FPGA Central

Hi.

I want to implement a VU meter for my dsp application. Does anyone know
if there is a VU meter standard out there that I should support.
Example implementations would also be great!!

I've read about a standard from Bell Labs written in the 30's, but all
I've read is that a 300ms rise and fall time seems to be common..

T- [25 Aug 2005 00:29:01 -0700]:
>I've read is that a 300ms rise and fall time seems to be common..

There's no need to limit yourself on the
response since you don't have any mass to
deal with. You WANT it to be as instant
as possible. The fall time -- that you
may want to trail off. I think the how
should be ob..., well, left as an exercise.
Here's a pick of a classic (needle) meter

http://iplay.40th.com/vga_shot.html

And if you want to see some bar-segment
types, here

http://iplay.40th.com/iplayc_big_picture.html


--
40th Floor - Software @ http://40th.com/
iPlay : the ultimate audio player for mobiles
parametric eq, xfeed, reverb; all on a mobile

"Tasslehoff" <[email protected]> writes:

> Hi.
>
> I want to implement a VU meter for my dsp application. Does anyone know
> if there is a VU meter standard out there that I should support.

There is of course a standard. It seems to be IEEE 152-1953.

* If you are going to implement a VU-meter, follow the standard for
VU-meters.

* If you are going to implement a PPM meter, follow the
standard for PPM meters (seems to be EBU 3205).

* If you are just going to implement some random level metering, go
ahead. But call it something else than a VU (or PPM) meter.

> Example implementations would also be great!!
>
> I've read about a standard from Bell Labs written in the 30's, but all
> I've read is that a 300ms rise and fall time seems to be common..

According to information on the web, the VU meter standards was 60
years old in 1999. And yes, 300ms rise and fall time seems to be part
of the specification.

Asbjørn
--
Asbjørn Sæbø, post.doc.
Centre for Quantifiable Quality of Service in Communication Systems
Norwegian University of Science and Technology
<URL: http://www.q2s.ntnu.no/ >

Asbjørn Sæbø <[email protected]> writes:

> "Tasslehoff" <[email protected]> writes:

> > I want to implement a VU meter for my dsp application. Does anyone know
> > if there is a VU meter standard out there that I should support.
>
> There is of course a standard. It seems to be IEEE 152-1953.
>
> [...]

After looking some more, it seems that you are looking for the
standard IEC 268-17 (IEC268-17:1990), with the title

Sound system equipment
Part 17: Methods for specifying and measuring the characteristics of
standard volume indicators

This standard seems to also be available as BS 6840-17:1991.

The standard for PPM meters seems to be IEC 268-10.

Asbjørn
--
Asbjørn Sæbø, post.doc.
Centre for Quantifiable Quality of Service in Communication Systems
Norwegian University of Science and Technology
<URL: http://www.q2s.ntnu.no/ >

On 25 Aug 2005 00:29:01 -0700, "Tasslehoff" <[email protected]>
wrote:

>I want to implement a VU meter for my dsp application. Does anyone know
>if there is a VU meter standard out there that I should support.
>
>I've read about a standard from Bell Labs written in the 30's, but all
>I've read is that a 300ms rise and fall time seems to be common..

In my notes I have, for a filter that emulates VU meter ballistics:
"2nd-order LPF set for 2.224 Hz, Q = 0.6053, provides 1% overshoot and
0-99% risetime of 0.3 seconds".

Greg Berchin

Tasslehoff wrote:
> Hi.
>
> I want to implement a VU meter for my dsp application. Does anyone know
> if there is a VU meter standard out there that I should support.
> Example implementations would also be great!!
>
> I've read about a standard from Bell Labs written in the 30's, but all
> I've read is that a 300ms rise and fall time seems to be common..

Here's what I said about audio level metering in 1999:
http://groups.google.com/group/comp....68566775413d1b
http://groups.google.com/group/comp....5763b10d24a7ca

Regards,
Allan

<[email protected]> wrote in message
news:[email protected] ps.com...
> Tasslehoff wrote:
> > Hi.
> >
> > I want to implement a VU meter for my dsp application. Does anyone know
> > if there is a VU meter standard out there that I should support.
> > Example implementations would also be great!!
> >
> > I've read about a standard from Bell Labs written in the 30's, but all
> > I've read is that a 300ms rise and fall time seems to be common..
>
> Here's what I said about audio level metering in 1999:
>
http://groups.google.com/group/comp....ba4e3742bc22/4
668566775413d1b
>
http://groups.google.com/group/comp....227eee917948/c
25763b10d24a7ca
>
> Regards,
> Allan
>

It seems to me that what you needis an rms meter (assuming that there is no
dc in teh signal).
You can get variance easily by

var(k)=beta*var(k-1)+(1-beta)*S(k)^2

where S(k) is the signal and var is the variance. beta is a forgetting
fact - make this about 0.9 - experiment with it a bit.There is a tradeoff
between tracking ability and smothness of estimate.

Once you have variance the take 10log(var) and thats it - dB Power.


Shytot