APRS Messenger Lite - Help file - dated 25 March 2011 How to use with a TNC... Set the TNC to 4800 bd TNC2 operation. The APRS TNC Digi Tracker in standard form is already ready to use. Open the program. From the choice of comm ports in the box on the right hand side click on the comm port that the TNC is connected to. If nothing immediately appears in the main window click the "Disp" button to get a response from the TNC. How to install the AX25-SCS DSP TNC program... Download the AX25-SCS DSP TNC program written by Frank Perkins, WB5IPM from this web site: http://www.tapr.org/~kb2scs/scs01.html Follow the instructions on the website to install the program. How to use with the AX25-SCS DSP TNC program... Tune your receiver to the APRS channel in your country, 144.800 MHz in Europe, Russia and South Africa, 144.390 MHz in the US and Canada, 145.175 MHz in Australia, 144.575 MHz New Zealand and 144.660 MHz in Japan. Open the AX25-SCS program and click the "Activate APRS-SCS support" button. Next select the 300 or 1200 bd data rate by the "Mode" tab. 1200 bd is the default. Click on the "Connect to AX25-SCS DSP TNC" bar in APRS Messenger Lite just above the "Received data" text box and the connection will open between the two programs and the AX25-SCS program will start decoding any received APRS If the TCP/IP connection is lost, close and re-start AX25-SCS again. Clicking the command bar will not re-start the connection to AX25-SCS as it is still thinks the connection is open. How to set up a receive internet gateway... When APRS packets are being decoded OK and you are reading the traffic in the main window you can now connect to the APRS-IS, a network of servers set up by radio amateurs around the worls to ditribute APRS traffic worldwide. Enter your callsign and any SSID (-0 to -15) in the "My callsign:" box. Enter your APRS-IS passcode (same as the one used for UI-View) in the "APRS-IS passcode:" box. (If you don't have a passcode email me at passcode@crosscountrywireless.net and I'll reply with the passcode). Click on the "Connect to server" button and if your computer is connected to the internet it will send all your local APRS traffic out so that others can see it worldwide. Use with HF APRS... Tune your HF receiver to 10.1476 MHz USB. You should hear APRS packets at 300 bd coming through. If you set the data rate to 300 bd in the Mode tab of AX25-SCS you will start decoding HF APRS traffic using the 300 bd AX.25 system. Tune your receiver carefully as the decode band is narrow +/- 80 Hz for 300 bd. You will also hear APRS over datamodes packets as well. If you want to receive and transmit on APRS over digimodes download APRS Messenger from http://www.crosscountrywireless.net/aprs_messenger.net FAQ... Can I use a TNC and the AX25-SCS DSP TNC together? If you use the output from the same receiver you will just double up on the packets received. However if you use two receivers say one on your local terrestrial APRS channel and a second one on 145.825 MHz for the International Space Station then you could Igate both channels. Can I Igate VHF and HF together? Yes, you can use a TNC with your VHF receiver and use the AX25-SCS DSP TNC with your HF receiver and Igate both to the APRs-IS. Which is best? A hardware TNC or the AX25-SCS program? In tests I've found that the AX25-SCS DSP TNC program beats nearly all hardware TNCs. It's using the strong DSP features in a Windows PC and sound card to good effect. It uses similar code to that used in SDR (software defined receiver) programs with excellent filtering and reliable detection of noisy packets. The 300 bd mode used on HF APRS works really well. Why have you added the DSP TNC when you make the APRS TNC Digi Tracker? I enjoy the APRS side of the amateur radio hobby so I like playing with different hardware and software. It's fun! Why have I never heard about the AX25-SCS DSP TNC program before? It's a good question. It's was designed to be used with the APRS-SCS program and since that's now discontinued and no longer under development it's only available from the TAPR website. As far as I know this program and APRS Messenger are the only current programs that use it. Credits... This feature used software copied from the now unsupported APRS-SCS program written by John Blowsky, KB2SCS originally used with the AX25-SCS program. Feedback... If you want to send feedback or have any comments on the program email me on chrism@crosscountrywireless.net 73, Chris, G4HYG