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Re: Hello, Thank You, a short (?) introduction - parabolas

Subject: Re: Hello, Thank You, a short (?) introduction - parabolas
From: "Gregory O'Drobinak" gmo_dunes=
2
Date: Mon Feb 17, 2014 9:37 pm ((PST))

David:

What exactly is the thermal noise level of the air ( I would suppose it wou=
ld vary with temperature) and how is it measured and defined?

Then how can the air 'noise level' be specified relative to the standard fo=
r used for microphones?
Is it equivalent (nominally) to a mic with a self-noise level of 1 dB or -3=
.2 dB or what?

Thanks in advance for being precise and stating the references you used.

Greg O.


From: "" <>
To: 
Sent: Monday, February 17, 2014 8:54 PM
Subject: [Nature Recordists] Re: Hello, Thank You, a short (?) introduction=
 - parabolas



=C2=A0
> First of all, let us please get the name correct, our company is named Wi=
ldtronics, not Wildtronic.

Bruce,

Just to be mischievous, I could suggest that wildtronic is an adjective and=

Wildtronics the noun. :-)

> David, some of our samples were directly recorded with a DSLR camera and =
not an external recorder that had more controls.

Let me first emphasise that my criticism was carefully made of the
recordings, and not the product. So saying, I would like to hear the produc=
t
on a clean uncompressed recording.

If it intended to use the system with an uncontrolled video recording
device, then a simple passive attenuator should be used of at least -12dB.=


> We stand by our specifications. We quote that the 4dB noise is an equival=
ency. To match the signal to noise performance of our dish microphone syste=
m, you would need to place a 4dB microphone into a standard, 22 inch or so,=
 parabolic dish.

Sorry, what is a 4dB microphone? I have a technical background and there is=

only one proper definition of "excess noise". Forgetting that and
concentrating on the practical, the focussing of the parabola boosts the
coherent (single source) sounds much more than the thermal random noise of=

the air, effectively swamping that and the internal mic noise. Putting a
quotable figure to this effect is a very different matter.

When recording videos, note that distance will delay the sound audibly and =
I
will leave it to readers to calculate the distance per video frame period.=

Put down that calculator - do it in your head. :-)

David Brinicombe







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