[From nobody Sat Aug 16 21:13:44 2008
From: Joerg Reisenweber <joerg@openmoko.org>
To: support@lists.openmoko.org
Subject: Re: Buzzing sound
Date: Tue, 5 Aug 2008 19:49:51 +0800
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Cc: "Jeffrey Ratcliffe" <jeffrey.ratcliffe@gmail.com>
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Am Di  5. August 2008 schrieb Jeffrey Ratcliffe:
> 2008/8/5 Andy Green <andy@openmoko.com>:
> > Like Ole says when I started looking at it, by calling a landline in the
> > same room and listening to its receiver lying on the desk, it varied
> > tremendously and not in a repeatable way.  Eg, it appeared to vary by
> > orientation of the phone, but when I traced the path backwards, the buzz
> > did not return.
>=20
> OK. Confirming this - the buzzing seems to come and go in waves of
> varying frequency. Even without touching the phone, the buzzing just
> comes and goes.

I noticed the buzz come and go in discrete steps. I guess that's basestatio=
n=20
sending PCF commands to mobile, to level up/down the TX-power.
BS decides on this depending on signal-quality of MS as BS sees it.
It would be *very* helpful to confirm this, by using some RF-meter (e.g.=20
microwave leakage tester?), and/or reading the battery current, while=20
observing the noise come and go-

>=20
> > Also, I had to keep whistling during this to provoke transmission
> > actions that seem to be the start of the issue.
>=20
> You obviously need a signal generator for repeatability - unless you
> have perfect pitch...

Nah, that's just to give some data to GSM-chip it has to transmit. Otherwis=
e=20
it will enter dicontinuous transmission mode, means simply stopping to=20
transmit as there's nothing but silence we had to send to the other end.
So the actual pitch is irrelevant. Any kind of noise will do, as long as it=
's=20
loud enough.

cheers
jOERG

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