> I am going to purchase a new toy, a GPS, as if I don't already lug a lot
> of stuff around when I go birdwatching or seeking orchids !! However for
> the particularly important records, pinpoint accuracy of location is
vital.
> I'd appreciate input as to what to look out for and/or specific
> recommendations. I'm one of those people that prefer to spend more to
> get better quality if necessary, rather than getting something cheaper
> but not so reliable.
I'd recommend one of the Garmin GPS units. They are the best supported
in terms of software have a good reputation, good performance and a wide
range of models and accessories. Their website is http://www.garmin.com
(There is a lot of freeware and shareware GPS programs available on
the Internet, so try them before paying for a commercial product.)
> So my keys, judging by previous emails on this subject, are:
> 1. Power/guts/reliability to work in remote places
Look for a waterproof unit, but treat it as water resistant. If it
gets wet, the electronics should be fine, but be sure to check and
clean the battery compartment and external connections (antenna,
power/data socket etc.) As always, prevention is better than cure!
As far as ruggedness goes, they are probably as tough as a mobile
phone; they'll probably survive being dropped or banged, but try
not to. (Unlike mobile phones, handheld GPS units usually have
a lanyard or wrist strap; a case that you can attach to a belt
is a worthwhile investment.)
An external (amplified) antenna option may be useful if you are
working in difficult situations (i.e. dense foliage cover or other
areas where there are a lot of obstacles that block "visibility"
of the satellites.) In my experience, the internal/supplied antennas
are fine for most situations; remember that amplified antennas draw
power and reduce battery life. The "Mighty Mouse" antenna is often
recommended for use with battery power, as it gives good performance
with only a small current drain. An external antenna is also useful
for use in a vehicle, in which case current drain is less important
since you will most likely also use the car's power for the GPS.
> 2. Speed of "locking into" a place and working out the co-ordinates
The key performance features to look for are a parallel channel
receiver. 12 channel receivers are commonplace now; I haven't seen
more than 12 channels (there are rarely, if ever, more than 12
satellites visible from any one place), and I wouldn't accept
less than this. A parallel receiver dedicates each channel to a
particular satellite rather than switching between satellites as
early models did; this gives faster "lock on" times, and better
resistance to signal drop-outs.
Giving the unit a regular "warm up" for about 10 minutes (locked on)
will also give much faster start up times; once the unit has been
on for around this long, you can turn it off and on during the
day and usually get a lock within 15 seconds (satellite visibility
permitting.)
> 3. Ability to use it to find my way back to my starting point (to avoid
> getting lost in the mallee!)
Never rely solely on a GPS for navigation; keep a compass and map
with you as a backup. That said, any GPS should be accurate to around
+/- 50 metres, so should be suitable. Be sure to take compass bearings
from your starting point to whatever landmarks are available; if the
GPS tells you that you are back at the starting point but can't see it,
you can use the landmarks to determine which way to go. GPS units
which allow you to take an average reading over a period of time
will help reduce the error somewhat.
GPS units usually use the WGS84 datum for their coordinates, while
Australian maps are usually based upon the AMG66 (or AMG84) datum.
If you are only using GPS coordinates, this is not really an issue
but you should be aware of which datum is used to avoid adding to
the GPS position error. A GPS that supports the Australian grids
and the UTM/UPS grid system (as well as the usual lat./long.
coordinates) should let you read and enter map grid coordinates
directly; I've played with this briefly, but as I rarely use
map coordinates, lat./long. is more intuitive.
Fortunately, AUSLIG are working on a new Australian datum which
will be the same as WGS84; this will remove this potential source
of error. (However, given the number of maps in existance using
AMG66, I expect this will take some time to happen.)
> 4. Smaller rather than bigger
A handheld GPS is ideal (roughly the size of a mobile phone.)
> 5. Length of time that the GPS works between battery recharge (I
> understand some can recharge/work using a car cigarette lighter)
I have a Garmin GPS II+; it uses 4 AA batteries which last up to 24 hours
(alkaline batteries.) The fancier models last up to 12 hours, though
curiously the new 12CX which has a colour screen is claimed to last up
to 36 hours (curious, because colour displays normally use *more* power
that B&W displays.) None of the units I am familar with have rechargable
batteries, but you can use NiCad or NiMH rechargable AA batteries, though
with a shorter battery life (keep a spare set or two charged.) You can
also run many GPS from an external power supply, which saves the batteries.
A good site with lots of information on various GPS models is
http://joe.mehaffey.com/
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Paul Taylor Veni, vidi, tici -
I came, I saw, I ticked.
To unsubscribe from this list, please send a message to
Include ONLY "unsubscribe birding-aus"
in the message body (without the quotes)
|
