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HCI_EXT_MODEMTESTRXCMD() in FCC testing

Jay Jones
Intellectual 330 points

Other Parts Discussed in Thread: CC2541

The FCC ETSI Test page provide suggested code for FCC certification testing of CC2541 applications.  Two main routines are presented, HCI_EXT_MODEMTESTRXCMD(x) (receive mode). and HCI_EXT_MODEMTESTTXCMD(x) (transmit mode).  The HCI_EXT_MODEMTESTTXCMD(x) generates a very distinct signal, easily measure against FCC limits.

However, HCI_EXT_MODEMTESTRXCMD(x) does not generate a signal so it is not clear how HCI_EXT_MODEMTESTRXCMD(x) is to be used in FCC testing.  In the HCI reference guide, this routine is apparently for use by the CC2541 to verify receiver functionality, but there is no indication how it is used in FCC EMI limit verification.

Perhaps HCI_EXT_MODEMTESTRXCMD(x) purpose in FCC verification is to ensure the device is not transmitting so that LO emissions can be measured and verified against the FCC limits.

In the context presented in the FCC ETSI Test page, how is HCI_EXT_MODEMTESTRXCMD(x) intended to be used for FCC verification?

Thanks.

Jay

  • 0
    TI__Guru** 105180 points
    Hello Jay,

    The RX test command doesn't generate any signal, this is only done with TX commands.

    Your test facility will know how to use these test commands as they will follow the relevant FCC test plan (15.209).

    Best wishes
  • 0 in reply to JXS
    Intellectual 330 points

    Thanks for replying and sorry to take so long to get back.

    Can you expand a bit on how the test facility will use/measure a device in HCI_EXT_MODEMTESTRXCMD()?

    They will be testing against Title 47 part 15.109 and they've informed me that the RX mode is for their measurement of LO harmonics for a class B digital device.

    I am curious as to how the HCI_EXT_MODEMTESTRXCMD() helps them, rather than have the device perform some other IDLE function.

  • 0 in reply to Jay Jones
    TI__Mastermind 18780 points
    Hi,
    CC2541 using the BLE PHY will be tested towards FCC 15.247 in the test house. In FCC part 15B.109 (a) you will see that there are specific requirements to the allowed field strength for RX spurious emission (normally referred to as the VCO leakage in this forum) and this must be tested holding the DUT in RX. You would not see this emission with the radio off like in idle.