Next, an example flow of the approximate replica generation process performed at step S332 in FIG. 26 will now be described below with reference to a flowchart of FIG. 27. In this case, once the approximate replica generation process is started, the amplitude detection unit 321 detects the amplitude of the reception signal subjected to the complex low-pass filtering at step S351. At step S352, the low-pass filter 322 subjects the result (i.e., an amplitude detection signal) of the amplitude detection obtained by the process of step S351 to low-pass filtering. At step S353, the phase detection unit 323 detects the phase of the reception signal subjected to the complex low-pass filtering. At step S354, the complex composition unit 324 subjects the envelope obtained by the process of step S352 and the phase detection result obtained by the process of step S353 to the complex composition.
At step S355, the comparator 325 determines whether or not the envelope obtained by the process of step S352 exceeds the predetermined threshold value TL. In a case where it is determined that the envelope exceeds the predetermined threshold value TL, control proceeds to step S356. At step S356, the switch 326 outputs, as the approximate replica signal, the complex composition result obtained by the process of step S354 to the computation unit 232. After the process of step S356 is finished, the approximate replica generation process is ended, and control returns to FIG. 26.
