ReticulumHF

Reticulum over HF radio using FreeDV.

Overview

Runs Reticulum over HF radio using FreeDV data modes. Provides encrypted peer-to-peer communication without internet infrastructure.

Supported FreeDV Modes:

Mode	Bitrate	Use Case
DATAC1	290 bps	Default - robust for most HF conditions
DATAC3	312 bps	Good conditions, slightly faster
DATAC4	87 bps	Weak signals, emergency comms

Two installation methods:

• Pre-built Image - Flash and go. Web-based setup wizard with mode selection.
• Manual Installation - Build everything yourself on existing Pi.

Pre-built Image

Download the SD card image, flash it, boot, configure via web portal.

Download

reticulumhf-20260126.img.xz

Setup

1. Flash to SD card using Raspberry Pi Imager - select "Use custom"
2. Insert SD card, connect radio via Digirig, power on
3. Connect phone to WiFi: ReticulumHF-Setup (password: reticulumhf)
4. Open http://192.168.4.1 in browser
5. Complete setup wizard - select radio model, verify audio levels
6. In Sideband, add TCP interface: 192.168.4.1:4242

What's Included

• Raspberry Pi OS Bookworm Lite (64-bit)
• RNS 1.1.3 with TCP server on port 4242
• freedvtnc2 (FreeDV modem - supports DATAC1/DATAC3/DATAC4)
• codec2 (built from source)
• Hamlib rigctld with PTT support
• Web portal with mode selection and service controls

Network

WiFi SSID	ReticulumHF-Setup
WiFi Password	reticulumhf
Gateway IP	192.168.4.1
Sideband/NomadNet Port	4242
MeshChat Port	8001
SSH	pi / reticulumhf

Client Connections

Sideband / NomadNet (port 4242, no KISS framing):

Setting	Value
Host	192.168.4.1
Port	4242
Interface Type	TCP Client

MeshChat (port 8001, KISS framing required):

Setting	Value
Target Host	192.168.4.1
Target Port	8001
KISS Framing	YES
Interface Mode	Full

Bitrate by FreeDV mode (set in MeshChat):

Mode	Inferred Bitrate
DATAC1	290
DATAC3	312
DATAC4	87

Audio Tuning

ssh pi@192.168.4.1
alsamixer

• Press F6 to select USB audio device
• Press F4 for capture view
• Set capture 70-80%, playback 40-60%
• Save: sudo alsactl store

---

Manual Installation

Build everything from scratch on a fresh Raspberry Pi OS installation.

Test Results

Tested January 2026 with G90, FT-818, and truSDX.

Test Environment

Component	Specification
Computer	Raspberry Pi 4 (4GB)
OS	Raspberry Pi OS Lite Bookworm 64-bit
Radio	Xiegu G90, Yaesu FT-818, (tr)uSDX
Interface	Digirig Mobile (CAT + Audio), Digirig Lite (Audio/VOX)
Reticulum	1.1.3
freedvtnc2	0.0.1
codec2	Built from source

FreeDV Mode Specifications

From codec2 documentation (https://github.com/drowe67/codec2/blob/main/README_data.md):

Mode	Bitrate	RF BW	Payload	Frame Duration	Min SNR
DATAC1	290 bps	1.7 kHz	510 bytes	4.18 sec	5 dB
DATAC3	312 bps	1.7 kHz	258 bytes	2.06 sec	8 dB
DATAC4	87 bps	500 Hz	128 bytes	5.17 sec	-2 dB

DATAC1 is recommended for most conditions. Use DATAC4 for emergency/weak signal work.

Range depends on HF propagation (ionosphere, solar activity, time of day).

Architecture

+-------------+      +----------+      +-----------+
|  NomadNet   |----->|Reticulum |----->|freedvtnc2 |
|   (LXMF)    |      |  Stack   |      |   (TNC)   |
+-------------+      +----------+      +-----------+
                                             |
                                             v
                                       +---------+
                                       | rigctld |
                                       |  (PTT)  |
                                       +---------+
                                             |
                                             v
                                       +---------+
                                       |Digirig  |
                                       | Audio+  |
                                       |  CAT    |
                                       +---------+
                                             |
                                             v
                                       +---------+
                                       | G90 HF  |
                                       |  Radio  |
                                       +---------+

Work Flow:

1. User writes message in client app (Sideband, NomadNet, MeshChat)
2. Reticulum encrypts packet with recipient's public key
3. freedvtnc2 modulates to FreeDV audio (DATAC1/DATAC3/DATAC4)
4. rigctld keys radio via RTS (or VOX for audio-only interfaces)
5. Audio transmits over HF, remote station decodes and delivers

Step 1: System Preparation

Flash Raspberry Pi OS Lite (Bookworm, 64-bit). Enable SSH.

ssh user@<pi-ip-address>
sudo apt update && sudo apt upgrade -y

Step 2: Install Dependencies

sudo apt install -y git build-essential cmake python3 python3-pip python3-venv \
    portaudio19-dev alsa-utils libhamlib-utils libhamlib-dev pipx
pipx ensurepath
source ~/.bashrc

Step 3: Build Codec2

cd ~
git clone https://github.com/drowe67/codec2.git
cd codec2
mkdir build_linux && cd build_linux
cmake ..
make
sudo make install
sudo ldconfig

Verify:

ldconfig -p | grep codec2

Step 4: Install Reticulum Stack

pipx install rns
pipx install nomadnet
pipx install freedvtnc2
pipx runpip rns install numpy pyaudio scipy
pipx runpip nomadnet install numpy pyaudio scipy

