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[TenTec] Slightly OT: SSB vs AM

To: <tentec@contesting.com>
Subject: [TenTec] Slightly OT: SSB vs AM
From: K3MIY@CSONLINE.NET (RON ZOND)
Date: Wed Apr 23 08:15:30 2003
Guys

What you ae discussing is called time compressd speech. It has been around
since the early fifties. There are tape recorders on the market (expensive)
which incorporate this feature.
There are also IC chips designed to do the same thing. If you compress the
speech by a factor of
five, you decrease the bandwith by a factor of five. When you slow the
speech down to normal,
you do not recover all of original information. i did research with this
thirty years ago.

Ron
K3MIY


-----Original Message-----
From: tentec-bounces@contesting.com
[mailto:tentec-bounces@contesting.com]On Behalf Of Mark Erbaugh
Sent: Tuesday, April 22, 2003 9:11 PM
To: tentec@contesting.com
Subject: Re: [TenTec] Slightly OT: SSB vs AM


Carl,

Yes, with that scheme we would change bandwidth for increased time. Kind of
like how we can send a picture in SSTV, but it takes many seconds.  However,
I was proposing first doubling the speed (but using some sort of magic to
keep the pitch constant) before slowing it down.  So a 5 second message
would first be sped up to 2.5 seconds, but holding the pitch constant. The
2.5 second message would then be played at half speed, getting back to the
original 5 seconds.

Mark

----- Original Message -----
From: "Carl Moreschi" <n4py@earthlink.net>
To: <tentec@contesting.com>
Sent: Tuesday, April 22, 2003 19:04 PM
Subject: Re: [TenTec] Slightly OT: SSB vs AM


> Assuming you recorded your voice message on a tape recorder and played it
> back at half the speed,  it would take twice the time to send the message.
> So we would be using half the bandwidth but twice the time.  So the bands
> would in effect be just as crowded.  You could get twice as many stations
on
> a particular band but everybody would need to talk twice as long.  You
would
> not gain anything and you definitly could not talk in "real" time.
>
> Carl Moreschi N4PY
> Franklinton, NC
> ----- Original Message -----
> From: "Mark Erbaugh" <mark@microenh.com>
> To: <tentec@contesting.com>
> Sent: Tuesday, April 22, 2003 8:45 PM
> Subject: Re: [TenTec] Slightly OT: SSB vs AM
>
>
> > How do the circuits they use on TV to keep the audio pitch the same when
> > they speed up the tape work? I know they do that so that can shorten the
> > program and squeeze in more commercials. I remember watching a show once
> and
> > after a commercial break, they didn't reengage the circuit and everybody
> was
> > Alvin the chipmunk.
> >
> > At any rate, suppose you played the audio twice as fast, but used a
> similar
> > circuit to restore the original pitch. Then you took that processed
audio
> > and played it at half speed, this time with no pitch correction.
Wouldn't
> > that compress each frequency to half it's original value?
> >
> >
> > 73,
> > Mark
> >
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>
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