The Marconiscope was a primitive form of radio telescope invented in 1911 by Laurence Scarman. The Fourth Doctor was surprised by this, as the radio telescope was not officially invented for another forty years. When the Doctor first met Scarman, the scientist was happy to demonstrate his new invention. When it picked up the signal from Mars, the apparatus overloaded and couldn't be turned off. It then burned out, at which point the Doctor produced a similar device from his pocket, in order to check and decode the signal. It proved simple to decipher as "Beware Sutekh".