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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.space
Subject: Re: Relative costs of Geostar and Navstar
Message-ID: <4185@utzoo.UUCP>
Date: Tue, 7-Aug-84 16:00:17 EDT
Article-I.D.: utzoo.4185
Posted: Tue Aug  7 16:00:17 1984
Date-Received: Tue, 7-Aug-84 16:00:17 EDT
References: <742@sri-arpa.UUCP>
Organization: U of Toronto Zoology
Lines: 47

> I don't understand why Geostar users will, at least in principle,
> pay so much less than Navstar users.  (Note that I am talking
> here about direct costs to the user, like hardware and user fees.
> I exclude indirect costs like the taxes that pay for the Navstar
> satellites.)  A Geostar transceiver
> consists of an antenna, a receiver, a processor, a display, and a
> transmitter.  A Navstar receiver consists of the same functional units,
> but without the transmitter section and its relatively expensive,
> high peak power components.  A Navstar receiver contains a
> much more complex processor, but this is just silicon, so once
> mass production starts, i.e., once the custom VLSI design is
> done, this should be negligible.  Geostar will charge a user fee,
> but DOD has announced that there will be no user fee for Navstar.
> A Navstar receiver will probably have a simpler antenna, since it
> will not need to handle transmitter power.  A Geostar transceiver
> will probably need an FCC radio station license.
> Present military Navstar prototype receivers are, of course, very
> expensive, but Aviation Week is already talking about pocket
> size receivers.  I expect the Japanese to produce a pocket size
> Navstar receiver for well under $1000 (1984 dollars).

As I said in a previous article, which may not have got to you yet,
the answer is simple.  A Geostar transceiver is basically just a
digital radio.  A Navstar receiver needs a complex receiver (it has
to decode time signals very accurately, something Geostar does in
the centralized part of the system), probably a very accurate clock,
and quite a bit of computing power.  This is not free, and not cheap,
despite the overblown claims of Navstar advocates.

The only reason DoD isn't going to charge a user fee for Navstar is
that they don't see any way to collect one, since the Navstar signals
are broadcast transmissions that anyone can pick up.  Geostar is in
a position to charge a fee, since getting your position from it needs
cooperation from the central computer.

A Geostar transceiver shouldn't need an FCC licence any more than a
cellular-mobile telephone needs one.  Both are radio transceivers,
but both get handled in different ways from normal transmitters.

Please note that one reason why Geostar is much more accurate than
Navstar is that the high-accuracy version of the Navstar signals can
be received only if you have the right decryption key, which will be
available only to the US military.  Civilian Navstar users get only
the low-accuracy version.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry