Radar

#1. Field of the Invention

#The present invention relates to a radar device for detecting a target by using a radio wave.

#2. Description of the Related Art

#FIG. 1 is a block diagram showing a first preferred embodiment of a radar device according to the present invention;

#FIGS. 2A to 2D are diagrams showing a process, performed in the radar device, to determine a peak frequency of a beat signal;

#FIG. 3 is a flow chart showing the entire process performed in the radar device;

#Referring to FIGS. 1 to 3, a first preferred embodiment of a radar device according to the present invention is described below.

#FIG. 1 is a block diagram showing the construction of the radar device. In FIG. 1, reference numeral 1 denotes an RF block, and reference numeral 2 denotes a signal processing block. The RF block 1 transmits and receives radio waves for detecting a target via radar. A beat signal between transmitted and received radio waves is output from the RF block 1 and supplied to the signal processing block 2. A modulation counter 11 in the signal processing block 2 converts a count value into a triangular-shaped signal via a microprocessor 14. A digital-to-analog converter 10 converts the value output from the modulation counter 11 into an analog signal and outputs the resultant analog signal to a VCO 8 in the RF block 1. The VCO 8 generates an oscillation signal frequency-modulated in accordance with the triangular-shaped signal received from the modulation counter 11.

#The oscillation signal output from the VCO 8 is supplied to a primary radiator 4 via an isolator 7, a coupler 6, and a circulator 5. The primary radiator 4 is located within or in the vicinity of the focal plane a dielectric lens 3. A millimeter wave signal radiated from the primary radiator 4 is focused into a narrow beam via the dielectric lens 3 and transmitted therefrom. If a reflected radio wave from a target such as a car is received by the primary radiator 4 via the dielectric lens 3, the received signal is transferred to a mixer 9 via the circulator 5. In addition to this received signal, a portion of the transmission signal is also applied, as a local signal, to the mixer 9 via the coupler 6. A beat signal having a frequency equal to the difference between the frequency of the received signal and the frequency of the local signal is output as an intermediate-frequency signal from the mixer 9 and applied to an analog-to-digital converter 12 in the signal processing block 2. The analog-to-digital converter 12 converts the received intermediate-frequency signal into digital data. A DSP (Digital Signal Processor) 13 determines a frequency spectrum of the beat signal by performing an FFT (Fast Fourier Transform) on a sequence of data received from the analog-to-digital converter 12.