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EVM430-FR6043: Need help to increase the number of Samples (Sampling rate)

Prayjit Tribhuwan
Prodigy 50 points
Part Number: EVM430-FR6043

We are using EVM430-FR6043 with Ultrasonic sensor (500KHz) for Air flow metering.

The airflow for 3-4 seconds is passed to do the waveform analysis, 
The Observation is that the samples which we get are less in numbers for our analysis( around 70-80). 
We want to increase the samples up-to 250-300.

Sensor : https://www.alibaba.com/product-detail/Piezoelectric-Transducer-Sensor-JIAKANG-Underwater-Flow_60408560566.html?spm=a2700.galleryofferlist.p_offer.d_title.288822efqGOtGM&s=p

Pipe Arrangement :



1 ] USS configuration tool settings are as mentioned below :

2 ] ADC Capture :

3 ] Saved Waveform : (Please have look into attachment for more details)

waveforms_500_29_12_23_1.csv

We also took some inputs from USS sensor vendor to improve sample number as mentioned below still there is no increase in sample number.

We are struggling to improve sampling rate & get the more samples so request you to supports us asap because we have also designed our custom board but first we are trying to achieve everything on EVM.

  • 0
    TI__Mastermind 34115 points

    Hi,


    The UPS0 to UPS1 gap is the time between measurements. you can change it to get a faster measurement rate.

    However, for the less than 20ms for the UPS0 to UPS1 gap in gas meter application using TI USS library sounds impossible to me. According to this figure in the app note https://www.ti.com/lit/ug/tiduej6a/tiduej6a.pdf.



    The major time consumption contributors for one measurement are UPS/DNS gap(7.82ms), Data processing time(4.05ms) and two UPS/DNS Pulses/Capture(2*1.05ms). You can lower the UPS0 to DNS0 gap. However, you need to consider the transducer ringing issue, multiple reflection issue and etc.. It mostly depends on transducer and pipe design. We do not want when we measure the DNS signal it is going to be influenced by the former UPS signal. So, it can not go very low, let’ use 3ms for example. It is hard to save time from the UPS/DNS Pulse parts so keep it as 2*1ms. Then is the Data processing time. In this figure, we give it as 4.05ms. However, the Data processing time varies significantly between measurements. I am not sure how deep you get into the USS algorithms. To be simple, there are two modes in the algorithm, one is called search mode and the other one is tracking mode. The search mode will use all the ADC capture data for calculation. And the tracking mode will use part of data for calculation and save power. In this figure, we pick a quite good data processing time around 4ms which is coming from the tracking mode data processing. It does not mean we can get this for every measurements. So, a reasonable UPS0 to UPS1 gap for gas meter application would be 50ms.

    Best regards,

    Cash Hao

  • 0 in reply to Cash Hao11
    Prodigy 50 points

    Hello h,

    Thanks for your input,
    We tried the settings on USS tool ie UPS0 to UPS1 gap : 50ms .

    But we did not get the expected number of samples. and waveform is more distorted.
     Results:

    Saved Waveform:

    waveforms_20_02_24_01.csv

    Regards,

    Prayjit

  • 0 in reply to Prayjit Tribhuwan
    TI__Mastermind 34115 points

    Hi,

    Do you also change other parameters? Why the ADC capture data looks much different between those two posts? It also seems that there is some noise in the second ADC capture. Do you also change the test environment? 

    Best regards,

    Cash Hao

  • 0 in reply to Cash Hao11
    Prodigy 50 points

    Hello,
    We only updated the "UPS0 to UPS1 gap : 50ms" and all other configuration setting remains same.
    Yes we can see the difference in ADC Capture waveform, the test environment is not changed 

    Regards,

    Prayjit Tribhuwan

  • 0 in reply to Prayjit Tribhuwan
    TI__Mastermind 34115 points

    Hi,

    Sorry for the late response. I somehow miss this message. 

    It is really strange that changing the UPS0 to UPS1 gap usually would not influence the ADC capture signal. So, could you record a video when changing the UPS0 to UPS1 gap parameter, the ADC Capture is also changed at the same test environment? Thanks.

    Best regards,

    Cash Hao

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