  • 0
    TI__Guru*** 138329 points

    Hi,

    300m/s corresponds to 1080 km/h

    We do not have a configuration that supports such high speeds

    thank you

    Cesar

  • 0 in reply to Cesar
    Prodigy 60 points

    Hi Cesar,

      When I calculate like bellow it seems it is possible.

    1. AWR1443's IFmax=5MHz, ADC sampling=12.5MHz, Slope of transmitted chirp: 100MHz/us then Range_max = (0.9 x 12.5MHz x 3x108)/(2 x 100MHz/us) = 16.8m
    2. Minimum idle time is 2us for ramp bandwith <1GHz, minimum chirp_time: IF cutoff frequency is 175kHz to 5MHz. So min chirp time for 5MHz minimum chirp time is 1/5MHz=200ns, Tc = min_chirp_time+min_idle_time = 200ns+2us=2.2us, λ=c/f=3x108/76GHz= 0.004 then Max velocity = 0.0039 / (4*2.2us) = 448.56m/s => 1614.8kmph => 1.3Mach
    3. Bandwith = Chirp Time x Chirp Slope = 200ns x 100MHz/us = 20MHz then Range_resolution = 3x108/(2 x 20MHz) = 3.75m


    Above solution is enough for us. So could it be possible? Otherwise what is wrong with calculations?

    Regards

    Volkan

  • 0
    TI__Guru*** 138329 points
    Hi,
     
    Could you please check this configuration with mmWave Sensing Estimator.
     
    I tried it and it does not work
     
     
    Thank you
    Cesar
  • 0 in reply to Cesar
    Prodigy 60 points

    Hi Cesar,

      I attached result with my setting. When i set my settings mmWave Sensing Estimator does not give any error. But as you can see, some information only parameters are strange, for instance frequency slope constant is negative or bandwidth is negative, etc... So how should we comment this results? Is it just bug of this program. Actually program should give a error. Am I wright? or could we comment this result as a chip is insufficient. If so Which TI family do you recommend us?

      Note: By the way i changed json extension as jpeg. Because i coud not uplad it

    RegardsAWR1443.estimator.doc

  • 0 in reply to volkan karaca
    TI__Mastermind 24955 points

    Volkan,

    Have you attempted to program these chirp parameters in our RF evaluation tool, mmWaveStudio?

    I have attempted to program your profile and it failed. There are a few important pieces to keep in mind why this profile failed.

    Here is the profile that I attempted to use:

    Start Frequency 76 GHz
    Frequency Slope 100 MHz/us
    Idle Time 2 us
    ADC Samples 64
    ADC Sampling Rate 12.5 MHz
    Ramp End Time 200 ns

    This configuration results in the 20 MHz bandwidth that you were trying to use. The important piece is the number of ADC samples. The BSS firmware requires a minimum of 64 samples per chirp. The 200 ns ramp time is not enough to capture 64 ADC samples when running the ADC at 12.5 MHz. This means the ADC samples every 80 ns. This would only give 2 samples in the 200 ns timeframe, which is not even close to 64. This configuration is simply not supported by the firmware. You need to have a longer ramp time to capture an adequate number of samples.

    Please refer to the example chirp configurations that are included in the mmWave SDK as part of the Out-of-Box Demo.

    Regards,

    Kyle

  • 0 in reply to Kyle Cousino
    Prodigy 60 points

    Hi Kyle,

      I use mmWaveSensingEstimator and it does not give any error. But it calculates negative frequency slope. I think it is a problem as you check it with mmWaveStudio.

      So, I change the part as a IWR1443FQAGABL which has a 37.5Mbps sampling frequency. I recalculate the maximum velocity. I also recalculate the chirp time for 64 samples which is 2us+ (1/35.5Mbpsx64(samples)) = 2us + 1.706us = 3.7us So:

      maximum velocity = lambda/(4xTc) = 0.0039/(4x3.7) = 257m/s Am I wright?

      My second question is about the note in the swra553 document. In section 2.2.1 Maximum velocity, It is said that "The actual measurable max velocity can be extended beyond the unambiguous max velocity using higher level algorithm." What does it mean?

      Is it possible to decrease idle time 2us or better rise than 100MHz/us? or different algorithms (without 64 sample) to detect the distance for high speed applications  Datasheet says no. But the note given in swra553 fells me that it may be possible. Am I wright?

    Regards,   

    Volkan

  • 0 in reply to volkan karaca
    Prodigy 60 points

    Hi Kyle,

      By the way I have different questions unrelated to this topic. Should open different case for bellow questions?

