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We are currently in the process of FCC certification for a product that uses nRF52832. Our testing house said the the test has failed because of not qualifying the minimum bandwidth requirement.

Configuration is all 12 combinations of the following 3 x channels, 2 x modulations, and 2 x bit rates were tested to find the worst case. More substantial testing was to follow using this worst case but we did not pass.

The worst case was determined to be Nrf (¿proprietary?) modulation at 1 Mbit, using a modulated carrier.

1) Do I need Nrf modulation to inter-operate with mobile devices?

2) If I don't have to enable Nrf to operate with iOS, Android devices (for example), how do I disable it?

Configuration Params (all 12 combinations of modes and "channels"):

  • modulated tx carrier
  • static const uint8_t txpower = RADIO_TXPOWER_TXPOWER_Pos4dBm; // max power according to my interpretation
  • static const uint8_t channels[] = {2, 40, 80};
  • static const uint8_t modes[] = {
    • RADIO_MODE_MODE_Ble_1Mbit,
    • RADIO_MODE_MODE_Ble_2Mbit,
    • RADIO_MODE_MODE_Nrf_1Mbit,
    • RADIO_MODE_MODE_Nrf_2Mbit
  • };
  • Data payload is random bytes

Note that "channels" is a misnomer... these are frequency offsets to 2400 NOT channel numbers. this is a bug in the SDK.

6dB BW plots.pdf

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  • Hi 

    1) You only need to test the bit rates that you will actually use in the end product, so if you are planning to use BLE only then you can remove the Nrf bit rates from the test.

    2) What example are you using to test the part? 
    It is common to use the DTM examples for BLE testing, in which case the Nrf bit rates are unavailable. 

    Have you had the hardware layout reviewed by us earlier? 
    Assuming the layout is done correctly you should be able to pass the test on all bit rates. 

    Best regards
    Torbjørn

     

Reply
  • Hi 

    1) You only need to test the bit rates that you will actually use in the end product, so if you are planning to use BLE only then you can remove the Nrf bit rates from the test.

    2) What example are you using to test the part? 
    It is common to use the DTM examples for BLE testing, in which case the Nrf bit rates are unavailable. 

    Have you had the hardware layout reviewed by us earlier? 
    Assuming the layout is done correctly you should be able to pass the test on all bit rates. 

    Best regards
    Torbjørn

     

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