APRS

At home, I have a Raspberry Pi connected to a Baofeng UV-5R running the Direwolf software listening for APRS beacons in the area.

So far, I've seen a half a dozen or so people driving down I84 as they pass by the Hollywood exit. Here's the aprs.fi report for my home station (and previous call sign) which lists the stations I've heard directly.

I also transmit APRS beacons from my handheld on occasion. You can see my last reported location here.

Stations Observed

Here are some of the stations that my base station has observed nearby. Full logs.

Bookmarks

Last night I went to a Pedalpalooza bike ride for hams called Bikes on the Air led by KC7JNU. On the ride I was transmitting APRS beacons from my TH-D72 handheld radio. None of my pings from the street level were picked up by anyone, but once we got up to Mt Tabor, I started seeing my radio on the map!

You can also see the list of stations that directly picked up my beacons

Some of them were over 20 miles away! My handheld was picking up APRS beacons from even farther too!

I just set up my Raspberry Pi to act as an APRS IGate transmitter, so that it relays packets on the radio that it receives from the Internet. There were a couple tricks that I couldn't figure out so I ended up disabling it for now and switching it back into just receive mode.

Configuring Direwolf

To configure Direwolf to transmit, I had to add the following settings to my config file:

IGTXVIA 0 WIDE1-1 # Transmit on audio channel 0 (defined earlier)
IGFILTER M/15 # Only transmit packets within 15 miles? km? of my location
IGTXLIMIT 6 10 # Transmit maximum 6 packets a minute and 10 packets in 5 minutes

Adding those settings quickly turns on a stream of stations transmitting through mine! I then plugged the headphone jack of my USB audio adapter into the Baofeng radio, and enabled VOX. I don't have a PTT circuit set up yet, so I had to rely on VOX. Here's where it got messy.

With squelch disabled, the VOX would never trip and I would never transmit. I had to turn squelch back on.

I wasn't able to keep both the headphone and microphone jack of the Baofeng connected, because it created some sort of loop where it kept the radio transmitting even when there was no audio. For testing purposes I used two separate Baofengs, one to transmit and one to receive.

I also had to mute the loopback audio from the Pi, otherwise anything that came through the mic was echoed back out the headphones and transmitted! To do this, I launched alsamixer and muted the microphone, which just disables it from being heard in the headphones but still is heard by Direwolf.

Once I got that hooked up, I started transmitting quite a bit! Here are some logs from my console:

[ig>tx] N6ZZY-10>TUSPVR,BULLMT*,WIDE2-1,qAR,N7BDW-10:`2J`o}<0x1e>k/`"5:}146.680MHz C114 -060_"
[0L] W7APK-10>APDW13,WIDE1-1:}N6ZZY-10>TUSPVR,TCPIP,W7APK-10*:`2J`o}<0x1e>k/`"5:}146.680MHz C114 -060_"

[ig>tx] N8WCR>GPSLV,WIDE1*,qAR,N7BDW-10:$GPGGA,215347.000,4539.6219,N,12237.7259,W,2,08,1.4,79.9,M,-19.2,M,0.8,0000*7B
[0L] W7APK-10>APDW13,WIDE1-1:}N8WCR>GPSLV,TCPIP,W7APK-10*:$GPGGA,215347.000,4539.6219,N,12237.7259,W,2,08,1.4,79.9,M,-19.2,M,0.8,0000*7B

[ig>tx] KC7ILK-13>GPSLV,qAR,N8WCR:$GPGGA,215447.000,4539.6251,N,12237.7256,W,2,10,1.0,67.7,M,-19.2,M,0.8,0000*73
[0L] W7APK-10>APDW13,WIDE1-1:}KC7ILK-13>GPSLV,TCPIP,W7APK-10*:$GPGGA,215447.000,4539.6251,N,12237.7256,W,2,10,1.0,67.7,M,-19.2,M,0.8,0000*73

[ig>tx] KC7ILK-13>GPSLV,qAR,N8WCR:$GPGGA,215547.000,4539.6251,N,12237.7260,W,2,10,1.0,66.1,M,-19.2,M,0.8,0000*70
[0L] W7APK-10>APDW13,WIDE1-1:}KC7ILK-13>GPSLV,TCPIP,W7APK-10*:$GPGGA,215547.000,4539.6251,N,12237.7260,W,2,10,1.0,66.1,M,-19.2,M,0.8,0000*70

[ig>tx] KM7LJ>APRS,WIDE1-1,qAR,N7BDW-10:>Final check

[ig>tx] KM7LJ>APRS,WIDE1-1,qAR,N7BDW-10:@215746h4537.88N/12234.90W- KM7LJ Vancouver, WA

Next time I try this again, I want to set up a proper PTT circuit so that I can use just one Baofeng. Hopefully I can get this to the point that I can launch it with a real antenna and be a helpful local digipeater!