Binary communications

The over-all system configuration is presented in Section 7.3.1. In Sections 7.3.2, 7.3.3, and 7.3,4, we consider applications of the system to a cw radar with sinewave, Gaussian/Gaussian, and Gaussian/Lorentzian input signals, respectively. Section 7.3.5 deals with its use in an analog communications system, whereas Section 7.3.6 is concerned with low-frequency applications of the technique. A numerical example in Section 7.3.7 is followed by evaluations of system performance for binary communications and pulsed radar in the vacuum channel (Sec, 7.3.8) and in the lognormal atmospheric channel (Sec. 7.3.9). A discussion is presented in Section 7.3.10. The main results are expressed as the output SNR for the system in terms of the input SNR. 

Application to Binary Communications and Puised Radar (Vacuum Channel)... 

We begin with an investigation of binary communications and pulsed radar for both nonorthogonal and orthogonal signaling formats in the vacuum channel. In Section 7.3.9, we examine envelope probability distributions and... 

Fig. 7.16a. Probability of error vs (SNR), for the three-frequency binary communication system in the vacuum channel. The input signals are assumed to be sinusoidal while the noise is Gaussian. The result for the conventional heterodyne system is shown for comparison (log vs linear plot)...

The digital results, in particular, may be easily extended in a number of directions. Stochastic signals, rather than sinewave signals, could be treated in the binary communication problem. An extensive treatment of M-ary communications is possible, as is the generalization from a single detector to an array of detectors [7.76-78]. Consideration could be given to the optimum matched filter detector rather than the envelope detector discussed earlier. While the present treatment consists of a per-symbol analysis, prediction could be used to estimate the atmospheric turbulence level over a time period from a particular symbol, for example. In short, the usual variations possible with the conventional heterodyne system may be extended and/or modified for application to the three-frequency nonlinear heterodyne technique. 

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