APRS Digipeater/iGate with Direwolf (Entry Level)

Goal

Goal: To create a modular APRS Digipeater/iGate that can operate with minimal maintenance and can take a variety of upgrades to better serve the user and community.

Time

Time: 2-4 Hours

Difficulty

Difficulty: Easy. All commands are laid out. No hardware modification is required.

Required Parts

ItemCost
Radio capable of 144.390 MHz$70.00
Audio Interface Cable$25.00
Raspberry Pi 4 2GB RAM kit$90.00
USB Sound Card$8.00
Audio Splitter Cable$5.50
System Total$270.50
Table 1: Recommended Parts List

Required Infrastructure

  • Home Internet Connection
  • Area the project can be tucked away and left alone when assembled

Configuring Raspi

I’m going to assume that the Raspberry Pi has been setup with the most current version of raspiban. To start out, we will need to remote into the RasPi. I would recommend using a direct connection or VNC for the following tasks. SSH will work for the install, but in order to keep the device running 24/7 SSH will not work in the end.

Most of these commands will be copy and paste directly into terminal.

First, lets get all updates for the RasPi and apply them. If this is a fresh install of Raspiban this task can take some time.

sudo apt-get update && sudo apt-get upgrade -y

We then need to see if a package named pulseaudio is installed. We don’t want this package to be installed.

dpkg-query -l 'pulseaudio*'
Figure 1: PulseAudio Package Query Output

Under “Version”, you want everything to say <none>. The location of where this information can be found is above in Figure 1. It does not matter how many items appear, they must all say <none> under “Version”.

If it is installed, then we must remove it. Run the following commands one line at a time. The last will reboot the device. If you are connected over VNC, it should auto reconnect when the pi powers back on.

sudo apt-get remove --purge pulseaudio
sudo apt-get autoremove
rm -rf /home/pi/.pulse
sudo reboot

Now that the Raspi has been prepared, it is time to start installing software. All supporting software can be installed in one line. Some of this software may be installed already, so this process may go by relatively quickly.

sudo apt-get install git gcc g++ make cmake libasound2-dev libudev-dev -y

It is now time to get the source code from Github. We will be pulling from the stable branch, then building the code on the raspi. Again, run each command here one line at a time. The last command will reboot the Raspi.

cd ~
git clone https://www.github.com/wb2osz/direwolf
cd direwolf
mkdir build && cd build
cmake ..
make -j4
sudo make install
make install-conf
sudo reboot

Configuring Direwolf

With everything installed, we need to configure Direwolf so it knows what hardware to use and how to behave.

Querying Audio Interface

Plug in the USB sound card to any port on the RasPi. Go to a new terminal window and run:

aplay -l

This will print out a list of audio out devices that the Raspi has access to. In Figure 2, it can be seen that Card 2, Device 0 contains the USB Audio sound card that was inserted earlier.

Figure 2: aplay Query Output

Now that we have the output path, lets get the input path. In the same terminal, run:

arecord -l

This will print out a list of audio in devices that the Raspi has access to. In Figure 3, it can be seen that again Card 2, Device 0 contains the USB sound card.

Figure 3: arecord Query Output

Take note of the card and device numbers. It is highly likely that by using the recommended hardware, it will be the same Card and Device for both input and output.

Modifying the direwolf.config File

All the settings for the direwolf.config file will setup how the APRS iGate/digipeater will behave. The file will be located on the RasPi at /home/pi/direwolf.config. Double click on the file to open it in text editor.

To make the instructions more direct, I will be identifying code changes by the line number. To enable them in the text editor, click View followed by Line Numbers.

When a change is done, it is important to delete the # symbol at the beginning of each line. This symbol is used as a comment and will be ignored by the Direwolf software. So even if the line is changed, it would not take effect if still commented out. You can insert your own lines in this file for notes just as long as a # precedes all text.

Line 86

Line 86 will appear similar to

#ADEVICE  plughw:0,0

You will need to update this to match your device. In this example with Card 2 Device 0, the line will change to

ADEVICE plughw:2,0

Line 141

Line 141 will take some effort for changes. The line will appear such as:

MYCALL N0CALL

N0CALL needs to be replaced with your call sign with the SSID of your APRS station. As for the SSID number, it is recommended to follow numbering convention and select -10 for this. Table 2 shows what the various SSIDs are used for.

SSID NumberStation Description
0Your primary station usually fixed and message capable
1generic additional station, digi, mobile, wx, etc
2generic additional station, digi, mobile, wx, etc
3generic additional station, digi, mobile, wx, etc
4generic additional station, digi, mobile, wx, etc
5Other networks (Dstar, Iphones, Androids, Blackberry’s etc)
6Special activity, Satellite ops, camping or 6 meters, etc
7walkie talkies, HT’s or other human portable
8boats, sailboats, RV’s or second main mobile
9Primary Mobile (usually message capable)
10internet, Igates, echolink, winlink, AVRS, APRN, etc
11balloons, aircraft, spacecraft, etc
12APRStt, DTMF, RFID, devices, one-way trackers
13Weather stations
14Truckers or generally full time drivers
15generic additional station, digi, mobile, wx, etc
Table 2: APRS SSID descriptions

For myself, this line would appear as:

MYCALL KI5GTB-10

Note that I have had issues getting the SSID of -0 to work properly. This may of been caused by other issues on my Raspi, but I now use 10 as the SSID as it is more descriptive.

