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PA2AGA > HDDIG 24.09.00 01:19l 219 Lines 7707 Bytes #999 (0) @ EU
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Date: Sat, 23 Sep 00 19:42:09 MET
Message-Id: <hd_2000_257A>
From: pa2aga@pe1mvx.ampr.org
To: hd_broadcast@pa2aga.ampr.org
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Ham-Digital Digest Wed, 20 Sep 2000 Volume 2000 : Issue 257
Today's Topics:
Digital Repeater (4 msgs)
FA: PC Computer for your radio's/modems!
FS: PK-96 TNC
PC Computer for your radio's/modems!
Site is now up and running!
Software for Packet (9 msgs)
So no APRS for Linux with SOUNDCARD? (6 msgs)
SOUNDCARD SAVES PACKET HAM RADIO? (3 msgs)
TCP/IP Address 2 (7 msgs)
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Loop-Detect: Ham-Digital:2000/257
----------------------------------------------------------------------
Date: Tue, 19 Sep 2000 06:43:49 -0500
From: "Steve Sampson \(K5OKC\)" <ssampson@nospam.radio-link.net>
Subject: Digital Repeater
"Charles Brain" says:
>
> You can run those AMBE chips at 1/2 their lowest datarate by
> throwing away every other frame on transmit and feeding each frame
> in twice on receive. The speech quality is not bad at 1200 bps, but
> at 600 bps it is awful.
Now that is interesting, and very novel!
------------------------------
Date: Tue, 19 Sep 2000 13:22:54 +0100
From: Charles Brain <chbrain@remove.me.dircon.co.uk>
Subject: Digital Repeater
"Steve Sampson (K5OKC)" wrote:
>
> "Charles Brain" says:
> >
> > You can run those AMBE chips at 1/2 their lowest datarate by
> > throwing away every other frame on transmit and feeding each frame
> > in twice on receive. The speech quality is not bad at 1200 bps, but
> > at 600 bps it is awful.
>
> Now that is interesting, and very novel!
A lot of the very lowrate rate vocoder do something similar, they interpolate
the Line Spectral Pairs (LSPs).
One scheme I saw sent the Pitch and magnitude on each frame but the LSPs on
every other frame and a quality bit to indicate whether the missing LSPs were
more similar to the ones before or the ones after the missing ones then used
interpolation to fill in.
Also because certain parameters in speech change in a fairly predictable way
it
is possible to use zero overhead error correction. For example the pitch
frequency
usually does not change more than about 10% per frame therefore if the
receiver
suddenly sees a rapid change in pitch it is likely due to a bit error.
There is a lot to speech coding and Vocoders that are used over the Internet
are
not normally ideal for highly errored radio channels.
Still it is fun writing ones own Vocoder, you certainly learn to have respect
for
people that do it for a living!
- Charles G4GUO
------------------------------
Date: Tue, 19 Sep 2000 07:55:56 -0500
From: "Steve Sampson \(K5OKC\)" <ssampson@nospam.radio-link.net>
Subject: Digital Repeater
> Still it is fun writing ones own Vocoder, you certainly learn to have
respect
for
> people that do it for a living!
>
> - Charles G4GUO
You are much advanced in your thinking. One of the papers you have to do
in signal processing, is a speech compression paper, but most people think in
terms of voice quality when doing their paper. I know the LPC stuff sounds
terrible, but you do get the message across. There is something to be said
about a Q5 signal in normal use, but when "it has to be there on time" and
Q2 will do, well then - slash and burn, interpolate, extrapolate... :-)
------------------------------
Date: Tue, 19 Sep 2000 14:14:43 GMT
From: nomail@rob.knoware.nl (Rob Janssen)
Subject: Digital Repeater
Steve Sampson \(K5OKC\) <ssampson@nospam.radio-link.net> wrote:
>"Charles Brain" says:
>>
>> You can run those AMBE chips at 1/2 their lowest datarate by
>> throwing away every other frame on transmit and feeding each frame
>> in twice on receive. The speech quality is not bad at 1200 bps, but
>> at 600 bps it is awful.
>Now that is interesting, and very novel!
Not really... you can do that with MP3 files as well. The MP3 player I am
using has options to control such omission and re-playing, and it can even
be used to do primitive pitch shifting.
Rob
--
+----------------------------------+--------------------------------------+
| Rob Janssen pe1chl@amsat.org | WWW: http://www.knoware.nl/users/rob |
| AMPRnet: rob@pe1chl.ampr.org | AX.25 BBS: PE1CHL@PI8WNO.#UTR.NLD.EU |
+----------------------------------+--------------------------------------+
------------------------------
Date: Tue, 19 Sep 2000 17:42:23 GMT
From: "Bill Crocker" <bcrocker@home.com>
Subject: FA: PC Computer for your radio's/modems!
For Auction on Ebay:
PC Computer System built in a high quality tower case with an Intel Pentium
OverDrive 200MMX CPU, Intel Advanced/EV Motherboard with built-in Sound
Blaster-16 Sound!, 64MB RAM, 3GB Western Digital Hard Drive, 3.5" Floppy
Disk Drive, 16X CD-ROM Drive, Parallel Printer Port, Two RS-232 Serial
Ports, Matrox Mystique, 64-bit, PCI 3D Accelerator Video Card, and 101-Key
Keyboard. (no monitor, no mouse) As you can see, this is a very clean
system, and everything works! Microsoft Windows 3.x/95/98 compatible! This
would also make an ideal LINUX system for your home network, firewall,
router, etc!
This system would be excellent for your computer programmable/controllable
radio equipment, as well as running all those data modem applications!
Just a little over one day left, and currently going at only $77.51, with no
reserve!
Thanks,
Bill Crocker
Warren, MI
------------------------------
Date: Tue, 19 Sep 2000 16:37:41 -0400
From: ZZZjim_cronin@juno.comZZZ
Subject: FS: PK-96 TNC
For sale: AEA PK-96 dual speed TNC.
Does 1200 and 9600 baud on the same radio.
$140 shipped to lower 48. For more info send email to
ZZZjim_cronin@juno.comZZZ (remove leading and trailing ZZZ).
Thanks and 73,
Jim
N2VNO
------------------------------
Date: Tue, 19 Sep 2000 17:45:58 GMT
From: "Bill Crocker" <bcrocker@home.com>
Subject: PC Computer for your radio's/modems!
I suppose a link would help...
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=441394272
"Bill Crocker" <bcrocker@home.com> wrote in message
news:3ANx5.467$hD4.94323@news1.rdc1.mi.home.com...
> For Auction on Ebay:
>
> PC Computer System built in a high quality tower case with an Intel
Pentium
> OverDrive 200MMX CPU, Intel Advanced/EV Motherboard with built-in Sound
> Blaster-16 Sound!, 64MB RAM, 3GB Western Digital Hard Drive, 3.5" Floppy
> Disk Drive, 16X CD-ROM Drive, Parallel Printer Port, Two RS-232 Serial
> Ports, Matrox Mystique, 64-bit, PCI 3D Accelerator Video Card, and 101-Key
> Keyboard. (no monitor, no mouse) As you can see, this is a very clean
> system, and everything works! Microsoft Windows 3.x/95/98 compatible! This
> would also make an ideal LINUX system for your home network, firewall,
> router, etc!
>
> This system would be excellent for your computer programmable/controllable
> radio equipment, as well as running all those data modem applications!
>
> Just a little over one day left, and currently going at only $77.51, with
To be continued in digest: hd_2000_257B
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