초록 ▼

A Doppler control circuit for a CW or pulse Doppler radar system for monitoring not only the phase shift between echo signals from several targets but also the amplitude difference between the several targets and to further tune the radar to a particular target among one or more targets from which e

A Doppler control circuit for a CW or pulse Doppler radar system for monitoring not only the phase shift between echo signals from several targets but also the amplitude difference between the several targets and to further tune the radar to a particular target among one or more targets from which echo signals return. The control circuit can be used in state of the art CW or pulse Doppler type radar systems. In a further system, a continuously generated radar signal is repeatedly transmitted at different frequencies in time division fashion to define a succession of transmit and receive frames. The receive frames are divided into a plurality of time interval windows with selected windows being used to detect received signals at the different frequencies. The remaining windows can be used for subsystems of the radar system. The rate of phase shift of received signals at a reference frequency is used to determine closing rate (positive or negative), while the phase shift difference between received signals at two frequencies is used to determine range and target direction. A target persistence and environment filter prevents the radar system from giving false alarms due to short duration target echoes resulting from birds or wayside objects.

대표청구항 ▼

In an automotive collision avoidance system in a vehicle having a Doppler radar system with means for successively transmitting a radar beam at a plurality of successive intervals and for receiving echo signals corresponding to the plurality of successive intervals from at least one target within th

In an automotive collision avoidance system in a vehicle having a Doppler radar system with means for successively transmitting a radar beam at a plurality of successive intervals and for receiving echo signals corresponding to the plurality of successive intervals from at least one target within the radar beam, a target persistence and environment filter comprising: a. means for receiving a first and a second echo signal from at least one target, and for generating a signal indicative of the relative phase difference between the first and the second received echo signals, such relative phase difference corresponding to a change in relative distance of such at least one target with respect to the vehicle, the generated signal having a first value when such relative distance is decreasing and a second value when such relative distance is increasing; b. persistence determination means, coupled to the generated signal, and including a programmable time delay means for determining a time period in accordance with a programmed value, for generating an output signal having a first value if the generated signal has its first value for the time period determined by the programmed value of the time delay means, and having a second value if the generated signal has its second value during the time period determined by the programmed value of the time delay means; c. speed determination means, for determining the speed of the vehicle; and d. programming means, coupled to the persistance determination means and to the speed determination means, for programming the time delay means with a value whereby the duratin of the time period is proportional to the speed of the vehicle.