Abstract: In an automatic speed monitoring system of the type in which data is incorporated into a photograph of a vehicle, security of the data is provided through the addition of redundant information to the recorded data. The data is processed to derive an alphanumeric test symbol that is based on the data symbols. This test symbol is recorded along with the data. In subsequent validation of the data, the data is processed in the same manner to derive a symbol, and this symbol is compared with the recorded test symbol to determine the correctness of the recorded data.

Abstract: A distance measuring apparatus based on a time-of-flight measurement of a light pulse is provided. The apparatus includes a light pulse transmitter having a diode laser and a light pulse receiver having a photodiode. Connected to the photodiode is a pulse amplifier and a pulse detector. The pulse detector includes a delay line connected to the pulse amplifier and having a short-circuited end, a threshold valve and zero crossing detector connected to the delay line at a predetermined distance from its short-circuited end, and a timer circuit. The delay line conducts an electrical pulse from the pulse amplifier to its short-circuited end where the pulse is reflected and inverted. The threshold value and zero crossing detector determines when a combination of the electrical pulse and its inverted copy crosses a threshold value and a zero value.

Abstract: The invention relates to a method and apparatus for measuring the velocity of a moving object. Measuring beams composed of sequences of optical pulses are directed towards the object which is to be measured and follow such object. Based upon transit time measurements of reflected pulses there are formed distance values and distance difference values. While taking into account the time interval of the pulse sequence there are computed velocity measuring values and velocity values computed from homogeneous groups of values are displayed as reliable velocity values.