Pre-recorded magnetic video tape having an information code on the synchronization track

Abstract

Abstract A method for transferring an information code onto the synchronization track of a video tape is described. The code is recorded during intervals between synch pulses by adding code pulses of the same magnetization as the recorded synch pulses to the synchronization track. The code pulses, at least in part, overlap the synch pulses with the length of the code pulses representing binary values. With this technique, an erasure of pre-recorded synch pulses is not required. A recording device is used that contains a generator of code pulses and at least two timing elements which are set when a synch signal is produced in response to a detected synch pulse. One of the timing elements operates a mode changeover switch and the other activates the code pulse generator. A reading device is used and contains two threshold detectors which detect two synch signals, representative of the beginning and end of the recorded synch signals. At least one timing element is started at the beginning of the synch signal. A code evaluation circuit is used to determine if the end of the synch signal appeared during the running period of the latter timing element or after it. A pre-recorded video tape carries twice-magnetized sections on its synchronization track. Each such section has a length at most about that of the synch pulse recording and is followed by a once-magnetized having one of two different lengths, both preferably being shorter than the synch pulse recording itself.

Inventors

• 👤 Peter Roggendorf

Bibliographic Details