I don't know if it makes any sense to look at it, but Audacity displays a V=
U
+ PPM meter for input and output signals. You might look at their (open
source) code to get an idea of the formulae they use. I have no idea how
good their ballistics are, but it might be a start.

~ Bob Ammerman
RAm Systems

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of
alan.b.pearce@stfc.ac.uk
Sent: Monday, August 11, 2014 7:49 AM
To: piclist@mit.edu
Subject: [PIC] RE: VU Meter

Added PIC tag ...

> I am interested in designing an LED VU meter based on a PIC for use in=20
> professional audio. I know there are several designs around on the net=20
> for consumer use BUT they all rectify the incoming signal before=20
> processing it in the PIC. This limits the ballistics that can be=20
> emulated and all of the examples I have come across so far have=20
> particularly poor ballistics. For professional use I would want to=20
> AtoD the audio and carry out all processing inside the PIC.
> Has this been done already or am I breaking new ground.
>=20
> Any help appreciated.

Are you looking at doing a VU meter or a PPM?

http://en.wikipedia.org/wiki/Peak_programme_meter

many of the LED VU meters seem to combine the two functions by having a
single bar showing the peak while the level dances around under it. The bar
showing the peak is then controlled in the manner of a PPM.


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