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'[OT] Active microphone filter'
2010\11\30@223004 by V G

picon face
Hey all,

I was wondering if anyone knew of active microphone filter software,
something that can actively filter out low frequencies?

I use my microphone with Skype and there seems to be a lot of low frequency
noise, far lower than any vocal frequency. I'd like to filter that out. It's
a USB microphone by the way


'[OT] Active microphone filter'
2010\12\01@075928 by Olin Lathrop
face picon face
part 1 209 bytes content-type:text/plain; charset="iso-8859-1" (decoded quoted-printable)

V G wrote:
> I was wondering if anyone knew of active microphone filter software,
> something that can actively filter out low frequencies?

See attached.


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part 3 181 bytes content-type:text/plain; name="ATT00001.txt"
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2010\12\01@085528 by Oli Glaser

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face
On 01/12/2010 13:00, Olin Lathrop wrote:
> V G wrote:
>> I was wondering if anyone knew of active microphone filter software,
>> something that can actively filter out low frequencies?
> See attached.

:-)
But he asked for something that "actively" filters... :-)
I agree though, try the simple stuff first. This will likely do the job fine whilst avoiding possible software latency issues...
If software is the only option though for whatever reason, then it shouldn't be hard to write a little app.. (or a dsPIC?)
In fact, surely Skype has some sort of plugin for this type of thing?




2010\12\01@090803 by Michael Rigby-Jones

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> -----Original Message-----
> From: spam_OUTpiclist-bouncesTakeThisOuTspammit.edu [.....piclist-bouncesKILLspamspam@spam@mit.edu] On
Behalf
{Quote hidden}

out.
> It's
> a USB microphone by the way.

http://skypefx.codeplex.com/ This does rather more than just a simple
high pass filter, but it's based on an open source audio library so you
should be able to modify it to suit your needs.

Mike

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2010\12\01@101541 by V G

picon face
On Wednesday, December 1, 2010, Olin Lathrop <olin_piclistspamKILLspamembedinc.com> wrote:
> See attached.


My mistake. Forgot to mention that the microphone is USB based. The
filter needs to be through software unless I can make an active filter
with a PIC32 with USB host

2010\12\01@103146 by Oli Glaser

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face
On 01/12/2010 15:15, V G wrote:
> On Wednesday, December 1, 2010, Olin Lathrop<.....olin_piclistKILLspamspam.....embedinc.com>  wrote:
>> See attached.
>
> My mistake. Forgot to mention that the microphone is USB based. The
> filter needs to be through software unless I can make an active filter
> with a PIC32 with USB host.

You did mention it actually, I didn't notice first time..
Have you checked for Skype plugins? (I would think it unlikely they don't have anything to deal with this kind of issue, but I may be wrong..)
 Also, Michaels suggestions looks like it might be workable..

2010\12\01@123828 by Olin Lathrop

face picon face
V G wrote:
> My mistake. Forgot to mention that the microphone is USB based. The
> filter needs to be through software unless I can make an active filter
> with a PIC32 with USB host.

Or you can hack into the analog signal inside the microphone unit.


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Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2010\12\01@124147 by Michael Watterson

face picon face
 On 01/12/2010 15:15, V G wrote:
> On Wednesday, December 1, 2010, Olin Lathrop<EraseMEolin_piclistspam_OUTspamTakeThisOuTembedinc.com>  wrote:
>> See attached.
>
> My mistake. Forgot to mention that the microphone is USB based. The
> filter needs to be through software unless I can make an active filter
> with a PIC32 with USB host.
no. the Microphone will be an electret.
There is an integrated USB sound card

2010\12\01@144730 by V G

picon face
On Wed, Dec 1, 2010 at 12:41 PM, Michael Watterson <mikespamspam_OUTradioway.org>wrote:

> no. the Microphone will be an electret.
> There is an integrated USB sound card.


