PDA form factor (was: Thoughts about iWalk)

Eugene Leitl Eugene.Leitl@lrz.uni-muenchen.de
Fri, 4 Jan 2002 19:21:27 +0100 (MET)


On Fri, 4 Jan 2002, Bill Kearney wrote:

> The single biggest reason all this hasn't been done before is battery
> life. Or lack thereof.  Followed up quickly by storage limitations and

All of these features, yes. A subset of these features, no.

> speed; both of which impact battery life.  Size is among the least of
> the hassles.

Neither weight nor size are a problem, unless you're running a power hog.
Caffeinoform gadgets are that.

> Reality check on GPS, it's not as accurate as you think.  Nor is it as

I don't think, I use GPS. It's plenty accurate for me.

> fast as you think.  Receiving GPS signals requires the ability to
> detect it's signals.  This requires line of sight access to at least
> 30 degrees of the sky.  Getting a 3D position requires even more.

Modern GPS units with hud-mounted active antenna are very adequate to the
task, and have sufficiently low power drain to not bloat your battery
overmuch. (Which actually should be a methanol fuel cell, apart from the
display another key technology missing).

> You go in a build, you don't get GPS, simple as that.  Yes,

I usually don't need GPS in buildings. I need GPS most in open,
featureless spaces.

> differential GPS does exist but requires ANOTHER receiver.  Thus we're
> back to battery life.  So unless you want to wait for your receiver to
> 'settle' then you have to leave it on AND have line-of-sight access to
> the sky.

Dunno, GPS works, and of course you can (and should) augment it with
inertial tracking. Which could be handy for a head tracker, too...

> Another factor to consider is health.  Any time you consider using
> something on a person you have to consider it's impact on their
> health.  People are still freaking about about high-tension lines and
> cell phones.  Personal area networks are certainly going to suffer
> from the same perceptions.  Want to get freaked out?  Put your cell
> phone near your monitor and then call it. Yeah, and you put it near
> your head, right?  No?  On a belt clip?  Hmmm, any reproductive risks?

I have no problem with a 5 W HF radiator residing in a fannypack with a
directional characteristic away from the body. On the head, no, unless
it's a Faraday hard hat.

> I'm not so keen on using a portable device in constantly networked
> environment.  The network is nowhere near as ubiquitous as that would

The network in the device cloud.

> require.  I'd just settle for one I could use casually everyday that
> didn't require being charged more than once a week.  Thus the success
> of the Palm devices.

-- Eugen* Leitl <a href="http://leitl.org">leitl</a>
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