2 Replies Latest reply on Sep 9, 2020 3:38 AM by KeTa_1341526

    Transmission Duty cycle when using EZ-Serial F/W

    KeTa_1341526

      Hello,

       

      The FCC test is conducted using CYBT-333047-02 and an antenna different from the reference antenna (B4844-01 etc.) described in the data sheet.

      The FCC test has failed the harmonic emission test in BLE.

      According to the certification agency, it is possible to correct the transmission power by using the duty ratio of the transmission time in 100 ms in the actual firmware.

       

      So I have a question.

      The firmware to use actually uses EZ-Serial.

      When transmitting with BLE, Notify and Advertise packet can be considered.

       

      In addition, it is necessary to request the duty of the packet to be sent under the following conditions.

      ・Observe the transmission packet of one channel when Frequency Hopping is effective.

      ・Frequency hopping is performed at each Connection Interval, but CH1 appears alternately in hopping (worst case)

       CH1 => CH2 => CH1 => CH3 => CH1 => CH4…

      ・The Connection Interval and the number of transmitted packets differ depending on iOS/Android

       - iOS: Connection Interval = 30ms / Number of Packets in connection interval = 4 packets

       - Android: Connection Interval = 48.75ms / Number of Packets in connection interval = 6 packets

       - Android(Worst case): Connection Interval = 7.5ms / Number of Packets in connection interval = 6 packets

      ・Hopping as follows for each Advertisement Interval

       CH37 => CH38 => CH39 => CH37 ...

      ・EZ-Serial Advertisment Interval default setting is 30ms (0.625ms x48)

       gap_set_adv_parameters (SAP, ID=4/23): H=0x0030 (48)

       

      [Question]

      Under the above conditions, I calculated the Tx Duty Cycle as follows.

      Is there a mistake in recognition?

       

      1. Notify for iOS (Connection Interval = 30ms / Number of Packets in connection interval = 4 packets)

         - On time: 328us x 8 = 2,624us (2.624ms)

         - Off time: 100,000us - 2,624us = 97,386us (97.386ms)

         Tx Time Duty : 2.624 %

       

      2. Notify for Android (Connection Interval = 48.75ms / Number of Packets in connection interval = 6 packets)

         - On time: 328us x 11 + 110us = 3,718us (3.718ms)

         - Off time: 100,000us - 3,718us = 96,282us (96.282ms)

         Tx Time Duty : 3.718 %

       

      3. Notify for Android - Worst case (Connection Interval = 7.5ms / Number of Packets in connection interval = 6 packets)

         - On time: 328us x 42 = 13,776us (13.776ms)

         - Off time: 100,000us - 13,776us = 86,224us (86.224ms)

        Tx Time Duty : 13.776%

       

      4. Advertisement (Advertisement Interval = 30ms)

         - On time: 328us x 2 = 656us (0.656ms)

         - Off time: 100,000us - 656us = 99,344us (99.344ms)

         Tx Time Duty : 0.656 %

       

       

      Best regards,

      Takahashi