This is an interesting idea. I assume by "frequency modulation" of data, he means adjusting the timing of the transmissions to create an out-of-band channel th

This is an interesting idea. I assume by "frequency modulation" of data, he means adjusting the timing of the transmissions to create an out-of-band channel that might be more difficult to notice when packet sniffing. As a crude example, if I uploaded War and Peace to you, not as a steady stream of traffic, but as bursts of dots and dashes, I could send "The Magic Words are Squeamish Ossifrage" in Morse code. (Although in the context of apps phoning phone, I'm not sure what the advantage is over simply encrypting the stream...)