| 摘要 |
PROBLEM TO BE SOLVED: To provide a signal discrimination method that is excellent in discriminating appearance and vanishing of a signal in the case that an energy change due to presence/absence of a signal (steadily or temporally) is very small due to AGC or fading or the like. SOLUTION: Fast Fourier transform (ST2) is applied to a digital signal to calculate the power spectrum of this signal and to detect a peak output level from this power spectrum (ST4), the output level is sequentially checked in both upper and lower limit directions within a prescribed range in the direction of frequency in the power spectrum, one point each in total two points is detected from both directions in output level points with an output level higher than a prescribed output level calculated on the basis of the peak output level (ST5), and comparing an estimate bandwidth denoted by a frequency difference between the two points with a specified request bandwidth in advance discriminates the appearance and vanishing of the signal (ST8-ST11). |
