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CC3220MODA: FCC Radiated Spurious Emissions Failing by 0.5dB when averaged and tested with continuous mode as recommended. Channel 6 (2437MHz) spurious emission at 6498MHz.

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Replies: 5

Views: 64

Part Number: CC3220MODA

We changed to the continuous mode of operation as was described by Seong and we are marginally failing by 0.5dB when the spurious emission (6498MHz with UUT @ channel6) is averaged.  We have had the design reviewed both schematic and layout for the UUT and no issues were found.  Can a duty cycle correction factor be applied to help in passing FCC class B limits?

  • Hi Nathan,

    My apologies, but I've recently learned that the Packetized Transmission Mode was also used during certification testing to reduce the duty cycle to 30%. This was done to prevent the PA from overheating and affecting the RF performance.

    By changing the transmission mode to Packetized on Radio Tool, the Size and Delay parameters can be modified. For 11b, try changing the size to ~400 Bytes and the Delay to ~12mSec. For 11g, try ~1400 Bytes and ~6mSec. Further tuning of these values may be required. Use the zero span on a spectrum analyzer to see how the duty cycle changes.

    Hope this helps,

    Seong 

  • In reply to Seong Kim:

    Hi Seong,

    Thank you.  We have been reviewing the FCC Part15 C report for the CC3220 Module and on page 120 of the report it shows the Duty Cycle at 96.2%.  Do you have another FCC report that shows the 30% duty cycle settings you are recommending?

    Thanks,

    Nate

  • In reply to Nathan Marion:

    Nathan,

    No, we do not have this in the reports.

    BR,

    Seong

  • In reply to Seong Kim:

    Hi Seong,

    How do we make sure that we can document these settings for the Test Lab?

    Thanks,

    Nate

  • In reply to Nathan Marion:

    Nathan,

    Inform the test house of the desired RadioTool settings. When they are testing, have them screen shot the RadioTool settings they are using and the duty cycle they are observing along with the test results.

    BR,

    Seong

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