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2024 Radio Topics




  • FT8900 : 2m I-Gate GM4SLV-2 - Raspberry Pi, TNC-Pi and APRX I-Gate software
    • UPDATE 6/4/24 : 2m APRS suspended. Coverage not adequate from low 2m antenna.
  • TM-D710 in van : GM4SLV-9 - will digipeat “WIDEn-N”
  • TH-D72 : GM4SLV-8
  • Anytone 878
    • analogue : GM4SLV-7,
    • DMR
      • Brandmeister → PC 234999 (Self-Care set to GM4SLV-7)
      • DMR+/Phoenix → PC 5057 → GM4SLV-7


  • Occasional use of 30m AFSK 10,147.6kHz USB as GM4SLV-10
    • IC-706 and Signalink-USB soundcard


  • Direwolf
    • HF (300 baud FSK) or VHF soundcard modem/TNC
    • AGW Packet Engine TCP/IP interface to other software
    • standalone iGate and Digipeater
  • Xastir
    • Can use the Direwolf TCP/IP AGW TNC across network
    • Can act as TCP/IP KISS mode TNC providing 300 or 600 baud Robust Packet TX/RX and also simultaneous 300 baud FSK RX
  • APRSISCE32 aprsis32.zip
    • Can use WinRPR's KISS mode TNC
  • UIView32 32full203.exe

HF Frequencies


  • 300 Baud FSK RF centre 10149.3kHz
    • 1700 Hz audio (1600/1800Hz tones)
    • Dial = 10147.6kHz USB
      • alternative dial = 10151.0kHz LSB (signal can be inverted without issues)
  • 300 baud RPR RF centre 10148.8kHz
    • 1500 Hz audio
    • Dial = 10147.3kHz USB
      • Normal 300 baud AFSK resolves at 2000Hz - and is decoded by WinRPR at this offset

Direwolf update : 10/04/24

  • Direwolf v1.6 in Debian has a minor annoyance - it decodes its own transmitted frames occasionally due to cross talk in the sound card
  • This is reported to be fixed in 1.7 release so I cloned the git repository and built the current 1.7 version
  • It has removed the annoyance of seeing (and reporting to APRS-IS) your own transmitted packets
  • There are other changes and improvements which I will investigate over time.
  • Steps to clone/build
sudo apt-get install libavahi-client-dev
git clone https://www.github.com/wb2osz/direwolf
cd direwolf
mkdir build && cd build
cmake ..
make -j4

Running the new version

cd src
./direwolf -c ~/direwolf.conf

A few red warnings due to changes for v1.7 not being fully compatible with the previous config options, but it runs and doesn't seem to decode its own transmissions any more.

A few tweaks to the config:

ADEVICE  plughw:2,0
#MODEM 300 7@30
MODEM 300 B+
PBEACON sendto=0 via="WIDE1-1" delay=0:00 every=10:00 symbol="\-" lat=60^17.31N long=1^25.51W comment="30m HF Direwolf AFSK"
#FILTER 0 0 ( ! d/* )
#FILTER 0 0 (! b/GM4SLV-10 )
#IGSERVER euro.aprs2.net
#IGLOGIN GM4SLV-10 19626
#PBEACON sendto=IG delay=0:30 every=60:00 symbol="\-" lat=60^17.31N long=1^25.51W comment="30m AFSK RX Igate"
DIGIPEAT 0 0 ^WIDE[3-7]-[1-7]$|^TEST$ ^WIDE[12]-[12]$ PREEMPT
  • I will remove the Debian version 1.6 and sudo make install the newly compiled v1.7 once I'm happy with it.
  • This version also decodes FX25 packets - which I don't fully understand yet
SP6PGH-10 audio level = 53   FX.25   75_______
[0.1] SP6PGH-10>APWW11,WIDE1-1:>100639zTest HF APRS station
Status Report, APRSISCE win32 version
Test HF APRS station
[0H] SP6PGH-10>APWW11,GM4SLV-10*:>100639zTest HF APRS station
  • a normal AX25 packet
IW4EGP-10 audio level = 46    _|||_____
[0.2] IW4EGP-10>APU25N,WIDE2-2:=4403.57N/01233.72E&APRS HF 30m -/D R-I  H24 {UIV32}<0x0d>
Position, HF Gateway  <= the original primary table definition, UIview 32 bit apps
N 44 03.5700, E 012 33.7200
APRS HF 30m -/D R-I  H24 {UIV32}
[0H] IW4EGP-10>APU25N,GM4SLV-10*,WIDE2-1:=4403.57N/01233.72E&APRS HF 30m -/D R-I  H24 {UIV32}<0x0d>
  • both of these are also digipeated my me, shown on the last line is my outgoing digipeated packet:
    • [0H] SP6PGH-10>APWW11,GM4SLV-10*:>100639zTest HF APRS station
    • [0H] IW4EGP-10>APU25N,GM4SLV-10*,WIDE2-1:=4403.57N/01233.72E&APRS HF 30m -/D R-I H24 {UIV32}<0x0d>

John Pumford-Green 21/03/24 16:14

Last Update : 10/04/24 09:08 BST

Further Information

Direwolf v1.7 User Manual user-guide_1_.pdf
aprs.fi https://aprs.fi/info/a/GM4SLV-10
public/radio/2024/aprs.txt · Last modified: 10/04/24 09:08 BST by john