> AI? What was the training data? Would seem a bit thin on the ground.

It's in the article.

To train the AI system, Ma inserted simulated signals into actual data, allowing the autoencoder to learn what to look for. Then the researchers fed the AI more than 150 terabytes of data from 480 observing hours at the Green Bank Telescope.

The AI identified 20,515 signals of interest, which the researchers had to inspect manually. Of those, eight had the characteristics of technosignatures and couldn’t be attributed to radio interference.

The researchers then returned to the telescope to look at systems from which all eight signals originated but couldn’t re-detect them.

"To be sure, because they don’t have real signals from an extraterrestrial civilization, the researchers had to rely on simulated signals to train their models. The researchers note that this could lead to the AI system learning artifacts that aren’t there.

Still, Cherry Ng, one of the paper’s co-authors, points out the team has a good idea of what to look for.

“A classic example of human-generated technology from space that we have detected is the Voyager,” said Ng, who studies fast radio bursts and pulsars, and is currently affiliated with the French National Centre for Scientific Research, known as CNRS.

“Peter’s machine learning algorithm is able to generate these signals that the aliens may or may not have sent,” she said."

Couldn't you train it to find things that don't correlate to anything from a given dataset that also pattern to non-random/unnatural signal?

They just asked ChatGPT to look /s