SEVENTY 9600 BAUD DATA CHANNELS ON 2M                    de WB4APR
-------------------------------------                    ---------


OVERVIEW:
---------
Here is how to stream more than 40 Megabytes per day per radio club
on 2 meters for all kinds of applications.  And there are over 70
channels on 2 meters available for this data already allocated.
Its all there, we just need to use it...

THink in terms of modern Internet type usage where users "request" data 
in small request packets and then the "web page" comes back with all you 
ever needed to know in response.  Thus the TO-USER channel has to be FAST
and BIG but the user XMT-channel can be trivial (even be 1200 baud)!

Here is how:
------------
The INPUT channel on every 2m repeater is rarely used.  In fact, in the
area of any repeater coverage, it is the ONLY "receiver" that is tuned
and listening to that frequency.  Every other user radio is listening 
only on the OUTPUT of the repeater.  THus, the only "receiver" in the 
whole county or state that is "listening" on that frequency is the repeater 
INPUT "receiver".

Now, then, the REPEATER, by listening on its input has full knowledge of
whether it has any users trying to access the repeater or not.  It is the
CZAR of authority on the use of that frequency.  If anyone keys
up on the input to the repeater, the repeater then brings up its transmitter 
and the system operates normally.  But that same INPUT receiver can also
tell completely if the channel is NOT BUSY.

When the input of the repeater is NOT busy, the REPEATER can decide to then
send out 1 second bursts of 9600 baud packet data ALL DAY LONG when the
repeater input channel is not busy.  Yet since it only sends the data in 
one second bursts, it can still hear any USER that wants to use the repeater
within one second of his keying his mic.  ANd since most repeaters have
ker-chunk filters on their control systems such that it takes at least one
full second of key down to bring up the repeater in the first place, the
mobile users already know to wait about 1 second before beginning to talk.

Thus, you have a system that can be used by the mobiles 100% just like they
do now.  BUT for the other 99% of the time when the repeater is NOT in use,
it can stream gigabytes of data to all HAMS in the county.

WHAT KIND OF DATA?
------------------
Answer, HAM RADIO WEB pages and Databases.  If your radio and PC are listening
all day long 24 hours a day, 7 days a week, then whenever you come home or
otherwise access your favorite HAM radio sites from your mobile, your PC will 
always have at least the most recent WEB page (no more than 24 hours old). 
For any one that you need an instant update, just ask.  Not only you, but 
everyone else will get the same instant update...

CONCLUSION:
-----------
We have the means to deliver almost 3 gigabytes a day to all HAMS in any area
on 2 meters.  Much Much more if we consider 220 and 440 repeater channels and
all at 9600 baud which any radio can do these days.

We have the bandwidth.  Even the most used yack-yack repeaters on 2 meters 
run well under say  10% usage (on a 24 hour basis).  And this technique
of data streaming FROM THE REPEATER on its own INPUT when it is not in use
can be applied to ANY repeater with no impact on users whatsoever.

DETAILS:
--------
The KEY to remember is that ONLY the repeater INPUT-RECEIVER is in the position
to make the decision as to whether the channel is in use and to react instantly
(within 1 second) to a user request for normal voice access.  No other receiver
at any other location can make this decision.  Thus the data to be "streamed"
must be "sourced" from that site.  But again, this is trivial to do via links,
telephone, modems or what have you.. and I dont need to detail that here...

This paper was written back in the 80's or 90's for the DCC proceedings but I 
have lost it.  SO I just retyped the essentials here.  Also look for a paper
by John Hanson on the WEB page FEEDING concepts...  I think he called it HAM-NET
or something like that...

de WB4APR, Bob