AMRAD-OSCAR 27 as well as EYESAT-1 or simply AO-27 is a satellite similar to UO-14. Of everything on board, it is the most interesting for radio amateurs FM Crossband Prevádzač. Dvanásťkilogramový satelit na obežnú dráhu s inklináciou 98,5° a dobou obletu 101 minút vyniesla Ariane 4, ktorá odštartovala 26.septembra 1993 01.47 UTC z Korou vo Francúzkej Guayane.
The shuttle carried a German laser reflector, Healthsat-II, PoSAT-1, and amateur satellites KITSAT-OSCAR-25 (KO-25) and Italy-OSCAR-26 (IO-26).
EYESAT-1 is a MICROSAT-class satellite built by Interferometrics Inc. of Chantilly, Virginia to monitor the movement of vehicles in industry. On board is the AO-27 converter, which was constructed by the members AMRAD P.O. Drawer 6148 McLean, Virginia, USA, 22106-6148, a technically oriented, non-profit, amateur radio organization.
AO-27 má kryštalom riadený FM prijímač na 145,850 MHz a tiež kryštalom riadený FM vysielač približne na 436,795 MHz s výstupným výkonom: cez 1W (zriedka používané); 0,5W alebo pod 0,1W (only from the exciter). The uplink antenna is a linearly polarized whip on the front of the satellite, the downlink antenna is 1/4 on the side of the satellite. The rotation and turning of the satellite thus causes a relatively significant effect QSB.
Aby satelit mohol pracovať mnoho rokov pri limitovanom množstve energie je zapínaný iba na časť obletu. Prevádzač je zapínaný, keď jeho imaginárna stopa na Zemi presiahne 37° severnej šírky pri osvetlení solárnych panelov, sometimes also during weekend and evening flights. After five years of operation, this philosophy proved to be correct, as the on-board battery showed only minimal wear.
Ako každý FM prevádzač, aj AO-27 môže v jednom okamihu prevádzať len jediný signál. In order for multiple stations to be able to communicate during the flyby, the cooperation and consideration of the individual operators is necessary - above all, listen before we press PTT.
Prijímač AO-27 je veľmi citlivý, dobrý signál je možné dosiahnuť už s 25W do priemerne ziskovej všesmerovej antény. Na uplink frekvencii nie je nutné korigovať Dopplerov posun frekvencie. S citlivým UHF FM prijímačom, predzosilňovačom a všesmerovou anténou je možné signál AO-27 prijímať s únikom, with a smaller directional antenna, the signal is already solid. The Doppler frequency shift at 436.795 MHz is already +/- 9 kHz and must be corrected.
Signál na downlinku je o 4-7 dB slabší oproti UO-14. Pri výkone 0,5W a vzdialenosti 800 – 3200 km medzi operátorom a satelitom je jasné, že s „gumovou“ anténou sa uspieť už nedá. At best, the signal will be very weak and unstable. When using 1/2 antenna, the recommended sensitivity of the receiver is at least 0.18uV 12 dB SINAD, if we want to achieve at least an average signal at an elevation of 10° or more. Improvement can be achieved by using a reflector and rotating the antenna.
For the first attempts, it is advisable to choose weekend tours with a higher elevation. We open the squelch and try to capture signals from the converter around the downlink frequency. UFB is tuning after 1 kHz, in emergency at least after 5 kHz. We have to 100% understand the station we want to call, if we have a suitable device for 2 m, we will give our call once or twice. And we are waiting for an answer….
The latest information is available from Weekly Satellite Report, the official AO-27 website http://www.ao27.org/ a AMRAD In Space — AO-27 .