ZERO-CROSSINGS BASED AUTOMATIC MODULATION IDENTIFICATION

Identification of the type of modulation of an intercepted communication signal out of the vast hierarchy of possible modulation types is fundamental before advising a suitable type of demodulator. This process is usually manual. In this paper, a new methodology is suggested- and validated (via computer simulations) for automatic identification of the modulation type (analog and digital) of intercepted communication signals[1]. The methodology is based on zero-based representation of signals and utilization of new algorithms for such identification. Another contribution presented in this paper is a novel ASK modulation and demodulation scheme utilizing zero-manipulation. Zero-crossing analysis describes any of several techniques which make use of information pertaining to the locations in time of successive zero-crossings of a time waveform. Such techniques have found applications for several signal processing and pattern recognition tasks. Some of these tasks include: speech analysis and recognition [2], communications applications [33,...etc. Each of these applications has its specific features regarding the nature of the zero-crossing " data measurements and the features extracted from such data, Someapplications utilize the number of zero-crossings, the other may count the time interval between successive zeros.In this paper we shall try tg extend the prowess of zero-based representations to cover important utilities in the field of identification of unknown modulation of intercepted signals. Further, a novel modulation scheme, based on manipulating the zeros of the base band and carrier waveforms, is illustrated. This scheme has been mathematically and experimentally verified to emulate most analog and digital modulation schemes.