Perytons and pigeons: learning about signal and noise

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I enjoyed reading Emily Petroff’s post in The Conversation (25 May 2015).

She raises some fascinating issues in her discussion of signal and noise at Australia’s Parkes radio telescope. Her discussion took me back to Arno Penzias and Robert Wilson’s work in the 1960s at the Bell Labs antenna in New Jersey.

Emily reports attempts at Parkes to identify the human-generated origin of pulses evident in data collected. She noted Sarah Burke Spolaor’s work published in 2011. In her paper, she notes:

The new detections cast doubt on the extragalactic interpretation of the original burst, and call for further sophistication in radio-pulse survey techniques to identify the origin of the anomalous terrestrial signals and definitively distinguish future extragalactic pulse detections from local signals.

Sarah called these anomalous terrestrial signals perytons.

Emily outlines work undertaken since 2011 to discover the source of the perytons. I do think her account is a great example of forensic attention to detail required when assertions are being made from data.

This is where I went back to the 1960s … and the search for cosmic background radiation.

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In 1964, Arno Penzias and Robert Wilson detected radio signals at the Bells Labs antenna. They wanted to be sure that these signals were not coming from New York or nuclear tests in the Pacific.

They removed two pigeons from the antenna too.

Throughout their search for the source of anomalous signals, the original radio signals remained. This led Arno and Robert to conclude “it was not the machine and it was not random noise causing the radiation”.

Their work led to the award of the Nobel Prize for physics in 1978 for their discoveries of cosmic background radiation … the signal they had detected in the noise of early data collection.

Photo Credits

The Dish (Luke Chapman, CC BY-NC-ND 2.0)

1933-30 (ITU Pictures, CC BY 2.0)

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