Marconi's Trans-Atlantic signaling. "S S S ... S S S" The frequency used is not known precisely, as Marconi did not measure wavelength or frequency, but it was between 166 and 984 kHz, probably around 500 kHz. He received the signal on the coast of St. John's, Newfoundland using an untuned coherer receiver with a 400 ft. wire antenna suspended from a kite. Shirt design was by a dear friend of mine, VU2BGH Bhogi Gondalia silent key and a former radio officer. He uses the infrequently used prosign "CP" which is addressing a restricted group of stations, rather than the general call to "all" of CQ.