Audio Idle noise, with Bluetooth device.

[Boki]

Hi All,

There is a Bluetooth device, it with A2DP and HFP.

Put it in simple, A2DP is stereo audio, HFP is mono audio.

When the audio trace ( layout ) close to Bluetooth antenna, I can see
the idle noise sometimes goes high abruptly ( test on HFP, mono), but
the idle noise never goes high when using A2DP (stereo).

Whatever stereo or mono audio output pin are the same, they are:

L+, L-, R+,R-

For mono, both audio output the same wave.

but just can't understand, why mono audio sometimes will suffer
abruptly idle noise....


Could you please advice ?

Thank you very much!
Best regards,
Boki.