AO-51 "Echo" Contact at the 2007 Dayton Hamvention

AO-51 is also known as "Echo". It is in low earth orbit with an altitude that varies from about 700 to 800 kilometers. The satellite itself is a cube that measures 25 centimeters on a side. When you do the math, that is less than 10 inches per side. The satellite supports several different modes: Mode V/U FM voice, Mode V/U FM voice in QRP mode, Mode V/U packet BBS at 9600 bps, Mode V/S FM voice, Mode L/U FM voice, Mode L/U packet BBS, Mode L/S FM voice, Mode L/S packet BBS at 9600 bps, and mode A/U with PSK31 on the uplink and FM on the downlink. The most commonly used mode is V/U FM voice. In the past the satellite required a CTCSS tone of 67 Hz on the uplink, but that is no longer the case. The satellite is pretty easy to work with the Arrow Antenna as used in the video and a dual-band handie-talkie. A HT that supports full duplex capability is preferred as it allows you to listen to yourself on the downlink. You typically need to use a headset to prevent audio feedback, and you need to adjust for Doppler on the downlink. The Doppler Effect occurs on the uplink as well, but your signal will generally stay within the passband of the satellite's receiver.

Last updated Friday, April 4, 2014. ©2004 - 2014 by Edward S. Raybould.  Extracting written content, images, audio clips, video clips, applets, and ActiveX controls, without written permission from the author is expressly prohibited.

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