Communications: directive radio wave systems and devices (e.g. – Determining velocity
Reexamination Certificate
2001-11-19
2002-10-08
Sotomayor, John B. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Determining velocity
C342S114000, C342S115000, C342S116000
Reexamination Certificate
active
06462702
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to a Doppler-based traffic radar system and, more particularly to a radar system and related method for determining the speed of target vehicles independent of the direction of the target vehicles relative to a patrol vehicle supporting the radar system.
BACKGROUND OF THE INVENTION
Law enforcement officers have utilized Doppler-based traffic radar systems to monitor vehicle speeds and enforce traffic speed limit laws for many years. Throughout this period of time, numerous improvements in both the underlying technology and in the specific application of new processing techniques for the traffic radar systems themselves, have afforded law enforcement officers greater flexibility and improved reliability in carrying out their duties. One such improvement evident in most traffic radar systems presently being marketed includes the capability to more accurately and reliably monitor the speed of certain vehicles while the patrol vehicle is either in a stationary or a moving mode of operation. In fact, the most recent traffic radar systems can now successfully monitor the speed of vehicles approaching the moving patrol vehicle in an opposite lane.
In addition to these capabilities, such radar systems also provide the law enforcement officer the capability to monitor a group of target vehicles simultaneously and to determine the fastest vehicle within the group and/or the vehicle presenting the traditional strongest reflected return signal. Importantly, each of these new or improved capabilities provide the law enforcement officer with a more complete picture of the traffic environment and thus, a more flexible and reliable basis for making more informed decisions.
Despite all the improvements in both the underlying technology utilized in these traffic radar systems and the radar systems themselves, however, a broadly recognized shortcoming of these systems involves the successful monitoring of the speed of vehicles approaching or receding away from the patrol vehicle in the same-lane moving mode without operator intervention. In practice, even the most recent traffic radar systems require the law enforcement officer to make an initial discretionary decision regarding the relative movement of a target vehicle operating in the same lane as the patrol vehicle.
In other words, the law enforcement officer must visually observe the target vehicle in front of or behind the patrol vehicle and decide whether the vehicle is approaching or receding relative to the patrol vehicle. Of course, these manual operations are conducted while also maintaining operation of the patrol vehicle. Additionally, the officer must continually update this information by manually inputting it into the radar system. Typically, a two-position manual switch located adjacent a display or a handheld remote control device of the radar system is utilized to dictate the approaching/receding status of the target vehicle and to indicate the requisite method of calculation to be utilized by the radar system in determining the speed of the target vehicle. These discretionary decisions and required manual operations contribute to the curtailment of the overall flexibility and reliability afforded law enforcement officers by both conventional and digital signal processing (DSP) capable radar systems.
Thus, while conventional and DSP traffic radar systems are both capable of a high degree of accuracy with regard to vehicle speed measurements, great care must be exercised in the use of such systems in properly and accurately attributing a speed to a particular target vehicle. This is of increased importance when monitoring the speed of vehicles approaching or receding away from the patrol vehicle in the same-lane when the law enforcement officer must initially visually observe and determine the direction of the target vehicle relative to the patrol vehicle.
Yet another broadly recognized shortcoming of these traffic radar systems includes the inability to accurately monitor the speeds of vehicles approaching or receding away from the patrol vehicle in the stationary mode of operation. Typically to overcome this shortcoming, the patrol vehicle must position itself between the driving lanes; for example, within the median area along interstates or other divided highways. This effectively eliminates the unwanted approaching or receding targets from the beam of the radar system, thus improving the accuracy and reliability afforded the law enforcement officer. The requirement that the patrol vehicle be located in a particular manner, however, severely limits the overall effectiveness of the radar system.
One alternative to establishing a monitoring position within the median of divided roadways presently available to law enforcement officers is to position the patrol vehicle on the shoulder of the roadway parallel to the highway. This alternative is satisfactory in some settings, particularly along isolated, low volume highways but is of only limited value along the busier and more frequently patrolled highways, such as main traffic arteries. When monitoring vehicle speeds along these highways, the law enforcement officer is forced to wait for openings or gaps in the traffic pattern before utilizing the radar system to determine the speed of approaching/receding opposing lane vehicles. This is due to the potential interference in the radar system processing created by intervening vehicles traveling in the same lane in which the patrol vehicle is positioned.
Accordingly, a need is clearly identified for a radar system and related methods capable of determining the actual speed of selected target vehicles traveling in the same lane as the moving patrol vehicle, or in a different lane than the stationary patrol vehicle. Such a radar system and related methods would effectively remove the reliance on discretionary decisions made by law enforcement officers in determining the relative direction of target vehicles operating in the same lane as the patrol vehicle, and would further increase the overall flexibility and reliability afforded the system operator, particularly in monitoring traffic across busy divided highways.
SUMMARY OF THE INVENTION
A Doppler-based traffic radar system is provided that increases the overall flexibility and reliability afforded the system operator, and most importantly eliminates the reliance on discretionary decision making. More specifically, the radar system of the present invention is adapted to determine the speed of at least one moving target traveling in generally the same direction as a platform supporting the radar system independent of the direction of the at least one target relative to the platform. This allows the speed of target vehicles traveling in the same lane and in the same direction as the patrol vehicle to be monitored without manual intervention by the operator. The radar system is further adapted in a stationary mode of operation to determine the speed of a selected moving target independent of the location of the patrol vehicle. This is accomplished in part by selectively eliminating all unwanted approaching or receding targets depending upon the present traffic/patrol scenario.
The radar system of the present invention splits the return signals reflected from the at least one moving target in order to form a test processing signal and a reference processing signal. More specifically, the return signals received from an antenna are split in a turnstile, thus generating first and second split signals. The split signals are substantially equivalent both containing information about the at least one target. A mixer within the turnstile mixes the first split signal with a first portion of the transmitted signal to form a test processing signal. Likewise, the second split signal is mixed with a second portion of the transmitted signal to form a reference processing signal.
Any suitable means may be used to insure that the first and second portions of the transmitted signal, and thus the resultant processing signals, are different in ph
King & Schickli PLLC
MPH Industries, Inc.
Sotomayor John B.
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