That's what I mean. I might be able to use the PIC32 as a USB host and
process the signal and re-output the signal through a USB slave or a DAC

2010\12\01@151416 by Carlos Marcano

picon face
2010/12/1 V G <@spam@x.solarwind.xKILLspamspamgmail.com>:
> On Wed, Dec 1, 2010 at 12:41 PM, Michael Watterson <KILLspammikeKILLspamspamradioway.org>wrote:
>
>> no. the Microphone will be an electret.
>> There is an integrated USB sound card.
>
>
> That's what I mean. I might be able to use the PIC32 as a USB host and
> process the signal and re-output the signal through a USB slave or a DAC.

IMO, that's overkill. Easiest choices:

1) Software based - The site Mike wrote about
(<http://skypefx.codeplex.com/>) should do the trick.

2) Hardware based - Olin's suggestion is pretty much the simplest.

This thread reminded me of Steve Ciarcia's November Priority Interrupt column:

<http://www.circuitcellar.com/archives/priorityinterrupt/244.html>

It is worth the read.

Regards,

Carlos

2010\12\01@154511 by RussellMc

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part 1 5016 bytes content-type:text/plain; charset="iso-8859-1" (decoded quoted-printable)

>> I was wondering if anyone knew of active microphone filter software,
>> something that can actively filter out low frequencies?

> See attached.

This response is incredibly sloppy and incompetent. The op asked for a
software solution but a hardware one was provided. The diagram has no
information block and title. Date, originator, time of last coffee
break and number of sheets are not given, just to take a
representative sample of defects.

Components are shown but there is no indication of component values,
or types, or tolerances, or any guidance as to how appropriate values
may be able to be arrived at. For example the capacitor may be
required to be ceramic, or mylar, or polystyrene, or polyproplylene,
or poly-2-ol-di-methyl-ketoxy-parabutadiene. Or something else.  Is
the resistor wattage rating relevant - would an 0805 or smaller
package be acceptable or does it need to be wirewound, and if the
latter is heatsinking required and if so how many degrees per Watt. If
a wirewound resistor is required, are inductive effects relevant?

There are labels "In" and "Out" but nothing to show actual termination
points. Just because the labels are near the end of a line does not
mean that a constructor can be sure that connection is actually
intended. Such sloppy presentation and uncertain meaning makes the
diagram useless and indeed highly dangerous to users who think
correctly. It's not even obvious that the diagram will wrap correctly
at 80 characters. Having a hard line break after "OUT" would avoid
this issue and the amount of work require is small compared to the
gains liable to be made.

The items labelled R1 and C1 are recognisable as probably
corresponding to standard components but what is the funny filled in
triangle shape at the bottom? It doesn't correspond to a standard
connector and the symbol is non standard for any other purpose. It
only has a single connection, which doesn't make any sense. Is it a
monopole or an infinite sink (or source) or does it work by waving
dead fish at full moon? It may be meant to be an adjustable precision
zener, which would be equally stupid.

Most redeculous of all is the complete and utter lack of any circuit
description. How does it work? What is it supposed to do? Is it
dangerous if left lying around the house.

Some clue as to construction and layout, while not absolutely
essential, can be expected if you want to be seen as a competent
engineer. Is layout critical, are there any feedback paths induced
through spurious couplings if it is not built correctly, does it have
to be built with some or all components facing true North, or magnetic
North, or Lunar north. Are there any special conditions? A proper
engineer will think about this sort of aspect in advance and will not
waste the valuable time of 2,000 list members, and the 100,000 or so
who may view  it on Nabble at some stage, and the billion or more
people on the web who are liable to have access to it sooner or later.
You need to remember that data is now persistent and this circuit may
be around for 10 or 20 years, so you have to do justice to the people
whose time you may be wasting by doing it the way you have.
Engineering is a serious business and you cannot take your social and
moral responsibilities so lightly. You have a lot to learn if you want
to become a top flight engineer in this lifetime. You should also
spilling-chuck your posts before you send them. There is no indication
anywhere in your post, not in either word, that you have done so.
People should not need to wonder about misspillings when trying to
understand your circuits and what it is that you are feebly struggling
to say.

