Timewave DSP-232, Operating Manual

Page: 115 / 271

Chapter 6 GPS Applications
1. Connect your TNC to your computer, and to your GPS receiver using the AEA APRS Adapter Cable
following the steps noted previously. Get the computer running APRS software and the TNC running. Leave
the GPS receiver off until you are ready to receive the NMEA string.
2. Press ALT-S to bring up the setup menu.
3. Now press G for GPS.
4. Press H for HSP.
5. Now press ALT-S to save.
6. Enter S for SAVE.
7. Now follow the prompt from APRS to validate your APRS registration and save the mode changes.
8. Turn your GPS receiver on, and you are ready for APRS HSP operation.
9. When finished using the DSP-232 for APRS HSP operation, simply quit APRS. APRS may ask you for some
information before quitting. Answer the questions and when done, your DSP-232 will be ready for non-GPS
activities.
APRS Dual Port Mode Set-up:
To set up APRS for dual mode operation, follow these steps:
1. Connect your DSP-232 to one of the COM ports on your computer. Get the TNC up and running following
the directions in Chapter 2 of this manual.
2. Connect you GPS receiver to the other COM port on your computer. (You will need to build your own cable
for this connection. Since there are many types of GPS receiver, all with different connection, we can’t
provide you with schematics on how to build this cable).
3. Get the APRS software program running. APRS will ask you some questions, simply answer the questions
and your TNC and APRS will be ready for dual port mode operation.
Building your own APRS adapter cable
The APRS adapter cable works as follows:
The adapter allows for Hardware Single Port mode (HSP) operation, so you only need one computer COM port for
both your GPS receiver and DSP-232. The adapter normally has the TNC switched to the computer until APRS
decides it’s time to send its location report. When it’s time to send position information, the computer running
APRS asserts flow control to the TNC to prevent it from sending any more data. The flow control line is also used
to switch the adapter to the GPS receiver. Once the GPS string is received, the computer running APRS releases
flow control, switching back to the TNC.
A pre-made and tested cable can be purchased from AEA for $30.00 by calling (206) 774-1722. For best pricing,
see your favorite amateur radio dealer.
An APRS adapter cable can be made from the following components with the schematic shown on the next page.
Item Description Qty AEA Part # Radio Shack Part #
1. PCB 1 013-141
2. 1K resistor 1 210-102 271-023
3. 10K resistor 2 210-103 271-034
4. IN4148 Diode 2 310-001 276-1122
5. 2N3904 NPN transistor 2 320-001 276-2016
6. DB-25 male connector 1 420-102
7. DB-25 female connector 1 420-105
8. DB-25 Hood 1 053-065
9. Screws for hood 1 053-065-1
10. Saddle washers 1 053-065-2
11. Hex nuts 1 053-065-3
6-6 September, 05