Advantages: Any radio + computer combination works, for example UVK6, without needing any other hardware.
Disadvantages: If the radio cannot be operated using serial communication, sending data can be more complicated.
- Make it possible to send audio from the speaker to a computer.
For the UVK6 handheld radio, you'll need an audio cable to connect the radio's output to your computer's microphone jack. Since the radio has a 2.5mm connector, you'll also need an adapter cable. You can use any of the inexpensive PDD radios.
I also have a DM9100, which has a 3.5mm audio output. You can simply plug a 3.5mm internal microphone cable directly into it and connect it to your computer's microphone.
If it's a radio like Yaesu with an integrated sound card, you can connect your computer and see a microphone device; that's the source of the audio played by the radio.
2. Configuring direwolf
In the 1980s, decoding AP systems required the use of hardware TNCs. Direwolf is an APRS modulation and demodulation software that allows for decoding using audio alone, without requiring any hardware devices. Many third-party APRS terminals have incorporated its libraries.
Latest version 1.8 https://github.com/wb2osz/direwolf/releases
Download the zip package directly from the release page. Unzip and use immediately.
First, double-click direwolf.exe to run it.
You will see the following message.
What we need to do is remember the numbers for the audio input and output devices here. For example, on my computer, I can see that there are 4 microphones (numbered 0 to 3) and 4 speakers. Since I've connected FTX-1, the 2nd device is FTX-1's input audio, and the 3rd device is FTX-1's output audio. So, we should record it as "2 2".
If I need to send audio from my UVK6 or DM9100 to a computer, I would connect the Line-in and output of the sound card, which are labeled "3 0".
To open the direwolf.conf configuration file, use a text editor. We need to edit the startup parameters.
If you find it too cumbersome, you can also delete this file or rename it, and manually enter the following parameters.
ADEVICE 4 1 # ADEVICE: Specifies the sound card. Format: ADEVICE <Input devices> [Output Device]
CHANNEL 0 # Channel 1 (left channel of the sound card or mono channel)
ARATE 44100 # Audio interface sample rate: The default is 44100, but Yaesu recommends 48000. This doesn't make a big difference; both the radio and DW will automatically convert.
MYCALL BI7KGD-10 # Radio callsigns and common SSIDs: -7 (handheld), -9 (mobile), -10 (IGate), -13 (weather station).
MODEM 1200 # Configure modem speed and type: 1200 baud rate (most common for VHF/UHF).
PTT COM4 RTS #Yaesu uses this to control the radio's PTT function. This corresponds to the radio's standard COM port in the device manager. The FTX-1 also requires setting "[MODE FM] menu to [RPTT SELECT] (Remote PTT Select) to RTS. You can also use VOX for hands-free PTT transmission, but each radio has different opening thresholds and times. It is not recommended to use the VOX method. The manual strongly recommends against using the radio's built-in VOX due to excessive delay, which can cause signal conflicts. If you must use VOX, please use an external VOX such as SignaLink USB and adjust the delay to the minimum.
AGWPORT 8000
KISSPORT 8001: These two parameters are intended for use with third-party software. If you do not need them, you can ignore them or set them to 0.
IGTXLIMIT 6 10 # Limits access from the internet (APRS-IS) Data packet rate sent to RF (radio), to prevent flooding of the local radio channel. It is not recommended to use IS-RF functionality, as this will cause some high-frequency internet APRS packets to be repeatedly transmitted via radio signals. The "6 10" represents a maximum of 6 packets within 1 minute and 10 packets within 5 minutes.
IGSERVER china.aprs2.net # Specifies the China Tier 2 server
IGLOGIN Callsign 12345 # Set the callsign and APRS-IS password required for connecting to the APRS-IS server.
TXDELAY 30 # This specifies a delay of 30 * 10 ms (300 milliseconds). It represents the time Dire Wolf waits after PTT (pressing the transmit key) before it starts sending actual data packets. This delay is to allow your radio transmitter to stabilize properly.
FX25TX 1: Adds error correction codes to standard AX.25 packets; 1 represents the default automatic setting.
Then, the next step is to configure the BEACON beacon if needed. Typically, only two types are used.
PBEACON: Used for sending location reports from a fixed position.
CBEACON: Used for sending custom data packets.
For example
PBEACON SENDTO=IG EVERY=10:00 SLOT=02:29 LAT=31^.N LONG = 121^.E COMMENT="E1 [This is a comment]" POWER=25 HEIGHT=40 GAIN=3 FREQ=145.1
SENDTO=IG: The beacon will be sent to APRS-IS (the Internet), not via radio. (RF) Transmit. If SENDTO=0: The beacon will transmit via radio channel 0 (RF) Launch
EVERY = 10:00, SLOT = 02:29: Send once every 2 minutes and 29 seconds, or every 10 minutes and 0 seconds. LAT = 31°.N LONG = 121^.E: Specify the fixed latitude and longitude of the reference point.
COMMENT = "...": Comment information associated with the beacon. The E1[] will be displayed in rainbow colors on aprs.tv.
POWER = 25 W, HEIGHT = 40 ft, GAIN = 3 dBi: The transmitting power is 25 watts. The antenna height is 40 feet, and the gain is 3 dBi.
FREQ=145.1: Voice (Monitoring) 145.1 MHz. The Yaesu transceiver can be easily tuned to this frequency with a single button press.
PBEACON SENDTO=0 EVERY=1:00 SLOT=00:59 LAT=31^.N LONG = 121^.E POWER = 25 HEIGHT = 40 GAIN = 3 FREQ = 145.1 VIA = WIDE1-1
VIA = WIDE1-1: The beacon will use the WIDE1-1 path for digital relaying.
This line configures Dire Wolf to transmit a fixed location report via radio channel 0 every minute (at the 59th second), with the path being WIDE1-1.
The final configuration file will look like this:
Once you have saved the configuration file, you can restart DireWolf again.
(Note: By default, double-clicking will start direwolf.conf, the configuration file. If you are using a different configuration file, you need to specify it with the -c parameter followed by the .conf filename. The details of this are not included here.)
After a while, you should be able to see the received signal as shown in the diagram above. You will also send the data packets you receive to the APRS website, and your station will appear on aprs.tv.
Audio level = 47(12/8) _ This is the received signal audio level. 47 represents the signal strength.(12/8) This refers to the relative level between Mark and Space tones.||This is a simple spectrum display showing decoder activity. If the peak isn't centered, with horizontal bars indicating left and right offset, it indicates that the volume may be incorrect and needs to be adjusted.
In reality, Direwolf's decoding capabilities are far superior to that of the "computer." The APRS data packets I successfully decoded using my FTX-1 were probably only about one-tenth of those that could be decoded simultaneously using a computer with Direwolf. This method doesn't require a Raspberry Pi or any other hardware; you can even use your headset microphone and hand radio to operate it (though this is not recommended, as the audio quality loss makes decoding difficult).
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