| 摘要 |
<p>A standard deviation of an amplitude is determined on a predetermined time of a beat signal between a transmission signal and a reception signal, and a threshold value is determined by adding a predetermined value to the standard deviation or by multiplying the standard deviation by a predetermined coefficient. Whether or not the beat signal is interfered is detected in accordance with the presence/absence of an amplitude larger than that threshold value. For example, an amplitude exceeding the value of the standard deviation multiplied by 2 is deemed as a spike noise (SPN), that is, as "interfered", and the threshold value for detecting the peak to appear on a frequency spectrum is raised. Thus, the detection of presence/absence of the spike noise to be superposed on the beat signal is made more reliable so that the operations can accord to the presence/absence of the interference.</p> |
