Good point: a moderately advanced civilization is likely to have no high-power baseband communication. Only intentional alien interstellar transmissions are lik

Good point: a moderately advanced civilization is likely to have no high-power baseband communication. Only intentional alien interstellar transmissions are likely to be powerful enough and decodable. Earth has made several intentional transmissions (https://en.wikipedia.org/wiki/Active_SETI https://en.wikipedia.org/wiki/Active_SETI) but it's unclear if we'll send any more, because they might attract hostile aliens.