any update on GSM interference issue

Andy Green andy at
Mon Aug 4 19:01:08 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:
|> Has anyone gotten a bluetooth headset (SCO type) to work with the 2007.2
|> distro for making calls?
| nope. i asked a while ago since i understood that there's a direct
| connection between bt and the gsm chip for this purpose (no need for
| and it's missing state-file), but never got a reply.
| bt audio seems the be rather orphaned -- the bluetoothsomething.state
| for alsa is missing completely and even questions regarding the state of
| bt audio at all were not answered.

You'll need something like the Alsa state file to configure internal
routing to make the connections.

|> If so, how did you do it, and did it fix this
|> interference issue?
| the buzzing is canceled when the fr's mic is set to 0 -- so my
| was by using a wireless headset to circumvent the issue (wired headset
| buzzes far louder than the fr itself). but see above ...

AFAIK in hardware this should be possible -- BT audio comes in on "VX"
digital interface of WM8753 and there should be a path to get in and out
of that to RXN/P pair and MONO1/2 pair.

It's actually an interesting test to do it... AFAIK nobody proved that
whatever makes the buzz (RF coupling or direct conduction from PSU rail
for example) does not infect Vref on the Codec, in which case more paths
than the mic might be infected as well because their reference is.  So
whether this is clean or not will be a clue.

- -Andy
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