Specifications

TNC GPS Upgrade Addendum/
55
55
5
Note: The NMEA sentence $GPRMC is the recommended sentence for tracking moving
objects as it contains time, latitude, longitude, course, and speed information.
6. Now type GPSAuto ON, then press ENTER. This will cause the TNC to look for GPS
data (coming from an attached GPS receiver) the next time it is powered on, and if it sees
GPS data the TNC will automatically switch to GPSMode 1.
7. Now you need to program the TNC’s terminal baud rate to match that of the GPS re-
ceiver, which is normally 4800 baud. To program the TNC terminal baud rate, type
TBAUD 4800, then press ENTER.
8. Now turn your TNC off and disconnect your TNC from the computer. Take the TNC to
your vehicle, connect the TNC to the GPS receiver and the radio, plug it in, power it up
and you’re in business. Note: Before powering up the TNC, be sure the GPS receiver is
powered up and outputting its NMEA sentences.
Connecting the GPS receiver to the TNC
Figure 4 below illustrates the pin assignments for connecting a GPS receiver to the TNC. The
same pin assignments can be used to connect to a Peet Bros. ULTIMETER II® weather station.
POWER
+13VDC
COMPUT ER
(RS-232)
TX
LEVEL
RADIO
2
GND
5
SQ
4
RX
1
TX
3
PTT
Rear View of the PK-12
Connect Ground to pin 1
Connect the GPS receiver or ULTIMETER II NMEA output to pin 2
Momentary c
l
osure to groun
d
causes TNC to imme
d
iate
l
y parse an
d
transmit its
l
ocation
(
pin 4
)
This option (not essential for operation) gives you the ability to configure a radio head button
to transmit position information at anytime.
9. When done using the TNC as a Stand Alone Tracking Device, connect your TNC to the
computer again, verify that your terminal baud rate is at 4800 baud, 8 bits, no parity, one
stop bit. A few seconds after powering up, the TNC should display its sign-on message and
command prompt.
APRS Hardware Single Port Mode (HSP) Set-Up: Requires a registered version of APRS
APRS version 4.03 and higher includes a routine that controls the switching of the Single Port
Mode between the TNC and any GPS receiver using the handshaking lines of the COM port. HSP
allows you to operate APRS on a computer with limited COM ports, such as a laptop which usu-
ally has only one COM port, or your PC which uses one of the two COM ports dedicated to a
mouse. This is the only configuration which uses the APRS adapter cable. You will need to have
a registered copy of APRS in able to activate the GPS input. Registration information is contained
in the APRS readme files.
FIGURE 4: Pin assignments for connecting the TNC to a GPS receiver or to an Ultimeter II weather stations. (Same for all Timewave
TNCs)