DISTANCE MEASURING DEVICE

摘要

From a transmitter (18) and a transmission antenna (10), a first frequency signal of a constant first frequency is transmitted for more than a predetermined time, a second frequency signal of a second frequency different by a certain value from the first frequency is transmitted for more than a predetermined time, and a third frequency signal of a third frequency different from the first frequency by twice the certain value is transmitted for more than a predetermined time. Signals of the transmission frequencies reflected from measurement objects are fed to a receiving antenna (11), a mixer (12), an analog circuit section (13), an A/D converter (14), an FFT (15), and a signal processing section (16). The Doppler frequencies of the reflected waves are determined, and the objects are separately detected for every Doppler frequency. Based on the information on the phase and amplitude of the received signal of each transmission frequency, the objects of the same Doppler frequency are separated and identified. In such a way, even when measurement objects moving at substantially the same relative speed are present, they can be separately detected.