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[aprssig] 2-way tracker enclosure poll

Scott Miller scott at opentrac.org
Wed Jan 4 20:36:38 UTC 2006


This got kind of buried in the discussion, so I'll ask it again.

I'm making good progress on my receive-capable OpenTracker.  It plots all
incoming positions, objects, and items as waypoints on a supported GPS
receiver.  It'll do generic NMEA output, and it will also support Garmin
binary protocol for certain models.  This allows the tracker to set the
waypoint symbol, altitude, and comment text on supported GPS receivers.
It'll also have some expanded telemetry capabilities, and will probably have
the ability to control I/O outputs remotely.

I'll probably have multiple hardware versions eventually, but for now I need
to focus on whatever form factor is going to benefit the most people.
Search and rescue use is one area I want to concentrate on, so it'd be nice
to be able to offer a self-contained, battery-powered unit.  That introduces
some other problems, though.

Here's a quick rundown of the options I'm looking at now:

* Plastic case with inline DB9 connectors
This would be the same as the new OT1x
(http://n1vg.net/opentracker/images/ot1x.jpg), a Pac-Tec CNS-0101 with
locking DB9 connectors.  For a couple bucks more, it could be metallized for
added RFI protection.  Overall cost is low, and it'd take the same cables as
current models.  But it'd have no room for internal batteries, and the chief
complaint with this layout is that it winds up being rather long with the
connector shells inline.

* Custom aluminum or steel enclosure
Like the TNC-X, but probably shorter.  Black powder-coated steel most
likely, and probably with mounting flanges.  Tough and durable, easy to
mount for automotive applications, lots of room on the board for telemetry
inputs and power connections.  With a power control option, screw terminals,
larger board, and so forth, maybe $15 or $20 more than the cheapest option
(above).  Could possibly have room for an internal 9-volt battery like the
KPC-3, but wouldn't be easy to change.

* Plastic case with single DB25 connector and 9-volt battery
Probably the Serpac A-21 or similar.  Reasonably compact, integrated 9-volt
battery compartment.  Fairly cheap since it's available with a DB25 panel
and wouldn't require machining.  Would require new cables to use the single
connector, but would have plenty of pins for telemetry inputs and control
outputs.

* Plastic case with AA batteries
Many cases that take a 9-volt battery can also take two AA size batteries.
That gives you higher energy density, but requires a DC-DC converter to get
the operating voltage, which adds cost and RFI/EMC issues.  6 or more
batteries would provide plenty of power for the tracker and a GPS receiver,
but would add bulk and weight.  Haven't identified a candidate for this case
style yet.

I've got a poll running at http://n1vg.net/vote.  Let me know what you
think... I'm open to other options.  At the moment, I think I'm leaning
toward the steel enclosure.  Not so convenient for man-portable operation,
but the most flexible all around.  And hopefully less headaches when it
comes to PCB layout - the CNS-0101 size prototype was a major pain.

Scott
N1VG







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