From: einhorn_d@apsicc.aps.edu (E. Drew Einhorn)
Subject: Re: Data Service to Begin
Date: Sun, 30 Aug 92 17:53:00 GMT
Organization: Albuquerque Public Schools - Career Enrichment Center
News-Software: VAX/VMS VNEWS 1.41    

In article <mWcbe-W74@lopez.marquette.MI.US>, flash@lopez.marquette.MI.US (Gary Bourgois,Hamshack) writes...
>We are off to the races.
> 
>    SDTS -- SATELLITE DATA TEXT SERVICE
>    Direct Satellite to Home ASCII information
> 
>We are starting at 300 baud.
> 
>My long term goal is to provide FREE and complete USENET via satellite.  I
>have talked with a number of people about a 24 hour donated subcarrier for
>the purpose.  

>While the commercial guys have an admirable project, quite frankly
>the cost for their hardware and subscription is out of MY league.  When I
>asked about them allowing me to purchase my OWN KU system (instead of their
>$1800 one) using scrounged and donated equipment, they did not even answer
>me.
> 
>In any case, the 300 baud transmissions should at least be encouraging and
>show the desireability of a non profit approach to satellite delivered text.
> 

First of all I would like to offer my congratulations and encouragement.

I wonder if you have considered the volume of traffic involved in a complete
USENET feed.  It sheds light on the need to go far beyond 300 baud and
explains the constraints that result in the "high" prices required for any
viable commercial approach. 

Check out the regularly posted article in news.answers entitile "How to 
become a USENET site".  Currently the traffic is about 400 MByte/month.
It is rapidly growing.  Exponentially.

300 baud ~      30 char/sec
             1,800 char/min
           108,000 char/hr
         2,592,000 char/day
        18,144,000 char/week
        78,624,000 char/month

Hmm.  It's not quite as bad as I thought.  Only need a 5 to 1 speed increase
in speed to get to where we are struggling to keep our head above water in a
exponentially growing flood. 

This does not allow for any redundancy for error control and lost packets
The commercial guys can assume dedicated equipment and have it easier here.
They only have to worry about solar transit phenomena and heavy rainstorms
for Ku transmissions.  We have to allow redundancy that allows us to point
our dishes at other points of the sky.  Think we would have to merge in a
12-hour delayed feed or maybe even an 8 and a 16 hour delayed feed.  Hmm.
This puts us up to needing 10 or 15 times the transmission speed.  The
commerical guys are piggy backing their feed on another data stream and
talking about packaging other services with their USENET feed and need to
allocate resources for them.

We both need to plan for the exponential growth.

May not want to consider the legal problems that could result
from broadcasting some of the bigger bandwidth consumers:

  alt.sex.pictures.*

Probably the best long term solution will involve a pc-based server with
gigabytes of disk and an internet connection the uplink site.  

Most of the cheap garden variety high speed modems on the market today depend
on feed back from the receiving modem to know how to compensate for the
defects of the communications channel.  I don't know if they would
work in a satellite broadcasting application.  

Keep up the good good work. We all appreciate your efforts.