Timewave PK-900, Operating Manual, Page: 356 / 392

44444 / TNC GPS Upgrade Addendum
The TNC can be connected to the ULTIMETER II weather station, interpret the weather data,
and transmit the weather and location information in packet so other APRS users can see your
location and the weather at your location. The remote polling features of the TNC make it easy
to set up a weather station in a remote location and receive the remote weather data via APRS at
your house, office, or wherever. While at work, you can keep track of the weather situation at
your home (inside or outside temperatures—whichever you prefer). Farmers can keep apprised
of rain, wind, and temperature at a remote field site. In addition, several weather stations set up
in your region can provide you with a comprehensive weather picture of your area—available to
you and all other users at anytime. The TNC, ULTIMETER II, and APRS add a whole new di-
mension to packet radio—we hope you experiment with this new application. Set-up proce-
dures for an Ultimeter II weather station are discussed later in this chapter.
Setting Up the TNC for GPS Operation
Set up procedures for the TNC are described below for three Packet/GPS configurations: Stand
Alone Tracking, APRS Hardware Single Port mode, and APRS Dual Port Mode. APRS software
automatically sets the parameters for your TNC, except when the TNC is used as a Stand Alone
Tracking Device (because APRS isn’t connected).
Stand Alone Tracking Device Set-up:
To set up the TNC for Stand Alone Tracking, follow these steps:
1. Connect your TNC to your computer and get it up and running following the directions in
Chapter 2.
2. Type MY <your call sign>-9, then press ENTER. For example, if your call sign is WA7GCI
you would enter MY WA7GCI-9, then press ENTER. The -9 will cause others to see you as
a car on the APRS map.
3. Program the UNPROTO command to: UN APRS via RELAY, then press ENTER. This
programs your unproto path to APRS via RELAY.
4. Type GLOCtx 6, then press ENTER. This causes the TNC to transmit its GPS location ev-
ery 60 seconds. The seconds can range from 0 (disabled) to 255 in ten second increments.
5. Now you need to program the commands, GNMEA1 and/or GNMEA2, for the desired
NMEA (GPS) sentences for the TNC to parse. Not all GPS receivers can send all NMEA
sentences. So, the instructions you see below depend on the ability of your GPS receiver to
send desired NMEA strings. In any case, the TNC can handle any NMEA strings your GPS
or Loran receiver can produce.
To program GNMEA1, type GNMEA1 $GPGLL and press ENTER. This command allows
the TNC to parse the Position-Only NMEA string coming from the GPS receiver and place
the string in the transmit buffer. The result of $GPGLL is that you will be able receive from
the GPS receiver Position-Only information and transmit it over the ham bands. (Any
NMEA string your GPS receiver can produce can be entered in this command line.)
The neat thing about the TNC is that you can choose not one, but two NMEA strings to
parse. You can, for instance, use Position-Only and Course/Speed. To program the second
NMEA string for the TNC, type GNMEA2 $GPVTG and press ENTER. This sentence
alone allows you to transmit course and speed. When coupled with the GNMEA1, your po-
sition, course, and speed will be transmitted together. (Again, you can use any NMEA string
your GPS receiver can produce in this command line.)