Software Modems

Software Modems:

Software solutions to decode satellite telemetry.

Today we no longer need hardware modems to receive, transmit, decode and encode digital signals. Computers and software make it possible to this all with the help of programs that are made just for this task. Below a list of populair and great programs that give you the ability to just this without the need of a hardware solution.

AGW Packet Engine

It is a special Windows utility for amateur radio packet users that interfaces multiple packet programs and multiple TNCs (Terminal Node Controllers) / modems.

  • let one TNC be used by more than one packet program
  • let one packet program use more than one TNC
  • let your sound card be used as a physical TNC or modem — no need to buy a TNC

WB2OSZ Direwolf

Dire Wolf is a software “soundcard” modem/TNC and APRS encoder/decoder. It can be used stand-alone to observe APRS traffic, as a digipeater, APRStt gateway, or Internet Gateway (IGate). It can also be used as a virtual TNC for other applications such as APRSIS32, UI-View32, Xastir, APRS-TW, YAAC, UISS, Linux AX25, SARTrack, RMS Express, and many more.


The UZ7HO sound modem program is very good example. This program started as a simple replacement for 1200bd AFSK packet but its current releases also supports the list as seen below. Currently there are three versions, the basic soundmodem version a BPSK 9600bd and hs_soundmodem.

UZ7HO Soundmodem

UZ7HO develops a software dual-port Packet-Radio TNC that uses a soundcard as a modem and supports AX.25 protocol (new protocols are being added). It has been tested on Windows XP, Vista, 7, 8, 10 and has proved stable in operation. The Soundmodem has two TCP/IP interfaces to link with client application: AGW PE and (X)KISS. In case of AGW PE interface, this modem is a direct replacement of original AGW Packet Engine and emulates AGW PE API. The Soundmodem may be used to build EMCOMM, APRS, BBS, Node station, for satellites etc.

With the news High-Speed SoundModem version there also extra libraries being added to decode Mobitex and fec. Make sure that all these files are in the main program directory.

Sound-Modem version 96 (16-09-2016)

  • AFSK 300, 600, 1200, 2400 baud.
  • (D)BPSK 300, 600, 1200, 2400 baud.
  • (D)QPSK 2400, 3600, 4800 baud.
BPSK Sound-Modem version 0.04 (06-09-2016)

  • BPSK 9600bd.
HS Sound-Modem version 15 (25-09-2016)

  • G3RUH 9600, 19200 baud.
  • Manchester 1200, 2400, 3600, 7200 baud.
  • HAPN 4800 baud.
  • AAUSAT-4 2400, 9600bd GMSK.
  • BEESAT-4 4800bd Mobitex
  • GOMX-1 2400, 4800, 9600bd GMSK
  • GOMX-3 4800bd GMSK
  • GOMX-3 19200bd GMSK
  • LilacSAT-2 4800bd GMSK

Because there is a lot of development being done, make sure to visit the UZ7HO SoundModem website for the latest versions. Start with the Changelog.txt file.