1. Introduction
The
OpenTracker
is
a
simple,
low
‐
cost
amateur
radio
data
encoder
capable
of
generating
1200
or
300
baud
AX.25
packets
using
both
APRS™
and
OpenTRAC
protocols,
as
well
as
PSK31
text
beacons.
It
can
be
connected
to
a
GPS
receiver
to
report
position,
course
and
speed,
time,
and
altitude,
and
will
also
report
telemetry
from
its
onboard
temperature
and
voltage
sensors.
With
its
expansion
connector
and
ease
of
reprogramming,
the
device
can
be
adapted
to
a
wide
variety
of
tasks.
Changes
PCB
Revision
4
includes
significant
changes
from
previous
hardware
revisions.
While
the
firmware
features
and
configuration
options
remain
the
same,
the
pin
header
configuration
and
power
specifications
have
changed.
Revision
4
incorporates
a
larger
voltage
regulator
capable
of
supplying
enough
current
to
power
many
popular
5
‐
volt
GPS
receivers
without
requiring
a
heat
sink.
Acknowledgements
The
OpenTracker
is
far
from
being
the
first
device
of
its
type,
and
owes
much
to
those
that
came
before
–
in
particular,
John
Hansen’s
GPS
‐
E
firmware
and
its
TAPR
PIC
‐
E
hardware,
Steve
Bragg’s
HamHUD,
and
Byon
Garrabrant’s
very
successful
TinyTrak
series.
Lessons
learned
from
all
of
these
devices
have
contributed
to
the
design
of
the
OpenTracker.
The
OpenTracker
is
very
similar
in
physical
layout
to
the
TinyTrak3
(in
its
‘trimmed’
version),
and
identical
in
connector
configuration,
allowing
enclosures
and
cables
to
be
used
interchangeably.
Despite
their
similarities,
though,
the
two
devices
have
very
different
processor
architectures,
different
digital
‐
to
‐
analog
conversion
systems,
and
entirely
unrelated
firmware.
The
SmartBeaconing™
algorithm
used
by
the
OpenTracker
was
originally
developed
by
Tony
Arnerich,
KD7TA,
and
Steve
Bragg,
KA9MVA.
APRS™
is
a
trademark
of
Bob
Bruninga,
WB4APR.
Brian
Riley,
N1BQ,
and
Keri
Morgret,
N6TME,
contributed
to
this
manual.
OpenTracker Manual - Version 1.05 – 6/25/06
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