Radar apparatuses are currently used in various fields. A fast chirp modulation (FCM)-type radar apparatus is known as one such radar apparatus. This radar apparatus uses a chirp wave of which the frequency continuously increases or decreases, as a radar wave. Furthermore, this radar apparatus measures distance and speed by performing a two-dimensional fast Fourier transformation (FFT) with respect to a beat signal generated from transmission and reception signals thereof. In the FCM scheme, a distance to a target is determined from the frequency of the beat signal generated from the transmission and reception signals. In addition, in the FCM scheme, a relative speed to the target (also referred to, hereafter, as simply speed) is determined from phase rotation of a frequency component continuously detected regarding the same target. However, the speed determined from phase rotation includes ambiguity caused by phase folding back in which when a detected phase is θ, the actual phase may be θ+2π·n (n being an integer) and therefore cannot be identified.
Regarding the foregoing, a technology is proposed in which the ambiguity in the detected speed (that is, speed ambiguity: synonymous with the above-described ambiguity caused by phase folding back) is reduced by sampling of the beat signal being performed at a high speed (refer to PTL 1). That is, to reduce the ambiguity in the speed, a cycle period of the chirp wave is required to be shortened. To do so, the duration of each individual chirp is shortened, while increasing the slope (rate of change) of the frequency in the chirp wave and ensuring a variation width of the frequency. Furthermore, to ensure the number of samplings required for a frequency analyzing process during the shortened period, a higher speed for sampling is required.