    1. IWR1443 power consumption is 1.7W for 1 TX and 1 RX antenna. What about the power consumption for 1 TX and 1 RX case? I could not find any power estimator tool.
    2. I want to use I2C interface for debug, program and communication interface. During development state I want to debug and program the boot memory via I2C interace. When the design is completed. The board will communicate other boards via I2C interface. Also for in system programming and debug. I should also use I2C interface. Is it possible? We have a lack of pin. We should use only 1 interface for debug, program and communication.

    Regards

    Volkan  

  • 0 in reply to volkan karaca
    TI__Mastermind 24955 points

    Volkan,

    Under the known issues for the mmWave Sensing Estimator Tool, it states that:

    "Some input combinations can generate a negative chirp time. This is an invalid configuration."

    The IWR1443 supports a maximum sampling frequency of 37.5 MHz when setting the ADC to real only.

    In many of the example labs and experiments that are released on ti.com, the ADC is set to either complex1x or complex2x format.

    In a previous E2E post, the following information is provided regarding Complex1x ADC format:

    "In a complex-1x baseband implementation, it is not necessary to double the ADC output interface rate. In fact, it is possible to frequency-shift the spectrum, perform image-reject filtering and send out decimated I and Q ADC samples to the DSP at max possible beat frequency. 

    Thus, the interface rate of the ADC samples going to the DSP does not really increase due to the use of the complex baseband. The "real output" at twice the max supported beat frequency changes to a "complex 1x output" at just a max supported beat frequency. 

    The frequency shift to center the spectrum around DC helps simplify the implementation of image-reject filtering (Thus improving the noise figure without increasing the interface bandwidth). TI’s radar chip includes a built-in digital frequency shifter to frequency-shift the samples, perform image-reject filtering and send out the complex baseband output at the reduced interface rate (similar to a real-only implementation)."

    For information regarding the complex baseband architecture of the mmWave devices, please refer to this whitepaper: http://www.ti.com/lit/wp/spyy007/spyy007.pdf

    With regards to your proposed frame time of 3.7 us, I still think that it is not enough time to allow for any meaningful inter-chirp or inter-frame processing.

    It is not possible to decrease the 2 us idle or increase the slope past 100 MHz/us. This is not supported in the firmware. You can refer to the mmwave link doxygen for this information found here; C:/ti/mmwave_sdk_03_02_00_04/packages/ti/control/mmwavelink/docs/doxygen/html/structrl_profile_cfg__t.html

    Ramp slope frequency,
    For 77GHz devices (76GHz to 81GHz):
    1 LSB = (3.6e6 * 900) / 2^26 = 48.279 kHz/uS
    Valid range: -2072 to 2072 (Max 100MHz/uS)

    From this whitepaper: http://www.ti.com/lit/an/swra553/swra553.pdf

    "The minimum required idle time is determined predominantly by the synthesizer ramp down settling time, which is a function of ramp down bandwidth."

    For a chirp with a less than 1 GHz bandwidth, this is 2 us.

    For your reference, that maximum velocity on our AWR1642 device is approximately 25 m/s

  • 0 in reply to Kyle Cousino
    TI__Mastermind 24955 points

    Volkan,

    You can expect a similar power consumption rate for the AWR1443 1 TX and 1 RX case. Please keep in mind that there are several other factors that can affect power consumption.

    Please refer to "Table 5-3. Average Power Consumption at Power Terminals" of the AWR1443 datasheet found here: http://www.ti.com/lit/ds/symlink/awr1443.pdf

    The SPI/I2C interface is used primarily for PMIC control on the AWR1443. This is seen in the functional block diagram found here: http://www.ti.com/data-sheets/diagram.tsp?genericPartNumber=AWR1443&diagramId=SWRS202A

    UART and JTAG are the primary serial peripherals used for programming and debug.

    Regards,
    Kyle

  • 0 in reply to Kyle Cousino
    Prodigy 60 points

    Hi Kyle,

    1.   How did you calculate 25m/s?
    2.   How can we extend measurable maximum velocity beyond the the unambiguous max velocity like it is said in swra553?  (using higher level algorithm ???)
    3.   Does TI offers any different IC for high speed proximity application?

    Thanks,

    Regards

      

  • 0 in reply to volkan karaca
    TI__Mastermind 24955 points

    Volkan,

    This comes from our Short Range Radar Demo (SRR) that is included in our Automotive toolbox that you can find on TI's Resource Explorer.

    For more discussion on vmax extension, please refer to this previous E2E thread: https://e2e.ti.com/support/sensors/f/1023/p/595633/2189676

    Regards,
    Kyle