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AWR1642: Why current AWR1642 sample can work well with ADC sampling rate as 10Msps which is invalid

Part Number: AWR1642

Hi,

As described in the AWR1642 SWRS203 RF specification, the maximum is 6.25Msps for complex, but my customer configure 10Msps, it can also work well, there is no problem reported, and the detectable range is correct. In my opinion invalid adc sampling rate would cause error range detection.

Would u pls help check the AWR1642 internal behavior with greater than 6.25Msps, why can it still work? Does the current sample support greater ADC sampling rate? 

 I have told my customer the valid value should be less than 6.25Msps, my customer want to know why can it still work with 10Msps, pls help confirm it asap, thank u very much.

BR,

Andy

  • Hi, Andy

               I have the same question, currently I could tune the sampling rate to 12Msps for complex without any error reported. But I don't know whether or not there are hidden risks.

  • Hello Andy, Jerry,
    It is not recommended to use the sampling rate higher than the specified values. In the future firmware we would be adding checks to avoid programming of a value beyond the allowed limit by mistake.

    regards,
    Vivek
  • Vivek,

    Got it but i cannot understand why can it still work if with 10Msps? What u said is to avoid the software program an value greater than 6.25Msps, but seems the hardware can support 10Msps in the current sample based on my customer's test. Is there any risk if the customer insist using 10Msps as they don't find any issue? Could u pls help confirm the hardware behavior if with an value greater than 6.25Msps?

    BR,
    Andy
  • Hello Andy,
    Incase of complex 2X mode you can go upto 12.5Mhz sampling since the IF would be restricted to 5Mhz but in complex 1x mode it would be only 6.25Mhz. Basically the IF is limited to 5Mhz .

    Regards,
    Vivek
  • Hi Vivek,

    I found in the xwr16xx capture demo there is below configuration, it configure complex 1x mode, ADC sampling frequency = 8000kps which is greater than 6.25Msps. Would u pls help double check why here in the demo it use an invalid sample rate for test, and the test still pass?

    //capture_demo_script.txt


    flushCfg
    dfeDataOutputMode 1
    channelCfg 2 1 0
    adcCfg 2 1
    adcbufCfg 0 0 1 1
    profileCfg 0 77 20 5 80 0 0 40 1 256 8000 0 0 30
    chirpCfg 0 0 0 0 0 0 0 1
    frameCfg 0 0 128 1 20 1 0
    lowPower 0 0
    sensorStart

    BR,
    Andy

  • Hello Andy,
    The device would be tested only for the limits specified in the datasheet and hence its recommended to use the device within the specified limits.
    We would be updating the capture demo to use the correct sampling frequency, that is a mistake.

    Regards,
    Vivek