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On 3/1/2011 5:55 PM, Wayne Sanderson wrote:
<blockquote
cite="mid:AANLkTik9Pe+MKkpi+e=K-GYBgSWZq34Z9LDU55-_xPWT@mail.gmail.com"
type="cite">
<pre wrap="">I regularly used a wireless PDA years ago that ran on a dedicated
packet data network. It used an interesting transmit/receive scheme.
The upload side of the device sent data up to the network at 4800, but
the downstream packets from the network came down at 19200. The idea
was that the end user in everyday use generally sent very little up
compared with receiving quite a bit down, which was how they got away
with the speed difference. It made sense too, considering that the end
user only sees the speed of the data he receives, and doesn't care
what speed the stuff he sends goes out, as long as it goes.
</pre>
</blockquote>
<br>
This is exactly how standard residential DSL Internet service works.
The service which is technically ADSL (Asymmetric Digital
Subscriber Line) normally has 3 to 5 times the speed on the downlink
side. Since the use normally only sends a few mouse clicks or
typed characters upstream to unleash a multi-megabyte flood down
stream it works very well ---- UNTIL you want to do FTP UPLOADS
of big files, or send (rather than receive) email with big
attachments. <br>
<br>
<br>
<blockquote
cite="mid:AANLkTik9Pe+MKkpi+e=K-GYBgSWZq34Z9LDU55-_xPWT@mail.gmail.com"
type="cite">
<pre wrap="">
I wonder whether a dedicated offset freq for digi access set to a
lower speed with network reception on the mobiles set at the higher
speed would ever be possible. I imagine one would either need 2 TNCs,
each set to a different speed, or a TNC set to 9600 or whatever speed
one wanted to run on the main channel and a straight one way transmit
only modem on the uplink channel set at a lower speed.
I wonder whether a skillfully written software modem might be able to
handle all speeds on the same channel and be able to send/receive them
all.
</pre>
</blockquote>
<br>
There are already at least two apps that can do more or less what
you want:<br>
<br>
<hr size="2" width="100%"><br>
The AGW Packet Engine soundcard softmodem can do this now. If you
have a soundcard with STEREO inputs, AGW can implement a separate
TNC on the left and right channels. They do not need to be running
at the same speed. By connecting the 300 baud side's input and
the 9600 baud side's output to the radio, you could do exactly what
you are proposing. <br>
<br>
Note that MIC inputs on computer sound systems are almost
universally single channel, while LINE level inputs are always
stereo. The only device I am aware of that provides stereo
low-level (i..e. mic level) inputs is the Griffen Electronics iMic
USB-connected external sound system. Review here on my web site:<br>
<br>
<a class="moz-txt-link-rfc2396E" href="http://wa8lmf.net/ham/imic.htm"><http://wa8lmf.net/ham/imic.htm></a><br>
<br>
_____________________________________________________________<br>
<br>
There is also already a ham "soundcard" app that autoselects
multiple baud rates and even modes on receive. G4HYG's APRS
Messenger HF APRS application can transmit on PSK63, PSK250,
QPSK63, QPSK125, QPSK250, GMSK125 and GMSK250 and automatically
receives ANY of these modes without switching! This application is
based on the mmVari dll that is the heart of mmSSTV and mmRTTY.
Details here:<br>
<br>
<a class="moz-txt-link-rfc2396E" href="http://wa8lmf.net/APRS_PSK63"><http://wa8lmf.net/APRS_PSK63></a><br>
<br>
<hr size="2" width="100%"><br>
--<br>
<br>
Stephen H. Smith wa8lmf (at) aol.com <br>
EchoLink Node: WA8LMF or 14400 [Think bottom of the 2M
band]<br>
Skype: WA8LMF<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.net">http://wa8lmf.net</a><br>
<br>
===== Vista & Win7 Install Issues for UI-View and Precision
Mapping =====<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/aprs/UIview_Notes.htm#VistaWin7">http://wa8lmf.net/aprs/UIview_Notes.htm#VistaWin7</a><br>
<br>
*** HF APRS over PSK63 ***<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/APRS_PSK63/index.htm">http://wa8lmf.net/APRS_PSK63/index.htm</a><br>
<br>
"APRS 101" Explanation of APRS Path Selection & Digipeating <br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/DigiPaths">http://wa8lmf.net/DigiPaths</a> <br>
<br>
<br>
<br>
<br>
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