초록 ▼

In an FMCW radar system, the velocity of obstacles relative to the radar couples a Doppler frequency shift into the return signal which causes an error in the range measurement. It is known to use a radar signal having a frequency ramp that both increases and decreases to distinguish the range of an

In an FMCW radar system, the velocity of obstacles relative to the radar couples a Doppler frequency shift into the return signal which causes an error in the range measurement. It is known to use a radar signal having a frequency ramp that both increases and decreases to distinguish the range of an obstacle from its velocity but when multiple obstacles are present this is not practical. By using a measure of velocity from a succesion of return signals, which of the radar output signals from the upsweep and downsweep of the radar signal that relate to a particular obstacle can be identified so that the range and velocity can be determined accurately. The FMCW radar system may be provided with a frequency scanned antenna, the beamwidth determined by the processing circuitry is variable according to the size of the obstacle being detected or the range at which the radar is searching for obstacles. Instead of scanning the beam of the radar, the variation in frequency can be made to alter the beamwidth of the radar so that, for example, a car radar will detect only vehicles in the lane ahead of the car, regardless of the range of the vehicles.

대표청구항 ▼

A frequency modulated continuous wave radar system comprising an oscillator having a radar output signal arranged to provide ascending and descending frequency ramps, means for transmitting the radar output signal, means for receiving a reflected radar signal from obstacles and processing means resp

A frequency modulated continuous wave radar system comprising an oscillator having a radar output signal arranged to provide ascending and descending frequency ramps, means for transmitting the radar output signal, means for receiving a reflected radar signal from obstacles and processing means responsive to the radar output signal and the reflected radar signal, characterised in that the processing means comprises means for deriving a first pseudorange for each obstacle reflecting a signal during the ascending frequency ramps, means for deriving a second pseudorange for each obstacle reflecting a signal during the descending frequency ramps, means for determining a first velocity estimate for each obstacle from a plurality of first pseudoranges, means for determining a second velocity estimate for each obstacle from a plurality of second pseudoranges, means for deriving a first range estimate for each obstacle in response to a first pseudorange and the first velocity estimate, means for deriving a second range estimate for each obstacle in response to a second pseudorange and the second velocity estimate for each obstacle, means for determining which first range estimate and which second range estimate correspond to the same obstacle.