cpdlc

[Narf]

                                                           
I use airnav to track hf flights in the shanwick oceanic area and have heard many flights saying "we are cpdlc, requesting selcal check on xyza" after some research and tv watching i have found out that it is a text message for planes, similar to acars. does anyone know what frequecy they operate on or how to intercept them.
any help greatly appriciated,
Paul.

[KSYR-pjr]

I use airnav to track hf flights ...

Request for more information:  Is that Airnav as in Airnav.com?   If so, how do you use Airnav to track HF flights?   I have been an avid user of Airnav's site for years and never knew this was a feature.

Thanks.

[sean]

Request for more information:  Is that Airnav as in Airnav.com?   If so, how do you use Airnav to track HF flights?   I have been an avid user of Airnav's site for years and never knew this was a feature.

Thanks.

He's referring to the software, http://www.airnavsystems.com/    Perhaps there's a connection?

CPDLC is Controller-Pilot DataLink Communication, and in the US (I believe) is operating on 136.700 MHz via VDL Mode 2.  Unfortunately, VDL is D8PSK (Differential 8 Phase Shift Keying) and is not the easiest thing for the hobbyist to decode. 

Sean

[KSYR-pjr]

Thanks, Sean.  I was unaware of this PC-based utility.

[Narf]

                                                           
I see, I see, (said The Blind Man)
well the closest i can get to thas it hfdl.
there is also a transponder in the aircrafts radar system which is said to give out position reports every second or so. But i am only a student and cant afford the reciever bundle that is out there (700 smackers). can i use my good old soundcard and scanner (or hf) to do anything with this.
As usual, any help greatly apreaciated.
Paul.
P.S is there any fourms directly aimed at amateur flight tracking??

[sean]

                                                           
there is also a transponder in the aircrafts radar system which is said to give out position reports every second or so. But i am only a student and cant afford the reciever bundle that is out there (700 smackers). can i use my good old soundcard and scanner (or hf) to do anything with this.

It sounds like you are referring to ADS-B.  That would actually be easier to do than VDL, but still hasn't been done.  About the only thing (aviation related) you can decode with a PC is ACARs.