Abstract: An adjustable balanced modulator includes first and second non-linear devices. The first non-linear device receives an RF input signal and an in-phase LO signal to produce a first mixed signal. The second non-linear device receives the RF input signal and the out-of-phase LO signal to produce a second mixed signal. A summer sums the two mixed signals to produce an output signal including sum and difference product terms and a suppressed RF input term. The performance of the balanced modulator is improved by using an adjustable phase corrector and/or adjustable bias voltages. An adjustable phase corrector can be used to adjust the RF input signals to the non-linear devices to be substantially in-phase to more effectively suppress the original RF input signal in the output signal. Bias voltages can be used to bias the non-linear devices to operate in a linear range and to equalize the levels of the sum and difference product terms.

Abstract: The present invention provides an emergency vehicle command and control system for preemption of intersection traffic signals. Specifically, the system employs coded microwave transmissions from the emergency vehicle which are received by a scanned antenna array at the intersection and are processed to determine the direction-of-arrival of the signal. Each coded transmission received at the intersection is demodulated and error checked for validity. Valid transmissions are communicated to an intersection controller to preempt traffic signals. The system is also equipped to handle multiple vehicle arrivals and to transmit a coded signal to adjacent or orthogonal intersections to execute around-the-corner preemption control. Additionally, all preemption events may be stored in a memory for later retrieval and analysis.

Abstract: A radar system for sensing the presence of obstacles in a vehicle's "blind spots" and generating a signal to the vehicle operator indicative of the presence of such an obstacle. The system uses a common radar transceiver that transmits a multi-frequency radio signal directed at a blind spot of the vehicle. The signal is reflected off any obstacles that are present in that blind spot region. Doppler shifts in the received reflected multi-frequency signal generally indicates that an obstacle has moved into the blind spot. Doppler frequencies attributable to objects which are of no interest, such as stationary objects, are filtered out. The system has a signal processor which determines if a potentially hazardous object is within a pre-determined range from the vehicle.

Abstract: 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 provide a phase lock loop which tunes 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 three 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.

Abstract: A method and apparatus for evaluating a driver's performance under actual real-time conditions and for using such evaluations to determine the driver's ability to safely operate a vehicle compares the information gathered by a radar system and other sensors with information previously stored in an event recording device. Conditions monitored are used to make a determination as to whether the driver is performing in conformity with normal driving standards and the driver's own past performance. The driver's performance is constantly monitored and compared to that driver's past performance to determine whether the driver's present performance is impaired, and if so, whether the impairment is detrimental to the driver's ability to safely operate the vehicle.

Abstract: A vehicular collision avoidance radar system using digital signal processing techniques including a transmit section that generates a two channel transmit frequency. An antenna both transmits the transmit signal and receives a reflected receive signal. A Schottky diode mixer generates a difference signal having a frequency equal to the transmit frequency minus the receive frequency. A signal switch in a front end electronics section time demultiplexes and samples the channel 1 and channel 2 signals. The samples are coupled to a two-channel analog to digital (A/D) converter. A digital electronics section receives the digital information and performs a Fast Fourier Transform (FFT) on each channel of digital data to determine relative speed and range of a target based upon the frequency and the difference in phase of the two channels.