Abstract: A pseudo-random measuring signal whose spectrum is constituted by lines of predetermined frequencies spaced apart from each other is applied to a system to be characterized, and one or, successively and one by one, a plurality of lines of the spectrum of the measuring signal are selected for making a comparison in phase and amplitude between the input and the output of the system; for a non-linear system, one or, successively and one by one, a plurality of lines of the spectrum of the measuring signal are eliminated at the input of the system, and the phase and/or amplitude of the corresponding line is measured at the output of the system.

Abstract: An anti-theft device for an automotive vehicle includes a lock and key housed separately and remote from a bolt and its actuating mechanism. The bolt portion is located in an inaccessible housing and connected to the lock by means of a burglar-proof connection. The electronic lock arrangement employed permits of a large number of combinations and thereby increases the security of the anti-theft device. By placing the bolt in an inaccessible housing, direct tampering with the locking bolt is precluded.