Abstract: The distance of a target object is determined from the time of travel of a measuring light pulse which is emitted by a transmitter toward the target object, reflected thereby and received by a receiver. In timed relation with the instant of generation of the measuring light pulse, a start signal for beginning a measuring signal transit time measurement is generated, and, on receipt of the reflected measuring light pulse, a stop signal is generated for terminating this time measurement. A completely independent reference light pulse is generated and forwarded along a reference light path establishing a predetermined time of travel from the transmitter to the receiver, and the respective reference signal transit time is measured which contains the same undesirable additional time spans contained in the measured transit time of the measuring signal.

Abstract: The invention provides a method and an apparatus for determining the difference between the transit times of measuring pulse signals from a transmitter to a receiver along a measuring signal path establishing an unknown time of travel which is representative for a physical quantity of interest, and the transit times of reference pulse signals generated by the same transmitter and forwarded to the same receiver along a reference signal path establishing a known, constant time of travel, whereby for the measurement of each of said transit times the time distance between a trigger signal triggering the generation of the respective measuring pulse or reference pulse signal and a time-significant signal is measured which is generated in a defined time relation to the instant at which the respective pulse signal is received by said receiver.

Abstract: An apparatus measures the distance of a target by measuring the time of travel of a light pulse from the measuring apparatus to the target and back wherein it is important to achieve high accuracy in timing to correlate, for a distant target, the time of transmission with the start of measuring the time of travel and the time of receiving a reflected light pulse and the end of the time measurement. For a near target, the start of distance measurement is correlated with receipt of a reflected measuring light pulse and a stop signal is correlated with a delayed reference light pulse. For this purpose a reference light pulse is branched off from a measuring light pulse and passed by light guides to a single receiver unit. The reference light pulse is passed to the receiver unit either through a short or a long light path depending on whether the target is distant or near, respectively.

Abstract: The invention provides a distance measuring apparatus for determining the distance of a target object as a function of the transit time of a measurement light pulse which is emitted by a transmitter in the transmission portion of the apparatus towards the target object, reflected thereby and received by the receiving portion of the measuring apparatus and for attainment of superior measurement accuracy the intensity of the measurement light pulse is correlated to the distance and reflectivity of the target object as well as to the "transparency" of the transmission medium between the measuring apparatus and the target object, such correlation being effected by optical damping of either the transmitted light pulses and/or the reference light pulse and/or the light pulses reflected by the target.

Abstract: A measuring cable with spaced measuring stations is laid. The measuring stations each have a sensor whose electrical conductivity depends on an ambient variable such as temperatures light etc., each sensor is provided with a control arrangement which, due to a transmitted signal from a control center, connects its sensor to a constant current source and returns a signal indicative of any voltage change dependent on the variable ambient which signal is measured by the control center. The measuring cable is divided into sections each having a selectable circuit which can be selected individually by the control center. A clock pulse signal is transmitted to all measuring stations but is only active for the cable section which has been selected. In this manner, the cable section can be chosen as desired, the time required for the control center to have access to certain measuring stations is shortened and semiconductor switches can be used because measurements are only made in the steady state.

Abstract: A time duration is measured precisely and with high resolution by making three time measurements as shown in FIG. 5. The time difference t.sub.A between the leading edge of a start signal and the next following leading edge of a constant frequency time base signal is measured. The number "n" of the following leading edges is then counted including the leading edge of the time base signal following a stop signal. The number n is multiplied by the period T.sub.Q of the time signal. The time difference t.sub.E between the leading edge of the stop signal and the next following leading edge of the time base signal is measured. The real time difference .DELTA.t is then calculated as follows .DELTA.t=t.sub.A +n.multidot.T.sub.Q -t.sub.E. A three part real time measurement is performed to correct the calculated result for drift and aging. Calibration measurements are made and the respective calibration factors are used in calculating the final results.

Abstract: The distance between a target and a measuring point is measured by optical and electronic elements forming an opto-electronic circuit arrangement wherein a light beam is modulated by a first frequency signal. The light beam is divided to produce a measuring beam and a reference beam. The measuring beam as reflected from the target and the reference beam are supplied through a single light scanner to a light sensitive detector in accordance with a predetermined scanning or sequencing function. The output signal of the detector and a second frequency signal are supplied to a mixing stage to form an intermediate frequency signal. A digital counter receives a start counting signal coinciding with the receipt of the the reference beam and a stop counting signal coinciding with the return of the reflected beam.

Abstract: The present apparatus measures distance with the aid of a laser beam. A reference channel provides a signal in response to the emission of a laser beam. A measuring channel provides a stop signal. Both channels are substantially identical and each includes an input circuit with a light sensitive diode having a barrier layer capacity. The input circuit is so arranged that the barrier layer capacity is connected in parallel to a parallel resonance circuit which is triggered by its respective light sensitive diode to generate a damped sine wave. In the reference channel the first passage through zero of the damped sine wave is detected. In the measuring channel the second passage through zero of the damped sine wave is detected. Thus, the time significant impulse flanks are precisely determined.

Abstract: The present distance measuring laser apparatus measures the delayed time occurring between two signals derived from a laser beam and a reflected light beam and received in two separate channels. One channel is the reference channel and provides a starting signal when a light signal is emitted by the laser. The other channel is the measuring channel and provides a stop signal at the time of the return of a reflected light beam. An identical input circuit is provided in each signal channel. The receiver input rectifier or diode of each input circuit has a working impedance including a parallel resonance circuit made up of the barrier layer capacity of the diode, of an inductance coil and a further, external capacity.