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WL1833: Audio pops are heard during phone call

Will Liao
Intellectual 540 points

We are hearing random popping noise when in a phone call, and the pops increases if the RF interference increases in our test. We have tried the following suggestions from Griffs, Brad, eSCO does improve this issue but we think it is not good enough:

  1. In general, it seems like this issue is only observed on SCO connections.  Any device from the last 6 years should support eSCO.  Make sure you’re connecting with eSCO whenever possible.
  2. In case of SCO connection, remove any page_scan calls.

It looks like the pops is caused by the error packets, we would like to know if it is possible to conceal the pops while receiving error packets? The attached is the bts we used, please let me know if you need any information.

https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/538/TI_5F00_WL18xx.7z

  • 0
    TI__Mastermind 29291 points

    Will,

    Does this issue only occur with a specific headset? 

    The WL18xx does include PLC (packet loss concealment) for eSCO. However, it will not completely eliminate pops if the RF performance is very poor.

    Additionally, have you debugged the cause of the error packets? May be using the air sniffer (e.g. frontline)?

    Best regards,

    Vihang

  • 0 in reply to Vihang Parmar
    Intellectual 540 points

    Actually our test is to put the DUT under a heavy RF interfered environment, and to see if we hear pops during BT phone call. The environment setup is as below, and the bandwidth of two WiFi AP is both 40MHz, as the result that WiFi 2.4G covers all BT channels:

    The packet error rate is this case is very high, is this a case that PLS can not completely eliminate pops?

  • 0 in reply to Will Liao
    TI__Mastermind 29291 points

    Will,

    Will Liao said:
    The packet error rate is this case is very high, is this a case that PLS can not completely eliminate pops?

    Yes. The eSCO connection typically has re-transmission efforts negotiated between the two devices. If for some reason an eSCO frame cannot be received by the WL18xx, for example due to intermittent RF interference on some of the BT channels, the PLC algorithm will try to estimate the missing frame from other valid frames to reduce the pop noise on the final PCM output. However, if there is strong RF interference on all BT channels all the time, the PLC will not be much effective. As you mentioned, the packet error rate would be very high in this type of environment and PLC would not have enough valid eSCO packets to estimate the missing packets. In this case the pop noise are inevitable even though the PLC is working, since there are so many eSCO frames dropped.

  • 0 in reply to Vihang Parmar
    Intellectual 540 points

    Thank you for the explanation, we can understand it. We have no further question now, this thread can be closed.