Back as far as the 60s, there were multiplex rtty circuits that sent the
same info on several channels. When the receiver received the separate
streams it then voted on whether the bit was a mark or a space. Whichever
one won the vote, (more channels showing that status) the receiver came
out with that as the proper data bit. It made it possible to send messages
in the same speed as a single channel, but much more accuracy was obtained.
We could actually send two messages at a time on that system, since we used
double sideband transmissions, with the upper sideband carrying one set of
signals, and the lower sideband another set of signals. I believe lthe Navy
also used something like that for broadcasts to all ships in an area?
Early sattilite systems had Frequency division multiplex - each embassy was
assigned a separate modem and a separate frequency on the bird. Later on,
it became Time Division Multiplex, which then allowed one channel on the
bird, to handle a half dozen or more ground stations all at the same time,
and each faster than the older modems - at that.
Danny Douglas N7DC
ex WN5QMX ET2US WA5UKR ET3USA
SV0WPP VS6DD N7DC/YV5 G5CTB all
DX 2-6 years each
.
QSL LOTW-buro- direct
As courtesty I upload to eQSL but if you
use that - also pls upload to LOTW
or hard card.
moderator [EMAIL PROTECTED]
- Original Message -
From: David Michael Gaytko // WD4KPD [EMAIL PROTECTED]
To: DIGITALRADIO digitalradio@yahoogroups.com
Sent: Friday, December 01, 2006 8:07 PM
Subject: [digitalradio] how to make a good mode
a question
is it better to spread the componets of a data stream across a band
width of frequencies along with some type of redundancy, or have
several independent streams with same info in each with maybe some
type of time delay per stream ?
like maybe 5 or so psk streams of independent data set side by side.
david/wd4kpd
Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org
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