From: Dave Emery <die@pig.die.com>
Date: Tue, 15 Sep 1998 22:40:19 +0800
To: "Brian B. Riley" <schear@lvcm.com>
Subject: Re: radio net
In-Reply-To: <199809152029.QAA03672@mx02.together.net>
Message-ID: <19980915234145.G26390@die.com>
MIME-Version: 1.0
Content-Type: text/plain



On Tue, Sep 15, 1998 at 04:29:06PM -0400, Brian B. Riley wrote:
> On 9/6/98 6:20 PM, Steve Schear (schear@lvcm.com)  passed this wisdom:
> 

> >It think it was Phil Karn (Qualcomm) who once mused that it would be rather
> >straightforward to masquarade a high process gain SS signal on a commercial
> >satellite transponder. To it's owners the SS signal would be almost
> >invisible, making itself known as only a very slight depression in the
> >transponder's gain. Effectively, this could offer an inexpensive covert
> >channel for tunneling packets and thwarting traffic analysis.
> >
> >After the Captain Midnight episode I discussed this possibility with a very
> >technically knowledgeable staffer at the FCC and was assured that discovery
> >of such signals were beyond (at that time) the ability of commercial and
> >national technical (e.g., Lacrosse) means.
> 
>  I would suppose the T-hunt aspects of a clandestine network would be 
> obviated by piggybacking it into a commercial satellite transponder 
> channels ... which brings to mind about how expensive one or two of those 
> channeles might be. I remeber in the early days of ham packet radio we 
> had several 'wormholes' where hams had obtained through their places of 
> employemnt temporary use of unused satellite channels where we were given 
> essentially RS232 access and we adapted the packet switches to an async 
> backchannel in place of another synch RF path. They did make for some 
> intersting network improvements. I guess it always comes down to how do 
> you fund such things.

	At one time I had some involvement with a company renting
satellite space, and the figure of around $1500 to $3000 a month for a
voice channel capable of being used on small VSAT sized dishes was
passed around.  It depends on how much bandwidth and power the channel
uses which in turn depends on how big the dishes are (G/T to be exact).
Bigger dishes mean weaker signals on the satellite and lower charges. I
could probably find out the formula used to price the service...

	I suspect that the cost of equipment and licensing and regulatory
compliance of various sorts might make it unpleasant for loosely knit
groups of private citizens - uplinks require competant installation
and maintainence to keep them from causing interference to other users
and various other problems such as RF radiation hazards under control.

	On the other hand, satellites are crawling with little signals
transmitting streams of data or voice or music to groups of receivers
scattered over wide geographic areas, so the econmics aren't prohibitive
for people who have some real need...

-- 
	Dave Emery N1PRE,  die@die.com  DIE Consulting, Weston, Mass. 
PGP fingerprint = 2047/4D7B08D1 DE 6E E1 CC 1F 1D 96 E2  5D 27 BD B0 24 88 C3 18