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somewhat more detail in Sec. 6.2.4.
The performance of the envelope detector in this example is given in Fig.
6.7. The general behavior is very similar to the known phase coherent detector
case of Fig. 6.5. Closer inspection, however, shows that for a given P , the
FA
coherent detector obtains a higher P . To make this point clearer, Fig. 6.8
D
compares the detection curves for the coherent and envelope detectors (known
and unknown phase, respectively), plotted two different ways. Part (a) of the
figure simply repeats the 10-dB curves from the two earlier figures. At P =
FA
–4
10 and χ = 10 dB, for example, P is about 0.74 for the coherent detector. This
D
figure drops to 0.6 when the envelope detector is used.
FIGURE 6.7 Performance of the linear envelope detector for the Gaussian
example with unknown phase.
