Here's my theory. Unfortunately I'm not able to duplicate this problem on my DE.
The digital to analog "output" side of the CODEC has two channels - since it's a Stereo CODEC. One side is used to send filtered and demodulated audio to the audio chain and then to the speaker. The other side is used to send IF signals to the transmitter strip. The software audio drivers that control the output side of the CODEC are manipulated by a parameter called the "Master" Volume level.
In receive the "Master" volume level is set by the radio's volume control. In transmit, the "Master" volume level is first set to 0 for 1 millisecond, then it is set to 95.
The audio buffers contain around 10 - 20 milliseconds of audio. If receiver audio is still being buffered and sent to the CODEC when the transmitter is engaged, that receiver audio will be sent to the speaker at a volume level of 95.
As part of the latest fixes incorporated into sbitx_sound.c, the size of the audio buffers was probably increased. So that burst of receiver noise at a volume level of 95 would be more noticeable. I can check to see if the buffer sizes can be minimized, which would reduce the length of time the receiver noise is heard. A better solution would be to somehow clear the receiver buffers, or to control the left and right side volume levels separately. Neither option may be possible, however.
Will try to have some test code to try in a couple days. Since my DE doesn't exhibit this issue, if one or two who are hearing this noise would be willing to be beta testers, please let me know.
73; Steve, N3SB
