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Return to Talk:Neo Freerunner audio subsystem.

Retrieved from "http://www.openmoko.org/wiki/Talk:Neo_Freerunner_audio_subsystem"
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User:RuiSeabra said:

    • State: GSM <-> Built-in Handset (file gsmhandset.state)
      • Mic volume:

...

      • Control 63: 'Mic Sidetone Mux' MANDATORY VALUE "Mic 2"!!!
        • User:RuiSeabra's GTA02v5 with buzz fix has horrible static with this value, but using either "Left PGA" or "Right PGA" works very well.


That's very interesting, but - as elaborated to Rui in IRC - doesn't mean much as buzz isn't related to using PGA. Rather using PGA "detunes" the overall setup of mic path, by introducing several new parameters (PGA controls in digital domain of mixer), which Rui hasn't looked at, taken into account, or even finally listed all the relevant settings' values here. Furthermore there's nothing (except AGC, which is considered contraproductive for calypso's NR&AEC, and very unlikely Rui had a working setup for AGC by mere incident) you could implement by using a routing via PGA, rather than just adjusting #5 (#48, #12. In that precedence) to compensate for pathgain changes done by PGA.

Finally buzz is basically completely unrelated to PGA (if not any mixer volume settings) at all

2009-12-01 jOERG--Openmoko HW development and synergy