Phase 3D (AO-40) Decoder

realtime soundcard modem & telemetry internet server

This program demodulates the telemetry data signal transmitted by the AO-40 satellite (aka Phase III-D) using the PC sound card. 

The modulation format used by the satellite is quite simple: it's a 400 BPSK Manchester-encoded transmission, frame oriented, no FEC, CRC 16 bit certified, containing 512 bytes of ASCII and binary data. 

In my opinion this format is quite inefficient due to the unnecessary Manchester encoding and the lack of any form of forward error correction wich make this simple system very prone to errors (one single bad received bit corrupts the whole frame). A simple convolutional code R=1/2 K=7 would have been wonderful.

This decoder program can run as Internet Server so the demodulated data can be available world-wide in realtime for everybody! 

Analysis of telemetry data is usually done (locally or remotely) with  the well known Stacey Mills' P3T program. To make the server of telemetry-data running, just click on the button "Start Server". You can have both programs running on the same machine, in this case specify the address as server address in the P3T program. The port number is 2001. Specify blocks of 514 bytes. Of course you also must have the TCP/IP protocol installed for server to work. 

The program provides also file-oriented logging of received blocks for processing with external programs (i.e. the DOS-based  TLMDEC.EXE program provided by Amsat-France). Blocks are written (appended) to the file P3D.TLM placed in the program's directory. 

Note for eventual software developers: at receiving of each block the registered Windows message IZ8BLY_P3D is broadcasted so you know exactly when in the file P3D.TLM is updated with fresh informations (the last 514 bytes). 

Note for slow PC owners: for the lastest version I've worked hardly to optimize the source code, so now it virtually runs on every PC (ever slower ones) with Windows 9x. 80486 processor isn't anyway supported.

Note for everybody: at this time there isn't any help file and I have reduced possibility to reply everybody on how to setup the program, doing connections, how to tune and so on. If in trouble please ask on the mailing list (see below) there are many kind people that will give a prompt help. 

If you want to contact me write to:
Nino Porcino IZ8BLY
Via dei Tulipani 21,
89133 Reggio Calabria,

If you want to support the development of the program you can make a donation of a small amount of your choice via the PayPal secure payment service. The donation is completely optional.

Download the program now!

Click here to dowload the V0.5 released 9 Dec 2000

2000-2004 Nino Porcino