Multipath Interference of Modulated Waves

Transmitter-Receiver systems are operationally defined in a fashion applicable to the treatment of multipath systems 0£ reception. The systems of modulation now in general use are divided into two groups, the continuous wave and the pulse methods, and each is discussed in detail. A method is established for the solution of the continuous wave problem and the solutions considered for several types of continuous wave modulated waves. It is found that to a first approximation none of the methods considered has any degree of superiority in the small percentage modulation case but a second order approximations shows frequency modulation to be superior to amplitude and phase modulation reception under conditions of multipath transmission. The expected wave form of the received wave is evaluated for small percentage modulation conditions. Comparison of the theory with a practical case of reception of frequency modulated waves is made. Methods of solution of the problem of the reception of modulated waves by diffraction as in physical optics are established.