Q Is there software available that will allow me to copy ACARS packet transmissions using my PC’s sound card as the analog-to-digital converter?
A For those who may be unfamiliar with the term, ACARS refers to packet data transmissions sent to and from commercial airliners and other ACARS-equipped aircraft. Flight crews use ACARS to report conditions aloft, request information, report minor problems, receive information from their companies and so on.
In the US you’ll hear the 2400-baud AM FSK bursts at 131.550 MHz, with 130.025 and 129.125 MHz as alternate frequencies in busy areas. Interest in ACARS monitoring has increased somewhat in recent years because so many hams own radios capable of receiving in the aeronautical band. ACARS transmissions sound like 1200-baud amateur packet, but at a higher audio pitch. The bursts are also much shorter in duration.
The Doctor knows of at least one freeware ACARS decoder for Windows that utilizes SoundBlaster-compatible sound cards. It requires a Pentium-class PC, but not a speed-demon computer. The software is known as WACARS and you’ll find it on the Web at http://www.mike.mcmail.com/acars.html.
From QST January 1999
