[talk-au] Overland Track added

John Henderson snowgum at gmx.com
Sun Feb 21 03:18:08 GMT 2010

Steve Bennett wrote:

> Dunno if I'd call PWS "the government". Personally, I'm glad. I
> wouldn't want to be passing 40 people a day with heavy packs on narrow
> boardwalks...not sure if that was the justification or not though.
> When everyone goes in one direction, it feels much less crowded, too.

I suppose it's more popular than when I first walked it - didn't see 
anyone for a couple of days.  A friend did a winter trip around that 
time and didn't encounter anyone else at all.

> Yeah, I switched on "automatic calibration", but I'm not sure what it
> does. Does it just take readings off the topo map (I'm using shonky
> maps)? If so, isn't that cheating...

What model GPS have you got?

I won't get if from the maps.

Mine's got a barometric altimeter, like an aeroplane does.  It measures 
air pressure very accurately.

The problem then is calibration for the atmospheric highs and lows which 
pass.  In a plane, you do that by entering the the current air pressure 
at your airport's altitude before you take off.  And you get the figure 
for that airport from the Weather Bureau.

The Garmin unit uses an rolling average of GPS-derived altitude to 
dynamically recalibrate.  You then get the best of both worlds.  The 
GPS-derived figure is accurate over a long time in the same position. 
The barometer is very accurate short term, but suffers in the long term 
unless recalibrated.

John H

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