Before revision: In effect it was a highly sensitive thermoresistor developed to permit the reception of amplitude modulated signals, something that the coherer (the standard detector of the time) could not do.History of Wireless Tapan K. Sarkar, Robert Mailloux, Arthur A. Oliner, Magdalena Salazar-Palma, Dipak L. Sengupta January 2006, Wiley-IEEE Press page 369 The first device used to demodulate audio signals, it was later superseded by the electrolytic detector, also generally attributed to Fessenden.
After revision: In effect it was a highly sensitive thermoresistor which could recover amplitude modulated signals, something that the coherer (the standard detector of the time) could not do.History of Wireless Tapan K. Sarkar, Robert Mailloux, Arthur A. Oliner, Magdalena Salazar-Palma, Dipak L. Sengupta January 2006, Wiley-IEEE Press page 369 The first device used to demodulate audio signals, it was later superseded by the electrolytic detector, also generally attributed to Fessenden.