Bulletins from the Pacific Packet Radio Society - page 107

What activity is expected to grow using AMTOR - opinions will be appreciated.

David, W6RAW - Please QSP to your UNIX contacts - I would especially appreciate comments from W8SDZ.

Larry Kayser,


To: All amateur satellite publications

From: Robert J. Diersing, N5AHD

Date: September 8th, 1982

Subj: Transmission and reception of digital packet data via Amsat-Oscar-8, amateur radio satellite


In recent weeks, Dr. Tom Clark, W31WI, of AMSAT and myself decided to begin testing the feasibility of transmitting and receiving packet radio data via satellite. We are both using the Terminal Node Controller (TNC) boards produced by the Vancouver Amateur Digital Communications Group (VADCG). Software was supplied by AMRAD, originally written by Doug Lockhart, VE7APU, and modified a great deal by AMRAD.

After several unsuccessful attempts to receive connect sequences from Tom via mode A we decided to abandon the two-way attempt and I would try to receive my own data. Since I already had three TNCs and two 1200 baud modems available, I would try sending QST packets and receiving them on another system. A small software modification had to be made such that the QST message and CW id were transmitted continuously rather than at 9 minute intervals as allowed by the original software. Better audio matching between modems and radios was also incorporated and testing resumed.

After several unsuccessful attempts, on September 1, 1982, 01:10 UTC, (an experimental day) orbit number 22887 mode J (or possibly AJ since I was not listening on mode A), digital packet data was transmitted and received at N5AHD. In some cases, the three line QST message was partially received and in others it was complete. The mode of transmission was NBFM in the middle of the satellite Mode J passband. At any time the signal was good quieting and the tuning for zero discriminator reading maintained, the copy was successful. No tests on SSB were made during the orbit.

Later, on September 6, 1982t 14:00 UTC, orbit number 22938, with satellite in mode J, several more successful receptions were made this time via SSB. The tuning in this mode was much more difficult which was expected. The number of complete packets

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