[LAU] Searching for audio interface with software-controlled mic gain

[Lorenzo Sutton]

On 04/09/2015 10:38, Thomas Janu wrote:
> Hi Lorenzo,
>
> On Fri, Sep 4, 2015 at 10:00 AM, Lorenzo Sutton
> <lorenzofsutton at gmail.com <mailto:lorenzofsutton at gmail.com>> wrote:

[..]
>
> No problem - it's still not solved on our side, as the two solutions so
> far were deemed too expensive for a test setup by my higher-ups.
>
>     On 25/08/2015 09:23, Thomas Janu wrote:
>     [...]
>
>         The whole setup will be mounted at a remote location inside a larger
>         machinery for audio surveillance of said machinery (fault detection
>         etc.). The larger machinery of course may not be running while
>         opened to
>         install our setup, thus setting the gain has to be done remotely.
>         The PC in this setup has an x86_64 CPU running Ubuntu 12.04 LTS,
>         but the
>         case is too small for PCI(e) solutions, doesn't have firewire,
>         so the
>         only option is USB.
>
>     Does the audio interface *have* to be inside the machine as well?
>     What I mean is Couldn't you just have the mics in the machine and
>     the audio interface outside (and accessible) so as to possible set
>     the gain, fine tune, turn on/off etc.?
>
> Sadly, it has to be inside. The bigger machine it's to be mounted in is
> itself stationary and outside, and not exactly at ground level. There's
> sadly no feasible way to have our stuff outside of the enclosure. If it
> were, the cables would be on the order of ~100m and the stuff outside
> the machinery would need to be secured against weather and - more
> importantly - humans that have nothing to do with it, as it would be
> publicly accessible.
>   As there is a climb involved, repeatedly turning the machine on,
> checking the levels, turning the machine off, climbing up, adjusting the
> levels, climbing down, turning the machine on, ... is also not feasible.

Well this clears a few points..

Interesting scenario... What is the importance of the microphones (and 
their quality) in the chain?
Which relates to another more general question.. what kind of audio 
analysis are you doing and what audio features are you measuring? e.g. 
are you monitoring very subtle differences in amplitude? spectrum etc.? 
Are you monitoring discreet audio events (e.g. a 'beep')...?

You do talk about a test scenario so I'm guessing budget constraints.

Probably you have already done all this analysis but it would be helpful 
to set the gear requirements (and I'm curious about it now :-)

Lorenzo.