From: roy@mchip00.med.nyu.edu (Roy Smith)
Newsgroups: rec.boats
Subject: Re: GPS fix quality (was: Celestial vs. GPS )
Date: 30 Dec 1992 21:54:01 GMT
Organization: New York University, School of Medicine
NNTP-Posting-Host: mchip00.med.nyu.edu

dudley@birch.cray.com writes:
> There was a diagnostic mode that you could bring up that displayed the
> quality [...] of the satellite signal [...] and the quality of the fix
> from that satellite [...]  Once I understood what it was trying to tell
> me, it was much easier to discern whether a fix was trustworthy or not, or
> even how bad it might be.

    While this is certainly good, it doesn't solve the problem I
originally complained about, which is that any dummy can (and many do) buy a
Loran, read enough of the manual to figure out how to plug it in and turn it
on, look at all those digits on the display, and think that he really does
know where he is to within a 1/10th of a mile, automatically, all the time,
without having to think.  If you have to go into some special diagnostic
mode to get the accuracy information, most people are never going to bother,
or even realize that it's there, or if they do, know what to do with the
information (in the story I told earlier, our "navigator" did indeed know
how to get the signal strengths, and would on occasion (when I started
casting doubts on his magic box) confidently show me that the signal
strengths were 47 microwhatzits per nautical steradian and go back to
whatever he was doing.

	This information needs to be thrown in their face every time they
turn the damn thing on.  Maybe by having the box automatically reduce the
number of digits displayed, maybe by having a little +/-NNN show up in the
side of the display.  To really understand the probable error in a reading,
you need more information than just a +/-NNN, but it's better than nothing.
Let's be realistic, telling somebody that there is a 67% probability that
they are within an ellipse of such-and-such ellipticity and orientation
centered on given point isn't particularly useful for most people.  Telling
them "you are here, plus or minus a half mile isn't quite as correct, but at
least it hits home the simple message that the position is only approximate.
What would be really cool (but I don't know if LCD displays are quite up to
this yet) would be to show your position graphically superimposed on a
chart, not as a dot, but as an ellipse of the proper size and shape, or even
better, a series of ellipses for 50%, 75%, 90%, 99%, etc confidence levels.
Or maybe, on a grey-level display, darker in the center, ramping down in
intensity as you get further away.

	Unfortunately, in the consumer electronics world (which is clearly
where most Lorans and GPSs fit these days), it's not real function, but
perceived function that sells boxes.  It would probably be marketing suicide
for a company to advertise that their Loran is better than the competition's
because it has the ability to show less accurate positions at times!  Here's
a wonderful quote from the Jan 1993 "Apple Direct (a newsletter Apple sends
to Macintosh software developers).  The article is titled "Understanding the
Competition" and it's about how to sell more of your product by better
understanding the competitors' products, and being able to look at your
product from the point of view of the consumer:

	In general, mainstream users don't care if the application's
	core engine is a technological wonder; they're not the early
	adopters, the enthusiasts who thrive on getting (and
	understanding) the latest and greatest technology.  Instead,
	mainstream users just want to be sure product will fill their
	needs with a minimum of disruption, frustration, and
	headaches."

	Paraphrasing the above, "nobody ever went broke under-estimating the
intelligence of the American public".  Or, if you prefer, "Don't give them
what they need, don't even give them what they want, give them what they
think they want".  People need to know where they are.  People want high
accuracy navigation, and they don't want to think.  People think they want
lots of digits telling them exactly where they are.  And there are lots of
electronics manufacturers perfectly willing to give it to them.
-- 
Roy Smith <roy@nyu.edu>
Hippocrates Project, Department of Microbiology, Coles 202
NYU School of Medicine, 550 First Avenue, New York, NY 10016
"This never happened to Bart Simpson."
Newsgroups: rec.boats