So it turns out that the great Hollywood star Hedy Lamarr played a role in enabling such technologies as Bluetooth. She had been married in Germany before the war to a man who made military equipment. He explained to her how easy it was to jam the guidance signal in enemy torpedoes. When she realised he was selling his products to the Nazis, she ran away from him, ending up in Hollywood. While there she seems to have invented a frequency-hopping transmitter, which generates a signal that is far harder to jam.
Bluetooth uses frequency-hopping to minimise collisions between messages that are being sent, both between Bluetooth devices and those on wifi, which uses the same frequencies.
I discovered this while reading my textbook on Networks, by Tanenbaum. Here is a link to the e-book:
http://books.google.co.uk/books?id=Pd-z64SJRBAC&dq=tanenbaum+networks&pg=PP1&ots=RBMSCs0ZhF&sig=nXybWj9LSUmHKpL9ACvcNbo44eQ&hl=en&prev=http://www.google.co.uk/search?q=tanenbaum+networks&ie=utf-8&oe=utf-8&rls=org.mozilla:en-GB:official&client=firefox-a&sa=X&oi=print&ct=title&cad=one-book-with-thumbnail
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