Data processing: measuring – calibrating – or testing – Measurement system – Speed
Reexamination Certificate
1999-07-16
2001-07-24
Shah, Kamini (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Speed
C702S149000, C702S150000, C342S107000, C342S109000, C340S936000, C340S937000
Reexamination Certificate
active
06266627
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The invention relates co a method for measuring the speed of a vehicle by transmitting a wave beam directed at the vehicle, receiving a part of the wave beam reflected by the vehicle, comparing the reflected beam part with the transmitted wave beam and deriving from this comparison the speed of the vehicle. Such a method is generally known and is frequently used by police in the form of radar speed measurements.
2) Description of the Prior Art
In the known method a radar beam is transmitted at an acute angle to a road axis from a fixed, generally concealed position along the road. When a vehicle passes through the beam a part of the beam is reflected. This reflected part is received at the measuring point and the frequency of the reflected beam is compared with the (exact) frequency of the transmitted beam. Because the beam is reflected by a moving vehicle it will undergo, as a result of the Doppler effect, a frequency change which is a measure for both the speed of movement and the direction of movement of the vehicle. When it is found from the comparison of the transmitted and received frequency that the speed of the vehicle exceeds the maximum allowed speed at that location a warning signal is generated. This signal is generally used to activate a camera whereby a recording is made of the vehicle committing the speeding offence. This recording then also shows the relevant data such as date and time of the recording and the measured speed.
Problems occur in the known method when it is applied on roads with a number of traffic lanes, such as motorways. Here several vehicles may pass through the measuring beam simultaneously. If one of these vehicles commits a speeding offence it is often not possible to determine indisputably which vehicle this was. When the speed measurement is combined with making a recording, complicated and time-consuming processing of the recording is required in order to determine the offender therefrom on the basis of secondary indications.
SUMMARY OF THE INVENTION
The invention now has for its object to provide a method of the above described type, wherein this drawback does not occur. This is achieved according to the invention in that during the speed measurement the position of the vehicle is determined. By determining not only the speed but simultaneously also the position of the vehicle, it is still possible to identify with certainty the vehicle which committed the offence, also when a number of vehicles passes through the beam.
An efficient manner of position determination is achieved when the position of the vehicle, as well as the speed thereof, is determined by comparing the reflected beam part with the transmitted wave beam. The speed of the vehicle can advantageously be determined from a difference in wavelength detected during the comparison between the reflected beam part and the transmitted wave beam, and the position of the vehicle can be determined from a time lag detected during the comparison between the moment of transmitting and the moment of receiving the reflected beam part. Both the speed and the position of the vehicle are thus determined with a single measurement. It will further be apparent that instead of the difference in wavelength the frequency change which after all is associated therewith could also be measured.
The wave beam is preferably transmitted in pulse form. By using separate wave pulses the time which has lapsed between the moment of transmission and the moment of reception can be determined unequivocally.
When during the speed measurement the direction of travel of the vehicle is also determined, even more certainty is obtained concerning the identity of the offending vehicle.
The wave beam is preferably transmitted at an acute angle to the direction of movement of the vehicle. A reliable measurement is thus obtained which can be performed from a concealed position.
The invention also relates to an apparatus for performing the above described method. According to the invention such an apparatus, which is provided with means for generating and transmitting a directed wave beam, means for receiving a part of the wave beam reflected by a vehicle and means for comparing the reflected beam part with the transmitted beam and deriving the speed of the vehicle from this comparison, is characterized by means for determining the position of the vehicle during the speed measurement.
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Elterich, A. “Vergleich unterschiedlicher mehrzielfähiger Radarverfahren zur Bestimmung von Geschwindigkeit und Entferrung im Nahbereich”, Kleinheubacher Berichte, vol. 35, pp. 731-740.
Bui Bryan
Shah Kamini
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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