From: Akram H. <ak...@aq...> - 2012-02-01 02:19:54
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Howdy folks, Experiencing what I suspect is a heat related noise issue with some Overo Water and TOBI board combinations. Been recording audio using ALSA via the line-in on TOBI and what I’ve observed is that when my equipment starts to warm up (it’s outside in a plastic sealed box where the external ambient can rise to ~30C) I get some wandering noise between 12 and 16kHz. It’s a reasonably powerful tone and screws up what I’m doing with the audio somewhat. A related issue is also that of USB hard drive noise appearing to get injected in to my audio recordings. The drive is written to periodically via the EHCI USB port and the movement of the mechanical portions of the drive appears in my audio file as a form of blipping. This noise is always present when I have a USB hard drive in the equation, but is of less concern to me than the tone between 12 & 16kHz. I noticed this known issue notice: http://gumstix.org/hardware-design/product-changes-known-issues-a-eol/67-known-issues/132-improved-pki-2009-5-quality-of-audio-output-on-overo-series.html However, since these particular parts were ordered 28th Jan 2010 and 5thJan 2010 I would have thought that this improvement was already present in my gear. The Water board revision is R2516, and TOBI is R2549. When I record from the same TRS connector in to an Edirol recorder I do not observe the noise in my recordings (same environment and recording source), hence my assumption it is being injected before the audio ADC but after the TRS connector. Confoundingly, I have a set of Overo Water + TOBI that perform flawlessly in the same environment. Anyone experienced this at all before? The ability to capture and analyse audio is critical to my application; I need to either work around this issue or get rid of it entirely. Cheers, Akram |
From: Francesco M. <fra...@mo...> - 2012-02-01 08:53:40
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Hi Akram, I don't know how to help you, but to me this seems due to some inefficiencies on the audio routes on the Overo COMs, that sometimes became apparent (maybe due to a slightly different component values on the board, in your case). I have a similar problem, but caused but the OTG port... and I've not found any solution. I've you tried to use a different combinations of board and module ? Regards Francesco 2012/2/1 Akram Hameed <ak...@aq...> > Howdy folks, > > > > Experiencing what I suspect is a heat related noise issue with some Overo > Water and TOBI board combinations. Been recording audio using ALSA via the > line-in on TOBI and what I’ve observed is that when my equipment starts to > warm up (it’s outside in a plastic sealed box where the external ambient > can rise to ~30C) I get some wandering noise between 12 and 16kHz. It’s a > reasonably powerful tone and screws up what I’m doing with the audio > somewhat. > > > > A related issue is also that of USB hard drive noise appearing to get > injected in to my audio recordings. The drive is written to periodically > via the EHCI USB port and the movement of the mechanical portions of the > drive appears in my audio file as a form of blipping. This noise is always > present when I have a USB hard drive in the equation, but is of less > concern to me than the tone between 12 & 16kHz. > > > > I noticed this known issue notice: > http://gumstix.org/hardware-design/product-changes-known-issues-a-eol/67-known-issues/132-improved-pki-2009-5-quality-of-audio-output-on-overo-series.html > > > > However, since these particular parts were ordered 28th Jan 2010 and 5thJan 2010 I would have thought that this improvement was already present in > my gear. The Water board revision is R2516, and TOBI is R2549. > > > > When I record from the same TRS connector in to an Edirol recorder I do > not observe the noise in my recordings (same environment and recording > source), hence my assumption it is being injected before the audio ADC but > after the TRS connector. Confoundingly, I have a set of Overo Water + TOBI > that perform flawlessly in the same environment. > > > > Anyone experienced this at all before? The ability to capture and analyse > audio is critical to my application; I need to either work around this > issue or get rid of it entirely. > > > > Cheers, > > > > Akram > > > > > > > ------------------------------------------------------------------------------ > Keep Your Developer Skills Current with LearnDevNow! > The most comprehensive online learning library for Microsoft developers > is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, > Metro Style Apps, more. Free future releases when you subscribe now! > http://p.sf.net/sfu/learndevnow-d2d > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > -- Francesco Marletta Development Manager Mobile: +39.3317332107 Email: fra...@mo... |
From: bhamadicharef <bha...@ho...> - 2012-08-13 15:29:22
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What is your signal source ? Could this Be from your source For example Some digital synthesizer ? Usb HD are surely noisy ... What command do you use with ALSA ? i can try to replicate with Overo and One ToBi and one Chestnut too. Regards Brahim -- View this message in context: http://gumstix.8.n6.nabble.com/noise-in-audio-recording-using-Water-TOBI-tp4355116p4965104.html Sent from the Gumstix mailing list archive at Nabble.com. |