Abstract: A device for protecting a fifth wheel in case the vehicle to which it is attached spins out or backs up for a considerable distance. The device comprises a pair of rods which project rearwardly and downwardly from the bracket mounted on the vehicle; when the vehicle backs up or spins out and the fifth wheel is moved through a horizontal arc toward the rear of the vehicle, its tongue rides up onto one of the rods and is lifted off the ground. When it is out of contact with the ground it can no longer be moved toward the vehicle.

Abstract: A digital Moving Target Indicator (MTI) radar system for rejection of low velocity "clutter" by utilizing techniques to identify those radar echo returns from targets having radial velocities lower than fixed predetermined values. For digital MTI radars that have a response which is a periodic function of the radar's Pulse Repetition Frequency (PRF) and doppler frequency shift of the received radar signal relationships exist whereby (a) optimum target velocities which correspond to the maximum canceler gain can be calculated from the radar's PRF; (b) the canceler response can be expressed in terms of a periodic canceler response function which incorporates the ratio of the actual target velocity to the optimum target velocity; and, (c) the output amplitude from the canceler can be determined from the input amplitude to the canceler produced by the MTI receiver's coherent phase detector and the periodic canceler response function.