I'd complain about the pathetic commenting, bad indenting, lack of
clear and consistent variable naming and of general logical rigor if
there were any such to critique. If this had been a software solution,
as requested, it would have made this aspect of reviewing a lot
easier. You have to think ahead about the implications of making
changes such as this. To you the change from software to hardware may
have seemed trivial, but the consequent lack of comments and code to
critique can be very upsetting to a certain class of
readers/reviewers.

I could go on and on and on and on and on but I think everyone here
knows where everyone is coming from and that should be enough. I'm not
going to waste my valuable time picking further holes in your pathetic
attempt at a solution when I have real work to do. One last time, in
case you've forgotten or didn't pay attention - People proposing
solutions need to know that if they don't do so in a consistent and
meaningless manner then they are wasting the time of 2000+ highly
skilled professionals who have better things to do with their time
than trying to work out how the circuit is meant to work.

So a D for effort and a C- for execution. Do try harder next time.




               RM   JoAT, MoEE.


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part 3 181 bytes content-type:text/plain; name="ATT00001.txt"
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2010\12\01@163423 by Michael Watterson

face picon face
 On 01/12/2010 20:44, RussellMc wrote:
> I could go on and on and on and on and on but I think everyone here
> knows where everyone is coming from and that should be enough.
;-)

2010\12\01@174133 by Herbert Graf

picon face
On Wed, 2010-12-01 at 14:47 -0500, V G wrote:
> On Wed, Dec 1, 2010 at 12:41 PM, Michael Watterson <RemoveMEmikeTakeThisOuTspamradioway.org>wrote:
>
> > no. the Microphone will be an electret.
> > There is an integrated USB sound card.
>
>
> That's what I mean. I might be able to use the PIC32 as a USB host and
> process the signal and re-output the signal through a USB slave or a DAC.

Or you could, as has been suggested, open up the headset, and put a very
simple low pass filter in.

All that work for something that could be solved with a resistor and
cap? I just don't understand the motivation.

TTYL

2010\12\01@175358 by Olin Lathrop

face picon face
RussellMc wrote:
> This response is incredibly sloppy and incompetent.

OK, just for you I'll refund all the money you paid for it.

> The op asked for a
> software solution but a hardware one was provided.

Yes, this was intentional.  I was not (and still am not) convinced that the
OP fully understood what could be done in analog.  My main point was how
simple it would be, making it perhaps worthwhile to investigate whether
analog might not be workable after all.

> Components are shown but there is no indication of component values, or
> types, or tolerances, or any guidance as to how appropriate values may be
> able to be arrived at. For example the capacitor may be required to be
> ceramic, or mylar, or polystyrene, or polyproplylene, or
> poly-2-ol-di-methyl-ketoxy-parabutadiene. Or something else.  Is the
> resistor wattage rating relevant - would an 0805 or smaller package be
> acceptable or does it need to be wirewound, and if the latter is
> heatsinking required and if so how many degrees per Watt. If a wirewound
> resistor is required, are inductive effects relevant?

My dead fish is on vacation, so I had no way of arriving at component
values.

> Most redeculous of all is the complete and utter lack of any circuit
> description. How does it work? What is it supposed to do? Is it dangerous
> if left lying around the house.

I thought I'd elaborate on the small chance that the response to my post
wasn't a snippy comment, as this OP has a history of doing.  He has
demonstrated on a number of occasions that spending significant time up
front is a waste of time.

> I'm not going to waste my valuable time picking further holes in
> your pathetic attempt at a solution when I have real work to do.
> ...
>
> So a D for effort and a C- for execution.

Wow, after all that still a passing grade for execution!?  Surely this
proves the point about grade inflation and the sorry state of our education
system.

