Abstract: A defective object such as a vehicle normally movable on a lane, assembly ne, or track is detected by a receiver on another object travelling behind the defective object, to avoid rear end collisions with the defective vehicle. For this purpose the vehicles are equipped with a signal receiver and with a signal damping member. The signal is transmitted in a transmission line extending along the lane, assembly line, or track. When a defect occurs, the damping member is moved into a position relative to the transmission line in which the damping member sufficiently dampens the signal so that the next following vehicle fails to receive the signal whereby a warning may be provided that the path ahead is not free or that it is blocked.

Abstract: The synchronism or tracking between two analog signals is compared by a cuit arrangement having two inputs to which these analog signals are applied. A comparator circuit compares the two signals and provides a trigger or energizing signal to a switch which in turn produces an error signal when the two compared signals deviate from each other to an extent larger than a predetermined limit. One input is connected to the comparator circuit through a heterodyning circuit wherein the respective analog signal is heterodyned by a heterodyning signal which varies in its polarity. The comparator circuit includes a polarity detector which provides a signal signifying a positive or a negative difference between the amplitudes of the two polarity signals. A discriminator circuit is operatively connected to the comparator to provide a switch energizing signal when the difference signal does not have any zero transitions or passages with the frequency of the heterodyning signal.

Abstract: A flat, high frequency cable having a number of longitudinal conductors, is provided with a transverse conductance between said longitudinal conductors. The transverse conductance is substantially smaller than the conductivity of said longitudinal conductors to provide a defined attenuation along the cable. The transverse conductance is determined by a plurality of discrete components such as resistors and capacitors electrically connected to said longitudinal conductors at spaced intervals. The present cable may comprise two or three conductors.