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'[EE] Sound card oscilloscope, IR remote signals'
2007\03\26@130555 by Mark Hanchey

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I posted a few days ago about doing a project with a pic and ir remotes.
It was suggested that I use a sound card oscilloscope.
I hadn't tried this sort of thing before and not having a regular
oscilloscope I gave it try.
I was surprised at how well it worked.

Heres a link to the results.
http://www.modworks.net/ir.html

The sound card I have can sample at 192Khz, not bad for something I
already own.
It shows the different output to the two different remotes, the first
one I understand somewhat , the second
has me a bit perplexed as to how its sending the data as multiple
buttons on that remote send signals that show almost the exact
waveforms.

Still, thanks for the suggestion of using a sound card for oscilloscope,
its going to be a great tool for me now.

Mark Hanchey

2007\03\26@132104 by Carl Denk

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What was the link to the O...scope again, having second thoughts.

Thanking in advance. :)

Mark Hanchey wrote:
{Quote hidden}

2007\03\26@140058 by Mark Hanchey

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Carl Denk wrote:
> What was the link to the O...scope again, having second thoughts.
>
> Thanking in advance. :)
>
> Mark Hanchey wrote:
>  
>> I posted a few days ago about doing a project with a pic and ir remotes.
>> It was suggested that I use a sound card oscilloscope.
>> I hadn't tried this sort of thing before and not having a regular
>> oscilloscope I gave it try.
>> I was surprised at how well it worked.
>>
>> Heres a link to the results.
>> http://www.modworks.net/ir.html
>>  
>>    

The software I am using is http://www.virtins.com/page2.html#Oscilloscope



2007\03\26@141117 by Kevin Timmerman

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All the buttons should look very much alike. Convert your scope
capture to a binary string. There are two distinct time periods. The
second capture shown would be:

1000100000000111

Do this for the other buttons, and you will send they are all distinct.

Remember that a sound card is limited to ~20 kHz, no matter what it's
sampling rate. Good enough for a demodulated IR signal, but too
little bandwidth to see the carrier accurately.



At 01:05 PM 3/26/2007, you wrote:
{Quote hidden}

>

2007\03\26@174125 by Jesse Lackey
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Hi -

Kevin Timmerman wrote:
> Remember that a sound card is limited to ~20 kHz, no matter what it's
> sampling rate. Good enough for a demodulated IR signal, but too
> little bandwidth to see the carrier accurately.

humm not necessarily; it would depend on the input section on the sound
card.  A 192Khz A/D like the cirrus CS5361 (this would be considered
high end on a soundcard) has -3db at about 0.39 * Fs, or approx 75Khz.
That said, the soundcard is likely to have an RC lowpass at 40Khz or
lower.  One must check the docs.  Or send it test signals and measure!

A more serious concern is the unavoidable DC blocking cap.  No way
around that.

Looks good though!  Nice to see work being done to make gear everyone
already has be usable in a simple way.

J


2007\03\26@175248 by peter green

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part 1 928 bytes content-type:text/plain; (unknown type 8bit not decoded)


> > Remember that a sound card is limited to ~20 kHz, no matter what it's
> > sampling rate. Good enough for a demodulated IR signal, but too
> > little bandwidth to see the carrier accurately.
>
> humm not necessarily; it would depend on the input section on the sound
> card.  A 192Khz A/D like the cirrus CS5361 (this would be considered
> high end on a soundcard) has -3db at about 0.39 * Fs, or approx 75Khz.
> That said, the soundcard is likely to have an RC lowpass at 40Khz or
> lower.  One must check the docs.  Or send it test signals and measure!
>
> A more serious concern is the unavoidable DC blocking cap.  No way
> around that.
a blob of solder?
--
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 268.18.18/733 - Release Date: 25/03/2007 11:07




part 2 35 bytes content-type:text/plain; charset="us-ascii"
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2007\03\26@190756 by Jesse Lackey

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part 1 761 bytes content-type:text/plain; charset=windows-1250; format=flowed (decoded 7bit)

Hahaha nice try.  :)  In my limited experience with audio A/Ds (I only
know a few parts in the high end) all analog inputs need to be biased to
2.5V.  The standard way to do this is a DC block cap going to a resistor
divider with one end at the +5V the A/D uses for the analog section (or
a trickier variation of this theme).  Many have built-in (tho usually
defeatable) highpass filters as well.  I'm not sure if DC of any
significant amount (i.e. more than say 200mV) can go thru the A/D
without completely throwing it off.  None of them are designed to handle DC.

J

peter green wrote:
>> A more serious concern is the unavoidable DC blocking cap.  No way
>> around that.
> a blob of solder?
>


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2007\03\27@122758 by James Holland

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> ------------------------------
>
>  From: Mark Hanchey <spam_OUTmworksTakeThisOuTspammodworks.net>
> Subject: [EE] Sound card oscilloscope, IR remote signals
> To: "Microcontroller discussion list - Public." <.....piclistKILLspamspam@spam@mit.edu>
> Message-ID: <4607FD6F.2080602spamKILLspammodworks.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> I posted a few days ago about doing a project with a pic and ir remotes.
> It was suggested that I use a sound card oscilloscope.
> I hadn't tried this sort of thing before and not having a regular
> oscilloscope I gave it try.
> I was surprised at how well it worked.
>
> Heres a link to the results.
> http://www.modworks.net/ir.html
>
snip
>

I just went to Google and it gives me a malware warning for their site

James

2007\03\27@141907 by Mark Hanchey

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James Holland wrote:
{Quote hidden}

Yeah, I know.
I don't understand why google says its a malware site.
If you just type in the address the site comes up fine with no malware.

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