Rene Harder wrote: > We keep the individual ECNs, in this way it's easier to have an overview > of the changes. > In the ECNs we shortly describe the reason/problem and refer to the ECN > with the name "global audio rework". > How does that sound?
Sounds great. > Maybe we should stay as it is right now or are there any problems with > the current configuration? As far as I know, there are no unresolved problems with the jack insertion detection logic. > I could not find a way to solve the biasing problem with a common ground > for headphone and microphone. So i guess we need to stay with the dc > blocking capacitors. So it seems :-( > These resistor will increase the resistance in the signal path and > improve this situation a little bit. Ah yes, that would make even more sense. > Do yo know how much it will decrease the channel separation 10, 20 or 60 dB? That's too deep in analog land for me to know, sorry :) > Do we have any data about that microphone, e.g. part number, vendor etc. It should be a Knowles SPM0208HE5: http://media.digikey.com/pdf/Data Sheets/Knowles Acoustics PDFs/SPM0208HE5 Rev B.pdf > I do not have a lot of information what the cause of this problem > was/is. I think it would be better to find and solve the source of the > problem. As far as I remember, the story went something like this: - JK4401 acts as an antenna receiving the GSM's RF we emit - the protection diodes of U4401 rectify the RF, thus acting as an AM demodulator - the demodulated AM creeps via R4408 into MICBIAS, overlaying the microphone signal - signal gets amplified, etc. I'm sure Joerg will set me straight if I missed any additional twist in this tale :-) - Werner _______________________________________________ hardware mailing list [email protected] http://lists.openmoko.org/mailman/listinfo/hardware
