Pastimes for the really bored! 24 Nov 2006 GM1SXX
Plane spotter types will probably like this. I was a bit bored, being laid up with a lung problem so to make some use of my time, I decided to experiment with ACARS.
Here's what Wikipedia says about ACARS... http://en.wikipedia.org/wiki/ACARS In essence, ACARS is a packet radio system for aircraft. My experiments to date suggest that ACARS is carried mainly by 'heavies', large transport or passenger aircraft to ease to workload on the pilots. Some smaller aircraft also use ACARS including business jets. I've seen quite a bit of data from Royal Bank of Scotland Bizzjets. (maybe thats why their interest rates are so poor!). I'd like a Dassault Falcon myself, but it's a bit beyond my financial reach <grin>.
Still, back to ACARS. In essence its rather like ordinary AX25 1200 bauds packet but with 1200/2400tones (like UoSAT2) rather than 1200/2200 ones like packet. It sounds just like the all familiar 'seagull squawk' of terrestrial 1200 bauds packet. The aircraft communicate with ground stations at airports around the world. Some of the smaller airfields also support ACARS operations.
The data itself is coded so much of it looks like gibberish. This is where the decoding software comes it. It keeps a database of message codes and aircraft registrations and routes so it can make sense of the coded packets.
In Europe, the primary ACARS frequency is 131.725Mhz AM 6Khz and I've been using my ICOM PCR-1000 set to the 6Khz filter setting. From there, I take the audio via a 3.5mm jack lead to the Line input of one of my PC's. The software I've been using is called WACARS and you can download matching map overlays for your specific area.
131.725 AM 6k Primary European
131.525 AM 6k Secondary European
136.925 AM 6k ARINC European
136.750 AM 6k Secondary European
131.850 AM 6k Secondary European
136.900 AM 6k Secondary European
131.550 AM 6k Worldwide Primary/US Primary channel
130.025 AM 6k USA and Canada Secondary
129.125 AM 6k USA and Canada Overflow
130.450 AM 6k USA and Canada Overflow
130.425 AM 6k USA Overflow
131.125 AM 6k USA Overflow
136.700 AM 6k USA Overflow
136.750 AM 6k USA Overflow
136.800 AM 6k USA Overflow
136.850 AM 6k North American SITA allocation
131.475 AM 6k Air Canada
131.450 AM 6k Japan Primary
WACARS can be downloaded from ... http://home.kabelfoon.nl/~pdw/alp/ and http://home.kpnplanet.nl/~D.Barg@kpnplanet.nl/index.htm
Here's a screenshot of WACARS in action. Much of the traffic is engineering information with some data carrying WX reports or information on aircraft weight, fuel load etc. Just the thing to keep a geek happy. One think I did notice is the number of aircraft flying with faults in their flight computers. Some errors are in the form of a numeric data dump... about as useful as that encountered when MS Windows BSD's and presents you with that screen of gobbledeygook that can only be decoded by a dedicated techie!
Other useful links include.
PDW v2.14 - Windows ACARS Decoder
PC-HFDL ARINC 635-3 Decoder
ACARS LOG ANALYSER