APRS hardware set-up

Built — Pending ReleaseRF APRS heard by your station
In Testing · not approved for useAPRS over radio through HAMORA Bridge

What goes into an APRS station with HAMORA: the HAMORA Bridge computer, a TNC, the radio, and the test equipment HAMORA uses. Receiving through HAMORA Bridge comes first. Transmit set-up is here for testing only: it’s In Testing and not approved.

What goes where

Your radio, on your area’s APRS frequency.
A TNC: Dire Wolf with a sound interface, or a hardware KISS TNC, connected to the HAMORA Bridge computer.
HAMORA Bridge on that computer, on your own network.
HAMORA on your phone, on the same network.

Today, with HAMORA Bridge 0.5, this path only receives: see RF through HAMORA Bridge. No HAMORA Bridge installer is published yet. Sending the other way is APRS over radio, part of the first Full APRS release, and In Testing · not approved for use.

The HAMORA Bridge computer

A Raspberry Pi 4 or 5, a Linux computer or a Mac.
On your station’s local network, wired if you can. Your phone joins the same network.
Its clock kept in sync automatically. Transmit checks need a trusted clock.
Never forward HAMORA Bridge’s port (8765) or your TNC’s port from your router. Neither belongs on the internet.

Installing and pairing: see Setting up HAMORA Bridge.

The TNC

Option A: Dire Wolf and a sound interface

Dire Wolf runs on the HAMORA Bridge computer. To receive, the radio’s audio goes into the computer: a radio with a built-in USB sound card, or a USB sound card with an audio cable.

For transmit testing, the interface must also key the radio, with PTT set up in Dire Wolf. Examples: a Digirig (USB audio, plus a serial port whose RTS line keys the radio) or a SignaLink USB (keyed by the audio itself, VOX).

How far it’s checked: HAMORA RF transmission has been verified in a controlled laboratory environment using HAMORA Bridge and Dire Wolf. Real radio transmission testing is pending. No sound interface has been connected yet.

Option B: a hardware KISS TNC

For example a Mobilinkd TNC4, a NinoTNC, or a radio with a built-in TNC in KISS mode, such as a Kenwood TH-D74 or TH-D75.
For receiving with HAMORA Bridge 0.5, the TNC needs a KISS port on the network (KISS over TCP).
For transmit testing, it connects to the HAMORA Bridge computer over USB, as a serial port, and must already be in KISS mode. HAMORA Bridge sends it data only, never commands or settings. Set its timing, such as TXDELAY, with the TNC’s own tool.
How far it’s checked: no hardware TNC has been connected to HAMORA Bridge yet. The names above are examples, not a list of supported TNCs.

The radio

A 2 m (VHF) FM radio that covers your APRS frequency, with a data port, or a mic and speaker cable for the interface.
Your APRS frequency: for example 144.390 MHz in North America, or 144.800 MHz in much of Europe. These are only examples: check your local band plan and your licence. HAMORA keeps no table of APRS frequencies.
A CAT cable, so HAMORA Bridge can read the radio’s frequency and mode back through Hamlib’s rigctld before each packet. See Connect your radio with rigctld. Without CAT, the channel has to be marked as a dedicated APRS radio on the HAMORA Bridge computer, with an explicit acknowledgement that nothing watches its SWR or ALC.
For testing, the lowest power setting the radio has.
A 13.8 V supply rated for the radio’s transmit current, and ferrite chokes on the USB and audio cables against RF feedback.

Test equipment and antenna

This is what HAMORA’s licensed test operators use before anything goes on air. The proposed beta documents ask the same of every invited tester’s first test. See how HAMORA tests RF first.

A 50 Ω dummy load, well matched at 144–148 MHz and rated above the radio’s maximum power. Every first transmission goes into it.
An inline SWR and power meter between the radio and the load.
A monitoring receiver, such as a second radio or an RTL-SDR with a second Dire Wolf, to decode what was sent, independently of HAMORA Bridge.
A 2 m antenna for the on-air steps only, its SWR checked first. During every dummy-load step it’s disconnected and out of reach.

Dire Wolf for receiving

For HAMORA Bridge 0.5, today. Install Dire Wolf on the HAMORA Bridge computer:

On a Raspberry Pi or Linux

sudo apt install direwolf

On a Mac

brew install direwolf

On Windows, or from source

Download it from Dire Wolf’s project page (opens in a new tab).

A minimal receive-only configuration, saved as ~/direwolf.conf:

direwolf.conf

# Audio from the radio's USB sound card
# (find yours with `arecord -l` / `aplay -l` on Linux).
ADEVICE plughw:1,0
ACHANNELS 1
CHANNEL 0
MODEM 1200
# No MYCALL, no PBEACON, no DIGIPEAT, no IGSERVER: nothing is transmitted.
KISSPORT 8001
AGWPORT 0

Change ADEVICE to your sound card. On a Raspberry Pi or Linux, arecord -l lists them: card 1 is plughw:1,0.
Add no PBEACON, DIGIPEAT, IGSERVER or CBEACON lines. Then Dire Wolf has nothing of its own to transmit.

For receiving, leave PTT unconfigured too.

Start it:

direwolf -c ~/direwolf.conf

It prints Ready to accept KISS TCP client application 0 on port 8001. HAMORA Bridge looks for it on 127.0.0.1:8001 every 30 seconds and connects by itself.
Set the radio’s receive audio so Dire Wolf’s “audio level” sits around 30 to 50.
A second receiver is a second Dire Wolf with its own configuration, sound card and port, such as 8002. Dire Wolf 1.8 keeps listening on 8001 as well unless KISSPORT 0 comes first:

KISSPORT 0
KISSPORT 8002

Dire Wolf for transmit testing

What changes from the receive set-up:

PTT. Set up PTT in Dire Wolf for your sound interface, explicitly, for example the serial port line a Digirig uses. Dire Wolf’s own documentation lists the options. Dire Wolf keys the radio; HAMORA Bridge never does.
KISS over TCP stays local. HAMORA Bridge hands packets to Dire Wolf’s KISS port on the same computer. From another device on your network, check that the port is refused.
The AGW port (8000) is optional and recommended. Through it HAMORA Bridge can see when Dire Wolf has taken a packet, so it keeps only one there at a time. Block it from your network too.
Dire Wolf’s own channel checks stay in charge. It waits for a clear channel as usual. HAMORA Bridge never changes Dire Wolf’s settings.
Still no PBEACON, DIGIPEAT or IGSERVER lines: HAMORA’s set-up doesn’t use Dire Wolf’s own beacons, digipeating or IGate.
HAMORA Bridge’s transmit side is set up only in its configuration file on its own computer, never from its setup page or a phone. It’s off until set up there.
Start on the lowest power, into the dummy load, with the antenna disconnected.