Audio ADC to Ethernet

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bclongwell
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Posted by bclongwell: Mon. Nov 21, 2011 - 09:13 PM
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I've started working with Ethernet applications and was wondering if anyone could give me some advice or point me in the right direction. I want to create a server that will monitor audio in a room that can be listened to remotely via Ethernet - live. I want to use an ADC input and take 8 bit samples at 8khz - just straight pcm. I'd like to just use a web browser at the other end to play the live audio. I have other functions but I already know how to do those.
I don't want to use a PC or other off the shelf solutions as may end up making these in some quantity.

Thanks - Brian

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Learning and Information, General Electronics
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jgmdesign
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Posted by jgmdesign: Mon. Nov 21, 2011 - 09:19 PM
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Wrong forum. GENERAL ELECTRONICS for this one

FWIW you will need something to control the process so a micro will be needed along with something to convert the data and send it over ethernet to the remote site
No easy task
Jim

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Bronze Markbobgardner
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Posted by bobgardner: Mon. Nov 21, 2011 - 10:08 PM
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An avr and a wiznet module could just send 1k udp datagrams every 8th of a second to the same ip address. On the pc, you just readfrom the ip address you want to listen to.

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leon_heller
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Posted by leon_heller: Mon. Nov 21, 2011 - 10:08 PM
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Simplest and cheapest solution would be an MCU with on-chip Ethernet. Several are available, and they generally have 10-bit ADCs; 8-bits isn't really adequate.

Leon Heller G1HSM

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Gold Markclawson
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Posted by clawson: Mon. Nov 21, 2011 - 10:19 PM
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Quote:

An avr and a wiznet module

Second that - I've just been doing audio (output not input) on a Wiz200Web from Wiznet - it's a complete Ethernet connected meag128 computer on a board.

Be warned that AVR ADC has a max sample rate of 15.3kHz though.

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Bronze Markbobgardner
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Posted by bobgardner: Tue. Nov 22, 2011 - 12:46 AM
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Cant you run it faster in 8 bit mode Cliff?

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Kartman
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Posted by Kartman: Tue. Nov 22, 2011 - 01:09 AM
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The spec called for pcm at 8 khz. Pcm is companded. Sounds like a voip module is the easiest solution. Something like a linksys spa3102

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bclongwell
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Posted by bclongwell: Tue. Nov 22, 2011 - 01:52 AM
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I'm using a Wiznet W5100 and an ATMEGA device. 8Khz sample rate will be fine with some external compression.
Thanks for the suggestions.

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Bronze Markbobgardner
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Posted by bobgardner: Tue. Nov 22, 2011 - 04:21 AM
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Pcm doesnt imply companded. Back in the soundblaster days when you were just a young whippersnapper, 8 bit unsigned was the main format. Raw samples. Crappy signal to noise ratrio I'll admit. I think you mean ulaw and alaw. That maps a 13 bit sample to an 8 bit wierd floating point format. Did I read your mind?

Hello Mr Longwell. I think you can read the a/d as 10 bit, then scan thru the buffer and see if either of the top two bits are on, and if so, shift right 1 or 2 bits.
Software gain reduction.

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bclongwell
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Posted by bclongwell: Tue. Nov 22, 2011 - 03:11 PM
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Bob - when I was a young whippersnapper, I was playing around with tubes. I'm retooling, so it just seems like I'm a youngster.
Thanks - B

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Bronze Markbobgardner
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Posted by bobgardner: Tue. Nov 22, 2011 - 04:34 PM
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I was razzin Kartman, who I reckon is younger than 60ish like me...

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Kartman
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Posted by Kartman: Wed. Nov 23, 2011 - 12:55 PM
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Bob, i'm a 60's boy and i was doing machine code before i had fur on my nuts. My first soundcard was putting the radio near the trs80 for sound fx. As for ulaw and alaw, yes, you read my mind. You da boss hog of AVR county!

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Bronze Markbobgardner
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Posted by bobgardner: Thu. Nov 24, 2011 - 12:37 AM
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The reason I like this forum is that it is like a novel... you hear the characters talking in their own voice in your head. I have developed a fondness for all the characters over the years. If I win the Florida Lottery, I'll quit work and take a walkabout in Oz.

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Bronze Markjs
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Posted by js: Thu. Nov 24, 2011 - 02:04 AM
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Quote:
you hear the characters talking in their own voice in your head.
I think you can get pills for that problem nowadays. :lol:

John Samperi

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www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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