Message-ID: <436F608D.4020407@web.de>
From: Dirk Stockmann <dirk.stockmann@web.de>
MIME-Version: 1.0
To: bluez-users@lists.sourceforge.net
Subject: Re: [Bluez-users] Periodic noise on microphone with bt_sco (BTA-6030
 Dongle, Motorola H500 Headset)
References: <436F1C3B.5020002@web.de> <436F4D85.4030404@csr.com> <436F5602.1040105@web.de> <436F5B5C.7070506@csr.com>
In-Reply-To: <436F5B5C.7070506@csr.com>
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Sender: bluez-users-admin@lists.sourceforge.net
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Date: Mon, 07 Nov 2005 15:11:25 +0100

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Hi,

Steven Singer wrote:
> I agree with this diagnostic. If the headset doesn't generate noise
> when attached to another device then the noise is probably not being
> inserted at the headset end.

No noise with two different mobile phones, but with two different dongles.

> One way to confirm whether it's electrical is to record digital signal
> received from the dongle into a file, shut down the SCO link and then
> play the file to the PC's loudspeakers.

When I record "silence" from the microphone (as silent as possible) then
there is clearly the noise with about -40db power.
Is there a way to record the digital from the headset directly, before
it is processed in alsa? Similar to the way hcidump works, maybe?

> Are you sending a signal to the headset and, if so, are you hearing a
> buzz in the headset's speaker? I'm wondering if a buzz in that
> direction (coming from the sensitive microphone input on the PC) is
> being looped through the air (or through the plastic) from the
> headset's speaker to its microphone.

Sound sent to the headset from the PC (e.g. an audiobook) is without the
buzz. It is quite low quality (like on a phone) but clear.

Regards,
Dirk

- --
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