A wireless digital transmission and receiving method combines phase reversal keying with pulse position modulation. Modulation of a transmitted signal implements pulses that are of extremely short duration to indicate ones and zeros. These pulses can be as narrow as one cycle of the carrier frequency....http://www.google.de/patents/US6445737?utm_source=gb-gplus-sharePatent US6445737 - Digital modulation device in a system and method of using the same
