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From: chris@hplvla.UUCP (chris)
Newsgroups: net.space
Subject: Re: Orphaned Response
Message-ID: <7100001@hplvle.UUCP>
Date: Tue, 16-Apr-85 12:44:00 EST
Article-I.D.: hplvle.7100001
Posted: Tue Apr 16 12:44:00 1985
Date-Received: Sun, 21-Apr-85 03:08:02 EST
References: <1353@mordor.UUCP>
Organization: HP Loveland Instrument Division
Lines: 29



I recently read about GPS accuracy (Microwave System News?) and its 
published claims are 100 meters or so accuracy, and varies depending 
on the receivers' view of the satellites (how many and what angles)
and whether or not the user has "pseudolites" or pseudo-satellites
nearby, such as near harbor entrances, etc. I believe that if the user
carried a time standard his accuracy would also be enhanced.

Present GPS receivers cost $15,000 or so, and are aparrently limited by
cost of signal processing LSI (SAW filters, etc). NOBODY has talked about
any $200 receivers of any accuracy within the forseeable future except
maybe in science fiction. The Hope is that the lower resolution receivers
cost will decrease to $1500 in the next 5 years so they may be economically
feasible for automobile options (with a CD ROM map and display on a CRT?).

If the lower resolution system gives me 100 meters in 3-space for $1500,
I might consider it useful for private ownership, but I'll wager the
10x accuracy increase would mean a 100x cost increase even if the military
chose to make that part of the system available, and few non-military 
users would have any need for this resolution, especially at that cost.

There are, of course, other navigation systems available with pretty good
accuracy, but not many systems serve the non-costal regions of the country.

					Happy Navigating
					(sounds like California talk)

					chris