This week I figured out how to set up my station to act as a fill-in/relay APRS digipeater using just MixW and the rig. This is useful if you don't want to buy a TNC and already use MixW for other digital modes. In addition to doing a bunch of research on APRS, documentation on how to do this with MixW is extremely scarce, so you have to piece it all together yourself. This "how to" assumes that you already have a sound card interface of some sort and you can trigger PTT from MixW.

Here's how you do it:

First download the MixW Com Port emulation driver. It is found here:
MixW - multimode software for radio amateurs
Install the driver and reboot. Basically, if you follow the instructions included, you won't have a problem.

Now you have to configure the Virtual TNC. In MixW, go to "Configure", then select "TNC Emulation". If you followed the instructions properly for the Com Port emulation driver, you will know what com port you configured. Select one of these for the TNC emulation port. Set the baud rate to 19200, data bits to 8, parity to None, Stop bits to 1. Make sure Echo and Disable Device are both turned off.

APRS uses the Packet mode, so you need to select that mode. Once you select that if you tune to 144.390 (or whatever is used in your area) you should start seeing Mixw read the APRS beacons and messages. If you hear the transmissions on your rig but don't see anything translated on MixW, you have a problem. Make sure Noise Reduction or other types of DSP processing are turned off on the rig as this will cause issues.

Now you have to configure Packet to be an APRS relay. Go to "Mode" then select "Mode Settings". Here's what you put in:

General Tab
Incoming MyCalls: Your call sign
Digi/My Digi's calls : Wide1-1
Enable Digipeating: checked
Emulate KISS TNC: checked

Wide1-1 in the "My Digi's calls" will make MixW respond to an APRS Wide1-1 routed message. If your area is still using the old APRS standard, you may need to put "RELAY" in there instead. If you want to make your digipeater for more private useage, you can put a different digipeater callsign in there, but then people will need to explicitly know the call to put in their APRS radio to get your digipeater to do anything.

Modem Tab
VHF 1200 baud (Standard)

Beacon/Unproto Tab
Source Call: Your Callsign here. You can add SSID's to this if you want
Dest Call: APMIXW
Beacon text: Your call sign plus something to tell others what this is. I put my call sign plus the words "fill-in digipeater"
Interval,s: 600
Enable Beacon: checked

Dest Call is what is transmitted along with the APRS beacon or message that is digipeated. Usually this is used to tell others what type of equipment you're using to digipeat. It's important to understand that APRS servers will only respond to something that starts with "AP". You can see I chose to put in "APMIXW" to idetify this as a MixW digipeater.

The Beacon Text is so that your station will automatically id itself every 10 minutes, as required by U.S. law. When MixW digipeats, you won't see your callsign in the outgoing packets, so this beacon text is kind've important.

That's it! If everything is working properly, you can take your APRS enabled HT or mobile and tell it to beacon. If you have Wide1-1 in your routing path, MixW will immediately relay your beacon.

Note, this setup only relays hoping that another APRS station will hear the packet and pass it on. It will only relay the Wide1-1 and it will add the * at the end of the Wide1-1 so other fill in relays will not relay it again. Of course, if you also have Wide2-2 (or other routing instructions) in your APRS transmission, the next relay that hears it will follow those instructions.

Another intersting thing you can do with this setup is UI-View (or some other APRS software) to be the digipeater or I-Gate instead. In this case, you turn off the MixW digipeater functionality, but still use the virtual Com ports and MixW to handle TNC duties.