SETI: The transmission rate of radio communication and the signal's   detection
  The transmission rate of communication between radio telescopes on Earth and extraterrestrial intelligence (ETI) is here calculated up to distances of 1000 light years. Both phase-shift-keying (PSK) and frequency-shift keying (FSK) modulation schemes are considered. It is shown that M-ary FSK is advantageous in terms of energy. Narrow-band pulses scattered over the spectrum sharing a common drift rate can be the probable signals of ETI. Modern SETI spectrum analyzers are well suited to searching for these types of signals. Such signals can be detected using the Hough transform which is a dedicated tool for detecting patterns in an image. The time-frequency plane representing the power output of the spectrum analyzer during the search for ETI gives an image from which the Hough transform (HT) can detect signal patterns with frequency drift. 
P. A. Fridman
astro-ph.IM