Outstanding in the Field
Hardware
Computers
There are three main types of field computing device available: Ruggedized laptops, pen-based
computers, and PDAs.
PDAs are becoming increasingly popular, particularly for data capture, but they are restricted to
fairly lightweight tasks because of the limitations on available memory and processing power.
These limitations are reduced with every model released, but a seamless office/PDA GIS
solution is hampered by the fact that PDAs use different Operating Systems from PCs and
servers. Windows CE devices will support Java applications, which at least opens the door to
interoperability, but the PDA with the greatest market share is the PalmPilot, which does not
support Java and uses its own proprietary Operating System.
Pen-based machines are a very popular field choice as they offer a natural method of user
interaction and are a lot easier to use while standing up than a conventional laptop. Increasingly
the performance of pen-computers is catching up with laptops, though the touch sensitivity of the
screen imposes limits on the screen size. Most pen-based computers also suffer from
comparatively short battery life, and this is compounded if the unit is also running a wireless
modem. Unlike PDAs, pen machines and ruggedized laptops typically run Windows 95/98 or
NT.
Communication Technology
Client-Server models require continual communication between the master and field systems.
Since the very nature of a field GIS normally precludes connecting to a landline, this
communication link must be wireless. Digital wireless communication does not have universal
coverage as yet, and its bandwidth (or throughput) is still approximately fifty percent lower than
that of a landline.
Radio networks have a comparable bandwidth to digital wireless, but their reliability of service
can be worse.
If the data being transmitted is sensitive it may be necessary to encrypt it to maintain security,
which adds to the processing time on both sides, though this is normally negligible compared to
the transmission time. On a related issue, Client-Server solutions require thorough authentication
of users to prevent unauthorized access to proprietary information.
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