Beacon

Line 278

Now we need to enable the beacon feature. This will let the station transmit its location information to nearby users.
Line 278 will have this information. The changes that need to be done here are the latitude/longitude, power, height, gain, and comment.
For the latitude and longitude, i recommend this website (https://www.findlatitudeandlongitude.com/). As a example, I will be using the following information, using the address for the clubhouse. The latitude and longitude information is shown in Table 3 is how the information should be entered into the configuration file.

AddressLatitudeLongitude
28, East Main Street, Edmond, Oklahoma County, Oklahoma, 73034, USA35^39.3114697^28.85964
Table 3: Location Data

The other settings should be self explanatory. Power of the radio, height of the antenna, gain of the antenna, and any comment you would like. This is the comment that will be broadcasted with the beacon and should be descriptive of the station.

PBEACON delay=1  every=30 overlay=S symbol="digi" lat=35^39.311460N long=097^28.85964W power=8 height=20 gain=4 comment="KI5GTB Home Station" via=WIDE1-1,WIDE2-1

Digipeater

Line 318

This step is easy. Line 318 needs to be uncommitted. No changes need to be made. This will turn on digipeating functionality for this project. It can be thought of as a APRS repeater.

iGate

Line 348

To link the project to the internet, we need to enable the services for a connection.

On line 348, you will need to modify the line to where it looks like this:

IGSERVER noam.aprs2.net

The next line requires getting a pass code to log into the servers. The pass code can be retrieved for free and instantly at http://apps.magicbug.co.uk/passcode/.
Table 4 has examples on what you should retrieve. Use your own call sign for this. The information for Table 4 is for reference and can be used as a sanity check to ensure that the generator is working properly

StationPasscode
KI5GTB-1022958
k5eok-1013976
Table 4: APRS Passcode Generation Results

Line 353

On line 353, you will need to enter in your callsign-SSID and pass code. Mine has been included as a example

IGLOGIN KI5GTB-10 22958

The last change will be to uncomment line 370. No changes will need to be made.

Line 363

On line 363, uncomment and modify the lat/long information. Use the same information and the same format used in line 278 above.

To recap quickly, the following lines should of been modified in some way. Make sure to save this file.

  • Line 86
  • Line 141
  • Line 278
  • Line 318
  • Line 348
  • Line 353
  • Line 363
  • Line 370

Hardware Configuration

To assemble the unit, the following connections need to be made:

  • Raspi -> USB Sound Card
  • USB Sound Card -> Headphone Splitter
  • Headphone Splitter -> APRS Cable
  • APRS Cable -> Radio

Figure 4 shows how my setup is currently connected together. This is using the recommended hardware in Table 1, but the concept can be applied to multiple different radios. The cable can also be DIYed if you so choose using this (https://github.com/johnboiles/BaofengUV5R-TRRS) board created by KK6GIP (Note that I have not tested this board personally).

Figure 4: Reference of Hardware Connections

For the radio, I am using a Baofeng BF-F8HP for my transceiver. The following settings in Table 5 will need to be changed and the frequency tuned to 144.390 MHz

SettingSetting NumberSetting Value
SQL (Squelch)01 (Lower the value is better)
TXP (Transmit Power)2HIGH
VOX41 (Lower is better)
R-DCS10OFF
R-CTCS11OFF
T-DCS12OFF
T-CTCS13OFF
VOICE14OFF
OFFSET26000.000
RODGER39OFF
Table 5: Baofeng Recommended Settings

While this is written for a specific radio, note the trend in the settings. We want it to transmit as high as possible, we want squelch and VOX to be low, we want to tones to be setup, and nothing that may interrupt a transmission.

Starting Direwolf and Verifying Operation

Connect to the Raspi or VNC into it. I do not recommend the use of SSH for this task.

Go to a terminal and run the following command

direwolf

After booting up, the terminal will look something seen in Figure 5. Note that I have received a transmission from myself on my Yaesu FT3D HT.

You should now be able to go to https://www.aprs.fi and search for your call sign.

At this point, the APRS beacon is live and working. For fun, I can inspect the server at http://198.50.198.139:14501. I see my station (KI5GTB-10) with the following stats.

Figure 5: Server Status

Sources/Useful Links

http://www.aprs.org/aprs11/SSIDs.txt
https://github.com/johnboiles/BaofengUV5R-TRRS
https://n1aae.com/raspberry-pi-aprs-direwolf-linux-igate-digipeater/ (This is the instruction set I followed when creating mine for the first time)

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