Initialize Reticulum config:

rnsd --config ~/.reticulum &
sleep 3
pkill rnsd

Step 5: Connect Hardware

1. Connect Digirig to Pi via USB
2. Connect Digirig audio cable to G90 ACC port
3. Connect Digirig CAT cable to G90 CAT port
4. Power on G90

Step 6: Verify Hardware

# Check USB devices
lsusb
# Expected: Silicon Labs CP210x (CAT) and C-Media CM108 (audio)

# Check audio
arecord -l
# Expected: USB PnP Sound Device

# Check serial
ls -la /dev/ttyUSB*
# Expected: /dev/ttyUSB0

# Add user to dialout group
sudo usermod -a -G dialout $USER
# Log out and back in

Step 7: Test Radio CAT

rigctl -m 3088 -r /dev/ttyUSB0 -s 19200 f

Expected: Returns current frequency (e.g., 7100000).

Step 8: Configure G90 Audio Input

On the G90:

1. Press FUNC
2. Press POW until you see "INPUT"
3. Use knob to select LINE (not MIC)

Set ALSA levels (adjust card number as needed):

amixer -c 3 sset 'Speaker' 64%
amixer -c 3 sset 'Mic',0 cap 75%
amixer -c 3 sset 'Mic' unmute
sudo alsactl store

Step 9: Configure Reticulum

Edit ~/.reticulum/config:

[reticulum]
  enable_transport = no

[interfaces]
  [[Default Interface]]
    type = AutoInterface
    enabled = yes

  [[FreeDV HF]]
    type = TCPClientInterface
    enabled = yes
    target_host = 127.0.0.1
    target_port = 8001
    kiss_framing = yes

Step 10: Start the Stack

Terminal 1 - Start rigctld and freedvtnc2:

rigctld -m 3088 -r /dev/ttyUSB0 -s 19200 -t 4532 -P RTS &

freedvtnc2 --input-device 1 --output-device 1 --mode DATAC1 \
    --rigctld-port 4532 --kiss-tcp-port 8001 --kiss-tcp-address 0.0.0.0 \
    --ptt-on-delay-ms 300 --ptt-off-delay-ms 200 --output-volume -3

Terminal 2 - Start NomadNet:

nomadnet

Step 11: Test Transmission

In NomadNet:

1. Select Network tab
2. Send an announcement

Radio should key up for 3-5 seconds and transmit.

---

Troubleshooting

Hardware Verification

lsusb                      # List USB devices
arecord -l                 # List audio devices
ls -la /dev/ttyUSB*        # List serial ports

CAT/PTT Test

rigctl -m 3088 -r /dev/ttyUSB0 -s 19200 T 1  # Key transmitter
rigctl -m 3088 -r /dev/ttyUSB0 -s 19200 T 0  # Unkey transmitter

Reticulum Status

rnstatus                        # Interface status
tail -f ~/.reticulum/logfile    # Live log

Common Issues

No /dev/ttyUSB0:

• Check USB cable connection
• Verify Digirig is powered (LED lit)
• Run dmesg | tail after plugging in

CAT command fails:

• Verify baud rate matches radio (G90 uses 19200)
• Check user is in dialout group
• Try rigctl -m 3088 -r /dev/ttyUSB0 -s 19200 f

No audio device:

• Run arecord -l to find device number
• Adjust --input-device and --output-device in freedvtnc2 command

Radio not keying:

• Test PTT manually: rigctl -m 3088 -r /dev/ttyUSB0 -s 19200 T 1
• Check G90 is in correct mode (USB-D for data)
• Verify rigctld is running on port 4532

WiFi AP not visible (pre-built image):

• Wait 60 seconds after power on
• Check Pi LEDs (solid green = booted)
• Power cycle Pi

Sideband won't connect (pre-built image):

• Verify connected to ReticulumHF-Setup WiFi
• Check rnsd running: ssh pi@192.168.4.1 "systemctl status reticulumhf-rnsd"
• Verify port 4242: ssh pi@192.168.4.1 "ss -tlnp | grep 4242"

Verified Hardware

Component	Model	Notes
Computer	Raspberry Pi 4 (4GB)
Radio	Xiegu G90	Hamlib 3088, PTT via RTS
Radio	Yaesu FT-818	Hamlib 1020 (use FT-817), PTT via RTS
Radio	(tr)uSDX	VOX mode (no CAT PTT)
Interface	Digirig Mobile	CAT + Audio
Interface	Digirig Lite	Audio only (use VOX)
Phone App	Sideband (Android)	Port 4242
Desktop App	MeshChat	Port 8001, KISS framing

References

Software:

• Reticulum Manual: https://markqvist.github.io/Reticulum/manual/
• codec2 Data Modes: https://github.com/drowe67/codec2/blob/main/README_data.md
• freedvtnc2: https://github.com/xssfox/freedvtnc2
• Sideband: https://github.com/markqvist/Sideband
• MeshChat: https://github.com/liamcottle/meshtastic-meshchat
• NomadNet: https://github.com/markqvist/NomadNet
• Hamlib Supported Radios: https://github.com/Hamlib/Hamlib/wiki/Supported-Radios

Propagation:

• prop.kc2g.com: https://prop.kc2g.com/ - Real-time MUF/foF2 maps
• VOACAP Online: https://www.voacap.com/hf/ - HF propagation prediction
• HamQSL Solar Data: https://www.hamqsl.com/solar.html - Current solar indices

License

MIT License - See LICENSE file

Author

Light Fighter Manifesto L.L.C. https://lightfightermanifesto.org