4. OpenTracker Setup and Operation
a. General
The
OpenTracker
radio
connector,
X1,
is
identical
to
that
used
by
the
Kantronics
KPC
‐
3
and
the
Byonics
TinyTrak3.
Any
cable
that
was
made
to
interface
a
radio
to
either
of
these
devices
should
work
with
OpenTracker.
BUX
Comm
provides
detailed
wiring
diagrams
and
pre
‐
assembled
cables
for
a
wide
variety
of
radios
at
http://www.packetradio.com/wiring.htm
Most
handheld
radios
(with
the
notable
exception
of
those
made
by
Kenwood)
assert
PTT
by
grounding
the
microphone
input.
Resistor
R3
is
used
for
this
purpose.
R3
should
be
omitted
when
the
tracker
is
used
with
mobile
radios
or
with
handhelds
that
do
not
use
this
method
of
PTT
keying.
If
the
tracker
will
be
used
with
both
mobile
and
handheld
radios,
R3
can
be
installed
in
the
cable
used
to
connect
the
tracker
to
the
handheld.
The
OpenTracker
requires
6.7
to
30
volts
DC.
If
R11
and
R12
are
installed,
the
OpenTracker
can
measure
and
report
its
voltage
input
level.
However,
the
measurement
range
is
limited
to
6.7
to
15
volts.
Power
may
be
supplied
at
three
points
on
the
OpenTracker
board.
Most
often,
it
is
supplied
through
pin
7
of
the
radio
connector.
It
may
also
be
supplied
through
pin
8
of
the
expansion
header.
In
addition,
if
a
jumper
is
installed
between
pins
8
and
9
of
the
expansion
header,
power
may
be
supplied
through
pin
4
of
the
data
connector.
b. Receive Adjustment
The
OpenTracker
cannot
decode
incoming
packet
data.
Instead,
it
watches
for
audio
energy
(voice,
data,
or
static)
to
avoid
transmitting
over
other
stations.
The
sensitivity
of
the
energy
detect
is
determined
by
the
trimpot
labeled
‘RX’.
Adjust
the
squelch
on
the
receiver
so
that
it
remains
closed
under
average
channel
conditions
with
no
signals
present.
Turn
RX
potentiometer
all
the
way
up
so
that
it
remains
lighted,
and
then
turn
it
back
down
until
it
stops
blinking
under
quiet
channel
conditions.
c. Transmit Adjustment
The
‘TX’
potentiometer
sets
the
unit’s
transmit
audio
level.
To
set
this
level
properly,
use
another
radio
to
listen
to
the
unit’s
transmitted
packets.
Turn
the
level
up
slowly
until
the
signal
doesn’t
get
any
louder,
and
then
turn
it
back
down
until
it
gets
noticeably
quieter.
Continue
turning
it
down
for
about
1/8
turn
after
that
point.
Proper
audio
level
is
critical
to
ensuring
the
transmitted
packets
can
be
received
and
decoded.
A
transmit
audio
level
set
too
high
will
cause
clipping
in
the
transmitter,
which
results
in
signals
that
are
difficult
to
decode.
The
configuration
software
also
allows
adjustment
of
the
audio
output
level
using
a
slider
control.
See
the
software
documentation
for
details.
OpenTracker Manual - Version 1.05 – 6/25/06
page
7
of
23
