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'[EE]: best method to add data stream to audio chan'
2001\02\06@103229 by Richard Sloan

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 I would like to inject data into a line level audio signal and recover it at the other end, of course you do not want to hear it and I am also limited by bandwidth of 20-20k, as this audio channel does get wirelessly transmitted. I may have some headroom and be able to put it at say 30K, what would be the best encoder/decoder pair?

Datarate required 19200bps

Richard.

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2001\02\06@112719 by Bob Ammerman

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Maybe take some kind of modem chip, which will output, typically a 3+KHz
bandwidth, then frequency shift the resulting signal up to 22-25KHz or so.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

{Original Message removed}

2001\02\06@124240 by Olin Lathrop

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>>
I would like to inject data into a line level audio signal and recover it at
the other end, of course you do not want to hear it and I am also limited by
bandwidth of 20-20k, as this audio channel does get wirelessly transmitted.
I may have some headroom and be able to put it at say 30K, what would be the
best encoder/decoder pair?

Datarate required 19200bps
<<

So, you are trying to tranmit a 19200bps digital stream over a 10KHz
channel.  This is theoretically possible if the 10KHz channel has sufficient
signal to noise ratio.  However, this will be quite tricky to do yourself
even if the signal to noise ratio is good enough.


*****************************************************************
Olin Lathrop, embedded systems consultant in Devens Massachusetts
(978) 772-3129, spam_OUTolinTakeThisOuTspamembedinc.com, http://www.embedinc.com

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2001\02\06@130914 by Richard Sloan

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Never thought of that!  Hmmmm....

So a modem type setup is probably required as it about the only way to get this kind of bitrate over a limited bandwidth similar to telephone systems. (33.6kbps over 4K bandwidth)

R.


>>  >>
 >>  I would like to inject data into a line level audio signal and recover it
 >>   at
 >>  the other end, of course you do not want to hear it and I am also limited
 >>   by
 >>  bandwidth of 20-20k, as this audio channel does get wirelessly
 >>   transmitted.
 >>  I may have some headroom and be able to put it at say 30K, what would be
 >>   the
 >>  best encoder/decoder pair?

 >>  Datarate required 19200bps
 >>  <<

 >>  So, you are trying to tranmit a 19200bps digital stream over a 10KHz
 >>  channel.  This is theoretically possible if the 10KHz channel has
 >>   sufficient
 >>  signal to noise ratio.  However, this will be quite tricky to do yourself
 >>  even if the signal to noise ratio is good enough.


 >>  *****************************************************************
 >>  Olin Lathrop, embedded systems consultant in Devens Massachusetts
 >>  (978) 772-3129, .....olinKILLspamspam@spam@embedinc.com, http://www.embedinc.com

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2001\02\06@131324 by Dan Michaels

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Richard, the first half of your requirement, to inject a
19200 datastream onto a bandlimited 20khz channel and also
"not" hear it does not sound very straightforward. As Bob
indicated, you may be able to get by by extending the
channel BW, and shifting the datastream up above the human
hearing range.

Also, you might do a search on modems and other devices that
combine voice and data onto one channel.

I am not sure, but believe some of these devices use a form
of time-multiplexing where data and voice are alternated in
time over the same bandwidth channel. However, to do this for
your particular requirements, you may have to employ data
compresison techniques with either/both the voice/data.

- danM
=====================



At 11:20 AM 2/6/01 -0500, you wrote:
>Maybe take some kind of modem chip, which will output, typically a 3+KHz
>bandwidth, then frequency shift the resulting signal up to 22-25KHz or so.
>
>Bob Ammerman
>RAm Systems
>(contract development of high performance, high function, low-level
>software)
>
>{Original Message removed}

2001\02\06@161751 by Bob Ammerman

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Modems transmit 56K- signals on a 3KHz+ channel

Shouldn't be impossible to transmit 19K on 10KHz

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

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2001\02\06@171406 by Richard Sloan

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Not impossible just not simply!

 >>  Modems transmit 56K- signals on a 3KHz+ channel

 >>  Shouldn't be impossible to transmit 19K on 10KHz

 >>  Bob Ammerman
 >>  RAm Systems
 >>  (contract development of high performance, high function, low-level
 >>  software)

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2001\02\07@021650 by Simon-Thijs=20de=20Feber?=

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Hi,


Ever heard of the Frauenhofer institute ???

They doe research for MPEG and etc.
At the AES in Paris 1 year ago i saw them do this.
Their purpose was to watermark a disk content (copy
protection and etc ).

They did it at a very low bit rate. (I would say ; one
byte a second). The system makes use of the hearing
imperfections (as with mp3) to put it in !


grtz,


Simon



--- Richard Sloan <rsloanspamKILLspamMP3KIT.COM> wrote: >
{Quote hidden}

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