Winter 2009 Issue


Beckoning Beacons, Part 2

By Dr. H. Paul Shuch, N6TX

In last quarter’s column, we discussed the challenges of calibrating amateur and professional SETI receiving stations (please see box with figures A and B). We concluded that a narrow-band signal from space, such as the S-band telemetry beacon aboard NASA’s Pioneer 10 spacecraft, would be ideal for this purpose. Unfortunately, that particular beacon now is not only beyond the edge of our solar system, it is also beyond the range of reception by even Earth’s most sensitive radio telescopes. In 2001, the nonprofit, grass roots SETI League sought to create a Pioneer 10 surrogate for use by radio astronomers around the world.

Radio amateurs have successfully been bouncing microwave signals off the rough lunar surface and detecting their echoes back on Earth since 1960. In 2001, SETI League members exploited the EME (Earth-Moon-Earth) path from W2ETI, their club station in New Jersey, for the benefit of radio astronomers worldwide. As seen in figure 1 and reported in QST1, W2ETI’s weak EME signal on 1296 MHz, its frequency precisely calibrated to atomic-clock accuracy, was first detected at the 20-watt level by the Arecibo Observatory in Puerto Rico, the world’s largest radio telescope. The beacon subsequently was copied by a handful of radio amateurs possessing state-of-the-art stations, including a few reception reports logged during ARRL EME Contests, although its low power limited its utility, restricting reception to only the best equipped stations. Clearly, more power was needed to turn this facility into a truly universal calibration source.

More Power Needed

Over the next two years, the author and station trustee Richard Factor, WA2IKL, upgraded the W2ETI beacon to automatic tracking, remote monitoring, and unattended QRO operation, with the addition of a solid-state power amplifier.

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