Amsat News carried a brief report of a successful AO-7 Mode B contact between Piraja, PS8RF in Brazil and Jean-Jacques, ON7EQ in Belgium.
Since last week's report, additional information has been received on how they accomplished their 4736 mile (7622 KM) contact.
Jean-Jacques wrote, "As the theoretical window between both stations only lasts about 1 minute, 30 seconds, careful preparation was required for selection of the optimal window and calculation of doppler shifts both ways.
The effective contact was only possible during about 20 seconds, just enough to exchange reports, while both stations met on the transponder within an offset of 500 Hz of calculated frequencies."
Well done and congratulations gents!
PS8RF has posted this video of the Satellite DX event on famous video sharing portal youtube. This video has been linked in the videos section of this website - should you need to review it later!
About AMSAT: The Radio Amateur Satellite Corporation (as AMSAT is officially known) was first formed in the District of Columbia in 1969 as an educational organization. Its goal was to foster Amateur Radio's participation in space research and communication. AMSAT was founded to continue the efforts, begun in 1961, by Project OSCAR, a west coast USA-based group which built and launched the very first Amateur Radio satellite, OSCAR, on December 12, 1961, barely four years after the launch of Russia's first Sputnik.
About AO-7: AMSAT-OSCAR 7 was launched November 15, 1974 by a Delta 2310 launcher from Vandenberg Air Force Base, Lompoc, California. AO-7 was launched piggyback with ITOS-G (NOAA 4) and the Spanish INTASAT. The second phase 2 satellite (Phase II-B). Weight 28.6 kg. Orbit 1444 x 1459 km. Inclination 101.7 degrees. Octahedrally shaped 360 mm high and 424 mm in diameter. Circularly polarized canted turnstile VHF/UHF antenna system and HF dipole.
Similar to AO-6. Built by a multi-national (German, Canadian, United States, and Australian) team of radio amateurs under the direction of AMSAT-NA. It carried Mode A (145.850-950 MHz uplink and 29.400-500 MHz downlink) and Mode B (432.180-120 MHz uplink and 145.920-980 MHz downlink (inverted)) linear transponders and 29.500 and 145.700 MHz beacons. The 2304.1 MHz was never turned on because of international treaty constraints.
Four radio masts mounted at 90 degree intervals on the base and two experimental repeater systems provided store-and-forward for morse and teletype messages (Codestore) as it orbited around the world. The Mode-B transponder was designed and build by Karl Meinzer, DJ4ZC and Werner Haas, DJ5KQ. The Mode-B transponder was the first using "HELAPS" (High Efficient Linear Amplification by Parametric Synthesis) technology was developed by Dr. Karl Meinzer as part of his Ph.D.
Additional information about AO-7 was printed in the September 1974 AMSAT Newsletter.
AO-7 was operational for 6.5 years until a battery failure ceased operation in mid 1981 and now the bird is considered to be semi-operational as it relies solely on solar power for it's operations.
