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MMWCAS-RF-EVM: Bandwidth Chirp

Angel Blanco Granja
Prodigy 150 points
Part Number: MMWCAS-RF-EVM
Other Parts Discussed in Thread: AWR2243

Hi, 

When I detect something with the MIMO configuration lua file and the capture.lua, the calculus made in mmWave Studio 03.00.00.07 are 3GHz of Bandwidth. When I check the tab of "calculated parameters" in PostProc, it says that the start frequency is 77GHz and the stop Frequency is 77.5 GHz (0.5 GHZ of bandwidth per chirp, instead of the 3 GHz which were set) 

Could you please tell me why Matlab calculates 1/6 the bandwidth? Which one is correct, Matlab's or mmWave Studio calculation?

Best regards,

  • 0
    TI__Mastermind 31680 points

    Hello Angel,

    If you check for "AWR_PROFILE_CONF_SET_SB" API in mmWave ICD, the VC0 select field points to the configured bandwidth Region. The MIMO lua script by default configures the devices for only 2GHz Bandwidth by selecting VCO1. (Please refer to the profile API in the script and the ICD)

    In case you have AWR2243 MMWCAS cascade board, you have to choose VCO2 for a 5GHz bandwidth.

    Hope the information helps.

    Thanks,

    Ishita

  • 0 in reply to Ishita Kochar
    Prodigy 150 points

    Hi,

    Thanks for your reply

    I have changed the "VCO Select" in "SensorConfig" in the mmWave Studio API and the chirps still remain at 500 MHz. According to the other parameters, the API calculates the bandwidth should be 3GHz

  • 0 in reply to Angel Blanco Granja
    TI__Mastermind 31680 points

    Hello Angel,

    Let me check the Postproc calculations internally, and I will get back to you before the end of this week.

    Thanks,

    Ishita

  • 0 in reply to Angel Blanco Granja
    TI__Guru 69960 points

    Hello Angel,

    Could you help me with the profileconfig setting in the LUA script or mmwave Studio snapshot for profileConfig?

    At a high level, bandwidth is calculated based on freqSlope and RampEndTime in profile config. This means device will transmit till rampEndTime duration.

    But captured ADC sample may not cover this full bandwidth, it may be lesser than that and this depends on multiple parameters like startFreq, numOfSample, SamplingRate, adcStartTime, freqSlope

    e.g. NumOfSample 256, startFreq 76GHz, samplingRate 10Msps, adcStartTime 6usec, slope 30 Mhz/usec, rampEndTime 60usec

    Duration required to capture 512 samples= 25.6usec

    frequency difference during 25.6usec = 768MHz ;  so bandwitdth for ADC capture is 768MHz not full sweep during the rampEndTime. (slope*rampEntTime= 30*60 = 1.8GHz)

    Matlab shows only bandwidth during the adc capture time.

    Regards,

    Jitendra