2010\12\01@183933 by V G

picon face
On Wed, Dec 1, 2010 at 5:41 PM, Herbert Graf <spamBeGonehkgrafspamBeGonespamgmail.com> wrote:

> Or you could, as has been suggested, open up the headset, and put a very
> simple low pass filter in.
>
> All that work for something that could be solved with a resistor and
> cap? I just don't understand the motivation.
>

It's an expensive USB recorder/microphone, I'd prefer not to open it up and
tinker inside. But yes, it's possible to probably take the analog signal
from the dynamic microphones inside

2010\12\01@183951 by Vitaliy

face
flavicon
face
Olin Lathrop wrote:
> RussellMc wrote:
>> I'm not going to waste my valuable time picking further holes in
>> your pathetic attempt at a solution when I have real work to do.
>> ...
>>
>> So a D for effort and a C- for execution.
>
> Wow, after all that still a passing grade for execution!?  Surely this
> proves the point about grade inflation and the sorry state of our
> education
> system.

Heh. Both of you get a B+ for humor (funny, but not hilarious).

2010\12\02@002504 by RussellMc

face picon face
> RussellMc wrote:
> > This response is incredibly sloppy and incompetent.

> OK, just for you I'll refund all the money you paid for it.

Hopefully the early on

> "The diagram has ... time of last coffee break ..."

and

>  " ... poly-2-ol-di-methyl-ketoxy-parabutadiene. Or something else.  ..."

managed to set the context for the rest of the response :-)

FWIW - it might, perhaps tidied up a little, almost be useful as a
tutorial on things that might be considered  in a "slightly more
complex"  real world case :-)


2010\12\02@100524 by Carlos Marcano

picon face
2010/12/1 Vitaliy <TakeThisOuTpiclistEraseMEspamspam_OUTmaksimov.org>:

>
> Heh. Both of you get a B+ for humor (funny, but not hilarious).
>

/Funnymodeon

Touché.

/Funnymodeoff

A thank you note and a petition to Russell, Olin, Vitaly and Bob:


Guys: In my own name, as I can't speak for this huge ecosystem called
the Piclist, I would like to thank you for all the contributions you
have made to the knowledge base of this place some call internet, www
or even, home. I haven't touched a PIC(tm) for developing a long time
ago but I keep reading lots of emails from the piclist as a daily
ritual because I find it a marvelous place where great minds get
together, great minds as you guys.

I have read the ping-pong threads that had surfaced in the last couple
of months and which have involved mostly you guys and while most of
the times even the rants had had very interesting points of view some
times things had gotten a little bit out of control and names had been
called and things had been said in anger, frustration or a mix mode of
them. Come on guys, You are better than that! We, The Lurkers (tm),
the silent witnesses of the
90%-of-the-time-best-brainstormings-on-the-web's-public-forums
politely ask you to rethink, redo and recover from these turbulent
past few 10% chit-chats (I have realized that even that I didn't want
to, I have taken the representation of a large part of fellows here
and I fell that I might regret this in the near future...).

What I find fascinating is that this semi-humorous thread (B+ as per
Vitaly's sharp grade) is I nice way of telling the world that in the
end, with all our divergences, our opposed points of view and our
different circumstances we are all human and there is not better
evener in our human nature than laugh. And to laugh on ourselves my
friends is an usually forgotten power.

"Death might have its day, humiliation hold both tormentor and
tormented in its cold stare, futility be the final tenant of every
house built on hope, but laughter, strong as water on a stone, would
always hollow out a place for the spirit to rest. To laugh was to
resist, to defy what couldn’t be denied and, more, to revel in that
bright-souled defiance — To bet once more on humanity, against all the
odds." **

** <http://www.stuffedfabulist.com/stories/laughter.html>

I am  sorry for disturbing a little bit more the S/N ratio.

Regards,

Carlos.

2010\12\02@102137 by RussellMc

face picon face
> > I am  sorry for disturbing a little bit more the S/N ratio.

That sort of S/N degradation we can easily tolerate :-).
Thanks for the input.


                Russell

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